gpg-interface: prefer "long" key format output when verifying pgp signatures
[git/debian.git] / tempfile.c
blob0af7ebf016745c4a114a12d207381342b29ccf4f
1 /*
2 * State diagram and cleanup
3 * -------------------------
5 * If the program exits while a temporary file is active, we want to
6 * make sure that we remove it. This is done by remembering the active
7 * temporary files in a linked list, `tempfile_list`. An `atexit(3)`
8 * handler and a signal handler are registered, to clean up any active
9 * temporary files.
11 * Because the signal handler can run at any time, `tempfile_list` and
12 * the `tempfile` objects that comprise it must be kept in
13 * self-consistent states at all times.
15 * The possible states of a `tempfile` object are as follows:
17 * - Uninitialized. In this state the object's `on_list` field must be
18 * zero but the rest of its contents need not be initialized. As
19 * soon as the object is used in any way, it is irrevocably
20 * registered in `tempfile_list`, and `on_list` is set.
22 * - Active, file open (after `create_tempfile()` or
23 * `reopen_tempfile()`). In this state:
25 * - the temporary file exists
26 * - `active` is set
27 * - `filename` holds the filename of the temporary file
28 * - `fd` holds a file descriptor open for writing to it
29 * - `fp` holds a pointer to an open `FILE` object if and only if
30 * `fdopen_tempfile()` has been called on the object
31 * - `owner` holds the PID of the process that created the file
33 * - Active, file closed (after successful `close_tempfile()`). Same
34 * as the previous state, except that the temporary file is closed,
35 * `fd` is -1, and `fp` is `NULL`.
37 * - Inactive (after `delete_tempfile()`, `rename_tempfile()`, a
38 * failed attempt to create a temporary file, or a failed
39 * `close_tempfile()`). In this state:
41 * - `active` is unset
42 * - `filename` is empty (usually, though there are transitory
43 * states in which this condition doesn't hold). Client code should
44 * *not* rely on the filename being empty in this state.
45 * - `fd` is -1 and `fp` is `NULL`
46 * - the object is left registered in the `tempfile_list`, and
47 * `on_list` is set.
49 * A temporary file is owned by the process that created it. The
50 * `tempfile` has an `owner` field that records the owner's PID. This
51 * field is used to prevent a forked process from deleting a temporary
52 * file created by its parent.
55 #include "cache.h"
56 #include "tempfile.h"
57 #include "sigchain.h"
59 static struct tempfile *volatile tempfile_list;
61 static void remove_tempfiles(int skip_fclose)
63 pid_t me = getpid();
65 while (tempfile_list) {
66 if (tempfile_list->owner == me) {
67 /* fclose() is not safe to call in a signal handler */
68 if (skip_fclose)
69 tempfile_list->fp = NULL;
70 delete_tempfile(tempfile_list);
72 tempfile_list = tempfile_list->next;
76 static void remove_tempfiles_on_exit(void)
78 remove_tempfiles(0);
81 static void remove_tempfiles_on_signal(int signo)
83 remove_tempfiles(1);
84 sigchain_pop(signo);
85 raise(signo);
89 * Initialize *tempfile if necessary and add it to tempfile_list.
91 static void prepare_tempfile_object(struct tempfile *tempfile)
93 if (!tempfile_list) {
94 /* One-time initialization */
95 sigchain_push_common(remove_tempfiles_on_signal);
96 atexit(remove_tempfiles_on_exit);
99 if (tempfile->active)
100 die("BUG: prepare_tempfile_object called for active object");
101 if (!tempfile->on_list) {
102 /* Initialize *tempfile and add it to tempfile_list: */
103 tempfile->fd = -1;
104 tempfile->fp = NULL;
105 tempfile->active = 0;
106 tempfile->owner = 0;
107 strbuf_init(&tempfile->filename, 0);
108 tempfile->next = tempfile_list;
109 tempfile_list = tempfile;
110 tempfile->on_list = 1;
111 } else if (tempfile->filename.len) {
112 /* This shouldn't happen, but better safe than sorry. */
113 die("BUG: prepare_tempfile_object called for improperly-reset object");
117 /* Make sure errno contains a meaningful value on error */
118 int create_tempfile(struct tempfile *tempfile, const char *path)
120 prepare_tempfile_object(tempfile);
122 strbuf_add_absolute_path(&tempfile->filename, path);
123 tempfile->fd = open(tempfile->filename.buf, O_RDWR | O_CREAT | O_EXCL, 0666);
124 if (tempfile->fd < 0) {
