Merge branch 'km/branch-get-push-while-detached' into next
[git] / archive-tar.c
1 /*
2  * Copyright (c) 2005, 2006 Rene Scharfe
3  */
4 #include "cache.h"
5 #include "tar.h"
6 #include "archive.h"
7 #include "streaming.h"
8 #include "run-command.h"
9
10 #define RECORDSIZE      (512)
11 #define BLOCKSIZE       (RECORDSIZE * 20)
12
13 static char block[BLOCKSIZE];
14 static unsigned long offset;
15
16 static int tar_umask = 002;
17
18 static int write_tar_filter_archive(const struct archiver *ar,
19                                     struct archiver_args *args);
20
21 /*
22  * This is the max value that a ustar size header can specify, as it is fixed
23  * at 11 octal digits. POSIX specifies that we switch to extended headers at
24  * this size.
25  *
26  * Likewise for the mtime (which happens to use a buffer of the same size).
27  */
28 #if ULONG_MAX == 0xFFFFFFFF
29 #define USTAR_MAX_SIZE ULONG_MAX
30 #define USTAR_MAX_MTIME ULONG_MAX
31 #else
32 #define USTAR_MAX_SIZE 077777777777UL
33 #define USTAR_MAX_MTIME 077777777777UL
34 #endif
35
36 /* writes out the whole block, but only if it is full */
37 static void write_if_needed(void)
38 {
39         if (offset == BLOCKSIZE) {
40                 write_or_die(1, block, BLOCKSIZE);
41                 offset = 0;
42         }
43 }
44
45 /*
46  * queues up writes, so that all our write(2) calls write exactly one
47  * full block; pads writes to RECORDSIZE
48  */
49 static void do_write_blocked(const void *data, unsigned long size)
50 {
51         const char *buf = data;
52
53         if (offset) {
54                 unsigned long chunk = BLOCKSIZE - offset;
55                 if (size < chunk)
56                         chunk = size;
57                 memcpy(block + offset, buf, chunk);
58                 size -= chunk;
59                 offset += chunk;
60                 buf += chunk;
61                 write_if_needed();
62         }
63         while (size >= BLOCKSIZE) {
64                 write_or_die(1, buf, BLOCKSIZE);
65                 size -= BLOCKSIZE;
66                 buf += BLOCKSIZE;
67         }
68         if (size) {
69                 memcpy(block + offset, buf, size);
70                 offset += size;
71         }
72 }
73
74 static void finish_record(void)
75 {
76         unsigned long tail;
77         tail = offset % RECORDSIZE;
78         if (tail)  {
79                 memset(block + offset, 0, RECORDSIZE - tail);
80                 offset += RECORDSIZE - tail;
81         }
82         write_if_needed();
83 }
84
85 static void write_blocked(const void *data, unsigned long size)
86 {
87         do_write_blocked(data, size);
88         finish_record();
89 }
90
91 /*
92  * The end of tar archives is marked by 2*512 nul bytes and after that
93  * follows the rest of the block (if any).
94  */
95 static void write_trailer(void)
96 {
97         int tail = BLOCKSIZE - offset;
98         memset(block + offset, 0, tail);
99         write_or_die(1, block, BLOCKSIZE);
100         if (tail < 2 * RECORDSIZE) {
101                 memset(block, 0, offset);
102                 write_or_die(1, block, BLOCKSIZE);
103         }
104 }
105
106 /*
107  * queues up writes, so that all our write(2) calls write exactly one
108  * full block; pads writes to RECORDSIZE
109  */
110 static int stream_blocked(const unsigned char *sha1)
111 {
112         struct git_istream *st;
113         enum object_type type;
114         unsigned long sz;
115         char buf[BLOCKSIZE];
116         ssize_t readlen;
117
118         st = open_istream(sha1, &type, &sz, NULL);
119         if (!st)
120                 return error("cannot stream blob %s", sha1_to_hex(sha1));
121         for (;;) {
122                 readlen = read_istream(st, buf, sizeof(buf));
123                 if (readlen <= 0)
124                         break;
125                 do_write_blocked(buf, readlen);
126         }
127         close_istream(st);
128         if (!readlen)
129                 finish_record();
130         return readlen;
131 }
132
133 /*
134  * pax extended header records have the format "%u %s=%s\n".  %u contains
135  * the size of the whole string (including the %u), the first %s is the
136  * keyword, the second one is the value.  This function constructs such a
137  * string and appends it to a struct strbuf.
