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/* See LICENSE file for copyright and license details. */
#include <sys/mount.h>
#include <sched.h>
#include <libsimple.h>
#include <libsimple-arg.h>
NUSAGE(125, "utility [argument] ...");
int
main(int argc, char *argv[])
{
int fds[2], status;
pid_t pid;
char *dir = NULL;
size_t dirsize = 0;
size_t dirlen = 0;
ssize_t r;
libsimple_default_failure_exit = 125;
ARGBEGIN {
default:
usage();
} ARGEND;
if (!argc)
usage();
if (unshare(CLONE_NEWNS))
eprintf("unshare CLONE_NEWNS:");
if (mount("none", "/", NULL, MS_REC | MS_SLAVE, NULL))
eprintf("mount none / NULL MS_REC|MS_SLAVE NULL:");
if (pipe(fds))
eprintf("pipe:");
pid = fork();
if (pid < 0)
eprintf("fork:");
if (pid == 0) {
if (setegid(getgid()))
eprintf("setegid <real group>:");
if (seteuid(getuid()))
eprintf("seteuid <real user>:");
close(fds[0]);
if (fds[1] != STDOUT_FILENO) {
if (dup2(fds[1], STDOUT_FILENO) != STDOUT_FILENO)
eprintf("dup2 <pipe> STDOUT_FILENO:");
close(fds[1]);
}
execlp(GIT_PATH, "git", "rev-parse", "--show-toplevel", NULL);
eprintf("execlp %s:", GIT_PATH);
}
close(fds[1]);
for (;;) {
if (dirlen == dirsize)
dir = erealloc(dir, dirsize += 512u);
r = read(fds[0], &dir[dirlen], dirsize - dirlen);
if (r <= 0) {
if (!r)
break;
if (errno == EINTR)
continue;
eprintf("read <pipe>:");
}
dirlen += (size_t)r;
if (!dirlen || dir[--dirlen] != '\n')
eprintf("received invalid output from `git rev-parse --show-toplevel`");
}
close(fds[0]);
if (waitpid(pid, &status, 0) != pid)
eprintf("waitpid <subprocess>:");
if (status) {
if (WIFSIGNALED(status))
eprintf("subprocess git was killed by signal %i\n", WTERMSIG(status));
exit(libsimple_default_failure_exit);
}
if (dirsize - dirlen < sizeof("/.git"))
dir = erealloc(dir, dirlen + sizeof("/.git"));
stpcpy(&dir[dirlen], "/.git");
if (mount(dir, dir, NULL, MS_BIND, NULL))
eprintf("mount %s %s NULL MS_BIND NULL:", dir, dir);
if (mount("none", dir, NULL, MS_BIND | MS_REMOUNT | MS_RDONLY, NULL))
eprintf("mount none %s NULL MS_BIND|MS_REMOUNT|MS_RDONLY NULL:", dir);
free(dir);
if (setegid(getgid()))
eprintf("setegid <real group>:");
if (seteuid(getuid()))
eprintf("seteuid <real user>:");
execvp(argv[0], argv);
enprintf(errno == ENOENT ? 127 : 126, "execvp %s:", argv[0]);
return 0;
}
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