125 strbuf_reset(&tempfile->filename);
126 return -1;
128 tempfile->owner = getpid();
129 tempfile->active = 1;
130 if (adjust_shared_perm(tempfile->filename.buf)) {
131 int save_errno = errno;
132 error("cannot fix permission bits on %s", tempfile->filename.buf);
133 delete_tempfile(tempfile);
134 errno = save_errno;
135 return -1;
137 return tempfile->fd;
140 void register_tempfile(struct tempfile *tempfile, const char *path)
142 prepare_tempfile_object(tempfile);
143 strbuf_add_absolute_path(&tempfile->filename, path);
144 tempfile->owner = getpid();
145 tempfile->active = 1;
148 int mks_tempfile_sm(struct tempfile *tempfile,
149 const char *template, int suffixlen, int mode)
151 prepare_tempfile_object(tempfile);
153 strbuf_add_absolute_path(&tempfile->filename, template);
154 tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode);
155 if (tempfile->fd < 0) {
156 strbuf_reset(&tempfile->filename);
157 return -1;
159 tempfile->owner = getpid();
160 tempfile->active = 1;
161 return tempfile->fd;
164 int mks_tempfile_tsm(struct tempfile *tempfile,
165 const char *template, int suffixlen, int mode)
167 const char *tmpdir;
169 prepare_tempfile_object(tempfile);
171 tmpdir = getenv("TMPDIR");
172 if (!tmpdir)
173 tmpdir = "/tmp";
175 strbuf_addf(&tempfile->filename, "%s/%s", tmpdir, template);
176 tempfile->fd = git_mkstemps_mode(tempfile->filename.buf, suffixlen, mode);
177 if (tempfile->fd < 0) {
178 strbuf_reset(&tempfile->filename);
179 return -1;
181 tempfile->owner = getpid();
182 tempfile->active = 1;
183 return tempfile->fd;
186 int xmks_tempfile_m(struct tempfile *tempfile, const char *template, int mode)
188 int fd;
189 struct strbuf full_template = STRBUF_INIT;
191 strbuf_add_absolute_path(&full_template, template);
192 fd = mks_tempfile_m(tempfile, full_template.buf, mode);
193 if (fd < 0)
194 die_errno("Unable to create temporary file '%s'",
195 full_template.buf);
197 strbuf_release(&full_template);
198 return fd;
201 FILE *fdopen_tempfile(struct tempfile *tempfile, const char *mode)
203 if (!tempfile->active)
204 die("BUG: fdopen_tempfile() called for inactive object");
205 if (tempfile->fp)
206 die("BUG: fdopen_tempfile() called for open object");
208 tempfile->fp = fdopen(tempfile->fd, mode);
209 return tempfile->fp;
212 const char *get_tempfile_path(struct tempfile *tempfile)
214 if (!tempfile->active)
215 die("BUG: get_tempfile_path() called for inactive object");
216 return tempfile->filename.buf;
219 int get_tempfile_fd(struct tempfile *tempfile)
221 if (!tempfile->active)
222 die("BUG: get_tempfile_fd() called for inactive object");
223 return tempfile->fd;
226 FILE *get_tempfile_fp(struct tempfile *tempfile)
228 if (!tempfile->active)
229 die("BUG: get_tempfile_fp() called for inactive object");
230 return tempfile->fp;
233 int close_tempfile(struct tempfile *tempfile)
235 int fd = tempfile->fd;
236 FILE *fp = tempfile->fp;
237 int err;
239 if (fd < 0)
240 return 0;
242 tempfile->fd = -1;
243 if (fp) {
244 tempfile->fp = NULL;
247 * Note: no short-circuiting here; we want to fclose()
248 * in any case!
250 err = ferror(fp) | fclose(fp);
251 } else {
252 err = close(fd);
255 if (err) {
256 int save_errno = errno;
257 delete_tempfile(tempfile);
258 errno = save_errno;
259 return -1;
262 return 0;
265 int reopen_tempfile(struct tempfile *tempfile)
267 if (0 <= tempfile->fd)
268 die("BUG: reopen_tempfile called for an open object");
269 if (!tempfile->active)
270 die("BUG: reopen_tempfile called for an inactive object");
271 tempfile->fd = open(tempfile->filename.buf, O_WRONLY);
272 return tempfile->fd;
275 int rename_tempfile(struct tempfile *tempfile, const char *path)
277 if (!tempfile->active)
278 die("BUG: rename_tempfile called for inactive object");
280 if (close_tempfile(tempfile))
281 return -1;
283 if (rename(tempfile->filename.buf, path)) {
284 int save_errno = errno;
285 delete_tempfile(tempfile);
286 errno = save_errno;
287 return -1;
290 tempfile->active = 0;
291 strbuf_reset(&tempfile->filename);
292 return 0;
295 void delete_tempfile(struct tempfile *tempfile)
297 if (!tempfile->active)
298 return;
300 if (!close_tempfile(tempfile)) {
301 unlink_or_warn(tempfile->filename.buf);
302 tempfile->active = 0;
303 strbuf_reset(&tempfile->filename);