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[git.git] / tar-tree.c
1 /*
2  * Copyright (c) 2005, 2006 Rene Scharfe
3  */
4 #include <time.h>
5 #include "cache.h"
6 #include "tree-walk.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                 offset += size;
98         }
99         tail = offset % RECORDSIZE;
100         if (tail)  {
101                 memset(block + offset, 0, RECORDSIZE - tail);
102                 offset += RECORDSIZE - tail;
103         }
104         write_if_needed();
105 }
106
107 static void strbuf_append_string(struct strbuf *sb, const char *s)
108 {
109         int slen = strlen(s);
110         int total = sb->len + slen;
111         if (total > sb->alloc) {
112                 sb->buf = xrealloc(sb->buf, total);
113                 sb->alloc = total;
114         }
115         memcpy(sb->buf + sb->len, s, slen);
116         sb->len = total;
117 }
118
119 /*
120  * pax extended header records have the format "%u %s=%s\n".  %u contains
121  * the size of the whole string (including the %u), the first %s is the
122  * keyword, the second one is the value.  This function constructs such a
123  * string and appends it to a struct strbuf.
124  */
125 static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
126                                      const char *value, unsigned int valuelen)
127 {
128         char *p;
129         int len, total, tmp;
130
131         /* "%u %s=%s\n" */
132         len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
133         for (tmp = len; tmp > 9; tmp /= 10)
134                 len++;
135
136         total = sb->len + len;
137         if (total > sb->alloc) {
138                 sb->buf = xrealloc(sb->buf, total);
139                 sb->alloc = total;
140         }
141
142         p = sb->buf;
143         p += sprintf(p, "%u %s=", len, keyword);
144         memcpy(p, value, valuelen);
145         p += valuelen;
146         *p = '\n';
147         sb->len = total;
148 }
149
150 static unsigned int ustar_header_chksum(const struct ustar_header *header)
151 {
152         char *p = (char *)header;
153         unsigned int chksum = 0;
154         while (p < header->chksum)
155                 chksum += *p++;
156         chksum += sizeof(header->chksum) * ' ';
157         p += sizeof(header->chksum);
158         while (p < (char *)header + sizeof(struct ustar_header))
159                 chksum += *p++;
160         return chksum;
161 }
162
163 static int get_path_prefix(const struct strbuf *path, int maxlen)
164 {
165         int i = path->len;
166         if (i > maxlen)
167                 i = maxlen;
168         while (i > 0 && path->buf[i] != '/')
169                 i--;
170         return i;
171 }
172
173 static void write_entry(const unsigned char *sha1, struct strbuf *path,
174                         unsigned int mode, void *buffer, unsigned long size)
175 {
176         struct ustar_header header;
177         struct strbuf ext_header;
178
179         memset(&header, 0, sizeof(header));
180         ext_header.buf = NULL;
181         ext_header.len = ext_header.alloc = 0;
182
183         if (!sha1) {
184                 *header.typeflag = TYPEFLAG_GLOBAL_HEADER;
185                 mode = 0100666;
186                 strcpy(header.name, "pax_global_header");
187         } else if (!path) {
188                 *header.typeflag = TYPEFLAG_EXT_HEADER;
189                 mode = 0100666;
190                 sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
191         } else {
192                 if (S_ISDIR(mode)) {
193                         *header.typeflag = TYPEFLAG_DIR;
194                         mode |= 0777;
195                 } else if (S_ISLNK(mode)) {
196                         *header.typeflag = TYPEFLAG_LNK;
197                         mode |= 0777;
198                 } else if (S_ISREG(mode)) {
199                         *header.typeflag = TYPEFLAG_REG;
200                         mode |= (mode & 0100) ? 0777 : 0666;
201                 } else {
202                         error("unsupported file mode: 0%o (SHA1: %s)",
203                               mode, sha1_to_hex(sha1));
204                         return;
205                 }
206                 if (path->len > sizeof(header.name)) {
207                         int plen = get_path_prefix(path, sizeof(header.prefix));
208                         int rest = path->len - plen - 1;
209                         if (plen > 0 && rest <= sizeof(header.name)) {
210                                 memcpy(header.prefix, path->buf, plen);
211                                 memcpy(header.name, path->buf + plen + 1, rest);
212                         } else {
213                                 sprintf(header.name, "%s.data",
214                                         sha1_to_hex(sha1));
215                                 strbuf_append_ext_header(&ext_header, "path",
216                                                          path->buf, path->len);
217                         }
218                 } else
