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fix: off-by-one error in convertPathnameToDirName #4454

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fix: off-by-one error in convertPathnameToDirName #4454

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6 changes: 3 additions & 3 deletions programs/util.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1148,11 +1148,11 @@ static void convertPathnameToDirName(char *pathname)
/* remove trailing '/' chars */
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@Cyan4973 Cyan4973 Aug 13, 2025 •
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To be fair, I'm not sure if this part of the code makes sense.

The goal of the method convertPathnameToDirName() is to convert a full path of a filename into a just its directory part.

But if pathname ends with a / character, then it already represents a directory name.
In which case, there should be no need to change anything.

In contrast, if we remove the last /, the next stage would strip the last part of the path, and we would end up with the upper directory. And I suspect that's not the wanted behavior.

At this point, my suspicion is that this paragraph is useless, and should just be removed. "Fixing" it could actually introduce problems.

Note: a good follow up could be to improve the tests, by finding scenarios that introduce problems if this function is badly defined. Since our CI signal is all-greens, that means it does not capture the issue.

len = strlen(pathname);
assert(len > 0);
while (pathname[len] == PATH_SEP) {
pathname[len] = '\0';
while (pathname[len-1] == PATH_SEP) {
pathname[len-1] = '\0';
len--;
if (len == 0) return;
}
if (len == 0) return;

/* if input is a single file, return '.' instead. i.e.
* "xyz/abc/file.txt" => "xyz/abc"
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