commit c55591825fedb0fe1db92fab7b654ccc15ad50d3 Author: teor teor@torproject.org Date: Fri Aug 30 21:17:56 2019 +1000

torerr: Try harder to flush raw assert messages before process termination

Some platforms (macOS, maybe others?) can swallow the last write before an abort. This issue is probably caused by a race condition between write buffer cache flushing, and process termination. So we write an extra newline, to make sure that the message always gets through.

Fixes bug 31571; bugfix on 0.3.5.1-alpha. --- changes/bug31571 | 7 +++++++ src/lib/err/torerr.c | 8 +++++++- 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/changes/bug31571 b/changes/bug31571 new file mode 100644 index 000000000..86de3537b --- /dev/null +++ b/changes/bug31571 @@ -0,0 +1,7 @@ + o Minor bugfixes (error handling): + - Report the tor version whenever an assertion fails. Previously, we only + reported the Tor version on some crashes, and some non-fatal assertions. + Fixes bug 31571; bugfix on 0.3.5.1-alpha. + - On abort, try harder to flush the output buffers of log messages. On + some platforms (macOS), log messages can be discarded when the process + terminates. Fixes bug 31571; bugfix on 0.3.5.1-alpha. diff --git a/src/lib/err/torerr.c b/src/lib/err/torerr.c index 88b19b732..6b5224273 100644 --- a/src/lib/err/torerr.c +++ b/src/lib/err/torerr.c @@ -146,13 +146,19 @@ tor_raw_assertion_failed_msg_(const char *file, int line, const char *expr, format_dec_number_sigsafe(line, linebuf, sizeof(linebuf)); tor_log_err_sigsafe("INTERNAL ERROR: Raw assertion failed in ", get_tor_backtrace_version(), " at ", - file, ":", linebuf, ": ", expr, NULL); + file, ":", linebuf, ": ", expr, "\n", NULL); if (msg) { tor_log_err_sigsafe_write(msg); tor_log_err_sigsafe_write("\n"); }

dump_stack_symbols_to_error_fds(); + + /* Some platforms (macOS, maybe others?) can swallow the last write before an + * abort. This issue is probably caused by a race condition between write + * buffer cache flushing, and process termination. So we write an extra + * newline, to make sure that the message always gets through. */ + tor_log_err_sigsafe_write("\n"); }

/* As format_{hex,dex}_number_sigsafe, but takes a <b>radix</b> argument