fix: close fd 0 when mmap fails

src/modulefinder/sentry_modulefinder_linux.c

@@ -74,7 +74,7 @@ sentry__mmap_file(sentry_mmap_t *rv, const char *path)
     return true;
 
 fail:
-    if (fd > 0) {
+    if (fd >= 0) {
         close(fd);
     }
     rv->ptr = NULL;

tests/unit/test_modulefinder.c

@@ -4,6 +4,9 @@
 
 #ifdef SENTRY_PLATFORM_LINUX
 #    include "modulefinder/sentry_modulefinder_linux.h"
+#    include <fcntl.h>
+#    include <stdlib.h>
+#    include <unistd.h>
 #endif
 
 SENTRY_TEST(module_finder)
@@ -74,6 +77,33 @@ SENTRY_TEST(module_addr)
 #endif
 }
 
+SENTRY_TEST(mmap_file_closes_fd_zero_on_failure)
+{
+#if !defined(SENTRY_PLATFORM_LINUX)
+    SKIP_TEST();
+#else
+    char tmp_path[] = "/tmp/sentry-native-mmap-XXXXXX";
+    int tmp_fd = mkstemp(tmp_path);
+    TEST_ASSERT(tmp_fd >= 0);
+    close(tmp_fd);
+
+    int saved_stdin = dup(STDIN_FILENO);
+    TEST_ASSERT(saved_stdin >= 0);
+    close(STDIN_FILENO);
+
+    sentry_mmap_t mmap = { 0 };
+    bool mapped = sentry__mmap_file(&mmap, tmp_path);
+    int fd_flags = fcntl(STDIN_FILENO, F_GETFD);
+
+    dup2(saved_stdin, STDIN_FILENO);
+    close(saved_stdin);
+    unlink(tmp_path);
+
+    TEST_CHECK(!mapped);
+    TEST_CHECK(fd_flags == -1);
+#endif
+}
+
 SENTRY_TEST(procmaps_parser)
 {
 #if !defined(SENTRY_PLATFORM_LINUX) || __SIZEOF_POINTER__ != 8

tests/unit/tests.inc

@@ -222,6 +222,7 @@ XX(minidump_stream_types)
 XX(minidump_structures_packed)
 XX(minidump_system_info)
 XX(minidump_thread_structure)
+XX(mmap_file_closes_fd_zero_on_failure)
 XX(module_addr)
 XX(module_finder)
 XX(mpack_newlines)