Merge "linker: simpler encoding for SHT_RELR sections."
diff --git a/docs/status.md b/docs/status.md
index d4ca913..8cef5b7 100644
--- a/docs/status.md
+++ b/docs/status.md
@@ -48,10 +48,12 @@
   * `hcreate`/`hcreate_r`/`hdestroy`/`hdestroy_r`/`hsearch`/`hsearch_r` (completing <search.h>)
   * `iconv`/`iconv_close`/`iconv_open` (adding <iconv.h>)
   * `pthread_attr_getinheritsched`/`pthread_attr_setinheritsched`/`pthread_setschedprio`
+  * `pthread_mutexattr_getprotocol`/`pthread_mutexattr_setprotocol` (mutex priority inheritance)
   * <spawn.h>
   * `swab`
   * `syncfs`
-  * %C and %S support in the printf family (previously only the wprintf family supported these).
+  * `%C` and `%S` support in the printf family (previously only the wprintf family supported these).
+  * `%mc`/`%ms`/`%m[` support in the scanf family.
 
 New libc functions in O:
   * `sendto` FORTIFY support
diff --git a/libc/bionic/abort.cpp b/libc/bionic/abort.cpp
index f401cab..9f1c31f 100644
--- a/libc/bionic/abort.cpp
+++ b/libc/bionic/abort.cpp
@@ -32,6 +32,8 @@
 #include <sys/syscall.h>
 #include <unistd.h>
 
+#include "private/kernel_sigset_t.h"
+
 // We call tgkill(2) directly instead of raise (or even the libc tgkill wrapper), to reduce the
 // number of uninteresting stack frames at the top of a crash.
 static inline __always_inline void inline_tgkill(pid_t pid, pid_t tid, int sig) {
@@ -60,10 +62,10 @@
 
   // Don't block SIGABRT to give any signal handler a chance; we ignore
   // any errors -- X311J doesn't allow abort to return anyway.
-  sigset_t mask;
-  sigfillset(&mask);
-  sigdelset(&mask, SIGABRT);
-  sigprocmask(SIG_SETMASK, &mask, NULL);
+  kernel_sigset_t mask;
+  mask.fill();
+  mask.clear(SIGABRT);
+  __rt_sigprocmask(SIG_SETMASK, &mask, nullptr, sizeof(mask));
 
   inline_tgkill(pid, tid, SIGABRT);
 
@@ -74,7 +76,7 @@
   sa.sa_flags   = SA_RESTART;
   sigemptyset(&sa.sa_mask);
   sigaction(SIGABRT, &sa, &sa);
-  sigprocmask(SIG_SETMASK, &mask, NULL);
+  __rt_sigprocmask(SIG_SETMASK, &mask, nullptr, sizeof(mask));
 
   inline_tgkill(pid, tid, SIGABRT);
 
diff --git a/libc/bionic/pause.cpp b/libc/bionic/pause.cpp
index 94a16fb..2a0779a 100644
--- a/libc/bionic/pause.cpp
+++ b/libc/bionic/pause.cpp
@@ -30,13 +30,8 @@
 
 #include "private/kernel_sigset_t.h"
 
-extern "C" int __rt_sigprocmask(int, const kernel_sigset_t*, kernel_sigset_t*, size_t);
-extern "C" int __rt_sigsuspend(const kernel_sigset_t*, size_t);
-
 int pause() {
   kernel_sigset_t mask;
-  if (__rt_sigprocmask(SIG_SETMASK, NULL, &mask, sizeof(mask)) == -1) {
-    return -1;
-  }
+  if (__rt_sigprocmask(SIG_SETMASK, nullptr, &mask, sizeof(mask)) == -1) return -1;
   return __rt_sigsuspend(&mask, sizeof(mask));
 }
diff --git a/libc/bionic/posix_timers.cpp b/libc/bionic/posix_timers.cpp
index c46965f..e3bb112 100644
--- a/libc/bionic/posix_timers.cpp
+++ b/libc/bionic/posix_timers.cpp
@@ -74,8 +74,7 @@
 static void* __timer_thread_start(void* arg) {
   PosixTimer* timer = reinterpret_cast<PosixTimer*>(arg);
 
-  kernel_sigset_t sigset;
-  sigaddset(sigset.get(), TIMER_SIGNAL);
+  kernel_sigset_t sigset{TIMER_SIGNAL};
 
   while (true) {
     // Wait for a signal...
@@ -150,14 +149,13 @@
 
   // We start the thread with TIMER_SIGNAL blocked by blocking the signal here and letting it
   // inherit. If it tried to block the signal itself, there would be a race.
-  kernel_sigset_t sigset;
-  sigaddset(sigset.get(), TIMER_SIGNAL);
+  kernel_sigset_t sigset{TIMER_SIGNAL};
   kernel_sigset_t old_sigset;
-  pthread_sigmask(SIG_BLOCK, sigset.get(), old_sigset.get());
+  __rt_sigprocmask(SIG_BLOCK, &sigset, &old_sigset, sizeof(sigset));
 
   int rc = pthread_create(&timer->callback_thread, &thread_attributes, __timer_thread_start, timer);
 
-  pthread_sigmask(SIG_SETMASK, old_sigset.get(), NULL);
+  __rt_sigprocmask(SIG_SETMASK, &old_sigset, nullptr, sizeof(sigset));
 
   if (rc != 0) {
     free(timer);
diff --git a/libc/bionic/pthread_exit.cpp b/libc/bionic/pthread_exit.cpp
index 8b4c44e..f1b65fd 100644
--- a/libc/bionic/pthread_exit.cpp
+++ b/libc/bionic/pthread_exit.cpp
@@ -34,6 +34,7 @@
 #include <sys/mman.h>
 
 #include "private/bionic_defs.h"
+#include "private/ScopedSignalBlocker.h"
 #include "pthread_internal.h"
 
 extern "C" __noreturn void _exit_with_stack_teardown(void*, size_t);
@@ -63,6 +64,12 @@
   }
 }
 
+static void __pthread_unmap_tls(pthread_internal_t* thread) {
+  // Unmap the bionic TLS, including guard pages.
+  void* allocation = reinterpret_cast<char*>(thread->bionic_tls) - PTHREAD_GUARD_SIZE;
+  munmap(allocation, BIONIC_TLS_SIZE + 2 * PTHREAD_GUARD_SIZE);
+}
+
 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
 void pthread_exit(void* return_value) {
   // Call dtors for thread_local objects first.
@@ -96,10 +103,6 @@
     thread->alternate_signal_stack = NULL;
   }
 
-  // Unmap the bionic TLS, including guard pages.
-  void* allocation = reinterpret_cast<char*>(thread->bionic_tls) - PTHREAD_GUARD_SIZE;
-  munmap(allocation, BIONIC_TLS_SIZE + 2 * PTHREAD_GUARD_SIZE);
-
   ThreadJoinState old_state = THREAD_NOT_JOINED;
   while (old_state == THREAD_NOT_JOINED &&
          !atomic_compare_exchange_weak(&thread->join_state, &old_state, THREAD_EXITED_NOT_JOINED)) {
@@ -120,16 +123,15 @@
       // That's not something we can do in C.
 
       // We don't want to take a signal after we've unmapped the stack.
-      // That's one last thing we can handle in C.
-      sigset_t mask;
-      sigfillset(&mask);
-      sigprocmask(SIG_SETMASK, &mask, NULL);
-
+      // That's one last thing we can do before dropping to assembler.
+      ScopedSignalBlocker ssb;
+      __pthread_unmap_tls(thread);
       _exit_with_stack_teardown(thread->attr.stack_base, thread->mmap_size);
     }
   }
 
   // No need to free mapped space. Either there was no space mapped, or it is left for
   // the pthread_join caller to clean up.
+  __pthread_unmap_tls(thread);
   __exit(0);
 }
diff --git a/libc/bionic/sigblock.c b/libc/bionic/sigblock.c
index 176bc13..cc47d5d 100644
--- a/libc/bionic/sigblock.c
+++ b/libc/bionic/sigblock.c
@@ -25,26 +25,18 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #include <signal.h>
 
-/* this function is called from the ARM assembly setjmp fragments */
-int
-sigblock(int mask)
-{
-    int  n;
-    union {
-        int       the_mask;
-        sigset_t  the_sigset;
-    } in, out;
+int sigblock(int mask) {
+  union {
+    int mask;
+    sigset_t set;
+  } in, out;
 
-    sigemptyset(&in.the_sigset);
-    in.the_mask = mask;
+  sigemptyset(&in.set);
+  in.mask = mask;
 
-    n = sigprocmask(SIG_BLOCK, &in.the_sigset, &out.the_sigset);
-    if (n)
-        return n;
-
-    return out.the_mask;
+  if (sigprocmask(SIG_BLOCK, &in.set, &out.set) == -1) return -1;
+  return out.mask;
 }
-
-
diff --git a/libc/bionic/sighold.cpp b/libc/bionic/sighold.cpp
index e9c8ca1..2800d10 100644
--- a/libc/bionic/sighold.cpp
+++ b/libc/bionic/sighold.cpp
@@ -28,9 +28,11 @@
 
 #include <signal.h>
 
+#include "private/kernel_sigset_t.h"
+
 int sighold(int sig) {
-  sigset_t set;
-  if (sigemptyset(&set) == -1) return -1;
-  if (sigaddset(&set, sig) == -1) return -1;
-  return sigprocmask(SIG_BLOCK, &set, nullptr);
+  kernel_sigset_t set;
+  set.clear();
+  if (!set.set(sig)) return -1;
+  return __rt_sigprocmask(SIG_BLOCK, &set, nullptr, sizeof(set));
 }
diff --git a/libc/bionic/sigpause.cpp b/libc/bionic/sigpause.cpp
index 8ba42d4..6b5d74a 100644
--- a/libc/bionic/sigpause.cpp
+++ b/libc/bionic/sigpause.cpp
@@ -28,9 +28,12 @@
 
