Date: Thu, 2 Aug 2018 13:51:21 -0400 From: Jonny Prouty <jonathanprouty@...il.com> To: musl@...ts.openwall.com Subject: Unexpected behaviour writing to /dev/full Hello all, I have a question regarding the interaction of atexit() (I believe its atexit, anyways) and exit statuses. First the issue I stumbled across, so you'll see where I'm coming from: # ls "$HOME" > /dev/full; echo $? 0 # echo "$HOME" > /dev/full; echo $? 1 I expected neither command to return 0 since ultimately an ENOSPC should be returned when writing to /dev/full. Indeed, failure statuses are returned for 'ls' and 'echo' derived from binaries built against glibc. I tried to walk the musl code and it looks like the exit codes are being set (or not set) by atexit(). In the case of 'ls', it seems that it was able to successfully get a directory listing, but the final fflush() of the output buffer fails with ENOSPC, but that is lost because it happened as a result of some function that was registered with atexit. I *think*. This interpretation is also borne of a desire to be able to ascribe this to the undefined re-entrant exit behaviour described in "Re-entrancy of exit" at https://wiki.musl-libc.org/functional-differences-from-glibc.html. 'echo' would be failing (as expected) because presumably stdout is flushed before it exits. Regardless, the fact that writing to /dev/full can return success seems wrong. Any thoughts are much appreciated. Please CC me on any responses. Thanks! Jonny P.S. musl behaves similarly to uClibc and uClibc-ng in my testing. Content of type "text/html" skipped
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