219                         memcpy(header.name, path->buf, path->len);
220         }
221
222         if (S_ISLNK(mode) && buffer) {
223                 if (size > sizeof(header.linkname)) {
224                         sprintf(header.linkname, "see %s.paxheader",
225                                 sha1_to_hex(sha1));
226                         strbuf_append_ext_header(&ext_header, "linkpath",
227                                                  buffer, size);
228                 } else
229                         memcpy(header.linkname, buffer, size);
230         }
231
232         sprintf(header.mode, "%07o", mode & 07777);
233         sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
234         sprintf(header.mtime, "%011lo", archive_time);
235
236         /* XXX: should we provide more meaningful info here? */
237         sprintf(header.uid, "%07o", 0);
238         sprintf(header.gid, "%07o", 0);
239         strncpy(header.uname, "git", 31);
240         strncpy(header.gname, "git", 31);
241         sprintf(header.devmajor, "%07o", 0);
242         sprintf(header.devminor, "%07o", 0);
243
244         memcpy(header.magic, "ustar", 6);
245         memcpy(header.version, "00", 2);
246
247         sprintf(header.chksum, "%07o", ustar_header_chksum(&header));
248
249         if (ext_header.len > 0) {
250                 write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
251                 free(ext_header.buf);
252         }
253         write_blocked(&header, sizeof(header));
254         if (S_ISREG(mode) && buffer && size > 0)
255                 write_blocked(buffer, size);
256 }
257
258 static void write_global_extended_header(const unsigned char *sha1)
259 {
260         struct strbuf ext_header;
261         ext_header.buf = NULL;
262         ext_header.len = ext_header.alloc = 0;
263         strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
264         write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
265         free(ext_header.buf);
266 }
267
268 static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
269 {
270         int pathlen = path->len;
271
272         while (tree->size) {
273                 const char *name;
274                 const unsigned char *sha1;
275                 unsigned mode;
276                 void *eltbuf;
277                 char elttype[20];
278                 unsigned long eltsize;
279
280                 sha1 = tree_entry_extract(tree, &name, &mode);
281                 update_tree_entry(tree);
282
283                 eltbuf = read_sha1_file(sha1, elttype, &eltsize);
284                 if (!eltbuf)
285                         die("cannot read %s", sha1_to_hex(sha1));
286
287                 path->len = pathlen;
288                 strbuf_append_string(path, name);
289                 if (S_ISDIR(mode))
290                         strbuf_append_string(path, "/");
291
292                 write_entry(sha1, path, mode, eltbuf, eltsize);
293
294                 if (S_ISDIR(mode)) {
295                         struct tree_desc subtree;
296                         subtree.buf = eltbuf;
297                         subtree.size = eltsize;
298                         traverse_tree(&subtree, path);
299                 }
300                 free(eltbuf);
301         }
302 }
303
304 int main(int argc, char **argv)
305 {
306         unsigned char sha1[20], tree_sha1[20];
307         struct commit *commit;
308         struct tree_desc tree;
309         struct strbuf current_path;
310
311         current_path.buf = xmalloc(PATH_MAX);
312         current_path.alloc = PATH_MAX;
313         current_path.len = current_path.eof = 0;
314
315         setup_git_directory();
316         git_config(git_default_config);
317
318         switch (argc) {
319         case 3:
320                 strbuf_append_string(&current_path, argv[2]);
321                 strbuf_append_string(&current_path, "/");
322                 /* FALLTHROUGH */
323         case 2:
324                 if (get_sha1(argv[1], sha1))
325                         die("Not a valid object name %s", argv[1]);
326                 break;
327         default:
328                 usage(tar_tree_usage);
329         }
330
331         commit = lookup_commit_reference_gently(sha1, 1);
332         if (commit) {
333                 write_global_extended_header(commit->object.sha1);
334                 archive_time = commit->date;
335         } else
336                 archive_time = time(NULL);
337
338         tree.buf = read_object_with_reference(sha1, tree_type, &tree.size,
339                                               tree_sha1);
340         if (!tree.buf)
341                 die("not a reference to a tag, commit or tree object: %s",
342                     sha1_to_hex(sha1));
343
344         if (current_path.len > 0)
345                 write_entry(tree_sha1, &current_path, 040777, NULL, 0);
346         traverse_tree(&tree, &current_path);
347         write_trailer();
348         free(current_path.buf);
349         return 0;
350 }