glibc/misc/dirname.c

80 lines
2.3 KiB
C

/* dirname - return directory part of PATH.
Copyright (C) 1996-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <libgen.h>
#include <string.h>
char *
dirname (char *path)
{
static const char dot[] = ".";
char *last_slash;
/* Find last '/'. */
last_slash = path != NULL ? strrchr (path, '/') : NULL;
if (last_slash != NULL && last_slash != path && last_slash[1] == '\0')
{
/* Determine whether all remaining characters are slashes. */
char *runp;
for (runp = last_slash; runp != path; --runp)
if (runp[-1] != '/')
break;
/* The '/' is the last character, we have to look further. */
if (runp != path)
last_slash = __memrchr (path, '/', runp - path);
}
if (last_slash != NULL)
{
/* Determine whether all remaining characters are slashes. */
char *runp;
for (runp = last_slash; runp != path; --runp)
if (runp[-1] != '/')
break;
/* Terminate the path. */
if (runp == path)
{
/* The last slash is the first character in the string. We have to
return "/". As a special case we have to return "//" if there
are exactly two slashes at the beginning of the string. See
XBD 4.10 Path Name Resolution for more information. */
if (last_slash == path + 1)
++last_slash;
else
last_slash = path + 1;
}
else
last_slash = runp;
last_slash[0] = '\0';
}
else
/* This assignment is ill-designed but the XPG specs require to
return a string containing "." in any case no directory part is
found and so a static and constant string is required. */
path = (char *) dot;
return path;
}