diff options
Diffstat (limited to 'libc/stdlib/realpath.c')
| -rw-r--r-- | libc/stdlib/realpath.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/libc/stdlib/realpath.c b/libc/stdlib/realpath.c new file mode 100644 index 000000000..d053cfcaf --- /dev/null +++ b/libc/stdlib/realpath.c @@ -0,0 +1,168 @@ +/* + * realpath.c -- canonicalize pathname by removing symlinks + * Copyright (C) 1993 Rick Sladkey <jrs@world.std.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU Library Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * This program 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 Library Public License for more details. + */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include <sys/types.h> +#include <unistd.h> +#include <stdio.h> +#include <string.h> +#include <strings.h> +#include <limits.h> /* for PATH_MAX */ +#include <sys/param.h> /* for MAXPATHLEN */ +#include <errno.h> + +#include <sys/stat.h> /* for S_IFLNK */ + +#ifndef PATH_MAX +#ifdef _POSIX_VERSION +#define PATH_MAX _POSIX_PATH_MAX +#else +#ifdef MAXPATHLEN +#define PATH_MAX MAXPATHLEN +#else +#define PATH_MAX 1024 +#endif +#endif +#endif + +#define MAX_READLINKS 32 + +#ifdef __STDC__ +char *realpath(const char *path, char resolved_path []) +#else +char *realpath(path, resolved_path) +const char *path; +char resolved_path []; +#endif +{ + char copy_path[PATH_MAX]; + char link_path[PATH_MAX]; + char got_path [PATH_MAX]; + char *new_path = got_path; + char *max_path; + int readlinks = 0; + int n; + + /* Make a copy of the source path since we may need to modify it. */ + if (strlen(path)>=PATH_MAX-2) { + errno = ENAMETOOLONG; + return NULL; + } + strcpy(copy_path, path); + path = copy_path; + max_path = copy_path + PATH_MAX - 2; + /* If it's a relative pathname use getwd for starters. */ + if (*path != '/') { + /* Ohoo... */ +#define HAVE_GETCWD +#ifdef HAVE_GETCWD + getcwd(new_path, PATH_MAX - 1); +#else + getwd(new_path); +#endif + new_path += strlen(new_path); + if (new_path[-1] != '/') + *new_path++ = '/'; + } + else { + *new_path++ = '/'; + path++; + } + /* Expand each slash-separated pathname component. */ + while (*path != '\0') { + /* Ignore stray "/". */ + if (*path == '/') { + path++; + continue; + } + if (*path == '.') { + /* Ignore ".". */ + if (path[1] == '\0' || path[1] == '/') { + path++; + continue; + } + if (path[1] == '.') { + if (path[2] == '\0' || path[2] == '/') { + path += 2; + /* Ignore ".." at root. */ + if (new_path == got_path + 1) + continue; + /* Handle ".." by backing up. */ + while ((--new_path)[-1] != '/') + ; + continue; + } + } + } + /* Safely copy the next pathname component. */ + while (*path != '\0' && *path != '/') { + if (path > max_path) { + errno = ENAMETOOLONG; + return NULL; + } + *new_path++ = *path++; + } +#ifdef S_IFLNK + /* Protect against infinite loops. */ + if (readlinks++ > MAX_READLINKS) { + errno = ELOOP; + return NULL; + } + /* See if latest pathname component is a symlink. */ + *new_path = '\0'; + n = readlink(got_path, link_path, PATH_MAX - 1); + if (n < 0) { + /* EINVAL means the file exists but isn't a symlink. */ + if (errno != EINVAL) { + /* Make sure it's null terminated. */ + *new_path = '\0'; + strcpy (resolved_path, got_path); + return NULL; + } + } + else { + /* Note: readlink doesn't add the null byte. */ + link_path[n] = '\0'; + if (*link_path == '/') + /* Start over for an absolute symlink. */ + new_path = got_path; + else + /* Otherwise back up over this component. */ + while (*(--new_path) != '/') + ; + /* Safe sex check. */ + if (strlen(path) + n >= PATH_MAX-2) { + errno = ENAMETOOLONG; + return NULL; + } + /* Insert symlink contents into path. */ + strcat(link_path, path); + strcpy(copy_path, link_path); + path = copy_path; + } +#endif /* S_IFLNK */ + *new_path++ = '/'; + } + /* Delete trailing slash but don't whomp a lone slash. */ + if (new_path != got_path + 1 && new_path[-1] == '/') + new_path--; + /* Make sure it's null terminated. */ + *new_path = '\0'; + strcpy (resolved_path, got_path); + return resolved_path; +} |