Merge branch 'ma/doc-diff-usage-fix'
[git] / archive-tar.c
1 /*
2  * Copyright (c) 2005, 2006 Rene Scharfe
3  */
4 #include "cache.h"
5 #include "config.h"
6 #include "tar.h"
7 #include "archive.h"
8 #include "object-store.h"
9 #include "streaming.h"
10 #include "run-command.h"
11
12 #define RECORDSIZE      (512)
13 #define BLOCKSIZE       (RECORDSIZE * 20)
14
15 static char block[BLOCKSIZE];
16 static unsigned long offset;
17
18 static int tar_umask = 002;
19
20 static int write_tar_filter_archive(const struct archiver *ar,
21                                     struct archiver_args *args);
22
23 /*
24  * This is the max value that a ustar size header can specify, as it is fixed
25  * at 11 octal digits. POSIX specifies that we switch to extended headers at
26  * this size.
27  *
28  * Likewise for the mtime (which happens to use a buffer of the same size).
29  */
30 #if ULONG_MAX == 0xFFFFFFFF
31 #define USTAR_MAX_SIZE ULONG_MAX
32 #else
33 #define USTAR_MAX_SIZE 077777777777UL
34 #endif
35 #if TIME_MAX == 0xFFFFFFFF
36 #define USTAR_MAX_MTIME TIME_MAX
37 #else
38 #define USTAR_MAX_MTIME 077777777777ULL
39 #endif
40
41 /* writes out the whole block, but only if it is full */
42 static void write_if_needed(void)
43 {
44         if (offset == BLOCKSIZE) {
45                 write_or_die(1, block, BLOCKSIZE);
46                 offset = 0;
47         }
48 }
49
50 /*
51  * queues up writes, so that all our write(2) calls write exactly one
52  * full block; pads writes to RECORDSIZE
53  */
54 static void do_write_blocked(const void *data, unsigned long size)
55 {
56         const char *buf = data;
57
58         if (offset) {
59                 unsigned long chunk = BLOCKSIZE - offset;
60                 if (size < chunk)
61                         chunk = size;
62                 memcpy(block + offset, buf, chunk);
63                 size -= chunk;
64                 offset += chunk;
65                 buf += chunk;
66                 write_if_needed();
67         }
68         while (size >= BLOCKSIZE) {
69                 write_or_die(1, buf, BLOCKSIZE);
70                 size -= BLOCKSIZE;
71                 buf += BLOCKSIZE;
72         }
73         if (size) {
74                 memcpy(block + offset, buf, size);
75                 offset += size;
76         }
77 }
78
79 static void finish_record(void)
80 {
81         unsigned long tail;
82         tail = offset % RECORDSIZE;
83         if (tail)  {
84                 memset(block + offset, 0, RECORDSIZE - tail);
85                 offset += RECORDSIZE - tail;
86         }
87         write_if_needed();
88 }
89
90 static void write_blocked(const void *data, unsigned long size)
91 {
92         do_write_blocked(data, size);
93         finish_record();
94 }
95
96 /*
97  * The end of tar archives is marked by 2*512 nul bytes and after that
98  * follows the rest of the block (if any).
99  */
100 static void write_trailer(void)
101 {
102         int tail = BLOCKSIZE - offset;
103         memset(block + offset, 0, tail);
104         write_or_die(1, block, BLOCKSIZE);
105         if (tail < 2 * RECORDSIZE) {
106                 memset(block, 0, offset);
107                 write_or_die(1, block, BLOCKSIZE);
108         }
109 }
110
111 /*
112  * queues up writes, so that all our write(2) calls write exactly one
113  * full block; pads writes to RECORDSIZE
114  */
115 static int stream_blocked(const struct object_id *oid)
116 {
117         struct git_istream *st;
118         enum object_type type;
119         unsigned long sz;
120         char buf[BLOCKSIZE];
121         ssize_t readlen;
122
123         st = open_istream(oid, &type, &sz, NULL);
124         if (!st)
125                 return error(_("cannot stream blob %s"), oid_to_hex(oid));
126         for (;;) {
127                 readlen = read_istream(st, buf, sizeof(buf));
128                 if (readlen <= 0)
129                         break;
130                 do_write_blocked(buf, readlen);
131         }
132         close_istream(st);
133         if (!readlen)
134                 finish_record();
135         return readlen;
136 }
137
138 /*
139  * pax extended header records have the format "%u %s=%s\n".  %u contains
140  * the size of the whole string (including the %u), the first %s is the
141  * keyword, the second one is the value.  This function constructs such a
142  * string and appends it to a struct strbuf.
143  */
144 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
145                                      const char *value, unsigned int valuelen)
146 {
147         int len, tmp;
148
149         /* "%u %s=%s\n" */
150         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
151         for (tmp = len; tmp > 9; tmp /= 10)
152                 len++;
153
154         strbuf_grow(sb, len);
155         strbuf_addf(sb, "%u %s=", len, keyword);
156         strbuf_add(sb, value, valuelen);
157         strbuf_addch(sb, '\n');
158 }
159
160 /*
161  * Like strbuf_append_ext_header, but for numeric values.
162  */
163 static void strbuf_append_ext_header_uint(struct strbuf *sb,
164                                           const char *keyword,
165                                           uintmax_t value)
166 {
167         char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
168         int len;
169
170         len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
171         strbuf_append_ext_header(sb, keyword, buf, len);
172 }
173
174 static unsigned int ustar_header_chksum(const struct ustar_header *header)
175 {
176         const unsigned char *p = (const unsigned char *)header;
177         unsigned int chksum = 0;
178         while (p < (const unsigned char *)header->chksum)
179                 chksum += *p++;
180         chksum += sizeof(header->chksum) * ' ';
181         p += sizeof(header->chksum);
182         while (p < (const unsigned char *)header + sizeof(struct ustar_header))
183                 chksum += *p++;
184         return chksum;
185 }
186
187 static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
188 {
189         size_t i = pathlen;
190         if (i > 1 && path[i - 1] == '/')
191                 i--;
192         if (i > maxlen)
193                 i = maxlen;
194         do {
195                 i--;
196         } while (i > 0 && path[i] != '/');
197         return i;
198 }
199
200 static void prepare_header(struct archiver_args *args,
201                            struct ustar_header *header,
202                            unsigned int mode, unsigned long size)
203 {
204         xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
205         xsnprintf(header->size, sizeof(header->size), "%011"PRIoMAX , S_ISREG(mode) ? (uintmax_t)size : (uintmax_t)0);
206         xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
207
208         xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
209         xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
210         strlcpy(header->uname, "root", sizeof(header->uname));
211         strlcpy(header->gname, "root", sizeof(header->gname));
212         xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
213         xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
214
215         memcpy(header->magic, "ustar", 6);
216         memcpy(header->version, "00", 2);
217
218         xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
219 }
220
221 static void write_extended_header(struct archiver_args *args,
222                                   const struct object_id *oid,
223                                   const void *buffer, unsigned long size)
224 {
225         struct ustar_header header;
226         unsigned int mode;
227         memset(&header, 0, sizeof(header));
228         *header.typeflag = TYPEFLAG_EXT_HEADER;
229         mode = 0100666;
230         xsnprintf(header.name, sizeof(header.name), "%s.paxheader", oid_to_hex(oid));
231         prepare_header(args, &header, mode, size);
232         write_blocked(&header, sizeof(header));
233         write_blocked(buffer, size);
234 }
235
236 static int write_tar_entry(struct archiver_args *args,
237                            const struct object_id *oid,
238                            const char *path, size_t pathlen,
239                            unsigned int mode)
240 {
241         struct ustar_header header;
242         struct strbuf ext_header = STRBUF_INIT;
243         unsigned int old_mode = mode;
244         unsigned long size, size_in_header;
245         void *buffer;
246         int err = 0;
247
248         memset(&header, 0, sizeof(header));
249
250         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
251                 *header.typeflag = TYPEFLAG_DIR;
252                 mode = (mode | 0777) & ~tar_umask;
253         } else if (S_ISLNK(mode)) {
254                 *header.typeflag = TYPEFLAG_LNK;
255                 mode |= 0777;
256         } else if (S_ISREG(mode)) {
257                 *header.typeflag = TYPEFLAG_REG;
258                 mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
259         } else {
260                 return error(_("unsupported file mode: 0%o (SHA1: %s)"),
261                              mode, oid_to_hex(oid));
262         }
263         if (pathlen > sizeof(header.name)) {
264                 size_t plen = get_path_prefix(path, pathlen,
265                                               sizeof(header.prefix));
266                 size_t rest = pathlen - plen - 1;
267                 if (plen > 0 && rest <= sizeof(header.name)) {
268                         memcpy(header.prefix, path, plen);
269                         memcpy(header.name, path + plen + 1, rest);
270                 } else {
271                         xsnprintf(header.name, sizeof(header.name), "%s.data",
272                                   oid_to_hex(oid));
273                         strbuf_append_ext_header(&ext_header, "path",
274                                                  path, pathlen);
275                 }
276         } else
277                 memcpy(header.name, path, pathlen);
278
279         if (S_ISREG(mode) && !args->convert &&
280             oid_object_info(args->repo, oid, &size) == OBJ_BLOB &&
281             size > big_file_threshold)
282                 buffer = NULL;
283         else if (S_ISLNK(mode) || S_ISREG(mode)) {
284                 enum object_type type;
285                 buffer = object_file_to_archive(args, path, oid, old_mode, &type, &size);
286                 if (!buffer)
287                         return error(_("cannot read %s"), oid_to_hex(oid));
288         } else {
289                 buffer = NULL;
290                 size = 0;
291         }
292
293         if (S_ISLNK(mode)) {
294                 if (size > sizeof(header.linkname)) {
295                         xsnprintf(header.linkname, sizeof(header.linkname),
296                                   "see %s.paxheader", oid_to_hex(oid));
297                         strbuf_append_ext_header(&ext_header, "linkpath",
298                                                  buffer, size);
299                 } else
300                         memcpy(header.linkname, buffer, size);
301         }
302
303         size_in_header = size;
304         if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
305                 size_in_header = 0;
306                 strbuf_append_ext_header_uint(&ext_header, "size", size);
307         }
308
309         prepare_header(args, &header, mode, size_in_header);
310
311         if (ext_header.len > 0) {
312                 write_extended_header(args, oid, ext_header.buf,
313                                       ext_header.len);
314         }
315         strbuf_release(&ext_header);
316         write_blocked(&header, sizeof(header));
317         if (S_ISREG(mode) && size > 0) {
318                 if (buffer)
319                         write_blocked(buffer, size);
320                 else
321                         err = stream_blocked(oid);
322         }
323         free(buffer);
324         return err;
325 }
326
327 static void write_global_extended_header(struct archiver_args *args)
328 {
329         const unsigned char *sha1 = args->commit_sha1;
330         struct strbuf ext_header = STRBUF_INIT;
331         struct ustar_header header;
332         unsigned int mode;
333
334         if (sha1)
335                 strbuf_append_ext_header(&ext_header, "comment",
336                                          sha1_to_hex(sha1), 40);
337         if (args->time > USTAR_MAX_MTIME) {
338                 strbuf_append_ext_header_uint(&ext_header, "mtime",
339                                               args->time);
340                 args->time = USTAR_MAX_MTIME;
341         }
342
343         if (!ext_header.len)
344                 return;
345
346         memset(&header, 0, sizeof(header));
347         *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
348         mode = 0100666;
349         xsnprintf(header.name, sizeof(header.name), "pax_global_header");
350         prepare_header(args, &header, mode, ext_header.len);
351         write_blocked(&header, sizeof(header));
352         write_blocked(ext_header.buf, ext_header.len);
353         strbuf_release(&ext_header);
354 }
355
356 static struct archiver **tar_filters;
357 static int nr_tar_filters;
358 static int alloc_tar_filters;
359
360 static struct archiver *find_tar_filter(const char *name, int len)
361 {
362         int i;
363         for (i = 0; i < nr_tar_filters; i++) {
