> Date: Tue, 8 Mar 2011 12:25:37 +0100 > From: Kai Tietz <ktiet...@googlemail.com> > Cc: binut...@sourceware.org, gdb-patc...@sourceware.org, > gcc-patches@gcc.gnu.org > > > Btw, why do we need filename_dirchr? The use case for > > filename_dirrchr is clear, but in what situations will we need the > > other one? > > As the comment notes. strchr/strrchr searches for one character. This > is for unix-file-system normally slash. On DOS based file-systems > there are two characters representing a directory-separator. Slash and > Backslash. Therefore this routine takes care that both are handled > similiar to a single character searching.
We are miscommunicating. I was asking when would a program want to find the _first_ directory separator character in a file name. Searching for the last one is a frequent use case: when you want to create a file in the same directory as another, or when you are looking for a basename of a file. But when do you need the first slash? > >> + if (!r || (r2 && r2 < r)) > > > > Why do you test for r2 being non-NULL? You are not going to > > dereference it in the next comparison, and NULL is comparable as any > > other value. > > As if we found slash, we don't want to override function's result by > backslash not found. If the null-check wouldn't be present condition > would be always true for r2 == NULL as, NULL is always less then a > pointer. But r shall be modified only if r2 (backslash) was found > before r (slash). > (same logic but here from right to left for the strrchr-case) But in strrchr-case, r2 cannot be greater than r1 if it is NULL, right?
