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traffic_crashlog: emit a well-formed report when the backtrace is empty #13360

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Merged
moonchen merged 1 commit into from
Jul 5, 2026
+6 −2
Merged

traffic_crashlog: emit a well-formed report when the backtrace is empty #13360

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8 changes: 6 additions & 2 deletions src/traffic_crashlog/traffic_crashlog.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -145,14 +145,18 @@ crashlog_write_backtrace(FILE *fp, const crashlog_target &target)
// can also happen without a debugger. Possibly in that case, there is a race with the
// kernel locking the process information?

if (mgmterr == 0 && trace != nullptr) {
if (mgmterr == 0 && trace != nullptr && trace[0] != '\0') {
// ServerBacktrace succeeded - this gives us backtraces for all threads.
fprintf(fp, "%s", trace);
free(trace);
return true;
}
free(trace);

@JosiahWI JosiahWI Jul 3, 2026

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This is a use case for free accepting nullptr. Interesting!


// ServerBacktrace failed. Fall back to the in-process backtrace from the crashing thread.
// ServerBacktrace reports success but yields no frames when the target's thread list is
// unreadable -- e.g. a fast-aborting target has already exited by the time the forked
// helper attaches. Fall back to the in-process backtrace from the crashing thread rather
// than emitting an empty report.
if ((target.flags & CRASHLOG_HAVE_BACKTRACE) && !target.backtrace.empty()) {
fprintf(fp, "Crashing Thread Backtrace:\n%s", target.backtrace.c_str());
return true;
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