So far links can only point to files. Implement links to directories. With this all kinds of links are supported:
- relative links - absolute links - links including ".." - link loops (are detected, return -EMLINK) Signed-off-by: Sascha Hauer <[email protected]> --- commands/readlink.c | 2 +- fs/fs.c | 272 +++++++++++++++++++++++++++++----------------------- include/fs.h | 3 +- 3 files changed, 157 insertions(+), 120 deletions(-) diff --git a/commands/readlink.c b/commands/readlink.c index 4ac576f16f..a19c8e0041 100644 --- a/commands/readlink.c +++ b/commands/readlink.c @@ -48,7 +48,7 @@ static int do_readlink(int argc, char *argv[]) goto err; if (canonicalize) { - char *buf = normalise_link(argv[optind], realname); + char *buf = canonicalize_path(realname); if (!buf) goto err; diff --git a/fs/fs.c b/fs/fs.c index 9cb15738b0..aaae5bbdd8 100644 --- a/fs/fs.c +++ b/fs/fs.c @@ -83,61 +83,6 @@ static int init_fs(void) postcore_initcall(init_fs); -char *normalise_link(const char *pathname, const char *symlink) -{ - const char *buf = symlink; - char *path_free, *path; - char *absolute_path; - int point = 0; - int dir = 1; - int len; - - if (symlink[0] == '/') - return strdup(symlink); - - while (*buf == '.' || *buf == '/') { - if (*buf == '.') { - point++; - } else if (*buf == '/') { - point = 0; - dir++; - } - if (point > 2) { - buf -= 2; - break; - } - buf++; - } - - path = path_free = strdup(pathname); - if (!path) - return NULL; - - while(dir) { - path = dirname(path); - dir--; - } - - len = strlen(buf) + strlen(path) + 1; - if (buf[0] != '/') - len++; - - absolute_path = calloc(sizeof(char), len); - - if (!absolute_path) - goto out; - - strcat(absolute_path, path); - if (buf[0] != '/') - strcat(absolute_path, "/"); - strcat(absolute_path, buf); - -out: - free(path_free); - - return absolute_path; -} - char *normalise_path(const char *pathname) { char *path = xzalloc(strlen(pathname) + strlen(cwd) + 2); @@ -197,6 +142,137 @@ char *normalise_path(const char *pathname) } EXPORT_SYMBOL(normalise_path); +static int __lstat(const char *filename, struct stat *s); + +static char *__canonicalize_path(const char *_pathname, int level) +{ + char *path, *freep; + char *outpath; + int ret; + struct stat s; + + if (level > 10) + return ERR_PTR(-ELOOP); + + path = freep = xstrdup(_pathname); + + if (*path == '/') + outpath = xstrdup("/"); + else + outpath = __canonicalize_path(cwd, level + 1); + + while (1) { + char *p = strsep(&path, "/"); + char *tmp; + char link[PATH_MAX] = {}; + + if (!p) + break; + if (p[0] == '\0') + continue; + if (!strcmp(p, ".")) + continue; + if (!strcmp(p, "..")) { + tmp = xstrdup(dirname(outpath)); + free(outpath); + outpath = tmp; + continue; + } + + tmp = basprintf("%s/%s", outpath, p); + free(outpath); + outpath = tmp; + + ret = __lstat(outpath, &s); + if (ret) + goto out; + + if (!S_ISLNK(s.st_mode)) + continue; + + ret = readlink(outpath, link, PATH_MAX - 1); + if (ret < 0) + goto out; + + if (link[0] == '/') { + free(outpath); + outpath = __canonicalize_path(link, level + 1); + } else { + tmp = basprintf("%s/%s", dirname(outpath), link); + free(outpath); + outpath = __canonicalize_path(tmp, level + 1); + free(tmp); + } + + if (IS_ERR(outpath)) + goto out; + } +out: + free(freep); + + return outpath; +} + +/* + * canonicalize_path - resolve links in path + * @pathname: The input path + * + * This function resolves all links in @pathname and returns + * a path without links in it. + * + * Return: Path with links resolved. Allocated, must be freed after use. + */ +char *canonicalize_path(const char *pathname) +{ + char *r, *p = __canonicalize_path(pathname, 0); + + if (IS_ERR(p)) + return ERR_CAST(p); + + r = normalise_path(p); + free(p); + + return r; +} + +/* + * canonicalize_dir - resolve links in path + * @pathname: The input path + * + * This function resolves all links except the last one. Needed to give + * access to the link itself. + * + * Return: Path with links resolved. Allocated, must be freed after use. + */ +char *canonicalize_dir(const char *pathname) +{ + char *f, *d, *r, *ret, *p; + char *freep1, *freep2; + + freep1 = xstrdup(pathname); + freep2 = xstrdup(pathname); + f = basename(freep1); + d = dirname(freep2); + + p = __canonicalize_path(d, 0); + if (IS_ERR(p)) { + ret = ERR_CAST(p); + goto out; + } + + r = basprintf("%s/%s", p, f); + + ret = normalise_path(r); + + free(r); + free(p); +out: + free(freep1); + free(freep2); + + return ret; +} + LIST_HEAD(fs_device_list); static struct fs_device_d *fs_dev_root; @@ -493,7 +569,7 @@ int unlink(const char *pathname) { struct fs_device_d *fsdev; struct fs_driver_d *fsdrv; - char *p = normalise_path(pathname); + char *p = canonicalize_path(pathname); char *freep = p; int ret; struct stat s; @@ -530,42 +606,6 @@ out: } EXPORT_SYMBOL(unlink); -static char *realfile(const char *pathname, struct stat *s) -{ - char *path = normalise_path(pathname); - int ret; - - ret = lstat(path, s); - if (ret) - goto out; - - if (S_ISLNK(s->st_mode)) { - char tmp[PATH_MAX]; - char *new_path; - - memset(tmp, 0, PATH_MAX); - - ret = readlink(path, tmp, PATH_MAX - 1); - if (ret < 0) - goto out; - - new_path = normalise_link(path, tmp); - free(path); - if (!new_path) - return ERR_PTR(-ENOMEM); - path = new_path; - - ret = lstat(path, s); - } - - if (!ret) - return path; - -out: - free(path); - return ERR_PTR(ret); -} - int open(const char *pathname, int flags, ...) { struct fs_device_d *fsdev; @@ -577,13 +617,14 @@ int open(const char *pathname, int flags, ...) char *freep; int ret; - path = realfile(pathname, &s); - + path = canonicalize_path(pathname); if (IS_ERR(path)) { - exist_err = PTR_ERR(path); - path = normalise_path(pathname); + ret = PTR_ERR(path); + goto out2; } + exist_err = stat(path, &s); + freep = path; if (!exist_err && S_ISDIR(s.st_mode)) { @@ -657,6 +698,7 @@ out: put_file(f); out1: free(freep); +out2: if (ret) errno = -ret; return ret; @@ -1026,7 +1068,7 @@ int readlink(const char *pathname, char *buf, size_t bufsiz) { struct fs_driver_d *fsdrv; struct fs_device_d *fsdev; - char *p = normalise_path(pathname); + char *p = canonicalize_dir(pathname); char *freep = p; int ret; struct stat s; @@ -1070,24 +1112,15 @@ int symlink(const char *pathname, const char *newpath) struct fs_driver_d *fsdrv; struct fs_device_d *fsdev; char *p; - char *freep = normalise_path(pathname); int ret; struct stat s; - if (!freep) - return -ENOMEM; - - if (!stat(freep, &s) && S_ISDIR(s.st_mode)) { - ret = -ENOSYS; + p = canonicalize_path(newpath); + if (IS_ERR(p)) { + ret = PTR_ERR(p); goto out; } - free(freep); - freep = p = normalise_path(newpath); - - if (!p) - return -ENOMEM; - ret = lstat(p, &s); if (!ret) { ret = -EEXIST; @@ -1108,7 +1141,7 @@ int symlink(const char *pathname, const char *newpath) } out: - free(freep); + free(p); if (ret) errno = -ret; @@ -1387,7 +1420,7 @@ DIR *opendir(const char *pathname) DIR *dir = NULL; struct fs_device_d *fsdev; struct fs_driver_d *fsdrv; - char *p = normalise_path(pathname); + char *p = canonicalize_path(pathname); char *freep = p; int ret; struct stat s; @@ -1467,18 +1500,21 @@ EXPORT_SYMBOL(closedir); int stat(const char *filename, struct stat *s) { - char *f; + char *path = canonicalize_path(filename); + int ret; - f = realfile(filename, s); - if (IS_ERR(f)) - return PTR_ERR(f); + if (IS_ERR(path)) + return PTR_ERR(path); - free(f); - return 0; + ret = lstat(path, s); + + free(path); + + return ret; } EXPORT_SYMBOL(stat); -int lstat(const char *filename, struct stat *s) +static int __lstat(const char *filename, struct stat *s) { struct fs_driver_d *fsdrv; struct fs_device_d *fsdev; diff --git a/include/fs.h b/include/fs.h index 6a592893a9..71edb22f26 100644 --- a/include/fs.h +++ b/include/fs.h @@ -128,7 +128,8 @@ char *mkmodestr(unsigned long mode, char *str); * of "..", "." and double slashes. The returned string must be freed wit free(). */ char *normalise_path(const char *path); -char *normalise_link(const char *pathname, const char* symlink); + +char *canonicalize_path(const char *pathname); char *get_mounted_path(const char *path); -- 2.11.0 _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
