/*
* Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
- * Copyright (C) 2013 Raphaël Beamonte <raphael.beamonte@gmail.com>
* Copyright (C) 2013 Jérémie Galarneau <jeremie.galarneau@efficios.com>
*
* SPDX-License-Identifier: GPL-2.0-only
#define FALLBACK_USER_BUFLEN 16384
#define FALLBACK_GROUP_BUFLEN 16384
-/*
- * 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.
- *
- * Return a newly-allocated string.
- */
-static
-char *utils_partial_realpath(const char *path)
-{
- char *cut_path = NULL, *try_path = NULL, *try_path_prev = NULL;
- const char *next, *prev, *end;
- char *resolved_path = NULL;
-
- /* Safety net */
- if (path == NULL) {
- 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--;
- }
-
- /* 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;
-
- /* Resolve the canonical path of the first part of the path */
- while (try_path != NULL && next != end) {
- char *try_path_buf = NULL;
-
- /*
- * If there is not any '/' left, we want to try with
- * the full path
- */
- next = strpbrk(next + 1, "/");
- if (next == NULL) {
- next = end;
- }
-
- /* Cut the part we will be trying to resolve */
- cut_path = lttng_strndup(path, next - path);
- if (cut_path == NULL) {
- PERROR("lttng_strndup");
- goto error;
- }
-
- try_path_buf = (char *) zmalloc(LTTNG_PATH_MAX);
- if (!try_path_buf) {
- PERROR("zmalloc");
- goto error;
- }
-
- /* Try to resolve this part */
- try_path = realpath((char *) cut_path, try_path_buf);
- if (try_path == NULL) {
- free(try_path_buf);
- /*
- * 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 */
- try_path_buf = NULL;
- free(try_path_prev);
- try_path_prev = try_path;
- prev = next;
- }
-
- /* Free the allocated memory */
- free(cut_path);
- cut_path = NULL;
- }
-
- /* Allocate memory for the resolved path. */
- resolved_path = (char *) zmalloc(LTTNG_PATH_MAX);
- if (resolved_path == NULL) {
- PERROR("zmalloc resolved path");
- goto error;
- }
-
- /*
- * 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';
- }
-
- /*
- * Duplicate the memory used by prev in case resolved_path and
- * path are pointers for the same memory space
- */
- cut_path = strdup(prev);
- if (cut_path == NULL) {
- PERROR("strdup");
- goto error;
- }
-
- /* Concatenate the strings */
- snprintf(resolved_path, LTTNG_PATH_MAX, "%s%s",
- try_path_prev, cut_path);
-
- /* Free the allocated memory */
- free(cut_path);
- free(try_path_prev);
- cut_path = NULL;
- try_path_prev = NULL;
- /*
- * Else, we just copy the path in our resolved_path to
- * return it as is
- */
- } else {
- strncpy(resolved_path, path, LTTNG_PATH_MAX);
- }
-
- /* Then we return the 'partially' resolved path */
- return resolved_path;
-
-error:
- free(resolved_path);
- free(cut_path);
- free(try_path);
- if (try_path_prev != try_path) {
- free(try_path_prev);
- }
- return NULL;
-}
-
-static
-int expand_double_slashes_dot_and_dotdot(char *path)
-{
- size_t expanded_path_len, path_len;
- const char *curr_char, *path_last_char, *next_slash, *prev_slash;
-
- path_len = strlen(path);
- path_last_char = &path[path_len];
-
- if (path_len == 0) {
- goto error;
- }
-
- expanded_path_len = 0;
-
- /* We iterate over the provided path to expand the "//", "../" and "./" */
- for (curr_char = path; curr_char <= path_last_char; curr_char = next_slash + 1) {
- /* Find the next forward slash. */
- size_t curr_token_len;
-
- if (curr_char == path_last_char) {
- expanded_path_len++;
- break;
- }
-
- next_slash = (const char *) memchr(curr_char, '/', path_last_char - curr_char);
- if (next_slash == NULL) {
- /* Reached the end of the provided path. */
- next_slash = path_last_char;
- }
-
- /* Compute how long is the previous token. */
- curr_token_len = next_slash - curr_char;
- switch(curr_token_len) {
- case 0:
- /*
- * The pointer has not move meaning that curr_char is
- * pointing to a slash. It that case there is no token
- * to copy, so continue the iteration to find the next
- * token
- */
- continue;
- case 1:
- /*
- * The pointer moved 1 character. Check if that
- * character is a dot ('.'), if it is: omit it, else
- * copy the token to the normalized path.