138  */
139 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
140                                      const char *value, unsigned int valuelen)
141 {
142         int len, tmp;
143
144         /* "%u %s=%s\n" */
145         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
146         for (tmp = len; tmp > 9; tmp /= 10)
147                 len++;
148
149         strbuf_grow(sb, len);
150         strbuf_addf(sb, "%u %s=", len, keyword);
151         strbuf_add(sb, value, valuelen);
152         strbuf_addch(sb, '\n');
153 }
154
155 /*
156  * Like strbuf_append_ext_header, but for numeric values.
157  */
158 static void strbuf_append_ext_header_uint(struct strbuf *sb,
159                                           const char *keyword,
160                                           uintmax_t value)
161 {
162         char buf[40]; /* big enough for 2^128 in decimal, plus NUL */
163         int len;
164
165         len = xsnprintf(buf, sizeof(buf), "%"PRIuMAX, value);
166         strbuf_append_ext_header(sb, keyword, buf, len);
167 }
168
169 static unsigned int ustar_header_chksum(const struct ustar_header *header)
170 {
171         const unsigned char *p = (const unsigned char *)header;
172         unsigned int chksum = 0;
173         while (p < (const unsigned char *)header->chksum)
174                 chksum += *p++;
175         chksum += sizeof(header->chksum) * ' ';
176         p += sizeof(header->chksum);
177         while (p < (const unsigned char *)header + sizeof(struct ustar_header))
178                 chksum += *p++;
179         return chksum;
180 }
181
182 static size_t get_path_prefix(const char *path, size_t pathlen, size_t maxlen)
183 {
184         size_t i = pathlen;
185         if (i > 1 && path[i - 1] == '/')
186                 i--;
187         if (i > maxlen)
188                 i = maxlen;
189         do {
190                 i--;
191         } while (i > 0 && path[i] != '/');
192         return i;
193 }
194
195 static void prepare_header(struct archiver_args *args,
196                            struct ustar_header *header,
197                            unsigned int mode, unsigned long size)
198 {
199         xsnprintf(header->mode, sizeof(header->mode), "%07o", mode & 07777);
200         xsnprintf(header->size, sizeof(header->size), "%011lo", S_ISREG(mode) ? size : 0);
201         xsnprintf(header->mtime, sizeof(header->mtime), "%011lo", (unsigned long) args->time);
202
203         xsnprintf(header->uid, sizeof(header->uid), "%07o", 0);
204         xsnprintf(header->gid, sizeof(header->gid), "%07o", 0);
205         strlcpy(header->uname, "root", sizeof(header->uname));
206         strlcpy(header->gname, "root", sizeof(header->gname));
207         xsnprintf(header->devmajor, sizeof(header->devmajor), "%07o", 0);
208         xsnprintf(header->devminor, sizeof(header->devminor), "%07o", 0);
209
210         memcpy(header->magic, "ustar", 6);
211         memcpy(header->version, "00", 2);
212
213         xsnprintf(header->chksum, sizeof(header->chksum), "%07o", ustar_header_chksum(header));
214 }
215
216 static void write_extended_header(struct archiver_args *args,
217                                   const unsigned char *sha1,
218                                   const void *buffer, unsigned long size)
219 {
220         struct ustar_header header;
221         unsigned int mode;
222         memset(&header, 0, sizeof(header));
223         *header.typeflag = TYPEFLAG_EXT_HEADER;
224         mode = 0100666;
225         xsnprintf(header.name, sizeof(header.name), "%s.paxheader", sha1_to_hex(sha1));
226         prepare_header(args, &header, mode, size);
227         write_blocked(&header, sizeof(header));
228         write_blocked(buffer, size);
229 }
230
231 static int write_tar_entry(struct archiver_args *args,
232                            const unsigned char *sha1,
233                            const char *path, size_t pathlen,
234                            unsigned int mode)
235 {
236         struct ustar_header header;
237         struct strbuf ext_header = STRBUF_INIT;
238         unsigned int old_mode = mode;
239         unsigned long size, size_in_header;
240         void *buffer;
241         int err = 0;
242
243         memset(&header, 0, sizeof(header));
244
245         if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
246                 *header.typeflag = TYPEFLAG_DIR;
247                 mode = (mode | 0777) & ~tar_umask;
248         } else if (S_ISLNK(mode)) {
249                 *header.typeflag = TYPEFLAG_LNK;
250                 mode |= 0777;
251         } else if (S_ISREG(mode)) {
252                 *header.typeflag = TYPEFLAG_REG;
253                 mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;
254         } else {
255                 return error("unsupported file mode: 0%o (SHA1: %s)",
256                              mode, sha1_to_hex(sha1));
257         }
258         if (pathlen > sizeof(header.name)) {
259                 size_t plen = get_path_prefix(path, pathlen,
260                                               sizeof(header.prefix));
261                 size_t rest = pathlen - plen - 1;
262                 if (plen > 0 && rest <= sizeof(header.name)) {
263                         memcpy(header.prefix, path, plen);
264                         memcpy(header.name, path + plen + 1, rest);
265                 } else {
266                         xsnprintf(header.name, sizeof(header.name), "%s.data",
267                                   sha1_to_hex(sha1));
268                         strbuf_append_ext_header(&ext_header, "path",
269                                                  path, pathlen);
270                 }
271         } else
272                 memcpy(header.name, path, pathlen);
273
274         if (S_ISREG(mode) && !args->convert &&
275             sha1_object_info(sha1, &size) == OBJ_BLOB &&
276             size > big_file_threshold)
277                 buffer = NULL;
278         else if (S_ISLNK(mode) || S_ISREG(mode)) {
279                 enum object_type type;
280                 buffer = sha1_file_to_archive(args, path, sha1, old_mode, &type, &size);
281                 if (!buffer)
282                         return error("cannot read %s", sha1_to_hex(sha1));
283         } else {
284                 buffer = NULL;
285                 size = 0;
286         }
287
288         if (S_ISLNK(mode)) {
289                 if (size > sizeof(header.linkname)) {
290                         xsnprintf(header.linkname, sizeof(header.linkname),
291                                   "see %s.paxheader", sha1_to_hex(sha1));
292                         strbuf_append_ext_header(&ext_header, "linkpath",
293                                                  buffer, size);
294                 } else
295                         memcpy(header.linkname, buffer, size);
296         }
297
298         size_in_header = size;
299         if (S_ISREG(mode) && size > USTAR_MAX_SIZE) {
300                 size_in_header = 0;
301                 strbuf_append_ext_header_uint(&ext_header, "size", size);
302         }
303
304         prepare_header(args, &header, mode, size_in_header);
305
306         if (ext_header.len > 0) {
307                 write_extended_header(args, sha1, ext_header.buf,
308                                       ext_header.len);
309         }
310         strbuf_release(&ext_header);
311         write_blocked(&header, sizeof(header));
312         if (S_ISREG(mode) && size > 0) {
313                 if (buffer)
314                         write_blocked(buffer, size);
315                 else
316                         err = stream_blocked(sha1);
317         }
318         free(buffer);
319         return err;
320 }
321
322 static void write_global_extended_header(struct archiver_args *args)
323 {
324         const unsigned char *sha1 = args->commit_sha1;
325         struct strbuf ext_header = STRBUF_INIT;
326         struct ustar_header header;
327         unsigned int mode;
328
329         if (sha1)
330                 strbuf_append_ext_header(&ext_header, "comment",
331                                          sha1_to_hex(sha1), 40);
332         if (args->time > USTAR_MAX_MTIME) {
333                 strbuf_append_ext_header_uint(&ext_header, "mtime",
334                                               args->time);
335                 args->time = USTAR_MAX_MTIME;
336         }
337
338         if (!ext_header.len)
339                 return;
340
341         memset(&header, 0, sizeof(header));
342         *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
343         mode = 0100666;
344         xsnprintf(header.name, sizeof(header.name), "pax_global_header");
345         prepare_header(args, &header, mode, ext_header.len);
346         write_blocked(&header, sizeof(header));
347         write_blocked(ext_header.buf, ext_header.len);
348         strbuf_release(&ext_header);
349 }
350
351 static struct archiver **tar_filters;
352 static int nr_tar_filters;
353 static int alloc_tar_filters;
354
355 static struct archiver *find_tar_filter(const char *name, int len)
356 {
357         int i;
