fdsan: minor refactoring.
Make it easier for other code to parse the fdsan table themselves by
making it so that they can include the bionic_fdsan.h header to get a
struct definition with the layout without bringing in other
dependencies.
Test: treehugger
Change-Id: I3583ef113991234aa83cd193a4eb139ad06737c7
diff --git a/libc/bionic/fdsan.cpp b/libc/bionic/fdsan.cpp
index b0c38bb..918fd37 100644
--- a/libc/bionic/fdsan.cpp
+++ b/libc/bionic/fdsan.cpp
@@ -50,6 +50,60 @@
static constexpr const char* kFdsanPropertyName = "debug.fdsan";
+template<size_t inline_fds>
+FdEntry* FdTableImpl<inline_fds>::at(size_t idx) {
+ if (idx < inline_fds) {
+ return &entries[idx];
+ }
+
+ // Try to create the overflow table ourselves.
+ FdTableOverflow* local_overflow = atomic_load(&overflow);
+ if (__predict_false(!local_overflow)) {
+ struct rlimit rlim = { .rlim_max = 32768 };
+ getrlimit(RLIMIT_NOFILE, &rlim);
+ rlim_t max = rlim.rlim_max;
+
+ if (max == RLIM_INFINITY) {
+ // This isn't actually possible (the kernel has a hard limit), but just
+ // in case...
+ max = 32768;
+ }
+
+ if (idx > max) {
+ // This can happen if an fd is created and then the rlimit is lowered.
+ // In this case, just return nullptr and ignore the fd.
+ return nullptr;
+ }
+
+ size_t required_count = max - inline_fds;
+ size_t required_size = sizeof(FdTableOverflow) + required_count * sizeof(FdEntry);
+ size_t aligned_size = __BIONIC_ALIGN(required_size, PAGE_SIZE);
+ size_t aligned_count = (aligned_size - sizeof(FdTableOverflow)) / sizeof(FdEntry);
+
+ void* allocation =
+ mmap(nullptr, aligned_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (allocation == MAP_FAILED) {
+ async_safe_fatal("fdsan: mmap failed: %s", strerror(errno));
+ }
+
+ FdTableOverflow* new_overflow = reinterpret_cast<FdTableOverflow*>(allocation);
+ new_overflow->len = aligned_count;
+
+ if (atomic_compare_exchange_strong(&overflow, &local_overflow, new_overflow)) {
+ local_overflow = new_overflow;
+ } else {
+ // Someone beat us to it. Deallocate and use theirs.
+ munmap(allocation, aligned_size);
+ }
+ }
+
+ size_t offset = idx - inline_fds;
+ if (local_overflow->len < offset) {
+ return nullptr;
+ }
+ return &local_overflow->entries[offset];
+}
+
void __libc_init_fdsan() {
constexpr auto default_level = ANDROID_FDSAN_ERROR_LEVEL_WARN_ONCE;
const prop_info* pi = __system_property_find(kFdsanPropertyName);
@@ -77,7 +131,7 @@
nullptr);
}
-static FdTable<128>* GetFdTable() {
+static FdTable* GetFdTable() {
if (!__libc_shared_globals) {
return nullptr;
}
diff --git a/libc/private/bionic_fdsan.h b/libc/private/bionic_fdsan.h
index b93260b..de14cf8 100644
--- a/libc/private/bionic_fdsan.h
+++ b/libc/private/bionic_fdsan.h
@@ -38,8 +38,6 @@
#include <sys/resource.h>
#include <sys/user.h>
-#include <async_safe/log.h>
-
struct FdEntry {
_Atomic(uint64_t) close_tag;
};
@@ -50,62 +48,14 @@
};
template <size_t inline_fds>
-struct FdTable {
+struct FdTableImpl {
+ uint32_t version; // currently 0, and hopefully it'll stay that way.
_Atomic(android_fdsan_error_level) error_level;
FdEntry entries[inline_fds];
_Atomic(FdTableOverflow*) overflow;
- FdEntry* at(size_t idx) {
- if (idx < inline_fds) {
- return &entries[idx];
- }
-
- // Try to create the overflow table ourselves.
- FdTableOverflow* local_overflow = atomic_load(&overflow);
- if (__predict_false(!local_overflow)) {
- struct rlimit rlim = { .rlim_max = 32768 };
- getrlimit(RLIMIT_NOFILE, &rlim);
- rlim_t max = rlim.rlim_max;
-
- if (max == RLIM_INFINITY) {
- // This isn't actually possible (the kernel has a hard limit), but just
- // in case...
- max = 32768;
- }
-
- if (idx > max) {
- // This can happen if an fd is created and then the rlimit is lowered.
- // In this case, just return nullptr and ignore the fd.
- return nullptr;
- }
-
- size_t required_count = max - inline_fds;
- size_t required_size = sizeof(FdTableOverflow) + required_count * sizeof(FdEntry);
- size_t aligned_size = __BIONIC_ALIGN(required_size, PAGE_SIZE);
- size_t aligned_count = (aligned_size - sizeof(FdTableOverflow)) / sizeof(FdEntry);
-
- void* allocation =
- mmap(nullptr, aligned_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
- if (allocation == MAP_FAILED) {
- async_safe_fatal("fdsan: mmap failed: %s", strerror(errno));
- }
-
- FdTableOverflow* new_overflow = reinterpret_cast<FdTableOverflow*>(allocation);
- new_overflow->len = aligned_count;
-
- if (atomic_compare_exchange_strong(&overflow, &local_overflow, new_overflow)) {
- local_overflow = new_overflow;
- } else {
- // Someone beat us to it. Deallocate and use theirs.
- munmap(allocation, aligned_size);
- }
- }
-
- size_t offset = idx - inline_fds;
- if (local_overflow->len < offset) {
- return nullptr;
- }
- return &local_overflow->entries[offset];
- }
+ FdEntry* at(size_t idx);
};
+
+using FdTable = FdTableImpl<128>;
diff --git a/libc/private/bionic_globals.h b/libc/private/bionic_globals.h
index e569209..eee33c9 100644
--- a/libc/private/bionic_globals.h
+++ b/libc/private/bionic_globals.h
@@ -46,7 +46,7 @@
// Globals shared between the dynamic linker and libc.so.
struct libc_shared_globals {
- FdTable<128> fd_table;
+ FdTable fd_table;
};
__LIBC_HIDDEN__ extern libc_shared_globals* __libc_shared_globals;