[PATCH] Rename and extend read_tree_with_tree_or_commit_sha1
[git/git.git] / tar-tree.c
1 #include <time.h>
2 #include "cache.h"
3
4 #define RECORDSIZE (512)
5 #define BLOCKSIZE (RECORDSIZE * 20)
6
7 static const char *tar_tree_usage = "tar-tree <key> [basedir]";
8
9 static char block[BLOCKSIZE];
10 static unsigned long offset;
11
12 static const char *basedir;
13 static time_t archive_time;
14
15 struct path_prefix {
16 struct path_prefix *prev;
17 const char *name;
18 };
19
20 /* tries hard to write, either succeeds or dies in the attempt */
21 static void reliable_write(void *buf, unsigned long size)
22 {
23 while (size > 0) {
24 long ret = write(1, buf, size);
25 if (ret < 0) {
26 if (errno == EAGAIN)
27 continue;
28 if (errno == EPIPE)
29 exit(0);
30 die("tar-tree: %s", strerror(errno));
31 } else if (!ret) {
32 die("tar-tree: disk full?");
33 }
34 size -= ret;
35 buf += ret;
36 }
37 }
38
39 /* writes out the whole block, but only if it is full */
40 static void write_if_needed(void)
41 {
42 if (offset == BLOCKSIZE) {
43 reliable_write(block, BLOCKSIZE);
44 offset = 0;
45 }
46 }
47
48 /*
49 * The end of tar archives is marked by 1024 nul bytes and after that
50 * follows the rest of the block (if any).
51 */
52 static void write_trailer(void)
53 {
54 memset(block + offset, 0, RECORDSIZE);
55 offset += RECORDSIZE;
56 write_if_needed();
57 memset(block + offset, 0, RECORDSIZE);
58 offset += RECORDSIZE;
59 write_if_needed();
60 if (offset) {
61 memset(block + offset, 0, BLOCKSIZE - offset);
62 reliable_write(block, BLOCKSIZE);
63 offset = 0;
64 }
65 }
66
67 /*
68 * queues up writes, so that all our write(2) calls write exactly one
69 * full block; pads writes to RECORDSIZE
70 */
71 static void write_blocked(void *buf, unsigned long size)
72 {
73 unsigned long tail;
74
75 if (offset) {
76 unsigned long chunk = BLOCKSIZE - offset;
77 if (size < chunk)
78 chunk = size;
79 memcpy(block + offset, buf, chunk);
80 size -= chunk;
81 offset += chunk;
82 buf += chunk;
83 write_if_needed();
84 }
85 while (size >= BLOCKSIZE) {
86 reliable_write(buf, BLOCKSIZE);
87 size -= BLOCKSIZE;
88 buf += BLOCKSIZE;
89 }
90 if (size) {
91 memcpy(block + offset, buf, size);
92 buf += size;
93 offset += size;
94 }
95 tail = offset % RECORDSIZE;
96 if (tail) {
97 memset(block + offset, 0, RECORDSIZE - tail);
98 offset += RECORDSIZE - tail;
99 }
100 write_if_needed();
101 }
102
103 static void append_string(char **p, const char *s)
104 {
105 unsigned int len = strlen(s);
106 memcpy(*p, s, len);
107 *p += len;
108 }
109
110 static void append_char(char **p, char c)
111 {
112 **p = c;
113 *p += 1;
114 }
115
116 static void append_long(char **p, long n)
117 {
118 int len = sprintf(*p, "%ld", n);
119 *p += len;
120 }
121
122 static void append_path_prefix(char **buffer, struct path_prefix *prefix)
123 {
124 if (!prefix)
125 return;
126 append_path_prefix(buffer, prefix->prev);
127 append_string(buffer, prefix->name);
128 append_char(buffer, '/');
129 }
130
131 static unsigned int path_prefix_len(struct path_prefix *prefix)
132 {
133 if (!prefix)
134 return 0;
135 return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1;
136 }
137
138 static void append_path(char **p, int is_dir, const char *basepath,
139 struct path_prefix *prefix, const char *path)
140 {
141 if (basepath) {
142 append_string(p, basepath);
143 append_char(p, '/');
144 }
145 append_path_prefix(p, prefix);
146 append_string(p, path);
147 if (is_dir)
148 append_char(p, '/');
149 }
150
151 static unsigned int path_len(int is_dir, const char *basepath,
152 struct path_prefix *prefix, const char *path)
153 {
154 unsigned int len = 0;
155 if (basepath)
156 len += strlen(basepath) + 1;
157 len += path_prefix_len(prefix) + strlen(path);
158 if (is_dir)
159 len++;
160 return len;
161 }
162
163 static void write_header(const char *, const char *, struct path_prefix *,
164 const char *, unsigned int, unsigned long);
165
166 /* stores a pax extended header directly in the block buffer */
167 static void write_extended_header(const char *headerfilename, int is_dir,
168 const char *basepath,
169 struct path_prefix *prefix,
170 const char *path, unsigned int namelen)
171 {
172 char *records, *p;
173 unsigned int size = 1 + 6 + namelen + 1;
