X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Futils.c;h=330c04e82916359053981b69025c9f6339ab1a1f;hp=6938a5ae52f6cac2e12465b37e3caafe8ae61d23;hb=2dcd84b7ef877129d6ae2525b97f9bf6c7a25a0d;hpb=116f95d94575a68aee90fff79c064119729d0d24 diff --git a/src/common/utils.c b/src/common/utils.c index 6938a5ae5..330c04e82 100644 --- a/src/common/utils.c +++ b/src/common/utils.c @@ -1,5 +1,6 @@ /* * Copyright (C) 2012 - David Goulet + * Copyright (C) 2013 - Raphaël Beamonte * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License, version 2 only, as @@ -36,168 +37,214 @@ #include "defaults.h" /* - * Resolve the './' and '../' strings in the middle of a path using - * our very own way to do it, so that it works even if the directory - * does not exist + * Return a partial realpath(3) of the path even if the full path does not + * exist. For instance, with /tmp/test1/test2/test3, if test2/ does not exist + * but the /tmp/test1 does, the real path for /tmp/test1 is concatened with + * /test2/test3 then returned. In normal time, realpath(3) fails if the end + * point directory does not exist. + * In case resolved_path is NULL, the string returned was allocated in the + * function and thus need to be freed by the caller. The size argument allows + * to specify the size of the resolved_path argument if given, or the size to + * allocate. */ LTTNG_HIDDEN -char *utils_resolve_relative(const char *path) +char *utils_partial_realpath(const char *path, char *resolved_path, size_t size) { - char *next, *previous, *slash, *start_path, *absolute_path = NULL; + char *cut_path, *try_path = NULL, *try_path_prev = NULL; + const char *next, *prev, *end; /* Safety net */ if (path == NULL) { goto error; } - /* Allocate memory for the absolute path */ - absolute_path = zmalloc(PATH_MAX); - if (absolute_path == NULL) { - PERROR("zmalloc expand path"); - goto error; + /* + * Identify the end of the path, we don't want to treat the + * last char if it is a '/', we will just keep it on the side + * to be added at the end, and return a value coherent with + * the path given as argument + */ + end = path + strlen(path); + if (*(end-1) == '/') { + end--; } - /* Copy the path in the absolute path */ - strncpy(absolute_path, path, PATH_MAX); - - /* As long as we find '/./' in the path string */ - while ((next = strstr(absolute_path, "/./"))) { + /* Initiate the values of the pointers before looping */ + next = path; + prev = next; + /* Only to ensure try_path is not NULL to enter the while */ + try_path = (char *)next; - /* We prepare the start_path not containing it */ - start_path = strndup(absolute_path, next - absolute_path); + /* Resolve the canonical path of the first part of the path */ + while (try_path != NULL && next != end) { + /* + * If there is not any '/' left, we want to try with + * the full path + */ + next = strpbrk(next + 1, "/"); + if (next == NULL) { + next = end; + } - /* And we concatenate it with the part after this string */ - snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 2); + /* Cut the part we will be trying to resolve */ + cut_path = strndup(path, next - path); + + /* Try to resolve this part */ + try_path = realpath((char *)cut_path, NULL); + if (try_path == NULL) { + /* + * There was an error, we just want to be assured it + * is linked to an unexistent directory, if it's another + * reason, we spawn an error + */ + switch (errno) { + case ENOENT: + /* Ignore the error */ + break; + default: + PERROR("realpath (partial_realpath)"); + goto error; + break; + } + } else { + /* Save the place we are before trying the next step */ + free(try_path_prev); + try_path_prev = try_path; + prev = next; + } - free(start_path); - } + /* Free the allocated memory */ + free(cut_path); + }; - /* As long as we find '/../' in the path string */ - while ((next = strstr(absolute_path, "/../"))) { - /* If the path starts with '/../', there's a problem */ - if (next == absolute_path) { - ERR("%s: Path cannot be resolved", path); + /* Allocate memory for the resolved path if necessary */ + if (resolved_path == NULL) { + resolved_path = zmalloc(size); + if (resolved_path == NULL) { + PERROR("zmalloc resolved path"); goto error; } + } - /* We find the last level of directory */ - previous = absolute_path; - while ((slash = strpbrk(previous + 1, "/")) && slash != next) { - previous = slash; + /* + * If we were able to solve at least partially the path, we can concatenate + * what worked and what didn't work + */ + if (try_path_prev != NULL) { + /* If we risk to concatenate two '/', we remove one of them */ + if (try_path_prev[strlen(try_path_prev) - 1] == '/' && prev[0] == '/') { + try_path_prev[strlen(try_path_prev) - 1] = '\0'; } - /* Then we prepare the start_path not containing it */ - start_path = strndup(absolute_path, previous - absolute_path); + /* + * Duplicate the memory used by prev in case resolved_path and + * path are pointers for the same memory space + */ + cut_path = strdup(prev); - /* And we concatenate it with the part after the '/../' */ - snprintf(absolute_path, PATH_MAX, "%s%s", start_path, next + 3); + /* Concatenate the strings */ + snprintf(resolved_path, size, "%s%s", try_path_prev, cut_path); - free(start_path); + /* Free the allocated memory */ + free(cut_path); + free(try_path_prev); + /* + * Else, we just copy the path in our resolved_path to + * return it as is + */ + } else { + strncpy(resolved_path, path, size); } - return absolute_path; + /* Then we return the 'partially' resolved path */ + return resolved_path; error: - free(absolute_path); + free(resolved_path); 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; }