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Comment by mieko | Hacker News Reader

I'd personally err on the side of clearer clean-up code, but this a good point (and a view shared with glibc and BSD-derived libcs that intentionally segfault in this case).

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I wouldn't describe that as an "intentional" segfault, but rather a "natural" one, the default behaviour you get on a system with an MMU. The null case with free() is a special-case extra check explicitly inserted in the code.

"Intentional" was perhaps the wrong word for glibc, but BSD libc (at least on FreeBSD and OS X) actually document it as intentional:

    NOTES
    
    The fclose() function does not handle NULL arguments; they will result in 
    a segmentation violation.  This is intentional - it makes it easier to make 
    sure programs written under FreeBSD are bug free.  This behaviour is an 
    implementation detail, and programs should not rely upon it.

I thought I remembered similar wording for glibc, but I appear to have been mistaken.

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