Merge branch 'lt/diffgen' into next
[git] / tar-tree.c
1 /*
2  * Copyright (c) 2005, 2006 Rene Scharfe
3  */
4 #include <time.h>
5 #include "cache.h"
6 #include "diff.h"
7 #include "commit.h"
8 #include "strbuf.h"
9 #include "tar.h"
10
11 #define RECORDSIZE      (512)
12 #define BLOCKSIZE       (RECORDSIZE * 20)
13
14 static const char tar_tree_usage[] = "git-tar-tree <key> [basedir]";
15
16 static char block[BLOCKSIZE];
17 static unsigned long offset;
18
19 static time_t archive_time;
20
21 /* tries hard to write, either succeeds or dies in the attempt */
22 static void reliable_write(void *buf, unsigned long size)
23 {
24         while (size > 0) {
25                 long ret = xwrite(1, buf, size);
26                 if (ret < 0) {
27                         if (errno == EPIPE)
28                                 exit(0);
29                         die("git-tar-tree: %s", strerror(errno));
30                 } else if (!ret) {
31                         die("git-tar-tree: disk full?");
32                 }
33                 size -= ret;
34                 buf += ret;
35         }
36 }
37
38 /* writes out the whole block, but only if it is full */
39 static void write_if_needed(void)
40 {
41         if (offset == BLOCKSIZE) {
42                 reliable_write(block, BLOCKSIZE);
43                 offset = 0;
44         }
45 }
46
47 /* acquire the next record from the buffer; user must call write_if_needed() */
48 static char *get_record(void)
49 {
50         char *p = block + offset;
51         memset(p, 0, RECORDSIZE);
52         offset += RECORDSIZE;
53         return p;
54 }
55
56 /*
57  * The end of tar archives is marked by 1024 nul bytes and after that
58  * follows the rest of the block (if any).
59  */
60 static void write_trailer(void)
61 {
62         get_record();
63         write_if_needed();
64         get_record();
65         write_if_needed();
66         while (offset) {
67                 get_record();
68                 write_if_needed();
69         }
70 }
71
72 /*
73  * queues up writes, so that all our write(2) calls write exactly one
74  * full block; pads writes to RECORDSIZE
75  */
76 static void write_blocked(void *buf, unsigned long size)
77 {
78         unsigned long tail;
79
80         if (offset) {
81                 unsigned long chunk = BLOCKSIZE - offset;
82                 if (size < chunk)
83                         chunk = size;
84                 memcpy(block + offset, buf, chunk);
85                 size -= chunk;
86                 offset += chunk;
87                 buf += chunk;
88                 write_if_needed();
89         }
90         while (size >= BLOCKSIZE) {
91                 reliable_write(buf, BLOCKSIZE);
92                 size -= BLOCKSIZE;
93                 buf += BLOCKSIZE;
94         }
95         if (size) {
96                 memcpy(block + offset, buf, size);
97                 buf += size;
98                 offset += size;
99         }
100         tail = offset % RECORDSIZE;
101         if (tail)  {
102                 memset(block + offset, 0, RECORDSIZE - tail);
103                 offset += RECORDSIZE - tail;
104         }
105         write_if_needed();
106 }
107
108 static void strbuf_append_string(struct strbuf *sb, const char *s)
109 {
110         int slen = strlen(s);
111         int total = sb->len + slen;
112         if (total > sb->alloc) {
113                 sb->buf = xrealloc(sb->buf, total);
114                 sb->alloc = total;
115         }
116         memcpy(sb->buf + sb->len, s, slen);
117         sb->len = total;
118 }
119
120 /*
121  * pax extended header records have the format "%u %s=%s\n".  %u contains
122  * the size of the whole string (including the %u), the first %s is the
123  * keyword, the second one is the value.  This function constructs such a
124  * string and appends it to a struct strbuf.
125  */
126 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
127                                      const char *value, unsigned int valuelen)
128 {
129         char *p;
130         int len, total, tmp;
131
132         /* "%u %s=%s\n" */
133         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
134         for (tmp = len; tmp > 9; tmp /= 10)
135                 len++;
136
137         total = sb->len + len;
138         if (total > sb->alloc) {
139                 sb->buf = xrealloc(sb->buf, total);
140                 sb->alloc = total;
141         }
142
143         p = sb->buf;
144         p += sprintf(p, "%u %s=", len, keyword);
145         memcpy(p, value, valuelen);
146         p += valuelen;
147         *p = '\n';
148         sb->len = total;
149 }
150
151 static unsigned int ustar_header_chksum(const struct ustar_header *header)
152 {
153         char *p = (char *)header;
154         unsigned int chksum = 0;
155         while (p < header->chksum)
156                 chksum += *p++;
157         chksum += sizeof(header->chksum) * ' ';
158         p += sizeof(header->chksum);
159         while (p < (char *)header + sizeof(struct ustar_header))
160                 chksum += *p++;
161         return chksum;
162 }
163
164 static int get_path_prefix(const struct strbuf *path, int maxlen)
165 {
166         int i = path->len;
167         if (i > maxlen)
168                 i = maxlen;
169         while (i > 0 && path->buf[i] != '/')
170                 i--;
171         return i;
172 }
173
174 static void write_entry(const unsigned char *sha1, struct strbuf *path,
175                         unsigned int mode, void *buffer, unsigned long size)
176 {
177         struct ustar_header header;
178         struct strbuf ext_header;
179
180         memset(&header, 0, sizeof(header));
181         ext_header.buf = NULL;
182         ext_header.len = ext_header.alloc = 0;
183
184         if (!sha1) {
185                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
186                 mode = 0100666;
187                 strcpy(header.name, "pax_global_header");
188         } else if (!path) {
189                 *header.typeflag = TYPEFLAG_EXT_HEADER;
190                 mode = 0100666;
191                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
192         } else {
193                 if (S_ISDIR(mode)) {
194                         *header.typeflag = TYPEFLAG_DIR;
195                         mode |= 0777;
