Fixed crashes on Alpine when profiling native apps

SAP · Oct 10, 2024 · 3992d6a · 3992d6a
1 parent 4208d5c
commit 3992d6a
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Showing 4 changed files with 19 additions and 12 deletions.
diff --git a/src/asprof.h b/src/asprof.h
@@ -14,6 +14,8 @@
 #  define DLLEXPORT __attribute__((visibility("default"),externally_visible))
 #endif
 
+#define WEAK __attribute__((weak))
+
 #ifdef __cplusplus
 extern "C" {
 #endif

diff --git a/src/chk.cpp b/src/chk.cpp
@@ -8,13 +8,13 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include "asprof.h"
 
 
 // libgcc refers to __sprintf_chk, but there is no such symbol in musl libc.
 // Export a weak symbol in order to make profiler library work both with glibc and musl.
-#define WEAK_EXPORT __attribute__((visibility("default"),externally_visible,weak))
 
-extern "C" WEAK_EXPORT
+extern "C" WEAK DLLEXPORT
 int __sprintf_chk(char* s, int flag, size_t slen, const char* format, ...) {
     va_list args;
     va_start(args, format);

diff --git a/src/hooks.cpp b/src/hooks.cpp
@@ -14,6 +14,11 @@
 #include "profiler.h"
 
 
+#define ADDRESS_OF(sym) ({ \
+    void* addr = dlsym(RTLD_NEXT, #sym); \
+    addr != NULL ? (sym##_t)addr : sym;  \
+})
+
 typedef void* (*ThreadFunc)(void*);
 
 struct ThreadEntry {
@@ -103,21 +108,21 @@ static void* dlopen_hook(const char* filename, int flags) {
 
 // LD_PRELOAD hooks
 
-extern "C" DLLEXPORT
+extern "C" WEAK DLLEXPORT
 int pthread_create(pthread_t* thread, const pthread_attr_t* attr, ThreadFunc start_routine, void* arg) {
     if (_orig_pthread_create == NULL) {
-        _orig_pthread_create = (pthread_create_t)dlsym(RTLD_NEXT, "pthread_create");
+        _orig_pthread_create = ADDRESS_OF(pthread_create);
     }
     if (Hooks::initialized()) {
         return pthread_create_hook(thread, attr, start_routine, arg);
     }
     return _orig_pthread_create(thread, attr, start_routine, arg);
 }
 
-extern "C" DLLEXPORT
+extern "C" WEAK DLLEXPORT
 void pthread_exit(void* retval) {
     if (_orig_pthread_exit == NULL) {
-        _orig_pthread_exit = (pthread_exit_t)dlsym(RTLD_NEXT, "pthread_exit");
+        _orig_pthread_exit = ADDRESS_OF(pthread_exit);
     }
     if (Hooks::initialized()) {
         pthread_exit_hook(retval);
@@ -127,10 +132,10 @@ void pthread_exit(void* retval) {
     abort();  // to suppress gcc warning
 }
 
-extern "C" DLLEXPORT
+extern "C" WEAK DLLEXPORT
 void* dlopen(const char* filename, int flags) {
     if (_orig_dlopen == NULL) {
-        _orig_dlopen = (dlopen_t)dlsym(RTLD_NEXT, "dlopen");
+        _orig_dlopen = ADDRESS_OF(dlopen);
     }
     if (Hooks::initialized()) {
         return dlopen_hook_impl(filename, flags, false);
@@ -152,9 +157,9 @@ bool Hooks::init(bool attach) {
     Profiler::setupSignalHandlers();
 
     if (attach) {
-        _orig_pthread_create = (pthread_create_t)dlsym(RTLD_NEXT, "pthread_create");
-        _orig_pthread_exit = (pthread_exit_t)dlsym(RTLD_NEXT, "pthread_exit");
-        _orig_dlopen = (dlopen_t)dlsym(RTLD_NEXT, "dlopen");
+        _orig_pthread_create = ADDRESS_OF(pthread_create);
+        _orig_pthread_exit = ADDRESS_OF(pthread_exit);
+        _orig_dlopen = ADDRESS_OF(dlopen);
         patchLibraries();
     }
 

diff --git a/src/vmStructs.cpp b/src/vmStructs.cpp
@@ -582,7 +582,7 @@ void VMStructs::initThreadBridge() {
 }
 
 VMThread* VMThread::current() {
-    return (VMThread*)pthread_getspecific((pthread_key_t)_tls_index);
+    return _tls_index >= 0 ? (VMThread*)pthread_getspecific((pthread_key_t)_tls_index) : NULL;
 }
 
 int VMThread::nativeThreadId(JNIEnv* jni, jthread thread) {