commit bfec3a315000e9fcfc8e2d3fcef25e747e3d2053
author Elliott Hughes <enh@google.com> Thu May 24 19:03:07 2012 -0700
committer Brian Carlstrom <bdc@google.com> Tue May 14 19:49:22 2013 -0700
tree 8e8c717620381e8f480470cce4517b54d57ed729
parent 7382459eca9632168b9d393bc77fb62bc21bb67a

Add basic Darwin support to libcorkscrew.

This might not seem like much, but it's already better than Mac OS'
backtrace(3).

(cherry picked from commit 2a46f6293f19b9d6100187fbd53088088e671b88)

Change-Id: I197b06c4c19f728ad6f194b2f473bd9dcd99b8a6

libcorkscrew/backtrace.c

diff --git a/libcorkscrew/backtrace.c b/libcorkscrew/backtrace.c
index 03dbd53..b365e5b 100644
--- a/libcorkscrew/backtrace.c
+++ b/libcorkscrew/backtrace.c
@@ -33,7 +33,6 @@
 #include <unwind.h>
 #include <cutils/log.h>
 #include <cutils/atomic.h>
-#include <elf.h>
 
 #define __USE_GNU // For dladdr(3) in glibc.
 #include <dlfcn.h>
@@ -43,6 +42,15 @@
 // Bionic implements and exports gettid but only implements tgkill.
 extern int tgkill(int tgid, int tid, int sig);
 
+#elif defined(__APPLE__)
+
+#include <sys/syscall.h>
+
+// Mac OS >= 10.6 has a system call equivalent to Linux's gettid().
+static pid_t gettid() {
+  return syscall(SYS_thread_selfid);
+}
+
 #else
 
 // glibc doesn't implement or export either gettid or tgkill.
@@ -97,7 +105,7 @@
     state.returned_frames = 0;
     init_memory(&state.memory, milist);
 
-    _Unwind_Reason_Code rc =_Unwind_Backtrace(unwind_backtrace_callback, &state);
+    _Unwind_Reason_Code rc = _Unwind_Backtrace(unwind_backtrace_callback, &state);
 
     release_my_map_info_list(milist);
 
@@ -146,7 +154,9 @@
 
     ALOGV("Unwinding thread %d from thread %d.", tid, gettid());
 
-#ifdef CORKSCREW_HAVE_ARCH
+    // TODO: there's no tgkill(2) on Mac OS, so we'd either need the
+    // mach_port_t or the pthread_t rather than the tid.
+#if defined(CORKSCREW_HAVE_ARCH) && !defined(__APPLE__)
     struct sigaction act;
     struct sigaction oact;
     memset(&act, 0, sizeof(act));
@@ -305,20 +315,20 @@
         const backtrace_symbol_t* symbol, char* buffer, size_t bufferSize) {
     const char* mapName = symbol->map_name ? symbol->map_name : "<unknown>";
     const char* symbolName = symbol->demangled_name ? symbol->demangled_name : symbol->symbol_name;
-    size_t fieldWidth = (bufferSize - 80) / 2;
+    int fieldWidth = (bufferSize - 80) / 2;
     if (symbolName) {
         uint32_t pc_offset = symbol->relative_pc - symbol->relative_symbol_addr;
         if (pc_offset) {
-            snprintf(buffer, bufferSize, "#%02d  pc %08x  %.*s (%.*s+%u)",
-                    frameNumber, symbol->relative_pc, fieldWidth, mapName,
+            snprintf(buffer, bufferSize, "#%02u  pc %p  %.*s (%.*s+%u)",
+                    frameNumber, (void*) symbol->relative_pc, fieldWidth, mapName,
                     fieldWidth, symbolName, pc_offset);
         } else {
-            snprintf(buffer, bufferSize, "#%02d  pc %08x  %.*s (%.*s)",
-                    frameNumber, symbol->relative_pc, fieldWidth, mapName,
+            snprintf(buffer, bufferSize, "#%02u  pc %p  %.*s (%.*s)",
+                    frameNumber, (void*) symbol->relative_pc, fieldWidth, mapName,
                     fieldWidth, symbolName);
         }
     } else {
-        snprintf(buffer, bufferSize, "#%02d  pc %08x  %.*s",
-                frameNumber, symbol->relative_pc, fieldWidth, mapName);
+        snprintf(buffer, bufferSize, "#%02u  pc %p  %.*s",
+                frameNumber, (void*) symbol->relative_pc, fieldWidth, mapName);
     }
 }