 #include <signal.h>
 
+#include "private/kernel_sigset_t.h"
+
 int sigpause(int sig) {
-  sigset_t set;
-  if (sigprocmask(SIG_SETMASK, nullptr, &set) == -1) return -1;
-  if (sigdelset(&set, sig) == -1) return -1;
-  return sigsuspend(&set);
+  kernel_sigset_t set;
+  set.clear();
+  if (__rt_sigprocmask(SIG_SETMASK, nullptr, &set, sizeof(set)) == -1) return -1;
+  if (!set.clear(sig)) return -1;
+  return __rt_sigsuspend(&set, sizeof(set));
 }
diff --git a/libc/bionic/sigpending.cpp b/libc/bionic/sigpending.cpp
index b6e503c..8a02de6 100644
--- a/libc/bionic/sigpending.cpp
+++ b/libc/bionic/sigpending.cpp
@@ -30,8 +30,6 @@
 
 #include "private/kernel_sigset_t.h"
 
-extern "C" int __rt_sigpending(const kernel_sigset_t*, size_t);
-
 int sigpending(sigset_t* bionic_set) {
   kernel_sigset_t set;
   int result = __rt_sigpending(&set, sizeof(set));
diff --git a/libc/bionic/sigprocmask.cpp b/libc/bionic/sigprocmask.cpp
index 61e2c63..c34e42e 100644
--- a/libc/bionic/sigprocmask.cpp
+++ b/libc/bionic/sigprocmask.cpp
@@ -32,8 +32,6 @@
 
 #include "private/kernel_sigset_t.h"
 
-extern "C" int __rt_sigprocmask(int, const kernel_sigset_t*, kernel_sigset_t*, size_t);
-
 int sigprocmask(int how, const sigset_t* bionic_new_set, sigset_t* bionic_old_set) {
   kernel_sigset_t new_set;
   kernel_sigset_t* new_set_ptr = NULL;
diff --git a/libc/bionic/sigrelse.cpp b/libc/bionic/sigrelse.cpp
index ab5554e..c4a484a 100644
--- a/libc/bionic/sigrelse.cpp
+++ b/libc/bionic/sigrelse.cpp
@@ -28,9 +28,11 @@
 
 #include <signal.h>
 
+#include "private/kernel_sigset_t.h"
+
 int sigrelse(int sig) {
-  sigset_t set;
-  if (sigemptyset(&set) == -1) return -1;
-  if (sigaddset(&set, sig) == -1) return -1;
-  return sigprocmask(SIG_UNBLOCK, &set, nullptr);
+  kernel_sigset_t set;
+  set.clear();
+  if (!set.set(sig)) return -1;
+  return __rt_sigprocmask(SIG_UNBLOCK, &set, nullptr, sizeof(set));
 }
diff --git a/libc/bionic/sigset.cpp b/libc/bionic/sigset.cpp
index e3f3e72..52820f2 100644
--- a/libc/bionic/sigset.cpp
+++ b/libc/bionic/sigset.cpp
@@ -29,6 +29,8 @@
 #include <signal.h>
 #include <string.h>
 
+#include "private/kernel_sigset_t.h"
+
 sighandler_t sigset(int sig, sighandler_t disp) {
   struct sigaction new_sa;
   if (disp != SIG_HOLD) {
@@ -38,19 +40,16 @@
   }
 
   struct sigaction old_sa;
-  if (sigaction(sig, disp == SIG_HOLD ? nullptr : &new_sa, &old_sa) == -1) {
+  if (sigaction(sig, (disp == SIG_HOLD) ? nullptr : &new_sa, &old_sa) == -1) {
     return SIG_ERR;
   }
 
-  sigset_t new_proc_mask;
-  sigemptyset(&new_proc_mask);
-  sigaddset(&new_proc_mask, sig);
-
-  sigset_t old_proc_mask;
-  if (sigprocmask(disp == SIG_HOLD ? SIG_BLOCK : SIG_UNBLOCK,
-                  &new_proc_mask, &old_proc_mask) == -1) {
+  kernel_sigset_t new_mask{sig};
+  kernel_sigset_t old_mask;
+  if (__rt_sigprocmask(disp == SIG_HOLD ? SIG_BLOCK : SIG_UNBLOCK, &new_mask, &old_mask,
+                       sizeof(new_mask)) == -1) {
     return SIG_ERR;
   }
 
-  return sigismember(&old_proc_mask, sig) ? SIG_HOLD : old_sa.sa_handler;
+  return old_mask.is_set(sig) ? SIG_HOLD : old_sa.sa_handler;
 }
diff --git a/libc/bionic/sigsetmask.c b/libc/bionic/sigsetmask.c
index 7842bf1..6a3b1d2 100644
--- a/libc/bionic/sigsetmask.c
+++ b/libc/bionic/sigsetmask.c
@@ -25,26 +25,18 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #include <signal.h>
 
-/* called from setjmp assembly fragment */
-int
-sigsetmask(int mask)
-{
-    int  n;
+int sigsetmask(int mask) {
+  union {
+    int mask;
+    sigset_t set;
+  } in, out;
 
-    union {
-        int       the_mask;
-        sigset_t  the_sigset;
-    } in, out;
+  sigemptyset(&in.set);
+  in.mask = mask;
 
-    sigemptyset(&in.the_sigset);
-    in.the_mask = mask;
-
-    n = sigprocmask(SIG_SETMASK, &in.the_sigset, &out.the_sigset);
-    if (n)
-        return n;
-
-    return out.the_mask;
+  if (sigprocmask(SIG_SETMASK, &in.set, &out.set) == -1) return -1;
+  return out.mask;
 }
-
diff --git a/libc/bionic/sigsuspend.cpp b/libc/bionic/sigsuspend.cpp
index fb846b8..1d89d4f 100644
--- a/libc/bionic/sigsuspend.cpp
+++ b/libc/bionic/sigsuspend.cpp
@@ -30,8 +30,6 @@
 
 #include "private/kernel_sigset_t.h"
 
-extern "C" int __rt_sigsuspend(const kernel_sigset_t*, size_t);
-
 int sigsuspend(const sigset_t* bionic_set) {
   kernel_sigset_t set(bionic_set);
   return __rt_sigsuspend(&set, sizeof(set));
diff --git a/libc/include/android/dlext.h b/libc/include/android/dlext.h
index c824544..2b4169e 100644
--- a/libc/include/android/dlext.h
+++ b/libc/include/android/dlext.h
@@ -23,88 +23,116 @@
 #include <sys/cdefs.h>
 #include <sys/types.h>  /* for off64_t */
 
+/**
+ * \file
+ * Advanced dynamic library opening support. Most users will want to use
+ * the standard [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html)
+ * functionality in `<dlfcn.h>` instead.
+ */
+
 __BEGIN_DECLS
 
-/* bitfield definitions for android_dlextinfo.flags */
+/** Bitfield definitions for `android_dlextinfo::flags`. */
 enum {
-  /* When set, the reserved_addr and reserved_size fields must point to an
+  /**
+   * When set, the `reserved_addr` and `reserved_size` fields must point to an
    * already-reserved region of address space which will be used to load the
-   * library if it fits. If the reserved region is not large enough, the load
-   * will fail.
+   * library if it fits.
+   *
+   * If the reserved region is not large enough, loading will fail.
    */
   ANDROID_DLEXT_RESERVED_ADDRESS      = 0x1,
 
-  /* As DLEXT_RESERVED_ADDRESS, but if the reserved region is not large enough,
+  /**
+   * Like `ANDROID_DLEXT_RESERVED_ADDRESS`, but if the reserved region is not large enough,
    * the linker will choose an available address instead.
    */
   ANDROID_DLEXT_RESERVED_ADDRESS_HINT = 0x2,
 
-  /* When set, write the GNU RELRO section of the mapped library to relro_fd
+  /**
+   * When set, write the GNU RELRO section of the mapped library to `relro_fd`
    * after relocation has been performed, to allow it to be reused by another
    * process loading the same library at the same address. This implies
-   * ANDROID_DLEXT_USE_RELRO.
+   * `ANDROID_DLEXT_USE_RELRO`.
+   *
+   * This is mainly useful for the system WebView implementation.
    */
   ANDROID_DLEXT_WRITE_RELRO           = 0x4,
 
-  /* When set, compare the GNU RELRO section of the mapped library to relro_fd
+  /**
+   * When set, compare the GNU RELRO section of the mapped library to `relro_fd`
    * after relocation has been performed, and replace any relocated pages that
    * are identical with a version mapped from the file.
+   *
+   * This is mainly useful for the system WebView implementation.
    */
   ANDROID_DLEXT_USE_RELRO             = 0x8,
 
-  /* Instruct dlopen to use library_fd instead of opening file by name.
+  /**
+   * Use `library_fd` instead of opening the file by name.
    * The filename parameter is still used to identify the library.
    */
   ANDROID_DLEXT_USE_LIBRARY_FD        = 0x10,
 
-  /* If opening a library using library_fd read it starting at library_fd_offset.
-   * This flag is only valid when ANDROID_DLEXT_USE_LIBRARY_FD is set.
+  /**
+   * If opening a library using `library_fd` read it starting at `library_fd_offset`.
+   * This is mainly useful for loading a library stored within another file (such as uncompressed
+   * inside a ZIP archive).
+   * This flag is only valid when `ANDROID_DLEXT_USE_LIBRARY_FD` is set.
    */
   ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET    = 0x20,
 
