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![Jeff King](/assets/img/avatar_default.png)
When this code was originally written, there wasn't much thought given to the timing between a client asking for "exit", the daemon signaling that the action is done (with EOF), and the actual cleanup of the socket. However, we need to care about this so that our test scripts do not end up racy (e.g., by asking for an exit and checking that the socket was cleaned up). The code that is already there happens to behave very reasonably; let's add a comment to make it clear that any changes should retain the same behavior. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
287 lines
6.6 KiB
C
287 lines
6.6 KiB
C
#include "cache.h"
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#include "tempfile.h"
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#include "credential.h"
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#include "unix-socket.h"
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#include "parse-options.h"
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static struct tempfile socket_file;
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struct credential_cache_entry {
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struct credential item;
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unsigned long expiration;
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};
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static struct credential_cache_entry *entries;
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static int entries_nr;
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static int entries_alloc;
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static void cache_credential(struct credential *c, int timeout)
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{
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struct credential_cache_entry *e;
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ALLOC_GROW(entries, entries_nr + 1, entries_alloc);
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e = &entries[entries_nr++];
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/* take ownership of pointers */
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memcpy(&e->item, c, sizeof(*c));
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memset(c, 0, sizeof(*c));
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e->expiration = time(NULL) + timeout;
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}
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static struct credential_cache_entry *lookup_credential(const struct credential *c)
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{
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int i;
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for (i = 0; i < entries_nr; i++) {
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struct credential *e = &entries[i].item;
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if (credential_match(c, e))
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return &entries[i];
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}
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return NULL;
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}
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static void remove_credential(const struct credential *c)
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{
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struct credential_cache_entry *e;
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e = lookup_credential(c);
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if (e)
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e->expiration = 0;
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}
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static int check_expirations(void)
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{
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static unsigned long wait_for_entry_until;
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int i = 0;
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unsigned long now = time(NULL);
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unsigned long next = (unsigned long)-1;
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/*
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* Initially give the client 30 seconds to actually contact us
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* and store a credential before we decide there's no point in
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* keeping the daemon around.
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*/
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if (!wait_for_entry_until)
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wait_for_entry_until = now + 30;
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while (i < entries_nr) {
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if (entries[i].expiration <= now) {
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entries_nr--;
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credential_clear(&entries[i].item);
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if (i != entries_nr)
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memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
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/*
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* Stick around 30 seconds in case a new credential
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* shows up (e.g., because we just removed a failed
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* one, and we will soon get the correct one).
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*/
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wait_for_entry_until = now + 30;
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}
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else {
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if (entries[i].expiration < next)
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next = entries[i].expiration;
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i++;
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}
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}
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if (!entries_nr) {
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if (wait_for_entry_until <= now)
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return 0;
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next = wait_for_entry_until;
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}
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return next - now;
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}
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static int read_request(FILE *fh, struct credential *c,
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struct strbuf *action, int *timeout) {
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static struct strbuf item = STRBUF_INIT;
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const char *p;
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strbuf_getline(&item, fh, '\n');
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if (!skip_prefix(item.buf, "action=", &p))
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return error("client sent bogus action line: %s", item.buf);
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strbuf_addstr(action, p);
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strbuf_getline(&item, fh, '\n');
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if (!skip_prefix(item.buf, "timeout=", &p))
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return error("client sent bogus timeout line: %s", item.buf);
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*timeout = atoi(p);
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if (credential_read(c, fh) < 0)
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return -1;
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return 0;
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}
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static void serve_one_client(FILE *in, FILE *out)
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{
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struct credential c = CREDENTIAL_INIT;
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struct strbuf action = STRBUF_INIT;
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int timeout = -1;
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if (read_request(in, &c, &action, &timeout) < 0)
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/* ignore error */ ;
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else if (!strcmp(action.buf, "get")) {
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struct credential_cache_entry *e = lookup_credential(&c);
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if (e) {
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fprintf(out, "username=%s\n", e->item.username);
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fprintf(out, "password=%s\n", e->item.password);
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}
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}
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else if (!strcmp(action.buf, "exit")) {
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/*
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* It's important that we clean up our socket first, and then
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* signal the client only once we have finished the cleanup.