- */
- if (curr_char[0] == '.') {
- continue;
- }
- break;
- case 2:
- /*
- * The pointer moved 2 characters. Check if these
- * characters are double dots ('..'). If that is the
- * case, we need to remove the last token of the
- * normalized path.
- */
- if (curr_char[0] == '.' && curr_char[1] == '.') {
- /*
- * Find the previous path component by
- * using the memrchr function to find the
- * previous forward slash and substract that
- * len to the resulting path.
- */
- prev_slash = (const char *) lttng_memrchr(path, '/', expanded_path_len);
- /*
- * If prev_slash is NULL, we reached the
- * beginning of the path. We can't go back any
- * further.
- */
- if (prev_slash != NULL) {
- expanded_path_len = prev_slash - path;
- }
- continue;
- }
- break;
- default:
- break;
- }
-
- /*
- * Copy the current token which is neither a '.' nor a '..'.
- */
- path[expanded_path_len++] = '/';
- memmove(&path[expanded_path_len], curr_char, curr_token_len);
- expanded_path_len += curr_token_len;
- }
-
- if (expanded_path_len == 0) {
- path[expanded_path_len++] = '/';
- }
-
- path[expanded_path_len] = '\0';
- return 0;
-error:
- return -1;
-}
-
-/*
- * 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.
- */
-static
-char *_utils_expand_path(const char *path, bool keep_symlink)
-{
- int ret;
- char *absolute_path = NULL;
- char *last_token;
- bool is_dot, is_dotdot;
-
- /* Safety net */
- if (path == NULL) {
- goto error;
- }
-
- /* Allocate memory for the absolute_path */
- absolute_path = (char *) zmalloc(LTTNG_PATH_MAX);
- if (absolute_path == NULL) {
- PERROR("zmalloc expand path");
- goto error;
- }
-
- if (path[0] == '/') {
- ret = lttng_strncpy(absolute_path, path, LTTNG_PATH_MAX);
- if (ret) {
- ERR("Path exceeds maximal size of %i bytes", LTTNG_PATH_MAX);
- goto error;
- }
- } else {
- /*
- * This is a relative path. We need to get the present working
- * directory and start the path walk from there.
- */
- char current_working_dir[LTTNG_PATH_MAX];
- char *cwd_ret;
-
- cwd_ret = getcwd(current_working_dir, sizeof(current_working_dir));
- if (!cwd_ret) {
- goto error;
- }
- /*
- * Get the number of character in the CWD and allocate an array
- * to can hold it and the path provided by the caller.
- */
- ret = snprintf(absolute_path, LTTNG_PATH_MAX, "%s/%s",
- current_working_dir, path);
- if (ret >= LTTNG_PATH_MAX) {
- ERR("Concatenating current working directory %s and path %s exceeds maximal size of %i bytes",
- current_working_dir, path, LTTNG_PATH_MAX);
- goto error;
- }
- }
-
- if (keep_symlink) {
- /* Resolve partially our path */
- char *new_absolute_path = utils_partial_realpath(absolute_path);
- if (!new_absolute_path) {
- goto error;
- }
-
- free(absolute_path);
- absolute_path = new_absolute_path;
- }
-
- ret = expand_double_slashes_dot_and_dotdot(absolute_path);
- if (ret) {
- goto error;
- }
-
- /* Identify the last token */
- last_token = strrchr(absolute_path, '/');
-
- /* Verify that this token is not a relative path */
- is_dotdot = (strcmp(last_token, "/..") == 0);
- is_dot = (strcmp(last_token, "/.") == 0);
-
- /* If it is, take action */
- if (is_dot || is_dotdot) {
- /* For both, remove this token */
- *last_token = '\0';
-
- /* If it was a reference to parent directory, go back one more time */
- if (is_dotdot) {
- last_token = strrchr(absolute_path, '/');
-
- /* If there was only one level left, we keep the first '/' */
- if (last_token == absolute_path) {
- last_token++;
- }
-
- *last_token = '\0';
- }
- }
-
- return absolute_path;
-
-error:
- free(absolute_path);
- return NULL;
-}
-char *utils_expand_path(const char *path)
-{
- return _utils_expand_path(path, true);
-}
-
-char *utils_expand_path_keep_symlink(const char *path)
-{
- return _utils_expand_path(path, false);
-}
/*
* Create a pipe in dst.
*/
projects / lttng-tools.git / blobdiff