-  /* When set, do not check if the library has already been loaded by file stat(2)s.
+  /**
+   * When set, do not use `stat(2)` to check if the library has already been loaded.
    *
    * This flag allows forced loading of the library in the case when for some
    * reason multiple ELF files share the same filename (because the already-loaded
    * library has been removed and overwritten, for example).
    *
-   * Note that if the library has the same dt_soname as an old one and some other
-   * library has the soname in DT_NEEDED list, the first one will be used to resolve any
+   * Note that if the library has the same `DT_SONAME` as an old one and some other
+   * library has the soname in its `DT_NEEDED` list, the first one will be used to resolve any
    * dependencies.
    */
   ANDROID_DLEXT_FORCE_LOAD = 0x40,
 
-  /* When set, if the minimum p_vaddr of the ELF file's PT_LOAD segments is non-zero,
+  /**
+   * When set, if the minimum `p_vaddr` of the ELF file's `PT_LOAD` segments is non-zero,
    * the dynamic linker will load it at that address.
    *
    * This flag is for ART internal use only.
    */
   ANDROID_DLEXT_FORCE_FIXED_VADDR = 0x80,
 
-  /* Instructs dlopen to load the library at the address specified by reserved_addr.
+  /**
+   * Instructs dlopen to load the library at the address specified by reserved_addr.
    *
-   * The difference between ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS and ANDROID_DLEXT_RESERVED_ADDRESS
-   * is that for ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS the linker reserves memory at reserved_addr
-   * whereas for ANDROID_DLEXT_RESERVED_ADDRESS the linker relies on the caller to reserve the memory.
+   * The difference between `ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS` and
+   * `ANDROID_DLEXT_RESERVED_ADDRESS` is that for `ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS` the linker
+   * reserves memory at `reserved_addr` whereas for `ANDROID_DLEXT_RESERVED_ADDRESS` the linker
+   * relies on the caller to reserve the memory.
    *
-   * This flag can be used with ANDROID_DLEXT_FORCE_FIXED_VADDR; when ANDROID_DLEXT_FORCE_FIXED_VADDR
-   * is set and load_bias is not 0 (load_bias is min(p_vaddr) of PT_LOAD segments) this flag is ignored.
-   * This is implemented this way because the linker has to pick one address over the other and this
-   * way is more convenient for art. Note that ANDROID_DLEXT_FORCE_FIXED_VADDR does not generate
-   * an error when min(p_vaddr) is 0.
+   * This flag can be used with `ANDROID_DLEXT_FORCE_FIXED_VADDR`. When
+   * `ANDROID_DLEXT_FORCE_FIXED_VADDR` is set and `load_bias` is not 0 (`load_bias` is the
+   * minimum `p_vaddr` of all `PT_LOAD` segments) this flag is ignored because the linker has to
+   * pick one address over the other and this way is more convenient for ART.
+   * Note that `ANDROID_DLEXT_FORCE_FIXED_VADDR` does not generate an error when the minimum
+   * `p_vaddr` is 0.
    *
-   * Cannot be used with ANDROID_DLEXT_RESERVED_ADDRESS or ANDROID_DLEXT_RESERVED_ADDRESS_HINT.
+   * Cannot be used with `ANDROID_DLEXT_RESERVED_ADDRESS` or `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`.
    *
    * This flag is for ART internal use only.
    */
   ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS = 0x100,
 
-  /* This flag used to load library in a different namespace. The namespace is
-   * specified in library_namespace.
+  /**
+   * This flag used to load library in a different namespace. The namespace is
+   * specified in `library_namespace`.
+   *
+   * This flag is for internal use only (since there is no NDK API for namespaces).
    */
   ANDROID_DLEXT_USE_NAMESPACE = 0x200,
 
-  /* Mask of valid bits */
+  /** Mask of valid bits. */
   ANDROID_DLEXT_VALID_FLAG_BITS       = ANDROID_DLEXT_RESERVED_ADDRESS |
                                         ANDROID_DLEXT_RESERVED_ADDRESS_HINT |
                                         ANDROID_DLEXT_WRITE_RELRO |
@@ -119,19 +147,36 @@
 
 struct android_namespace_t;
 
+/** Used to pass Android-specific arguments to `android_dlopen_ext`. */
 typedef struct {
+  /** A bitmask of `ANDROID_DLEXT_` enum values. */
   uint64_t flags;
+
+  /** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
   void*   reserved_addr;
+  /** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
   size_t  reserved_size;
+
+  /** Used by `ANDROID_DLEXT_WRITE_RELRO` and `ANDROID_DLEXT_USE_RELRO`. */
   int     relro_fd;
+
+  /** Used by `ANDROID_DLEXT_USE_LIBRARY_FD`. */
   int     library_fd;
+  /** Used by `ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET` */
   off64_t library_fd_offset;
+
+  /** Used by `ANDROID_DLEXT_USE_NAMESPACE`. */
   struct android_namespace_t* library_namespace;
 } android_dlextinfo;
 
+/**
+ * Opens the given library. The `__filename` and `__flags` arguments are
+ * the same as for [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html),
+ * with the Android-specific flags supplied via the `flags` member of `__info`.
+ */
 void* android_dlopen_ext(const char* __filename, int __flags, const android_dlextinfo* __info)
   __INTRODUCED_IN(21);
 
 __END_DECLS
 
-#endif /* __ANDROID_DLEXT_H__ */
+#endif
diff --git a/libc/include/bits/fortify/fcntl.h b/libc/include/bits/fortify/fcntl.h
index 6d90341..75cd4f2 100644
--- a/libc/include/bits/fortify/fcntl.h
+++ b/libc/include/bits/fortify/fcntl.h
@@ -98,7 +98,7 @@
 __errordecl(__creat_too_many_args, __open_too_many_args_error);
 
 #if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE
+__BIONIC_FORTIFY_VARIADIC
 int open(const char* pathname, int flags, ...) {
     if (__builtin_constant_p(flags)) {
         if (__open_modes_useful(flags) && __builtin_va_arg_pack_len() == 0) {
@@ -117,7 +117,7 @@
     return __open_real(pathname, flags, __builtin_va_arg_pack());
 }
 
-__BIONIC_FORTIFY_INLINE
+__BIONIC_FORTIFY_VARIADIC
 int openat(int dirfd, const char* pathname, int flags, ...) {
     if (__builtin_constant_p(flags)) {
         if (__open_modes_useful(flags) && __builtin_va_arg_pack_len() == 0) {
diff --git a/libc/include/bits/fortify/stdio.h b/libc/include/bits/fortify/stdio.h
index cfc78d7..6a6b433 100644
--- a/libc/include/bits/fortify/stdio.h
+++ b/libc/include/bits/fortify/stdio.h
@@ -63,8 +63,7 @@
                 "format string will always overflow destination buffer")
     __errorattr("format string will always overflow destination buffer");
 
-__BIONIC_FORTIFY_INLINE
-__printflike(3, 4)
+__BIONIC_FORTIFY_VARIADIC __printflike(3, 4)
 int snprintf(char* const __pass_object_size dest, size_t size, const char* format, ...)
         __overloadable {
     va_list va;
@@ -82,8 +81,7 @@
                 "format string will always overflow destination buffer")
     __errorattr("format string will always overflow destination buffer");
 
-__BIONIC_FORTIFY_INLINE
-__printflike(2, 3)
+__BIONIC_FORTIFY_VARIADIC __printflike(2, 3)
 int sprintf(char* const __pass_object_size dest, const char* format, ...) __overloadable {
     va_list va;
     va_start(va, format);
@@ -159,12 +157,12 @@
 
 
 #if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE __printflike(3, 4)
+__BIONIC_FORTIFY_VARIADIC __printflike(3, 4)
 int snprintf(char* dest, size_t size, const char* format, ...) {
     return __builtin___snprintf_chk(dest, size, 0, __bos(dest), format, __builtin_va_arg_pack());
 }
 
-__BIONIC_FORTIFY_INLINE __printflike(2, 3)
+__BIONIC_FORTIFY_VARIADIC __printflike(2, 3)
 int sprintf(char* dest, const char* format, ...) {
     return __builtin___sprintf_chk(dest, 0, __bos(dest), format, __builtin_va_arg_pack());
 }
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index 3cf6723..be07007 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -300,6 +300,13 @@
  * inline` without making them available externally.
  */
 #    define __BIONIC_FORTIFY_INLINE static __inline__ __always_inline
+/*
+ * We should use __BIONIC_FORTIFY_VARIADIC instead of __BIONIC_FORTIFY_INLINE
+ * for variadic functions because compilers cannot inline them.
+ * The __always_inline attribute is useless, misleading, and could trigger
+ * clang compiler bug to incorrectly inline variadic functions.
+ */
+#    define __BIONIC_FORTIFY_VARIADIC static __inline__
 /* Error functions don't have bodies, so they can just be static. */
 #    define __BIONIC_ERROR_FUNCTION_VISIBILITY static
 #  else
@@ -311,6 +318,8 @@
 #    define __call_bypassing_fortify(fn) (fn)
 /* __BIONIC_FORTIFY_NONSTATIC_INLINE is pointless in GCC's FORTIFY */
 #    define __BIONIC_FORTIFY_INLINE extern __inline__ __always_inline __attribute__((gnu_inline)) __attribute__((__artificial__))
+/* __always_inline is probably okay and ignored by gcc in __BIONIC_FORTIFY_VARIADIC */
+#    define __BIONIC_FORTIFY_VARIADIC __BIONIC_FORTIFY_INLINE
 #  endif
 #else
 /* Further increase sharing for some inline functions */
diff --git a/libc/include/sys/ioctl.h b/libc/include/sys/ioctl.h
index 76dc1ff..b48b7f9 100644
--- a/libc/include/sys/ioctl.h
+++ b/libc/include/sys/ioctl.h
@@ -36,8 +36,6 @@
  * terminal-related ioctl data structures such as struct winsize.
  */
 #include <linux/termios.h>
-#include <asm/ioctls.h>
-#include <asm/termbits.h>
 #include <linux/tty.h>
 
