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diff --git a/lib/sh/pathcanon.c b/lib/sh/pathcanon.c
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+/* pathcanon.c -- canonicalize and manipulate pathnames. */
+
+/* Copyright (C) 2000 Free Software Foundation, Inc.
+
+ This file is part of GNU Bash, the Bourne Again SHell.
+
+ Bash is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Bash 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with Bash. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <config.h>
+
+#include <bashtypes.h>
+#if defined (HAVE_SYS_PARAM_H)
+# include <sys/param.h>
+#endif
+#include <posixstat.h>
+
+#if defined (HAVE_UNISTD_H)
+# include <unistd.h>
+#endif
+
+#include <filecntl.h>
+#include <bashansi.h>
+#include <stdio.h>
+#include <chartypes.h>
+#include <errno.h>
+
+#include "shell.h"
+
+#if !defined (errno)
+extern int errno;
+#endif
+
+#if defined (__CYGWIN__)
+#include <sys/cygwin.h>
+
+static int
+_is_cygdrive (path)
+ char *path;
+{
+ static char user[MAXPATHLEN];
+ static char system[MAXPATHLEN];
+ static int first_time = 1;
+
+ /* If the path is the first part of a network path, treat it as
+ existing. */
+ if (path[0] == '/' && path[1] == '/' && !strchr (path + 2, '/'))
+ return 1;
+ /* Otherwise check for /cygdrive prefix. */
+ if (first_time)
+ {
+ char user_flags[MAXPATHLEN];
+ char system_flags[MAXPATHLEN];
+ /* Get the cygdrive info */
+ cygwin_internal (CW_GET_CYGDRIVE_INFO, user, system, user_flags, system_flags);
+ first_time = 0;
+ }
+ return !strcasecmp (path, user) || !strcasecmp (path, system);
+}
+#endif /* __CYGWIN__ */
+
+/* Return 1 if PATH corresponds to a directory. A function for debugging. */
+static int
+_path_isdir (path)
+ char *path;
+{
+ int l;
+ struct stat sb;
+
+ /* This should leave errno set to the correct value. */
+ errno = 0;
+ l = stat (path, &sb) == 0 && S_ISDIR (sb.st_mode);
+#if defined (__CYGWIN__)
+ if (l == 0)
+ l = _is_cygdrive (path);
+#endif
+ return l;
+}
+
+/* Canonicalize PATH, and return a new path. The new path differs from PATH
+ in that:
+ Multple `/'s are collapsed to a single `/'.
+ Leading `./'s and trailing `/.'s are removed.
+ Trailing `/'s are removed.
+ Non-leading `../'s and trailing `..'s are handled by removing
+ portions of the path. */
+
+/* Look for ROOTEDPATH, PATHSEP, DIRSEP, and ISDIRSEP in ../../general.h */
+
+#define DOUBLE_SLASH(p) ((p[0] == '/') && (p[1] == '/') && p[2] != '/')
+
+char *
+sh_canonpath (path, flags)
+ char *path;
+ int flags;
+{
+ char stub_char;
+ char *result, *p, *q, *base, *dotdot;
+ int rooted, double_slash_path;
+
+ /* The result cannot be larger than the input PATH. */
+ result = (flags & PATH_NOALLOC) ? path : savestring (path);
+
+ /* POSIX.2 says to leave a leading `//' alone. On cygwin, we skip over any
+ leading `x:' (dos drive name). */
+ if (rooted = ROOTEDPATH(path))
+ {
+ stub_char = DIRSEP;
+#if defined (__CYGWIN__)
+ base = (ISALPHA((unsigned char)result[0]) && result[1] == ':') ? result + 3 : result + 1;
+#else
+ base = result + 1;
+#endif
+ double_slash_path = DOUBLE_SLASH (path);
+ base += double_slash_path;
+ }
+ else
+ {
+ stub_char = '.';
+#if defined (__CYGWIN__)
+ base = (ISALPHA((unsigned char)result[0]) && result[1] == ':') ? result + 2 : result;
+#else
+ base = result;
+#endif
+ double_slash_path = 0;
+ }
+
+ /*
+ * invariants:
+ * base points to the portion of the path we want to modify
+ * p points at beginning of path element we're considering.
+ * q points just past the last path element we wrote (no slash).
+ * dotdot points just past the point where .. cannot backtrack
+ * any further (no slash).
+ */
+ p = q = dotdot = base;
+
+ while (*p)
+ {
+ if (ISDIRSEP(p[0])) /* null element */
+ p++;
+ else if(p[0] == '.' && PATHSEP(p[1])) /* . and ./ */
+ p += 1; /* don't count the separator in case it is nul */
+ else if (p[0] == '.' && p[1] == '.' && PATHSEP(p[2])) /* .. and ../ */
+ {
+ p += 2; /* skip `..' */
+ if (q > dotdot) /* can backtrack */
+ {
+ if (flags & PATH_CHECKDOTDOT)
+ {
+ char c;
+
+ /* Make sure what we have so far corresponds to a valid
+ path before we chop some of it off. */
+ c = *q;
+ *q = '\0';
+ if (_path_isdir (result) == 0)
+ {
+ if ((flags & PATH_NOALLOC) == 0)
+ free (result);
+ return ((char *)NULL);
+ }
+ *q = c;
+ }
+
+ while (--q > dotdot && ISDIRSEP(*q) == 0)
+ ;
+ }
+ else if (rooted == 0)
+ {
+ /* /.. is / but ./../ is .. */
+ if (q != base)
+ *q++ = DIRSEP;
+ *q++ = '.';
+ *q++ = '.';
+ dotdot = q;
+ }
+ }
+ else /* real path element */
+ {
+ /* add separator if not at start of work portion of result */
+ if (q != base)
+ *q++ = DIRSEP;
+ while (*p && (ISDIRSEP(*p) == 0))
+ *q++ = *p++;
+ /* Check here for a valid directory with _path_isdir. */
+ if (flags & PATH_CHECKEXISTS)
+ {
+ char c;
+
+ /* Make sure what we have so far corresponds to a valid
+ path before we chop some of it off. */
+ c = *q;
+ *q = '\0';
+ if (_path_isdir (result) == 0)
+ {
+ if ((flags & PATH_NOALLOC) == 0)
+ free (result);
+ return ((char *)NULL);
+ }
+ *q = c;
+ }
+ }
+ }
+
+ /* Empty string is really ``.'' or `/', depending on what we started with. */
+ if (q == result)
+ *q++ = stub_char;
+ *q = '\0';
+
+ /* If the result starts with `//', but the original path does not, we
+ can turn the // into /. Because of how we set `base', this should never
+ be true, but it's a sanity check. */
+ if (DOUBLE_SLASH(result) && double_slash_path == 0)
+ {
+ if (result[2] == '\0') /* short-circuit for bare `//' */
+ result[1] = '\0';
+ else
+ memmove (result, result + 1, strlen (result + 1) + 1);
+ }
+
+ return (result);
+}