2 * Utility functions to track file descriptors.
4 * Copyright (C) 2013 Simon Ruderich
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
23 /* List of tracked file descriptors. */
24 static int *tracked_fds;
25 /* Current number of items in the list. */
26 static size_t tracked_fds_count;
27 /* Allocated items, used to reduce realloc()s. */
28 static size_t tracked_fds_space;
31 /* Load tracked file descriptors from the environment. The environment is used
32 * to pass the information to child processes.
34 * ENV_NAME_FDS has the following format: Each descriptor as string followed
35 * by a comma; there's a trailing comma. Example: "2,4,". */
36 static void init_from_environment(void) {
37 tracked_fds_count = 0;
39 const char *env = getenv(ENV_NAME_FDS);
43 /* Environment is read-only. */
44 char *env_copy = strdup(env);
52 for (x = env_copy; *x; x++) {
57 tracked_fds_space = count + TRACKFDS_REALLOC_STEP;
59 tracked_fds = malloc(tracked_fds_space * sizeof(*tracked_fds));
67 /* Parse file descriptor numbers from environment string and store them as
68 * integers in tracked_fds. */
70 for (x = env_copy, last = env_copy; *x; x++) {
74 /* ',' at the beginning or double ',' - ignore. */
85 tracked_fds[i++] = atoi(last);
90 tracked_fds_count = count;
95 static void update_environment(void) {
96 /* An integer (32-bit) has at most 10 digits, + 1 for the comma after each
97 * number. Bigger file descriptors (which shouldn't occur in reality) are
99 char env[tracked_fds_count * (10 + 1) * sizeof(char)];
103 for (i = 0; i < tracked_fds_count; i++) {
104 int length = snprintf(x, 10 + 1, "%d", tracked_fds[i]);
105 if (length >= 10 + 1)
108 /* Write comma after number. */
111 /* Make sure the string is always zero terminated. */
115 setenv(ENV_NAME_FDS, env, 1 /* overwrite */);
120 static void tracked_fds_debug(void) {
121 debug("tracked_fds: %d/%d\t[%d]\n", tracked_fds_count, tracked_fds_space,
124 for (i = 0; i < tracked_fds_count; i++) {
125 debug("tracked_fds[%d]: %d\n", i, tracked_fds[i]);
130 static void tracked_fds_add(int fd) {
131 if (tracked_fds_count >= tracked_fds_space) {
132 size_t new_space = tracked_fds_space + TRACKFDS_REALLOC_STEP;
133 if (!realloc(tracked_fds, sizeof(*tracked_fds) * new_space)) {
134 /* We can do nothing, just ignore the error. We made sure not to
135 * destroy our state, so the new descriptor is ignored without any
136 * other consequences. */
139 tracked_fds_space = new_space;
142 tracked_fds[tracked_fds_count++] = fd;
148 static int tracked_fds_remove(int fd) {
150 for (i = 0; i < tracked_fds_count; i++) {
151 if (fd != tracked_fds[i]) {
155 memmove(tracked_fds + i, tracked_fds + i + 1,
156 sizeof(*tracked_fds) * (tracked_fds_count - i - 1));
170 static int tracked_fds_find(int fd) {
172 for (i = 0; i < tracked_fds_count; i++) {
173 if (fd == tracked_fds[i]) {