 #include <bits/ioctl.h>
diff --git a/libc/private/ScopedSignalBlocker.h b/libc/private/ScopedSignalBlocker.h
index 35d1c58..c3ab307 100644
--- a/libc/private/ScopedSignalBlocker.h
+++ b/libc/private/ScopedSignalBlocker.h
@@ -20,13 +20,14 @@
 #include <signal.h>
 
 #include "bionic_macros.h"
+#include "kernel_sigset_t.h"
 
 class ScopedSignalBlocker {
  public:
   explicit ScopedSignalBlocker() {
-    sigset_t set;
-    sigfillset(&set);
-    sigprocmask(SIG_BLOCK, &set, &old_set_);
+    kernel_sigset_t set;
+    set.fill();
+    __rt_sigprocmask(SIG_SETMASK, &set, &old_set_, sizeof(set));
   }
 
   ~ScopedSignalBlocker() {
@@ -34,11 +35,11 @@
   }
 
   void reset() {
-    sigprocmask(SIG_SETMASK, &old_set_, nullptr);
+    __rt_sigprocmask(SIG_SETMASK, &old_set_, nullptr, sizeof(old_set_));
   }
 
  private:
-  sigset_t old_set_;
+  kernel_sigset_t old_set_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedSignalBlocker);
 };
diff --git a/libc/private/kernel_sigset_t.h b/libc/private/kernel_sigset_t.h
index 9415fcf..bdfb729 100644
--- a/libc/private/kernel_sigset_t.h
+++ b/libc/private/kernel_sigset_t.h
@@ -17,18 +17,27 @@
 #ifndef LIBC_PRIVATE_KERNEL_SIGSET_T_H_
 #define LIBC_PRIVATE_KERNEL_SIGSET_T_H_
 
+#include <errno.h>
 #include <signal.h>
 
+#include <async_safe/log.h>
+
 // Our sigset_t is wrong for ARM and x86. It's 32-bit but the kernel expects 64 bits.
-// This means we can't support real-time signals correctly until we can change the ABI.
+// This means we can't support real-time signals correctly without breaking the ABI.
 // In the meantime, we can use this union to pass an appropriately-sized block of memory
-// to the kernel, at the cost of not being able to refer to real-time signals.
+// to the kernel, at the cost of not being able to refer to real-time signals when
+// initializing from a sigset_t on LP32.
 union kernel_sigset_t {
+ public:
   kernel_sigset_t() {
-    clear();
   }
 
-  kernel_sigset_t(const sigset_t* value) {
+  explicit kernel_sigset_t(int signal_number) {
+    clear();
+    if (!set(signal_number)) async_safe_fatal("kernel_sigset_t(%d)", signal_number);
+  }
+
+  explicit kernel_sigset_t(const sigset_t* value) {
     clear();
     set(value);
   }
@@ -37,7 +46,32 @@
     __builtin_memset(this, 0, sizeof(*this));
   }
 
+  bool clear(int signal_number) {
+    int bit = bit_of(signal_number);
+    if (bit == -1) return false;
+    bits[bit / LONG_BIT] &= ~(1UL << (bit % LONG_BIT));
+    return true;
+  }
+
+  void fill() {
+    __builtin_memset(this, 0xff, sizeof(*this));
+  }
+
+  bool is_set(int signal_number) {
+    int bit = bit_of(signal_number);
+    if (bit == -1) return false;
+    return ((bits[bit / LONG_BIT] >> (bit % LONG_BIT)) & 1) == 1;
+  }
+
+  bool set(int signal_number) {
+    int bit = bit_of(signal_number);
+    if (bit == -1) return false;
+    bits[bit / LONG_BIT] |= 1UL << (bit % LONG_BIT);
+    return true;
+  }
+
   void set(const sigset_t* value) {
+    clear();
     bionic = *value;
   }
 
@@ -46,9 +80,21 @@
   }
 
   sigset_t bionic;
-#ifndef __mips__
-  uint32_t kernel[2];
-#endif
+  unsigned long bits[_KERNEL__NSIG/LONG_BIT];
+
+ private:
+  int bit_of(int signal_number) {
+    int bit = signal_number - 1; // Signal numbers start at 1, but bit positions start at 0.
+    if (bit < 0 || bit >= static_cast<int>(8*sizeof(*this))) {
+      errno = EINVAL;
+      return -1;
+    }
+    return bit;
+  }
 };
 
+extern "C" int __rt_sigpending(const kernel_sigset_t*, size_t);
+extern "C" int __rt_sigprocmask(int, const kernel_sigset_t*, kernel_sigset_t*, size_t);
+extern "C" int __rt_sigsuspend(const kernel_sigset_t*, size_t);
+
 #endif
diff --git a/libdl/libdl.arm.map b/libdl/libdl.arm.map
index 1fcfc58..7ed9503 100644
--- a/libdl/libdl.arm.map
+++ b/libdl/libdl.arm.map
@@ -41,6 +41,11 @@
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.arm64.map b/libdl/libdl.arm64.map
index 8d4019c..199f2e3 100644
--- a/libdl/libdl.arm64.map
+++ b/libdl/libdl.arm64.map
@@ -40,6 +40,11 @@
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.cpp b/libdl/libdl.cpp
index c834088..4c2415f 100644
--- a/libdl/libdl.cpp
+++ b/libdl/libdl.cpp
@@ -93,6 +93,11 @@
                                 const char* shared_libs_sonames);
 
 __attribute__((__weak__, visibility("default")))
+bool __loader_android_link_namespaces_all_libs(
+                                struct android_namespace_t* namespace_from,
+                                struct android_namespace_t* namespace_to);
+
+__attribute__((__weak__, visibility("default")))
 void __loader_android_dlwarning(void* obj, void (*f)(void*, const char*));
 
 __attribute__((__weak__, visibility("default")))
@@ -205,6 +210,12 @@
 }
 
 __attribute__((__weak__))
+bool android_link_namespaces_all_libs(struct android_namespace_t* namespace_from,
+                                      struct android_namespace_t* namespace_to) {
+  return __loader_android_link_namespaces_all_libs(namespace_from, namespace_to);
+}
+
+__attribute__((__weak__))
 void android_dlwarning(void* obj, void (*f)(void*, const char*)) {
   __loader_android_dlwarning(obj, f);
 }
diff --git a/libdl/libdl.map.txt b/libdl/libdl.map.txt
index 002e9f8..579ffa7 100644
--- a/libdl/libdl.map.txt
+++ b/libdl/libdl.map.txt
@@ -40,6 +40,11 @@
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.mips.map b/libdl/libdl.mips.map
index 8d4019c..199f2e3 100644
--- a/libdl/libdl.mips.map
+++ b/libdl/libdl.mips.map
@@ -40,6 +40,11 @@
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.mips64.map b/libdl/libdl.mips64.map
index 8d4019c..199f2e3 100644
--- a/libdl/libdl.mips64.map
+++ b/libdl/libdl.mips64.map
@@ -40,6 +40,11 @@
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.x86.map b/libdl/libdl.x86.map
index 8d4019c..199f2e3 100644
--- a/libdl/libdl.x86.map
+++ b/libdl/libdl.x86.map
@@ -40,6 +40,11 @@
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/libdl/libdl.x86_64.map b/libdl/libdl.x86_64.map
index 8d4019c..199f2e3 100644
--- a/libdl/libdl.x86_64.map
+++ b/libdl/libdl.x86_64.map
@@ -40,6 +40,11 @@
     __cfi_slowpath_diag;
 } LIBC_N;
 
+LIBC_PRIVATE {
+  global:
+    android_link_namespaces_all_libs;
+} LIBC_OMR1;
+
 LIBC_PLATFORM {
   global:
     __cfi_init;
diff --git a/linker/dlfcn.cpp b/linker/dlfcn.cpp
index 7f40f90..4b84537 100644
--- a/linker/dlfcn.cpp
+++ b/linker/dlfcn.cpp
@@ -65,6 +65,8 @@
 bool __loader_android_link_namespaces(android_namespace_t* namespace_from,
                                       android_namespace_t* namespace_to,
                                       const char* shared_libs_sonames) __LINKER_PUBLIC__;
+bool __loader_android_link_namespaces_all_libs(android_namespace_t* namespace_from,
+                                               android_namespace_t* namespace_to) __LINKER_PUBLIC__;
 void __loader_android_set_application_target_sdk_version(uint32_t target) __LINKER_PUBLIC__;
 void __loader_android_update_LD_LIBRARY_PATH(const char* ld_library_path) __LINKER_PUBLIC__;
 void __loader_cfi_fail(uint64_t CallSiteTypeId,
@@ -266,6 +268,19 @@
   return success;
 }
 
