tor

commit 85b4a5c27659a7d162c2e476e1e0dfbeefd73095
parent 8ac9af2330e99032445055d6728e9b3fe34a3470
Author: Alexander Færøy <ahf@torproject.org>
Date:   Thu, 17 Oct 2019 16:39:05 +0200

Handle errors from execve() in the Unix process backend more gracefully.

This patch removes a call to tor_assert_unreached() after execve()
failed. This assertion leads to the child process emitting a stack trace
on its standard output, which makes the error harder for the user to
demystify, since they think it is an internal error in Tor instead of
"just" being a "no such file or directory" error.

The process will now instead output "Error from child process: X" where
X is the stringified version of the errno value.

See: https://bugs.torproject.org/31810

Diffstat:
A
changes/bug31810
 | 
4
++++
M
src/lib/process/process_unix.c
 | 
9
+--------

2 files changed, 5 insertions(+), 8 deletions(-)
diff --git a/changes/bug31810 b/changes/bug31810
@@ -0,0 +1,4 @@
+  o Minor bugfixes (process management):
+    - Remove assertion in the Unix process backend. This assertion would trigger
+      when a new process is spawned where the executable is not found leading to
+      a stack trace from the child process. Fixes bug 31810; bugfix on 0.4.0.1-alpha.
diff --git a/src/lib/process/process_unix.c b/src/lib/process/process_unix.c
@@ -253,22 +253,15 @@ process_unix_exec(process_t *process)
     process_environment_t *env = process_get_environment(process);
 
     /* Call the requested program. */
-    retval = execve(argv[0], argv, env->unixoid_environment_block);
+    execve(argv[0], argv, env->unixoid_environment_block);
 
     /* If we made it here it is because execve failed :-( */
-    if (-1 == retval)
-      fprintf(stderr, "Call to execve() failed: %s", strerror(errno));
-
     tor_free(argv);
     process_environment_free(env);
 
-    tor_assert_unreached();
-
  error:
-    /* LCOV_EXCL_START */
     fprintf(stderr, "Error from child process: %s", strerror(errno));
     _exit(1);
-    /* LCOV_EXCL_STOP */
   }
 
   /* We are in the parent process. */