Fix read_all() and write_all() to always set errno on failure #86
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read(2) will return 0 to designate end-of-file and in this case it will not set errno, but read_all() will return false, leaving errno as it were before the call. An EOF is not an error for read(2) itself, but read_all() is supposed to read exactly the requested number of bytes (not less), so set errno to EBADMSG "Bad message" in this case.
write(2) could return 0 (no bytes written), but that is not an error condition, write(2) will not set errno, and the operation should be retried. This patch, in addition to making a retry on 0, also ensures that errno is always set whenever false is returned from write_all().
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About the failing travis tests: I can reproduce some hangs (maybe the same as in travis, maybe not) even without this patch, using 39b46a0 (latest or |
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Make sure
errnois always set iffalseis to be returned. Also retry ifwrite(2)returns 0.