fix: open the file lock on "UNIX" with O_RDRW (#791)

For some reason, the file lock on UNIX was always opened using O_RDONLY.
This doesn't make sense in combination with O_TRUNC, since this is a
write operation. On some systems (customer-scenario was AWS EFS) this
will lead to an EBADF if we try to flock that descriptor. The docs
consider this combination undefined.

This change also gets rid of the AIX compile conditional, since this
should work on all systems now.

I also added a warning to the run-initialization in case we get an error
when trying to lock.

macOS-11 CI runner needed to be updated to llvm15:

https://github.com/actions/runner-images/blob/macOS-11/20230117.2/images/macos/macos-11-Readme.md

.github/workflows/ci.yml

@@ -134,7 +134,7 @@ jobs:
 
       - name: Expose llvm PATH for Mac
         if: ${{ runner.os == 'macOS' }}
-        run: echo $(brew --prefix llvm@14)/bin >> $GITHUB_PATH
+        run: echo $(brew --prefix llvm@15)/bin >> $GITHUB_PATH
 
       - name: Installing Android SDK Dependencies
         if: ${{ env['ANDROID_API'] }}

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 **Fixes**:
 
+- Open the database file-lock on "UNIX" with `O_RDRW` ([#791](https://github.com/getsentry/sentry-native/pull/791))
 - Better error messages in `sentry_transport_curl`. ([#777](https://github.com/getsentry/sentry-native/pull/777))
 - Fix sporadic crash on Windows due to race condition when initializing background-worker thread-id. ([#785](https://github.com/getsentry/sentry-native/pull/785))
 - Increased curl headers buffer size to 512 (in `sentry_transport_curl`). ([#784](https://github.com/getsentry/sentry-native/pull/784))

src/path/sentry_path_unix.c

@@ -54,15 +54,7 @@ sentry__filelock_try_lock(sentry_filelock_t *lock)
 {
     lock->is_locked = false;
 
-    const int oflags =
-#ifdef SENTRY_PLATFORM_AIX
-        // Under AIX, O_TRUNC can only be set if it can be written to, and
-        // flock (well, fcntl) will return EBADF if the fd is not read-write.
-        O_RDWR | O_CREAT | O_TRUNC;
-#else
-        O_RDONLY | O_CREAT | O_TRUNC;
-#endif
-    int fd = open(lock->path->path, oflags,
+    int fd = open(lock->path->path, O_RDWR | O_CREAT | O_TRUNC,
         S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
     if (fd < 0) {
         return false;

src/sentry_database.c

@@ -4,6 +4,7 @@
 #include "sentry_json.h"
 #include "sentry_options.h"
 #include "sentry_session.h"
+#include <errno.h>
 #include <string.h>
 
 sentry_run_t *
@@ -49,13 +50,20 @@ sentry__run_new(const sentry_path_t *database_path)
     run->run_path = run_path;
     run->session_path = session_path;
     run->lock = sentry__filelock_new(lock_path);
-    if (!run->lock || !sentry__filelock_try_lock(run->lock)) {
-        sentry__run_free(run);
-        return NULL;
+    if (!run->lock) {
+        goto error;
+    }
+    if (!sentry__filelock_try_lock(run->lock)) {
+        SENTRY_WARNF("failed to lock file \"%s\" (%s)", lock_path->path,
+            strerror(errno));
+        goto error;
     }
-
     sentry__path_create_dir_all(run->run_path);
     return run;
+
+error:
+    sentry__run_free(run);
+    return NULL;
 }
 
 void