[PATCH] D48451: [sanitizers_common] when spawning a subprocess for symbolizers, use posix_spawn instead of fork()

[Alex Gaynor via Phabricator via llvm-commits]

alex created this revision.
alex added reviewers: kcc, eugenis.
Herald added subscribers: Sanitizers, llvm-commits, delcypher, kubamracek.

Fixes: https://github.com/google/sanitizers/issues/979

Note that I can't seem to get the tests running locally, so I haven't been able to properly verify this!


Repository:
  rCRT Compiler Runtime

https://reviews.llvm.org/D48451

Files:
  lib/sanitizer_common/sanitizer_posix_libcdep.cc


Index: lib/sanitizer_common/sanitizer_posix_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_posix_libcdep.cc
+++ lib/sanitizer_common/sanitizer_posix_libcdep.cc
@@ -29,6 +29,7 @@
 #include <fcntl.h>
 #include <pthread.h>
 #include <signal.h>
+#include <spawn.h>
 #include <stdlib.h>
 #include <sys/mman.h>
 #include <sys/resource.h>
@@ -45,6 +46,8 @@
 #define MAP_NORESERVE 0
 #endif
 
+extern char **environ;
+
 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
 
 namespace __sanitizer {
@@ -448,40 +451,40 @@
     }
   });
 
-  int pid = internal_fork();
-
-  if (pid < 0) {
-    int rverrno;
-    if (internal_iserror(pid, &rverrno)) {
-      Report("WARNING: failed to fork (errno %d)\n", rverrno);
-    }
-    return pid;
+  posix_spawn_file_actions_t fa;
+  int result = posix_spawn_file_actions_init(&fa);
+  if (result != 0) {
+    Report("WARNING: posix_spawn_file_actions_init failed (result %d)\n", result);
+    return -1;
   }
-
-  if (pid == 0) {
-    // Child subprocess
-    if (stdin_fd != kInvalidFd) {
-      internal_close(STDIN_FILENO);
-      internal_dup2(stdin_fd, STDIN_FILENO);
-      internal_close(stdin_fd);
+  if (stdin_fd != kInvalidFd) {
+    result = posix_spawn_file_actions_adddup2(&fa, stdin_fd, STDIN_FILENO);
+    if (result != 0) {
+      Report("WARNING: posix_spawn_file_actions_adddup2 failed (result %d)\n", result);
+      return -1;
     }
-    if (stdout_fd != kInvalidFd) {
-      internal_close(STDOUT_FILENO);
-      internal_dup2(stdout_fd, STDOUT_FILENO);
-      internal_close(stdout_fd);
+  }
+  if (stdout_fd != kInvalidFd) {
+    result = posix_spawn_file_actions_adddup2(&fa, stdout_fd, STDOUT_FILENO);
+    if (result != 0) {
+      Report("WARNING: posix_spawn_file_actions_adddup2 failed (result %d)\n", result);
+      return -1;
     }
-    if (stderr_fd != kInvalidFd) {
-      internal_close(STDERR_FILENO);
-      internal_dup2(stderr_fd, STDERR_FILENO);
-      internal_close(stderr_fd);
+  }
+  if (stderr_fd != kInvalidFd) {
+    result = posix_spawn_file_actions_adddup2(&fa, stderr_fd, STDERR_FILENO);
+    if (result != 0) {
+      Report("WARNING: posix_spawn_file_actions_adddup2 failed (result %d)\n", result);
+      return -1;
     }
-
-    for (int fd = sysconf(_SC_OPEN_MAX); fd > 2; fd--) internal_close(fd);
-
-    execv(program, const_cast<char **>(&argv[0]));
-    internal__exit(1);
   }
 
+  pid_t pid;
+  result = posix_spawn(&pid, program, &fa, nullptr, const_cast<char **>(argv), environ);
+  if (result != 0) {
+    Report("WARNING: failed to spawn process (result %d)\n", result);
+    return -1;
+  }
   return pid;
 }
 


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