+bool __loader_android_link_namespaces_all_libs(android_namespace_t* namespace_from,
+                                               android_namespace_t* namespace_to) {
+  ScopedPthreadMutexLocker locker(&g_dl_mutex);
+
+  bool success = link_namespaces_all_libs(namespace_from, namespace_to);
+
+  if (!success) {
+    __bionic_format_dlerror("android_link_namespaces_all_libs failed", linker_get_error_buffer());
+  }
+
+  return success;
+}
+
 android_namespace_t* __loader_android_get_exported_namespace(const char* name) {
   return get_exported_namespace(name);
 }
diff --git a/linker/ld_android.cpp b/linker/ld_android.cpp
index c4ce1b9..4a05772 100644
--- a/linker/ld_android.cpp
+++ b/linker/ld_android.cpp
@@ -49,6 +49,7 @@
 __strong_alias(__loader_android_get_exported_namespace, __internal_linker_error);
 __strong_alias(__loader_android_init_anonymous_namespace, __internal_linker_error);
 __strong_alias(__loader_android_link_namespaces, __internal_linker_error);
+__strong_alias(__loader_android_link_namespaces_all_libs, __internal_linker_error);
 __strong_alias(__loader_android_set_application_target_sdk_version, __internal_linker_error);
 __strong_alias(__loader_android_update_LD_LIBRARY_PATH, __internal_linker_error);
 __strong_alias(__loader_cfi_fail, __internal_linker_error);
diff --git a/linker/linker.arm.map b/linker/linker.arm.map
index 4a3f177..a58e7c8 100644
--- a/linker/linker.arm.map
+++ b/linker/linker.arm.map
@@ -17,6 +17,7 @@
     __loader_android_dlwarning;
     __loader_cfi_fail;
     __loader_android_link_namespaces;
+    __loader_android_link_namespaces_all_libs;
     __loader_android_get_exported_namespace;
     __loader_dl_unwind_find_exidx;
     __loader_add_thread_local_dtor;
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 7489721..3f898ba 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -1430,7 +1430,7 @@
   }
 
   // returning true with empty soinfo means that the library is okay to be
-  // loaded in the namespace buy has not yet been loaded there before.
+  // loaded in the namespace but has not yet been loaded there before.
   task->set_soinfo(nullptr);
   return true;
 }
@@ -2363,7 +2363,8 @@
     add_soinfos_to_namespace(parent_namespace->soinfo_list(), ns);
     // and copy parent namespace links
     for (auto& link : parent_namespace->linked_namespaces()) {
-      ns->add_linked_namespace(link.linked_namespace(), link.shared_lib_sonames());
+      ns->add_linked_namespace(link.linked_namespace(), link.shared_lib_sonames(),
+                               link.allow_all_shared_libs());
     }
   } else {
     // If not shared - copy only the shared group
@@ -2399,7 +2400,25 @@
   std::unordered_set<std::string> sonames_set(sonames.begin(), sonames.end());
 
   ProtectedDataGuard guard;
-  namespace_from->add_linked_namespace(namespace_to, sonames_set);
+  namespace_from->add_linked_namespace(namespace_to, sonames_set, false);
+
+  return true;
+}
+
+bool link_namespaces_all_libs(android_namespace_t* namespace_from,
+                              android_namespace_t* namespace_to) {
+  if (namespace_from == nullptr) {
+    DL_ERR("error linking namespaces: namespace_from is null.");
+    return false;
+  }
+
+  if (namespace_to == nullptr) {
+    DL_ERR("error linking namespaces: namespace_to is null.");
+    return false;
+  }
+
+  ProtectedDataGuard guard;
+  namespace_from->add_linked_namespace(namespace_to, std::unordered_set<std::string>(), true);
 
   return true;
 }
@@ -3778,7 +3797,11 @@
       auto it_to = namespaces.find(ns_link.ns_name());
       CHECK(it_to != namespaces.end());
       android_namespace_t* namespace_to = it_to->second;
-      link_namespaces(namespace_from, namespace_to, ns_link.shared_libs().c_str());
+      if (ns_link.allow_all_shared_libs()) {
+        link_namespaces_all_libs(namespace_from, namespace_to);
+      } else {
+        link_namespaces(namespace_from, namespace_to, ns_link.shared_libs().c_str());
+      }
     }
   }
   // we can no longer rely on the fact that libdl.so is part of default namespace
diff --git a/linker/linker.generic.map b/linker/linker.generic.map
index 04f4c8a..45bb0b5 100644
--- a/linker/linker.generic.map
+++ b/linker/linker.generic.map
@@ -17,6 +17,7 @@
     __loader_android_dlwarning;
     __loader_cfi_fail;
     __loader_android_link_namespaces;
+    __loader_android_link_namespaces_all_libs;
     __loader_android_get_exported_namespace;
     __loader_add_thread_local_dtor;
     __loader_remove_thread_local_dtor;
diff --git a/linker/linker.h b/linker/linker.h
index 6ebca4c..29d40fa 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -180,6 +180,9 @@
                      android_namespace_t* namespace_to,
                      const char* shared_lib_sonames);
 
+bool link_namespaces_all_libs(android_namespace_t* namespace_from,
+                              android_namespace_t* namespace_to);
+
 android_namespace_t* get_exported_namespace(const char* name);
 
 void increment_dso_handle_reference_counter(void* dso_handle);
diff --git a/linker/linker_config.cpp b/linker/linker_config.cpp
index 60b7ad9..83c2f36 100644
--- a/linker/linker_config.cpp
+++ b/linker/linker_config.cpp
@@ -489,12 +489,15 @@
         return false;
       }
 
+      bool allow_all_shared_libs = properties.get_bool(property_name_prefix + ".link." +
+                                                       linked_ns_name + ".allow_all_shared_libs");
+
       std::string shared_libs = properties.get_string(property_name_prefix +
                                                       ".link." +
                                                       linked_ns_name +
                                                       ".shared_libs", &lineno);
 
-      if (shared_libs.empty()) {
+      if (!allow_all_shared_libs && shared_libs.empty()) {
         *error_msg = create_error_msg(ld_config_file_path,
                                       lineno,
                                       std::string("list of shared_libs for ") +
@@ -505,7 +508,15 @@
         return false;
       }
 
-      ns_config->add_namespace_link(linked_ns_name, shared_libs);
+      if (allow_all_shared_libs && !shared_libs.empty()) {
+        *error_msg = create_error_msg(ld_config_file_path, lineno,
+                                      std::string("both shared_libs and allow_all_shared_libs "
+                                                  "are set for ") +
+                                      name + "->" + linked_ns_name + " link.");
+        return false;
+      }
+
+      ns_config->add_namespace_link(linked_ns_name, shared_libs, allow_all_shared_libs);
     }
 
     ns_config->set_isolated(properties.get_bool(property_name_prefix + ".isolated"));
diff --git a/linker/linker_config.h b/linker/linker_config.h
index dde9362..0c50d57 100644
--- a/linker/linker_config.h
+++ b/linker/linker_config.h
@@ -43,8 +43,10 @@
 class NamespaceLinkConfig {
  public:
   NamespaceLinkConfig() = default;
-  NamespaceLinkConfig(const std::string& ns_name, const std::string& shared_libs)
-      : ns_name_(ns_name), shared_libs_(shared_libs)  {}
+  NamespaceLinkConfig(const std::string& ns_name, const std::string& shared_libs,
+                      bool allow_all_shared_libs)
+      : ns_name_(ns_name), shared_libs_(shared_libs),
+        allow_all_shared_libs_(allow_all_shared_libs) {}
 
   const std::string& ns_name() const {
     return ns_name_;
@@ -54,9 +56,14 @@
     return shared_libs_;
   }
 
+  bool allow_all_shared_libs() const {
+    return allow_all_shared_libs_;
+  }
+
  private:
   std::string ns_name_;
   std::string shared_libs_;
+  bool allow_all_shared_libs_;
 };
 
 class NamespaceConfig {
@@ -89,8 +96,9 @@
     return namespace_links_;
   }
 
-  void add_namespace_link(const std::string& ns_name, const std::string& shared_libs) {
-    namespace_links_.push_back(NamespaceLinkConfig(ns_name, shared_libs));
+  void add_namespace_link(const std::string& ns_name, const std::string& shared_libs,
+                          bool allow_all_shared_libs) {
+    namespace_links_.push_back(NamespaceLinkConfig(ns_name, shared_libs, allow_all_shared_libs));
   }
 
   void set_isolated(bool isolated) {
diff --git a/linker/linker_namespaces.h b/linker/linker_namespaces.h
index 16906d6..a7fe0d5 100644
--- a/linker/linker_namespaces.h
+++ b/linker/linker_namespaces.h
@@ -40,8 +40,10 @@
 struct android_namespace_link_t {
  public:
   android_namespace_link_t(android_namespace_t* linked_namespace,
-                           const std::unordered_set<std::string>& shared_lib_sonames)
-      : linked_namespace_(linked_namespace), shared_lib_sonames_(shared_lib_sonames)
+                           const std::unordered_set<std::string>& shared_lib_sonames,
+                           bool allow_all_shared_libs)
+      : linked_namespace_(linked_namespace), shared_lib_sonames_(shared_lib_sonames),
+        allow_all_shared_libs_(allow_all_shared_libs)
   {}
 
   android_namespace_t* linked_namespace() const {
@@ -53,12 +55,17 @@
   }
 
   bool is_accessible(const char* soname) const {
-    return shared_lib_sonames_.find(soname) != shared_lib_sonames_.end();
+    return allow_all_shared_libs_ || shared_lib_sonames_.find(soname) != shared_lib_sonames_.end();
+  }
+
+  bool allow_all_shared_libs() const {
+    return allow_all_shared_libs_;
   }
 
  private:
   android_namespace_t* const linked_namespace_;
   const std::unordered_set<std::string> shared_lib_sonames_;
+  bool allow_all_shared_libs_;
 };
 
 struct android_namespace_t {
@@ -105,8 +112,10 @@
     return linked_namespaces_;
   }
   void add_linked_namespace(android_namespace_t* linked_namespace,
-                            const std::unordered_set<std::string>& shared_lib_sonames) {
-    linked_namespaces_.push_back(android_namespace_link_t(linked_namespace, shared_lib_sonames));
+                            const std::unordered_set<std::string>& shared_lib_sonames,
+                            bool allow_all_shared_libs) {
+    linked_namespaces_.push_back(
+        android_namespace_link_t(linked_namespace, shared_lib_sonames, allow_all_shared_libs));
   }
 
