From: Raphaël Beamonte Date: Fri, 15 Nov 2013 00:58:34 +0000 (-0500) Subject: Change the utils_expand_path function to use utils_partial_realpath X-Git-Tag: v2.4.0-rc1~3 X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=3d229795de7f38cce87d6d5ea76ef413dbb71f1d;hp=5154230f59b7f66abe33166cf14ef49d2c4e2219 Change the utils_expand_path function to use utils_partial_realpath As most of the resolve-related work can now be done using utils_partial_realpath, the utils_expand_path function can call it and concentrate on resolving the relative paths in the middle of a path string, such as '/./' and '/../'. Signed-off-by: Raphaël Beamonte Signed-off-by: David Goulet --- diff --git a/src/common/utils.c b/src/common/utils.c index 57add319b..d28e31349 100644 --- a/src/common/utils.c +++ b/src/common/utils.c @@ -230,102 +230,87 @@ error: return NULL; } - /* - * Return the realpath(3) of the path even if the last directory token does not - * exist. For example, with /tmp/test1/test2, if test2/ does not exist but the - * /tmp/test1 does, the real path is returned. In normal time, realpath(3) - * fails if the end point directory does not exist. + * Make a full resolution of the given path even if it doesn't exist. + * This function uses the utils_partial_realpath function to resolve + * symlinks and relatives paths at the start of the string, and + * implements functionnalities to resolve the './' and '../' strings + * in the middle of a path. This function is only necessary because + * realpath(3) does not accept to resolve unexistent paths. + * The returned string was allocated in the function, it is thus of + * the responsibility of the caller to free this memory. */ LTTNG_HIDDEN char *utils_expand_path(const char *path) { - const char *end_path = NULL; - char *next, *cut_path = NULL, *expanded_path = NULL; + char *next, *previous, *slash, *start_path, *absolute_path = NULL; /* Safety net */ if (path == NULL) { goto error; } - /* Allocate memory for the expanded path */ - expanded_path = zmalloc(PATH_MAX); - if (expanded_path == NULL) { + /* Allocate memory for the absolute_path */ + absolute_path = zmalloc(PATH_MAX); + if (absolute_path == NULL) { PERROR("zmalloc expand path"); goto error; } - /* If given path is already absolute */ - if (*path == '/') { - strncpy(expanded_path, path, PATH_MAX); - /* Else, we have some work to do */ + /* + * If the path is not already absolute nor explicitly relative, + * consider we're in the current directory + */ + if (*path != '/' && strncmp(path, "./", 2) != 0 && + strncmp(path, "../", 3) != 0) { + snprintf(absolute_path, PATH_MAX, "./%s", path); + /* Else, we just copy the path */ } else { - /* Pointer to the last char of the path */ - const char *last_char = path + strlen(path) - 1; + strncpy(absolute_path, path, PATH_MAX); + } - end_path = path; + /* Resolve partially our path */ + absolute_path = utils_partial_realpath(absolute_path, + absolute_path, PATH_MAX); - /* Split part that will be resolved by realpath (relative path from - * current directory using ./ or ../ only) and part that could not - * (directory names) - */ - while ((next = strpbrk(end_path, "/")) && (next != last_char)) { - end_path = next + 1; - if (strncmp(end_path, "./", 2) != 0 && - strncmp(end_path, "../", 3) != 0) { - break; - } - } + /* As long as we find '/./' in the working_path string */ + while ((next = strstr(absolute_path, "/./"))) { - /* If this is the end of the string, and we still can resolve it */ - if (strncmp(end_path, "..\0", 3) == 0 || - strncmp(end_path, ".\0", 2) == 0) { - end_path += strlen(end_path); - } + /* We prepare the start_path not containing it */ + start_path = strndup(absolute_path, next - absolute_path); - /* If the end part is the whole path, we are in the current dir */ - if (end_path == path) { - cut_path = strdup("."); - /* Else, cut the resolvable part from original path */ - } else { - cut_path = strndup(path, end_path - path); - } + /* And we concatenate it with the part after this string */ + snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 2); - /* Resolve the canonical path of the first part of the path */ - expanded_path = realpath((char *)cut_path, expanded_path); - if (expanded_path == NULL) { - switch (errno) { - case ENOENT: - ERR("%s: No such file or directory", cut_path); - break; - default: - PERROR("realpath utils expand path"); - break; - } - goto error; - } + free(start_path); + } - /* Add end part to expanded path if not empty */ - if (*end_path != 0) { - strncat(expanded_path, "/", PATH_MAX - strlen(expanded_path) - 1); - strncat(expanded_path, end_path, - PATH_MAX - strlen(expanded_path) - 1); + /* As long as we find '/../' in the working_path string */ + while ((next = strstr(absolute_path, "/../"))) { + /* We find the last level of directory */ + previous = absolute_path; + while ((slash = strpbrk(previous, "/")) && slash != next) { + previous = slash + 1; } - } - /* Resolve the internal './' and '../' strings */ - next = utils_resolve_relative(expanded_path); - if (next == NULL) { - goto error; + /* Then we prepare the start_path not containing it */ + start_path = strndup(absolute_path, previous - absolute_path); + + /* And we concatenate it with the part after the '/../' */ + snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 4); + + /* We can free the memory used for the start path*/ + free(start_path); + + /* Then we verify for symlinks using partial_realpath */ + absolute_path = utils_partial_realpath(absolute_path, + absolute_path, PATH_MAX); } - free(expanded_path); - free(cut_path); - return next; + return absolute_path; error: - free(expanded_path); - free(cut_path); + free(absolute_path); return NULL; }