196                 } else if (S_ISLNK(mode)) {
197                         *header.typeflag = TYPEFLAG_LNK;
198                         mode |= 0777;
199                 } else if (S_ISREG(mode)) {
200                         *header.typeflag = TYPEFLAG_REG;
201                         mode |= (mode & 0100) ? 0777 : 0666;
202                 } else {
203                         error("unsupported file mode: 0%o (SHA1: %s)",
204                               mode, sha1_to_hex(sha1));
205                         return;
206                 }
207                 if (path->len > sizeof(header.name)) {
208                         int plen = get_path_prefix(path, sizeof(header.prefix));
209                         int rest = path->len - plen - 1;
210                         if (plen > 0 && rest <= sizeof(header.name)) {
211                                 memcpy(header.prefix, path->buf, plen);
212                                 memcpy(header.name, path->buf + plen + 1, rest);
213                         } else {
214                                 sprintf(header.name, "%s.data",
215                                         sha1_to_hex(sha1));
216                                 strbuf_append_ext_header(&ext_header, "path",
217                                                          path->buf, path->len);
218                         }
219                 } else
220                         memcpy(header.name, path->buf, path->len);
221         }
222
223         if (S_ISLNK(mode) && buffer) {
224                 if (size > sizeof(header.linkname)) {
225                         sprintf(header.linkname, "see %s.paxheader",
226                                 sha1_to_hex(sha1));
227                         strbuf_append_ext_header(&ext_header, "linkpath",
228                                                  buffer, size);
229                 } else
230                         memcpy(header.linkname, buffer, size);
231         }
232
233         sprintf(header.mode, "%07o", mode & 07777);
234         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
235         sprintf(header.mtime, "%011lo", archive_time);
236
237         /* XXX: should we provide more meaningful info here? */
238         sprintf(header.uid, "%07o", 0);
239         sprintf(header.gid, "%07o", 0);
240         strncpy(header.uname, "git", 31);
241         strncpy(header.gname, "git", 31);
242         sprintf(header.devmajor, "%07o", 0);
243         sprintf(header.devminor, "%07o", 0);
244
245         memcpy(header.magic, "ustar", 6);
246         memcpy(header.version, "00", 2);
247
248         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
249
250         if (ext_header.len > 0) {
251                 write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
252                 free(ext_header.buf);
253         }
254         write_blocked(&header, sizeof(header));
255         if (S_ISREG(mode) && buffer && size > 0)
256                 write_blocked(buffer, size);
257 }
258
259 static void write_global_extended_header(const unsigned char *sha1)
260 {
261         struct strbuf ext_header;
262         ext_header.buf = NULL;
263         ext_header.len = ext_header.alloc = 0;
264         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
265         write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
266         free(ext_header.buf);
267 }
268
269 static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
270 {
271         int pathlen = path->len;
272
273         while (tree->size) {
274                 const char *name;
275                 const unsigned char *sha1;
276                 unsigned mode;
277                 void *eltbuf;
278                 char elttype[20];
279                 unsigned long eltsize;
280
281                 sha1 = tree_entry_extract(tree, &name, &mode);
282                 update_tree_entry(tree);
283
284                 eltbuf = read_sha1_file(sha1, elttype, &eltsize);
285                 if (!eltbuf)
286                         die("cannot read %s", sha1_to_hex(sha1));
287
288                 path->len = pathlen;
289                 strbuf_append_string(path, name);
290                 if (S_ISDIR(mode))
291                         strbuf_append_string(path, "/");
292
293                 write_entry(sha1, path, mode, eltbuf, eltsize);
294
295                 if (S_ISDIR(mode)) {
296                         struct tree_desc subtree;
297                         subtree.buf = eltbuf;
298                         subtree.size = eltsize;
299                         traverse_tree(&subtree, path);
300                 }
301                 free(eltbuf);
302         }
303 }
304
305 int main(int argc, char **argv)
306 {
307         unsigned char sha1[20], tree_sha1[20];
308         struct commit *commit;
309         struct tree_desc tree;
310         struct strbuf current_path;
311
312         current_path.buf = xmalloc(PATH_MAX);
313         current_path.alloc = PATH_MAX;
314         current_path.len = current_path.eof = 0;
315
316         setup_git_directory();
317         git_config(git_default_config);
318
319         switch (argc) {
320         case 3:
321                 strbuf_append_string(&current_path, argv[2]);
322                 strbuf_append_string(&current_path, "/");
323                 /* FALLTHROUGH */
324         case 2:
325                 if (get_sha1(argv[1], sha1) < 0)
326                         usage(tar_tree_usage);
327                 break;
328         default:
329                 usage(tar_tree_usage);
330         }
331
332         commit = lookup_commit_reference_gently(sha1, 1);
333         if (commit) {
334                 write_global_extended_header(commit->object.sha1);
335                 archive_time = commit->date;
336         } else
337                 archive_time = time(NULL);
338
339         tree.buf = read_object_with_reference(sha1, "tree", &tree.size,
340                                               tree_sha1);
341         if (!tree.buf)
342                 die("not a reference to a tag, commit or tree object: %s",
343                     sha1_to_hex(sha1));
344
345         if (current_path.len > 0)
346                 write_entry(tree_sha1, &current_path, 040777, NULL, 0);
347         traverse_tree(&tree, &current_path);
348         write_trailer();
349         free(current_path.buf);
350         return 0;
351 }