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/****************************************************************************
* bfs *
* Copyright (C) 2019 Tavian Barnes <tavianator@tavianator.com> *
* *
* Permission to use, copy, modify, and/or distribute this software for any *
* purpose with or without fee is hereby granted. *
* *
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF *
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR *
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES *
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN *
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF *
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *
****************************************************************************/
/**
* There's no standard Unix utility that creates a socket file, so this small
* program does the job.
*/
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>
/**
* Print an error message.
*/
static void errmsg(const char *cmd, const char *path) {
fprintf(stderr, "%s: '%s': %s.\n", cmd, path, strerror(errno));
}
/**
* struct sockaddr_un::sun_path is very short, so we chdir() into the target
* directory before creating sockets in case the full path is too long but the
* file name is not.
*/
static int chdir_parent(const char *path) {
char *copy = strdup(path);
if (!copy) {
return -1;
}
const char *dir = dirname(copy);
int ret = chdir(dir);
int error = errno;
free(copy);
errno = error;
return ret;
}
/**
* Initialize a struct sockaddr_un with the right filename.
*/
static int init_sun(struct sockaddr_un *sock, const char *path) {
size_t len = strlen(path);
if (len == 0 || path[len - 1] == '/') {
errno = ENOENT;
return -1;
}
char *copy = strdup(path);
if (!copy) {
return -1;
}
const char *base = basename(copy);
len = strlen(base);
if (len >= sizeof(sock->sun_path)) {
free(copy);
errno = ENAMETOOLONG;
return -1;
}
sock->sun_family = AF_UNIX;
memcpy(sock->sun_path, base, len + 1);
free(copy);
return 0;
}
int main(int argc, char *argv[]) {
const char *cmd = argc > 0 ? argv[0] : "mksock";
if (argc != 2) {
fprintf(stderr, "Usage: %s NAME\n", cmd);
return EXIT_FAILURE;
}
const char *path = argv[1];
if (chdir_parent(path) != 0) {
errmsg(cmd, path);
return EXIT_FAILURE;
}
struct sockaddr_un sock;
if (init_sun(&sock, path) != 0) {
errmsg(cmd, path);
return EXIT_FAILURE;
}
int fd = socket(AF_UNIX, SOCK_STREAM, 0);
if (fd < 0) {
errmsg(cmd, path);
return EXIT_FAILURE;
}
int ret = EXIT_SUCCESS;
if (bind(fd, (struct sockaddr *)&sock, sizeof(sock)) != 0) {
errmsg(cmd, path);
ret = EXIT_FAILURE;
}
if (close(fd) != 0) {
errmsg(cmd, path);
ret = EXIT_FAILURE;
}
return ret;
}
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