   void add_soinfo(soinfo* si) {
diff --git a/linker/tests/linker_config_test.cpp b/linker/tests/linker_config_test.cpp
index 4c0dcdd..e716879 100644
--- a/linker/tests/linker_config_test.cpp
+++ b/linker/tests/linker_config_test.cpp
@@ -81,6 +81,8 @@
   "namespace.vndk.search.paths = /system/${LIB}/vndk\n"
   "namespace.vndk.asan.search.paths = /data\n"
   "namespace.vndk.asan.search.paths += /system/${LIB}/vndk\n"
+  "namespace.vndk.links = default\n"
+  "namespace.vndk.link.default.allow_all_shared_libs = true\n"
   "\n";
 
 static bool write_version(const std::string& path, uint32_t version) {
@@ -154,10 +156,14 @@
 
   const auto& default_ns_links = default_ns_config->links();
   ASSERT_EQ(2U, default_ns_links.size());
+
   ASSERT_EQ("system", default_ns_links[0].ns_name());
   ASSERT_EQ("libc.so:libm.so:libdl.so:libstdc++.so", default_ns_links[0].shared_libs());
+  ASSERT_FALSE(default_ns_links[0].allow_all_shared_libs());
+
   ASSERT_EQ("vndk", default_ns_links[1].ns_name());
   ASSERT_EQ("libcutils.so:libbase.so", default_ns_links[1].shared_libs());
+  ASSERT_FALSE(default_ns_links[1].allow_all_shared_libs());
 
   auto& ns_configs = config->namespace_configs();
   ASSERT_EQ(3U, ns_configs.size());
@@ -187,8 +193,13 @@
   ASSERT_TRUE(ns_vndk != nullptr) << "vndk namespace was not found";
 
   ASSERT_FALSE(ns_vndk->isolated()); // malformed bool property
-  ASSERT_FALSE(ns_vndk->visible()); // undefined bool property 
+  ASSERT_FALSE(ns_vndk->visible()); // undefined bool property
   ASSERT_EQ(kExpectedVndkSearchPath, ns_vndk->search_paths());
+
+  const auto& ns_vndk_links = ns_vndk->links();
+  ASSERT_EQ(1U, ns_vndk_links.size());
+  ASSERT_EQ("default", ns_vndk_links[0].ns_name());
+  ASSERT_TRUE(ns_vndk_links[0].allow_all_shared_libs());
 }
 
 TEST(linker_config, smoke) {
@@ -198,3 +209,40 @@
 TEST(linker_config, asan_smoke) {
   run_linker_config_smoke_test(true);
 }
+
+TEST(linker_config, ns_link_shared_libs_invalid_settings) {
+  // This unit test ensures an error is emitted when a namespace link in ld.config.txt specifies
+  // both shared_libs and allow_all_shared_libs.
+
+  static const char config_str[] =
+    "dir.test = /data/local/tmp\n"
+    "\n"
+    "[test]\n"
+    "additional.namespaces = system\n"
+    "namespace.default.links = system\n"
+    "namespace.default.link.system.shared_libs = libc.so:libm.so\n"
+    "namespace.default.link.system.allow_all_shared_libs = true\n"
+    "\n";
+
+  TemporaryFile tmp_file;
+  close(tmp_file.fd);
+  tmp_file.fd = -1;
+
+  android::base::WriteStringToFile(config_str, tmp_file.path);
+
+  TemporaryDir tmp_dir;
+
+  std::string executable_path = std::string(tmp_dir.path) + "/some-binary";
+
+  const Config* config = nullptr;
+  std::string error_msg;
+  ASSERT_FALSE(Config::read_binary_config(tmp_file.path,
+                                          executable_path.c_str(),
+                                          false,
+                                          &config,
+                                          &error_msg));
+  ASSERT_TRUE(config == nullptr);
+  ASSERT_EQ(std::string(tmp_file.path) + ":6: "
+            "error: both shared_libs and allow_all_shared_libs are set for default->system link.",
+            error_msg);
+}
diff --git a/tests/Android.bp b/tests/Android.bp
index c1e455d..1521b73 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -554,6 +554,10 @@
         "libnstest_root",
         "libnstest_public",
         "libnstest_public_internal",
+        "libnstest_ns_a_public1",
+        "libnstest_ns_a_public1_internal",
+        "libnstest_ns_b_public2",
+        "libnstest_ns_b_public3",
     ],
 }
 
diff --git a/tests/ScopedSignalHandler.h b/tests/ScopedSignalHandler.h
index 8998d0d..71f22dc 100644
--- a/tests/ScopedSignalHandler.h
+++ b/tests/ScopedSignalHandler.h
@@ -53,13 +53,13 @@
   const int signal_number_;
 };
 
-class ScopedSignalMask {
+class SignalMaskRestorer {
  public:
-  ScopedSignalMask() {
+  SignalMaskRestorer() {
     sigprocmask(SIG_SETMASK, nullptr, &old_mask_);
   }
 
-  ~ScopedSignalMask() {
+  ~SignalMaskRestorer() {
     sigprocmask(SIG_SETMASK, &old_mask_, nullptr);
   }
 
diff --git a/tests/dlext_private.h b/tests/dlext_private.h
index dea92ee..2621a68 100644
--- a/tests/dlext_private.h
+++ b/tests/dlext_private.h
@@ -95,6 +95,9 @@
                                     android_namespace_t* to,
                                     const char* shared_libs_sonames);
 
+extern bool android_link_namespaces_all_libs(android_namespace_t* from,
+                                             android_namespace_t* to);
+
 extern void android_set_application_target_sdk_version(uint32_t target);
 
 __END_DECLS
diff --git a/tests/dlext_test.cpp b/tests/dlext_test.cpp
index 64cfa08..bb2d8a3 100644
--- a/tests/dlext_test.cpp
+++ b/tests/dlext_test.cpp
@@ -1737,6 +1737,123 @@
   ASSERT_EQ(expected_dlerror, dlerror());
 }
 
+TEST(dlext, ns_link_namespaces_invalid_arguments) {
+  ASSERT_TRUE(android_init_anonymous_namespace(g_core_shared_libs.c_str(), nullptr));
+
+  android_namespace_t* ns =
+          android_create_namespace("private",
+                                   nullptr,
+                                   (get_testlib_root() + "/private_namespace_libs").c_str(),
+                                   ANDROID_NAMESPACE_TYPE_REGULAR,
+                                   nullptr,
+                                   nullptr);
+  ASSERT_TRUE(ns != nullptr) << dlerror();
+
+  // Test android_link_namespaces()
+  ASSERT_FALSE(android_link_namespaces(nullptr, nullptr, "libc.so"));
+  ASSERT_STREQ("android_link_namespaces failed: error linking namespaces: namespace_from is null.",
+               dlerror());
+
+  ASSERT_FALSE(android_link_namespaces(ns, nullptr, nullptr));
+  ASSERT_STREQ("android_link_namespaces failed: "
+               "error linking namespaces \"private\"->\"(default)\": "
+               "the list of shared libraries is empty.", dlerror());
+
+  ASSERT_FALSE(android_link_namespaces(ns, nullptr, ""));
+  ASSERT_STREQ("android_link_namespaces failed: "
+               "error linking namespaces \"private\"->\"(default)\": "
+               "the list of shared libraries is empty.", dlerror());
+
+  // Test android_link_namespaces_all_libs()
+  ASSERT_FALSE(android_link_namespaces_all_libs(nullptr, nullptr));
+  ASSERT_STREQ("android_link_namespaces_all_libs failed: "
+               "error linking namespaces: namespace_from is null.", dlerror());
+
+  ASSERT_FALSE(android_link_namespaces_all_libs(nullptr, ns));
+  ASSERT_STREQ("android_link_namespaces_all_libs failed: "
+               "error linking namespaces: namespace_from is null.", dlerror());
+
+  ASSERT_FALSE(android_link_namespaces_all_libs(ns, nullptr));
+  ASSERT_STREQ("android_link_namespaces_all_libs failed: "
+               "error linking namespaces: namespace_to is null.", dlerror());
+}
+
+TEST(dlext, ns_allow_all_shared_libs) {
+  ASSERT_TRUE(android_init_anonymous_namespace(g_core_shared_libs.c_str(), nullptr));
+
+  android_namespace_t* ns_a =
+          android_create_namespace("ns_a",
+                                   nullptr,
+                                   (get_testlib_root() + "/ns_a").c_str(),
+                                   ANDROID_NAMESPACE_TYPE_ISOLATED,
+                                   nullptr,
+                                   nullptr);
+  ASSERT_TRUE(ns_a != nullptr) << dlerror();
+  ASSERT_TRUE(android_link_namespaces(ns_a, nullptr, g_core_shared_libs.c_str())) << dlerror();
+
+  android_namespace_t* ns_b =
+          android_create_namespace("ns_b",
+                                   nullptr,
+                                   (get_testlib_root() + "/ns_b").c_str(),
+                                   ANDROID_NAMESPACE_TYPE_ISOLATED,
+                                   nullptr,
+                                   nullptr);
+  ASSERT_TRUE(ns_b != nullptr) << dlerror();
+  ASSERT_TRUE(android_link_namespaces(ns_b, nullptr, g_core_shared_libs.c_str())) << dlerror();
+
+  ASSERT_TRUE(android_link_namespaces(ns_b, ns_a, "libnstest_ns_a_public1.so")) << dlerror();
+  ASSERT_TRUE(android_link_namespaces_all_libs(ns_a, ns_b)) << dlerror();
+
+  // Load libs with android_dlopen_ext() from namespace b
+  android_dlextinfo extinfo;
+  extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;
+  extinfo.library_namespace = ns_b;
+
+  void* ns_b_handle1 = android_dlopen_ext("libnstest_ns_a_public1.so", RTLD_NOW, &extinfo);
+  ASSERT_TRUE(ns_b_handle1 != nullptr) << dlerror();
+
+  void* ns_b_handle1_internal =
+      android_dlopen_ext("libnstest_ns_a_public1_internal.so", RTLD_NOW, &extinfo);
+  ASSERT_TRUE(ns_b_handle1_internal == nullptr);
+
+  void* ns_b_handle2 = android_dlopen_ext("libnstest_ns_b_public2.so", RTLD_NOW, &extinfo);
+  ASSERT_TRUE(ns_b_handle2 != nullptr) << dlerror();
+
+  void* ns_b_handle3 = android_dlopen_ext("libnstest_ns_b_public3.so", RTLD_NOW, &extinfo);
+  ASSERT_TRUE(ns_b_handle3 != nullptr) << dlerror();
+
+  // Load libs with android_dlopen_ext() from namespace a
+  extinfo.library_namespace = ns_a;
+
+  void* ns_a_handle1 = android_dlopen_ext("libnstest_ns_a_public1.so", RTLD_NOW, &extinfo);
+  ASSERT_TRUE(ns_a_handle1 != nullptr) << dlerror();
+
+  void* ns_a_handle1_internal =
+      android_dlopen_ext("libnstest_ns_a_public1_internal.so", RTLD_NOW, &extinfo);
+  ASSERT_TRUE(ns_a_handle1_internal != nullptr) << dlerror();
+
+  void* ns_a_handle2 = android_dlopen_ext("libnstest_ns_b_public2.so", RTLD_NOW, &extinfo);
+  ASSERT_TRUE(ns_a_handle2 != nullptr) << dlerror();
+
+  void* ns_a_handle3 = android_dlopen_ext("libnstest_ns_b_public3.so", RTLD_NOW, &extinfo);
+  ASSERT_TRUE(ns_a_handle3 != nullptr) << dlerror();
+
+  // Compare the dlopen handle
+  ASSERT_EQ(ns_b_handle1, ns_a_handle1);
+  ASSERT_EQ(ns_b_handle2, ns_a_handle2);
+  ASSERT_EQ(ns_b_handle3, ns_a_handle3);
+
+  // Close libs
+  dlclose(ns_b_handle1);
+  dlclose(ns_b_handle2);
+  dlclose(ns_b_handle3);
+
+  dlclose(ns_a_handle1);
+  dlclose(ns_a_handle1_internal);
+  dlclose(ns_a_handle2);
+  dlclose(ns_a_handle3);
+}
+
 TEST(dlext, ns_anonymous) {
   static const char* root_lib = "libnstest_root.so";
   std::string shared_libs = g_core_shared_libs + ":" + g_public_lib;
diff --git a/tests/headers/posix/pthread_h.c b/tests/headers/posix/pthread_h.c
index 4fa5b9d..4be822c 100644
--- a/tests/headers/posix/pthread_h.c
+++ b/tests/headers/posix/pthread_h.c
@@ -57,9 +57,9 @@
 
