Log the thread id and name for fatal signals.

This adds the thread id and name to the "Fatal signal" logging,
making it easier to track down where in process it actually crashed.

Change-Id: I17a365042b2f10b161debe98bc2e7070af055dfb

diff --git a/linker/debugger.c b/linker/debugger.c
index ef8286c..40411b1 100644 (file)
--- a/linker/debugger.c
+++ b/linker/debugger.c
@@ -32,6 +32,7 @@
 #include <ctype.h>
 #include <signal.h>
 #include <sys/mman.h>
+#include <sys/prctl.h>
 #include <errno.h>
 
 #include "linker.h"
@@ -46,6 +47,8 @@ void notify_gdb_of_libraries();
         ret = (cond); \
     } while (ret < 0 && errno == EINTR)
 
+// see man(2) prctl, specifically the section about PR_GET_NAME
+#define MAX_TASK_NAME_LEN (16)
 
 static int socket_abstract_client(const char *name, int type)
 {
@@ -100,6 +103,7 @@ static int socket_abstract_client(const char *name, int type)
 static void logSignalSummary(int signum, const siginfo_t* info)
 {
     char buffer[128];
+    char threadname[MAX_TASK_NAME_LEN + 1]; // one more for termination
 
     char* signame;
     switch (signum) {
@@ -113,9 +117,16 @@ static void logSignalSummary(int signum, const siginfo_t* info)
         default:        signame = "???";        break;
     }
 
+    if (prctl(PR_GET_NAME, (unsigned long)threadname, 0, 0, 0) != 0) {
+        strcpy(threadname, "<name unknown>");
+    } else {
+        // short names are null terminated by prctl, but the manpage
+        // implies that 16 byte names are not.
+        threadname[MAX_TASK_NAME_LEN] = 0;
+    }
     format_buffer(buffer, sizeof(buffer),
-        "Fatal signal %d (%s) at 0x%08x (code=%d)",
-        signum, signame, info->si_addr, info->si_code);
+        "Fatal signal %d (%s) at 0x%08x (code=%d), thread %d (%s)",
+        signum, signame, info->si_addr, info->si_code, gettid(), threadname);
 
     __libc_android_log_write(ANDROID_LOG_FATAL, "libc", buffer);
 }