Re: [libvirt] [PATCH] libxl: Check for regcomp failure

On 09/04/2013 02:03 PM, Jim Fehlig wrote: >> >> Yeah, good question. I found a few occurrences of regcomp() and friends >> throughout the sources and most seem to do regfree() even when regcomp() >> fails. The man page is not very clear, but the notes on regfree() >> suggest it is not necessary >> >> POSIX Pattern Buffer Freeing >> Supplying regfree() with a precompiled pattern buffer, preg will >> free the memory allocated to the pattern buffer by the compiling >> process, regcomp(). >> >> But does the pattern buffer contain any allocated memory when regcomp() >> fails? The notes on regcomp() are not clear about this. Thankfully, we can read the source :) In glibc, regcomp assigns into preg, but is careful to undo any allocation on failure; it is also careful to make regfree() a no-op on an already-freed buffer (whether by calling regfree() twice in a row, or using it on preg after a failed regcomp). Gnulib copies this behavior. But it is not universally standard: