| /* |
| * Copyright (c) 2005, Junio C Hamano |
| */ |
| #include "cache.h" |
| #include "sigchain.h" |
| |
| static struct lock_file *lock_file_list; |
| static const char *alternate_index_output; |
| |
| static void remove_lock_file(void) |
| { |
| pid_t me = getpid(); |
| |
| while (lock_file_list) { |
| if (lock_file_list->owner == me && |
| lock_file_list->filename[0]) { |
| if (lock_file_list->fd >= 0) |
| close(lock_file_list->fd); |
| unlink_or_warn(lock_file_list->filename); |
| } |
| lock_file_list = lock_file_list->next; |
| } |
| } |
| |
| static void remove_lock_file_on_signal(int signo) |
| { |
| remove_lock_file(); |
| sigchain_pop(signo); |
| raise(signo); |
| } |
| |
| /* |
| * p = absolute or relative path name |
| * |
| * Return a pointer into p showing the beginning of the last path name |
| * element. If p is empty or the root directory ("/"), just return p. |
| */ |
| static char *last_path_elm(char *p) |
| { |
| /* r starts pointing to null at the end of the string */ |
| char *r = strchr(p, '\0'); |
| |
| if (r == p) |
| return p; /* just return empty string */ |
| |
| r--; /* back up to last non-null character */ |
| |
| /* back up past trailing slashes, if any */ |
| while (r > p && *r == '/') |
| r--; |
| |
| /* |
| * then go backwards until I hit a slash, or the beginning of |
| * the string |
| */ |
| while (r > p && *(r-1) != '/') |
| r--; |
| return r; |
| } |
| |
| |
| /* We allow "recursive" symbolic links. Only within reason, though */ |
| #define MAXDEPTH 5 |
| |
| /* |
| * p = path that may be a symlink |
| * s = full size of p |
| * |
| * If p is a symlink, attempt to overwrite p with a path to the real |
| * file or directory (which may or may not exist), following a chain of |
| * symlinks if necessary. Otherwise, leave p unmodified. |
| * |
| * This is a best-effort routine. If an error occurs, p will either be |
| * left unmodified or will name a different symlink in a symlink chain |
| * that started with p's initial contents. |
| * |
| * Always returns p. |
| */ |
| |
| static char *resolve_symlink(char *p, size_t s) |
| { |
| int depth = MAXDEPTH; |
| |
| while (depth--) { |
| char link[PATH_MAX]; |
| int link_len = readlink(p, link, sizeof(link)); |
| if (link_len < 0) { |
| /* not a symlink anymore */ |
| return p; |
| } |
| else if (link_len < sizeof(link)) |
| /* readlink() never null-terminates */ |
| link[link_len] = '\0'; |
| else { |
| warning("%s: symlink too long", p); |
| return p; |
| } |
| |
| if (is_absolute_path(link)) { |
| /* absolute path simply replaces p */ |
| if (link_len < s) |
| strcpy(p, link); |
| else { |
| warning("%s: symlink too long", p); |
| return p; |
| } |
| } else { |
| /* |
| * link is a relative path, so I must replace the |
| * last element of p with it. |
| */ |
| char *r = (char *)last_path_elm(p); |
| if (r - p + link_len < s) |
| strcpy(r, link); |
| else { |
| warning("%s: symlink too long", p); |
| return p; |
| } |
| } |
| } |
| return p; |
| } |
| |
| |
| static int lock_file(struct lock_file *lk, const char *path, int flags) |
| { |
| if (strlen(path) >= sizeof(lk->filename)) |
| return -1; |
| strcpy(lk->filename, path); |
| /* |
| * subtract 5 from size to make sure there's room for adding |
| * ".lock" for the lock file name |
| */ |
| if (!(flags & LOCK_NODEREF)) |
| resolve_symlink(lk->filename, sizeof(lk->filename)-5); |
| strcat(lk->filename, ".lock"); |
| lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666); |
| if (0 <= lk->fd) { |
| if (!lock_file_list) { |
| sigchain_push_common(remove_lock_file_on_signal); |
| atexit(remove_lock_file); |
| } |
| lk->owner = getpid(); |
| if (!lk->on_list) { |
| lk->next = lock_file_list; |
| lock_file_list = lk; |
| lk->on_list = 1; |
| } |
| if (adjust_shared_perm(lk->filename)) |
| return error("cannot fix permission bits on %s", |
| lk->filename); |
| } |
| else |
| lk->filename[0] = 0; |
| return lk->fd; |
| } |
| |
| static char *unable_to_lock_message(const char *path, int err) |
| { |
| struct strbuf buf = STRBUF_INIT; |
| |
| if (err == EEXIST) { |
| strbuf_addf(&buf, "Unable to create '%s.lock': %s.\n\n" |
| "If no other git process is currently running, this probably means a\n" |
| "git process crashed in this repository earlier. Make sure no other git\n" |
| "process is running and remove the file manually to continue.", |
| absolute_path(path), strerror(err)); |
| } else |
| strbuf_addf(&buf, "Unable to create '%s.lock': %s", |
| absolute_path(path), strerror(err)); |
| return strbuf_detach(&buf, NULL); |
| } |
| |
| int unable_to_lock_error(const char *path, int err) |
| { |
| char *msg = unable_to_lock_message(path, err); |
| error("%s", msg); |
| free(msg); |
| return -1; |
| } |
| |
| NORETURN void unable_to_lock_index_die(const char *path, int err) |
| { |
| die("%s", unable_to_lock_message(path, err)); |
| } |
| |
| int hold_lock_file_for_update(struct lock_file *lk, const char *path, int flags) |
| { |
| int fd = lock_file(lk, path, flags); |
| if (fd < 0 && (flags & LOCK_DIE_ON_ERROR)) |
| unable_to_lock_index_die(path, errno); |
| return fd; |
| } |
| |
| int hold_lock_file_for_append(struct lock_file *lk, const char *path, int flags) |
| { |
| int fd, orig_fd; |
| |
| fd = lock_file(lk, path, flags); |
| if (fd < 0) { |
| if (flags & LOCK_DIE_ON_ERROR) |
| unable_to_lock_index_die(path, errno); |
| return fd; |
| } |
| |
| orig_fd = open(path, O_RDONLY); |
| if (orig_fd < 0) { |
| if (errno != ENOENT) { |
| if (flags & LOCK_DIE_ON_ERROR) |
| die("cannot open '%s' for copying", path); |
| close(fd); |
| return error("cannot open '%s' for copying", path); |
| } |
| } else if (copy_fd(orig_fd, fd)) { |
| if (flags & LOCK_DIE_ON_ERROR) |
| exit(128); |
| close(fd); |
| return -1; |
| } |
| return fd; |
| } |
| |
| int close_lock_file(struct lock_file *lk) |
| { |
| int fd = lk->fd; |
| lk->fd = -1; |
| return close(fd); |
| } |
| |
| int commit_lock_file(struct lock_file *lk) |
| { |
| char result_file[PATH_MAX]; |
| size_t i; |
| if (lk->fd >= 0 && close_lock_file(lk)) |
| return -1; |
| strcpy(result_file, lk->filename); |
| i = strlen(result_file) - 5; /* .lock */ |
| result_file[i] = 0; |
| if (rename(lk->filename, result_file)) |
| return -1; |
| lk->filename[0] = 0; |
| return 0; |
| } |
| |
| int hold_locked_index(struct lock_file *lk, int die_on_error) |
| { |
| return hold_lock_file_for_update(lk, get_index_file(), |
| die_on_error |
| ? LOCK_DIE_ON_ERROR |
| : 0); |
| } |
| |
| void set_alternate_index_output(const char *name) |
| { |
| alternate_index_output = name; |
| } |
| |
| int commit_locked_index(struct lock_file *lk) |
| { |
| if (alternate_index_output) { |
| if (lk->fd >= 0 && close_lock_file(lk)) |
| return -1; |
| if (rename(lk->filename, alternate_index_output)) |
| return -1; |
| lk->filename[0] = 0; |
| return 0; |
| } |
| else |
| return commit_lock_file(lk); |
| } |
| |
| void rollback_lock_file(struct lock_file *lk) |
| { |
| if (lk->filename[0]) { |
| if (lk->fd >= 0) |
| close(lk->fd); |
| unlink_or_warn(lk->filename); |
| } |
| lk->filename[0] = 0; |
| } |