364                 struct archiver *ar = tar_filters[i];
365                 if (!strncmp(ar->name, name, len) && !ar->name[len])
366                         return ar;
367         }
368         return NULL;
369 }
370
371 static int tar_filter_config(const char *var, const char *value, void *data)
372 {
373         struct archiver *ar;
374         const char *name;
375         const char *type;
376         int namelen;
377
378         if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
379                 return 0;
380
381         ar = find_tar_filter(name, namelen);
382         if (!ar) {
383                 ar = xcalloc(1, sizeof(*ar));
384                 ar->name = xmemdupz(name, namelen);
385                 ar->write_archive = write_tar_filter_archive;
386                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
387                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
388                 tar_filters[nr_tar_filters++] = ar;
389         }
390
391         if (!strcmp(type, "command")) {
392                 if (!value)
393                         return config_error_nonbool(var);
394                 free(ar->data);
395                 ar->data = xstrdup(value);
396                 return 0;
397         }
398         if (!strcmp(type, "remote")) {
399                 if (git_config_bool(var, value))
400                         ar->flags |= ARCHIVER_REMOTE;
401                 else
402                         ar->flags &= ~ARCHIVER_REMOTE;
403                 return 0;
404         }
405
406         return 0;
407 }
408
409 static int git_tar_config(const char *var, const char *value, void *cb)
410 {
411         if (!strcmp(var, "tar.umask")) {
412                 if (value && !strcmp(value, "user")) {
413                         tar_umask = umask(0);
414                         umask(tar_umask);
415                 } else {
416                         tar_umask = git_config_int(var, value);
417                 }
418                 return 0;
419         }
420
421         return tar_filter_config(var, value, cb);
422 }
423
424 static int write_tar_archive(const struct archiver *ar,
425                              struct archiver_args *args)
426 {
427         int err = 0;
428
429         write_global_extended_header(args);
430         err = write_archive_entries(args, write_tar_entry);
431         if (!err)
432                 write_trailer();
433         return err;
434 }
435
436 static int write_tar_filter_archive(const struct archiver *ar,
437                                     struct archiver_args *args)
438 {
439         struct strbuf cmd = STRBUF_INIT;
440         struct child_process filter = CHILD_PROCESS_INIT;
441         const char *argv[2];
442         int r;
443
444         if (!ar->data)
445                 BUG("tar-filter archiver called with no filter defined");
446
447         strbuf_addstr(&cmd, ar->data);
448         if (args->compression_level >= 0)
449                 strbuf_addf(&cmd, " -%d", args->compression_level);
450
451         argv[0] = cmd.buf;
452         argv[1] = NULL;
453         filter.argv = argv;
454         filter.use_shell = 1;
455         filter.in = -1;
456
457         if (start_command(&filter) < 0)
458                 die_errno(_("unable to start '%s' filter"), argv[0]);
459         close(1);
460         if (dup2(filter.in, 1) < 0)
461                 die_errno(_("unable to redirect descriptor"));
462         close(filter.in);
463
464         r = write_tar_archive(ar, args);
465
466         close(1);
467         if (finish_command(&filter) != 0)
468                 die(_("'%s' filter reported error"), argv[0]);
469
470         strbuf_release(&cmd);
471         return r;
472 }
473
474 static struct archiver tar_archiver = {
475         "tar",
476         write_tar_archive,
477         ARCHIVER_REMOTE
478 };
479
480 void init_tar_archiver(void)
481 {
482         int i;
483         register_archiver(&tar_archiver);
484
485         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
486         tar_filter_config("tar.tgz.remote", "true", NULL);
487         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
488         tar_filter_config("tar.tar.gz.remote", "true", NULL);
489         git_config(git_tar_config, NULL);
490         for (i = 0; i < nr_tar_filters; i++) {
491                 /* omit any filters that never had a command configured */
492                 if (tar_filters[i]->data)
493                         register_archiver(tar_filters[i]);
494         }
495 }