358         for (i = 0; i < nr_tar_filters; i++) {
359                 struct archiver *ar = tar_filters[i];
360                 if (!strncmp(ar->name, name, len) && !ar->name[len])
361                         return ar;
362         }
363         return NULL;
364 }
365
366 static int tar_filter_config(const char *var, const char *value, void *data)
367 {
368         struct archiver *ar;
369         const char *name;
370         const char *type;
371         int namelen;
372
373         if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
374                 return 0;
375
376         ar = find_tar_filter(name, namelen);
377         if (!ar) {
378                 ar = xcalloc(1, sizeof(*ar));
379                 ar->name = xmemdupz(name, namelen);
380                 ar->write_archive = write_tar_filter_archive;
381                 ar->flags = ARCHIVER_WANT_COMPRESSION_LEVELS;
382                 ALLOC_GROW(tar_filters, nr_tar_filters + 1, alloc_tar_filters);
383                 tar_filters[nr_tar_filters++] = ar;
384         }
385
386         if (!strcmp(type, "command")) {
387                 if (!value)
388                         return config_error_nonbool(var);
389                 free(ar->data);
390                 ar->data = xstrdup(value);
391                 return 0;
392         }
393         if (!strcmp(type, "remote")) {
394                 if (git_config_bool(var, value))
395                         ar->flags |= ARCHIVER_REMOTE;
396                 else
397                         ar->flags &= ~ARCHIVER_REMOTE;
398                 return 0;
399         }
400
401         return 0;
402 }
403
404 static int git_tar_config(const char *var, const char *value, void *cb)
405 {
406         if (!strcmp(var, "tar.umask")) {
407                 if (value && !strcmp(value, "user")) {
408                         tar_umask = umask(0);
409                         umask(tar_umask);
410                 } else {
411                         tar_umask = git_config_int(var, value);
412                 }
413                 return 0;
414         }
415
416         return tar_filter_config(var, value, cb);
417 }
418
419 static int write_tar_archive(const struct archiver *ar,
420                              struct archiver_args *args)
421 {
422         int err = 0;
423
424         write_global_extended_header(args);
425         err = write_archive_entries(args, write_tar_entry);
426         if (!err)
427                 write_trailer();
428         return err;
429 }
430
431 static int write_tar_filter_archive(const struct archiver *ar,
432                                     struct archiver_args *args)
433 {
434         struct strbuf cmd = STRBUF_INIT;
435         struct child_process filter = CHILD_PROCESS_INIT;
436         const char *argv[2];
437         int r;
438
439         if (!ar->data)
440                 die("BUG: tar-filter archiver called with no filter defined");
441
442         strbuf_addstr(&cmd, ar->data);
443         if (args->compression_level >= 0)
444                 strbuf_addf(&cmd, " -%d", args->compression_level);
445
446         argv[0] = cmd.buf;
447         argv[1] = NULL;
448         filter.argv = argv;
449         filter.use_shell = 1;
450         filter.in = -1;
451
452         if (start_command(&filter) < 0)
453                 die_errno("unable to start '%s' filter", argv[0]);
454         close(1);
455         if (dup2(filter.in, 1) < 0)
456                 die_errno("unable to redirect descriptor");
457         close(filter.in);
458
459         r = write_tar_archive(ar, args);
460
461         close(1);
462         if (finish_command(&filter) != 0)
463                 die("'%s' filter reported error", argv[0]);
464
465         strbuf_release(&cmd);
466         return r;
467 }
468
469 static struct archiver tar_archiver = {
470         "tar",
471         write_tar_archive,
472         ARCHIVER_REMOTE
473 };
474
475 void init_tar_archiver(void)
476 {
477         int i;
478         register_archiver(&tar_archiver);
479
480         tar_filter_config("tar.tgz.command", "gzip -cn", NULL);
481         tar_filter_config("tar.tgz.remote", "true", NULL);
482         tar_filter_config("tar.tar.gz.command", "gzip -cn", NULL);
483         tar_filter_config("tar.tar.gz.remote", "true", NULL);
484         git_config(git_tar_config, NULL);
485         for (i = 0; i < nr_tar_filters; i++) {
486                 /* omit any filters that never had a command configured */
487                 if (tar_filters[i]->data)
488                         register_archiver(tar_filters[i]);
489         }
490 }