   MACRO(PTHREAD_ONCE_INIT);
 
-#if !defined(__BIONIC__) // No robust mutexes on Android.
   MACRO(PTHREAD_PRIO_INHERIT);
   MACRO(PTHREAD_PRIO_NONE);
+#if !defined(__BIONIC__)
   MACRO(PTHREAD_PRIO_PROTECT);
 #endif
 
@@ -158,8 +158,8 @@
   FUNCTION(pthread_mutexattr_destroy, int (*f)(pthread_mutexattr_t*));
 #if !defined(__BIONIC__) // No robust mutexes on Android.
   FUNCTION(pthread_mutexattr_getprioceiling, int (*f)(const pthread_mutexattr_t*, int*));
-  FUNCTION(pthread_mutexattr_getprotocol, int (*f)(const pthread_mutexattr_t*, int*));
 #endif
+  FUNCTION(pthread_mutexattr_getprotocol, int (*f)(const pthread_mutexattr_t*, int*));
   FUNCTION(pthread_mutexattr_getpshared, int (*f)(const pthread_mutexattr_t*, int*));
 #if !defined(__BIONIC__) // No robust mutexes on Android.
   FUNCTION(pthread_mutexattr_getrobust, int (*f)(const pthread_mutexattr_t*, int*));
@@ -168,8 +168,8 @@
   FUNCTION(pthread_mutexattr_init, int (*f)(pthread_mutexattr_t*));
 #if !defined(__BIONIC__) // No robust mutexes on Android.
   FUNCTION(pthread_mutexattr_setprioceiling, int (*f)(pthread_mutexattr_t*, int));
-  FUNCTION(pthread_mutexattr_setprotocol, int (*f)(pthread_mutexattr_t*, int));
 #endif
+  FUNCTION(pthread_mutexattr_setprotocol, int (*f)(pthread_mutexattr_t*, int));
   FUNCTION(pthread_mutexattr_setpshared, int (*f)(pthread_mutexattr_t*, int));
 #if !defined(__BIONIC__) // No robust mutexes on Android.
   FUNCTION(pthread_mutexattr_setrobust, int (*f)(pthread_mutexattr_t*, int));
diff --git a/tests/libs/Android.bp b/tests/libs/Android.bp
index 61a837f..cae30b5 100644
--- a/tests/libs/Android.bp
+++ b/tests/libs/Android.bp
@@ -259,6 +259,58 @@
 }
 
 // -----------------------------------------------------------------------------
+// Build test helper libraries for linker namespaces for allow all shared libs
+//
+// This set of libraries is used to verify linker namespaces for allow all
+// shared libs.
+//
+// Test cases
+// 1. Check that namespace a exposes libnstest_ns_a_public1 to
+//    namespace b while keeping libnstest_ns_a_public1_internal as an
+//    internal lib.
+// 2. Check that namespace b exposes all libraries to namespace a.
+//
+// Dependency tree (visibility)
+// libnstest_ns_b_public2.so  (ns:b)
+// +-> libnstest_ns_a_public1.so  (ns:a)
+//     +-> libnstest_ns_a_public2_internal.so  (ns:a)
+//     +-> libnstest_ns_b_public3.so  (ns:b)
+//
+// -----------------------------------------------------------------------------
+cc_test_library {
+    name: "libnstest_ns_a_public1",
+    defaults: ["bionic_testlib_defaults"],
+    srcs: ["libnstest_ns_a_public1.cpp"],
+    relative_install_path: "bionic-loader-test-libs/ns_a",
+    shared_libs: [
+        "libnstest_ns_a_public1_internal",
+        "libnstest_ns_b_public3",
+    ],
+}
+
+cc_test_library {
+    name: "libnstest_ns_a_public1_internal",
+    defaults: ["bionic_testlib_defaults"],
+    srcs: ["libnstest_ns_a_public1_internal.cpp"],
+    relative_install_path: "bionic-loader-test-libs/ns_a",
+}
+
+cc_test_library {
+    name: "libnstest_ns_b_public2",
+    defaults: ["bionic_testlib_defaults"],
+    srcs: ["libnstest_ns_b_public2.cpp"],
+    relative_install_path: "bionic-loader-test-libs/ns_b",
+    shared_libs: ["libnstest_ns_a_public1"],
+}
+
+cc_test_library {
+    name: "libnstest_ns_b_public3",
+    defaults: ["bionic_testlib_defaults"],
+    srcs: ["libnstest_ns_b_public3.cpp"],
+    relative_install_path: "bionic-loader-test-libs/ns_b",
+}
+
+// -----------------------------------------------------------------------------
 // Build DT_RUNPATH test helper libraries
 // -----------------------------------------------------------------------------
 // include $(LOCAL_PATH)/Android.build.dt_runpath.mk
diff --git a/tests/libs/libnstest_ns_a_public1.cpp b/tests/libs/libnstest_ns_a_public1.cpp
new file mode 100644
index 0000000..c095e60
--- /dev/null
+++ b/tests/libs/libnstest_ns_a_public1.cpp
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+static const char ns_a_public1_string[] = "libnstest_ns_a_public1.so";
+
+extern "C" const char* get_ns_a_public1_string() {
+  return ns_a_public1_string;
+}
+
+
+extern "C" const char *get_ns_a_public1_internal_string();
+
+extern "C" const char *delegate_get_ns_a_public1_internal_string() {
+  return get_ns_a_public1_internal_string();
+}
+
+
+extern "C" const char *get_ns_b_public3_string();
+
+extern "C" const char *delegate_get_ns_b_public3_string() {
+  return get_ns_b_public3_string();
+}
diff --git a/tests/libs/libnstest_ns_a_public1_internal.cpp b/tests/libs/libnstest_ns_a_public1_internal.cpp
new file mode 100644
index 0000000..6529936
--- /dev/null
+++ b/tests/libs/libnstest_ns_a_public1_internal.cpp
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+static const char ns_a_public1_internal_string[] = "libnstest_ns_a_public1_internal.so";
+
+extern "C" const char* get_ns_a_public1_internal_string() {
+  return ns_a_public1_internal_string;
+}
diff --git a/tests/libs/libnstest_ns_b_public2.cpp b/tests/libs/libnstest_ns_b_public2.cpp
new file mode 100644
index 0000000..6251a8d
--- /dev/null
+++ b/tests/libs/libnstest_ns_b_public2.cpp
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+static const char ns_b_public2_string[] = "libnstest_ns_b_public2.so";
+
+extern "C" const char* get_ns_b_public2_string() {
+  return ns_b_public2_string;
+}
+
+
+extern "C" const char* get_ns_a_public1_string();
+
+extern "C" const char* delegate_get_ns_a_public1_string() {
+  return get_ns_a_public1_string();
+}
diff --git a/tests/libs/libnstest_ns_b_public3.cpp b/tests/libs/libnstest_ns_b_public3.cpp
new file mode 100644
index 0000000..b332445
--- /dev/null
+++ b/tests/libs/libnstest_ns_b_public3.cpp
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+static const char ns_b_public3_string[] = "libnstest_ns_b_public3.so";
+
+extern "C" const char* get_ns_b_public3_string() {
+  return ns_b_public3_string;
+}
diff --git a/tests/signal_test.cpp b/tests/signal_test.cpp
index 207c156..5cbec88 100644
--- a/tests/signal_test.cpp
+++ b/tests/signal_test.cpp
@@ -464,33 +464,45 @@
   ASSERT_EQ(EINVAL, errno);
 }
 