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* Calling exit() directly does this, because we clean up in
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* our atexit() handler, and then signal the client when our
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* process actually ends, which closes the socket and gives
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* them EOF.
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*/
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exit(0);
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}
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else if (!strcmp(action.buf, "erase"))
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remove_credential(&c);
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else if (!strcmp(action.buf, "store")) {
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if (timeout < 0)
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warning("cache client didn't specify a timeout");
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else if (!c.username || !c.password)
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warning("cache client gave us a partial credential");
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else {
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remove_credential(&c);
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cache_credential(&c, timeout);
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}
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}
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else
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warning("cache client sent unknown action: %s", action.buf);
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credential_clear(&c);
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strbuf_release(&action);
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}
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static int serve_cache_loop(int fd)
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{
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struct pollfd pfd;
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unsigned long wakeup;
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wakeup = check_expirations();
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if (!wakeup)
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return 0;
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pfd.fd = fd;
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pfd.events = POLLIN;
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if (poll(&pfd, 1, 1000 * wakeup) < 0) {
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if (errno != EINTR)
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die_errno("poll failed");
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return 1;
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}
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if (pfd.revents & POLLIN) {
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int client, client2;
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FILE *in, *out;
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client = accept(fd, NULL, NULL);
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if (client < 0) {
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warning("accept failed: %s", strerror(errno));
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return 1;
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}
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client2 = dup(client);
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if (client2 < 0) {
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warning("dup failed: %s", strerror(errno));
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close(client);
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return 1;
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}
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in = xfdopen(client, "r");
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out = xfdopen(client2, "w");
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serve_one_client(in, out);
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fclose(in);
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fclose(out);
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}
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return 1;
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}
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static void serve_cache(const char *socket_path, int debug)
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{
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int fd;
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fd = unix_stream_listen(socket_path);
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if (fd < 0)
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die_errno("unable to bind to '%s'", socket_path);
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printf("ok\n");
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fclose(stdout);
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if (!debug) {
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if (!freopen("/dev/null", "w", stderr))
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die_errno("unable to point stderr to /dev/null");
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}
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while (serve_cache_loop(fd))
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; /* nothing */
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close(fd);
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}
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static const char permissions_advice[] =
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"The permissions on your socket directory are too loose; other\n"
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"users may be able to read your cached credentials. Consider running:\n"
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"\n"
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" chmod 0700 %s";
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static void check_socket_directory(const char *path)
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{
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struct stat st;
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char *path_copy = xstrdup(path);
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char *dir = dirname(path_copy);
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if (!stat(dir, &st)) {
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if (st.st_mode & 077)
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die(permissions_advice, dir);
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free(path_copy);
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return;
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}
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/*
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* We must be sure to create the directory with the correct mode,
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* not just chmod it after the fact; otherwise, there is a race
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* condition in which somebody can chdir to it, sleep, then try to open
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* our protected socket.
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*/
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if (safe_create_leading_directories_const(dir) < 0)
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die_errno("unable to create directories for '%s'", dir);
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if (mkdir(dir, 0700) < 0)
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die_errno("unable to mkdir '%s'", dir);
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free(path_copy);
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}
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int main(int argc, const char **argv)
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{
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const char *socket_path;
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int ignore_sighup = 0;
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static const char *usage[] = {
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"git-credential-cache--daemon [opts] <socket_path>",
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NULL
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};
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int debug = 0;
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const struct option options[] = {
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OPT_BOOL(0, "debug", &debug,
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N_("print debugging messages to stderr")),
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OPT_END()
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};
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git_config_get_bool("credentialcache.ignoresighup", &ignore_sighup);
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argc = parse_options(argc, argv, NULL, options, usage, 0);
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socket_path = argv[0];
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if (!socket_path)
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usage_with_options(usage, options);
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check_socket_directory(socket_path);
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register_tempfile(&socket_file, socket_path);
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if (ignore_sighup)
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signal(SIGHUP, SIG_IGN);
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serve_cache(socket_path, debug);
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delete_tempfile(&socket_file);
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return 0;
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}
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