commit 9915b8f0bc3e6a1b6c8413fbb87c41137ea89104 Author: Alexander Færøy ahf@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. */