-TEST(signal, sighold_sigpause_sigrelse) {
-  static int sigalrm_handler_call_count;
-  auto sigalrm_handler = [](int) { sigalrm_handler_call_count++; };
-  ScopedSignalHandler sigalrm{SIGALRM, sigalrm_handler};
-  ScopedSignalMask mask;
+static void TestSigholdSigpauseSigrelse(int sig) {
+  static int signal_handler_call_count = 0;
+  ScopedSignalHandler ssh{sig, [](int) { signal_handler_call_count++; }};
+  SignalMaskRestorer mask_restorer;
   sigset_t set;
 
-  // sighold(SIGALRM) should add SIGALRM to the signal mask ...
-  ASSERT_EQ(0, sighold(SIGALRM));
+  // sighold(SIGALRM/SIGRTMIN) should add SIGALRM/SIGRTMIN to the signal mask ...
+  ASSERT_EQ(0, sighold(sig));
   ASSERT_EQ(0, sigprocmask(SIG_SETMASK, 0, &set));
-  EXPECT_TRUE(sigismember(&set, SIGALRM));
+  EXPECT_TRUE(sigismember(&set, sig));
 
-  // ... preventing our SIGALRM handler from running ...
-  raise(SIGALRM);
-  ASSERT_EQ(0, sigalrm_handler_call_count);
-  // ... until sigpause(SIGALRM) temporarily unblocks it.
-  ASSERT_EQ(-1, sigpause(SIGALRM));
+  // ... preventing our SIGALRM/SIGRTMIN handler from running ...
+  raise(sig);
+  ASSERT_EQ(0, signal_handler_call_count);
+  // ... until sigpause(SIGALRM/SIGRTMIN) temporarily unblocks it.
+  ASSERT_EQ(-1, sigpause(sig));
   ASSERT_EQ(EINTR, errno);
-  ASSERT_EQ(1, sigalrm_handler_call_count);
+  ASSERT_EQ(1, signal_handler_call_count);
 
-  // But sigpause(SIGALRM) shouldn't permanently unblock SIGALRM.
-  ASSERT_EQ(0, sigprocmask(SIG_SETMASK, 0, &set));
-  EXPECT_TRUE(sigismember(&set, SIGALRM));
+  if (sig >= SIGRTMIN && sizeof(void*) == 8) {
+    // But sigpause(SIGALRM/SIGRTMIN) shouldn't permanently unblock SIGALRM/SIGRTMIN.
+    ASSERT_EQ(0, sigprocmask(SIG_SETMASK, 0, &set));
+    EXPECT_TRUE(sigismember(&set, sig));
 
-  ASSERT_EQ(0, sigrelse(SIGALRM));
-  ASSERT_EQ(0, sigprocmask(SIG_SETMASK, 0, &set));
-  EXPECT_FALSE(sigismember(&set, SIGALRM));
+    // Whereas sigrelse(SIGALRM/SIGRTMIN) should.
+    ASSERT_EQ(0, sigrelse(sig));
+    ASSERT_EQ(0, sigprocmask(SIG_SETMASK, 0, &set));
+    EXPECT_FALSE(sigismember(&set, sig));
+  } else {
+    // sigismember won't work for SIGRTMIN on LP32.
+  }
+}
+
+TEST(signal, sighold_sigpause_sigrelse) {
+  TestSigholdSigpauseSigrelse(SIGALRM);
+}
+
+TEST(signal, sighold_sigpause_sigrelse_RT) {
+  TestSigholdSigpauseSigrelse(SIGRTMIN);
 }
 
 TEST(signal, sigset_EINVAL) {
@@ -499,23 +511,48 @@
   ASSERT_EQ(EINVAL, errno);
 }
 
-TEST(signal, sigset) {
-  auto sigalrm_handler = [](int) { };
-  ScopedSignalHandler sigalrm{SIGALRM, sigalrm_handler};
-  ScopedSignalMask mask;
+TEST(signal, sigset_RT) {
+  static int signal_handler_call_count = 0;
+  auto signal_handler = [](int) { signal_handler_call_count++; };
+  ScopedSignalHandler ssh{SIGRTMIN, signal_handler};
+  SignalMaskRestorer mask_restorer;
 
-  // block SIGALRM so the next sigset(SIGARLM) call will return SIG_HOLD
-  sigset_t sigalrm_set;
-  sigemptyset(&sigalrm_set);
-  sigaddset(&sigalrm_set, SIGALRM);
-  ASSERT_EQ(0, sigprocmask(SIG_BLOCK, &sigalrm_set, nullptr));
-
+  ASSERT_EQ(signal_handler, sigset(SIGRTMIN, SIG_HOLD));
+#if defined(__LP64__)
   sigset_t set;
-  ASSERT_EQ(SIG_HOLD, sigset(SIGALRM, sigalrm_handler));
+  ASSERT_EQ(0, sigprocmask(SIG_BLOCK, nullptr, &set));
+  ASSERT_TRUE(sigismember(&set, SIGRTMIN));
+#endif
+
+  ASSERT_EQ(SIG_HOLD, sigset(SIGRTMIN, signal_handler));
+  ASSERT_EQ(signal_handler, sigset(SIGRTMIN, signal_handler));
+  ASSERT_EQ(0, signal_handler_call_count);
+  raise(SIGRTMIN);
+  ASSERT_EQ(1, signal_handler_call_count);
+}
+
+TEST(signal, sigset) {
+  static int signal_handler_call_count = 0;
+  auto signal_handler = [](int) { signal_handler_call_count++; };
+  ScopedSignalHandler ssh{SIGALRM, signal_handler};
+  SignalMaskRestorer mask_restorer;
+
+  ASSERT_EQ(0, signal_handler_call_count);
+  raise(SIGALRM);
+  ASSERT_EQ(1, signal_handler_call_count);
+
+  // Block SIGALRM so the next sigset(SIGARLM) call will return SIG_HOLD.
+  sigset_t set;
+  sigemptyset(&set);
+  sigaddset(&set, SIGALRM);
+  ASSERT_EQ(0, sigprocmask(SIG_BLOCK, &set, nullptr));
+
+  sigemptyset(&set);
+  ASSERT_EQ(SIG_HOLD, sigset(SIGALRM, signal_handler));
   ASSERT_EQ(0, sigprocmask(SIG_BLOCK, nullptr, &set));
   EXPECT_FALSE(sigismember(&set, SIGALRM));
 
-  ASSERT_EQ(sigalrm_handler, sigset(SIGALRM, SIG_IGN));
+  ASSERT_EQ(signal_handler, sigset(SIGALRM, SIG_IGN));
   ASSERT_EQ(0, sigprocmask(SIG_BLOCK, nullptr, &set));
   EXPECT_FALSE(sigismember(&set, SIGALRM));
 
diff --git a/tests/spawn_test.cpp b/tests/spawn_test.cpp
index d2e4ea1..dfce0dc 100644
--- a/tests/spawn_test.cpp
+++ b/tests/spawn_test.cpp
@@ -376,6 +376,7 @@
   sigset_t just_SIGALRM;
   sigemptyset(&just_SIGALRM);
   sigaddset(&just_SIGALRM, SIGALRM);
+
   ASSERT_EQ(0, posix_spawnattr_setsigdefault(&sa, &just_SIGALRM));
   ASSERT_EQ(0, posix_spawnattr_setflags(&sa, POSIX_SPAWN_SETSIGDEF));
 
@@ -393,15 +394,18 @@
   // child without first defaulting any caught signals (http://b/68707996).
   static pid_t parent = getpid();
 
+  setpgid(0, 0);
+
   pid_t pid = fork();
   ASSERT_NE(-1, pid);
 
   if (pid == 0) {
+    signal(SIGRTMIN, SIG_IGN);
     for (size_t i = 0; i < 1024; ++i) {
-      kill(0, SIGWINCH);
+      kill(0, SIGRTMIN);
       usleep(10);
     }
-    return;
+    _exit(99);
   }
 
   // We test both with and without attributes, because they used to be
@@ -417,11 +421,15 @@
 
   posix_spawnattr_t* attrs[] = { nullptr, &attr1, &attr2 };
 
-  ScopedSignalHandler ssh(SIGWINCH, [](int) { ASSERT_EQ(getpid(), parent); });
+  // We use a real-time signal because that's a tricky case for LP32
+  // because our sigset_t was too small.
+  ScopedSignalHandler ssh(SIGRTMIN, [](int) { ASSERT_EQ(getpid(), parent); });
 
   ExecTestHelper eth;
   eth.SetArgs({"true", nullptr});
   for (size_t i = 0; i < 128; ++i) {
     posix_spawn(nullptr, "true", nullptr, attrs[i % 3], eth.GetArgs(), nullptr);
   }
+
+  AssertChildExited(pid, 99);
 }