kjellsbells 7 days ago

around line 663. there's a call to strrchr, checking for a period in the filename. then immediately after that, there's a strlen that uses the results.

Which is fine, unless the first call returns NULL, because there was no period in the name, and then the program will crash.

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  • JdeBP 7 days ago

    Much has been said about Daniel J. Bernstein eschewing the Standard C library in publicfile and other softwares. But Bernstein's str_rchr() function was designed to expressly avoid this well-known gotcha of the Standard C string functions.

    Here's str_rchr() which uses the offset of the terminating NUL as the returned sentinel value:

    * https://github.com/jdebp/djbwares/blob/trunk/source/str_rchr...

    And here's it being used (by publicfile's httpd and indeed other programs) to find the basename's extension in order to infer a content type:

    * https://github.com/jdebp/djbwares/blob/trunk/source/filetype...

    The extension is always a non-NULL string, that can always be passed to str_equal(). It is just sometimes a zero-length string.

    It's possible, but a bit clunky, to achieve the same effect with two successive calls to Standard C/C++ strrchr(), or strchr(), the second being:

            if (!result) result = std::strchr(s, '\0');
    Here's me doing that in my own code:

    * https://github.com/jdebp/nosh/blob/c8d635c284b41b483067d5f58...

    One can get very lost in the weeds on the comparative merits on different instruction architectures of compiler intrinsics, explicit loop unrolling, whole program optimization, and whatnot. (-:

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