[tor-commits] [tor/maint-0.4.1] Handle errors from execve() in the Unix process backend more gracefully.

[teor at torproject.org]

commit 9915b8f0bc3e6a1b6c8413fbb87c41137ea89104
Author: Alexander Færøy <ahf at torproject.org>
Date:   Thu Oct 17 16:39:05 2019 +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
---
 changes/bug31810               | 4 ++++
 src/lib/process/process_unix.c | 9 +--------
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/changes/bug31810 b/changes/bug31810
new file mode 100644
index 000000000..628d12f09
--- /dev/null
+++ 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
index 790ab897e..b102afff4 100644
--- 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. */