174 if (size > 9)
175 size++;
176 if (size > 99)
177 size++;
178 if (size > RECORDSIZE)
179 die("tar-tree: extended header too big, wtf?");
180 write_header(NULL, NULL, NULL, headerfilename, 0100600, size);
181
182 records = block + offset;
183 memset(records, 0, RECORDSIZE);
184 offset += RECORDSIZE;
185 p = records;
186 append_long(&p, size);
187 append_string(&p, " path=");
188 append_path(&p, is_dir, basepath, prefix, path);
189 append_char(&p, '\n');
190 write_if_needed();
191 }
192
193 /* stores a ustar header directly in the block buffer */
194 static void write_header(const char *sha1, const char *basepath,
195 struct path_prefix *prefix, const char *path,
196 unsigned int mode, unsigned long size)
197 {
198 unsigned int namelen;
199 char *p, *header = NULL;
200 unsigned int checksum = 0;
201 int i;
202
203 namelen = path_len(S_ISDIR(mode), basepath, prefix, path);
204 if (namelen > 500) {
205 die("tar-tree: name too log of object %s\n", sha1_to_hex(sha1));
206 } else if (namelen > 100) {
207 char *sha1_hex = sha1_to_hex(sha1);
208 char headerfilename[51];
209 sprintf(headerfilename, "%s.paxheader", sha1_hex);
210 /* the extended header must be written before the normal one */
211 write_extended_header(headerfilename, S_ISDIR(mode), basepath,
212 prefix, path, namelen);
213
214 header = block + offset;
215 memset(header, 0, RECORDSIZE);
216 offset += RECORDSIZE;
217 sprintf(header, "%s.data", sha1_hex);
218 } else {
219 header = block + offset;
220 memset(header, 0, RECORDSIZE);
221 offset += RECORDSIZE;
222 p = header;
223 append_path(&p, S_ISDIR(mode), basepath, prefix, path);
224 }
225
226 if (S_ISDIR(mode))
227 mode |= 0755; /* GIT doesn't store permissions of dirs */
228 sprintf(&header[100], "%07o", mode & 07777);
229
230 /* XXX: should we provide more meaningful info here? */
231 sprintf(&header[108], "%07o", 0); /* uid */
232 sprintf(&header[116], "%07o", 0); /* gid */
233 strncpy(&header[265], "git", 31); /* uname */
234 strncpy(&header[297], "git", 31); /* gname */
235
236 sprintf(&header[124], "%011lo", S_ISDIR(mode) ? 0 : size);
237 sprintf(&header[136], "%011lo", archive_time);
238
239 /* typeflag */
240 if (!sha1)
241 header[156] = 'x'; /* extended header */
242 else
243 header[156] = S_ISDIR(mode) ? '5' : '0';
244
245 memcpy(&header[257], "ustar", 6);
246 memcpy(&header[263], "00", 2);
247
248 printf(&header[329], "%07o", 0); /* devmajor */
249 printf(&header[337], "%07o", 0); /* devminor */
250
251 memset(&header[148], ' ', 8);
252 for (i = 0; i < RECORDSIZE; i++)
253 checksum += header[i];
254 sprintf(&header[148], "%07o", checksum & 0x1fffff);
255
256 write_if_needed();
257 }
258
259 static void traverse_tree(void *buffer, unsigned long size,
260 struct path_prefix *prefix)
261 {
262 struct path_prefix this_prefix;
263 this_prefix.prev = prefix;
264
265 while (size) {
266 int namelen = strlen(buffer)+1;
267 void *eltbuf;
268 char elttype[20];
269 unsigned long eltsize;
270 unsigned char *sha1 = buffer + namelen;
271 char *path = strchr(buffer, ' ') + 1;
272 unsigned int mode;
273
274 if (size < namelen + 20 || sscanf(buffer, "%o", &mode) != 1)
275 die("corrupt 'tree' file");
276 buffer = sha1 + 20;
277 size -= namelen + 20;
278
279 eltbuf = read_sha1_file(sha1, elttype, &eltsize);
280 if (!eltbuf)
281 die("cannot read %s", sha1_to_hex(sha1));
282 write_header(sha1, basedir, prefix, path, mode, eltsize);
283 if (!strcmp(elttype, "tree")) {
284 this_prefix.name = path;
285 traverse_tree(eltbuf, eltsize, &this_prefix);
286 } else if (!strcmp(elttype, "blob")) {
287 write_blocked(eltbuf, eltsize);
288 }
289 free(eltbuf);
290 }
291 }
292
293 /* get commit time from committer line of commit object */
294 time_t commit_time(const unsigned char *sha1)
295 {
296 char type[20];
297 void *buffer;
298 unsigned long size;
299 time_t result = 0;
300
301 buffer = read_sha1_file(sha1, type, &size);
302 if (buffer) {
303 char *p = buffer;
304 while (size > 0) {
305 char *endp = memchr(p, '\n', size);
306 if (!endp || endp == p)
307 break;
308 *endp = '\0';
309 if (endp - p > 10 && !memcmp(p, "committer ", 10)) {
310 char *nump = strrchr(p, '>');
311 if (!nump)
312 break;
313 nump++;
314 result = strtoul(nump, &endp, 10);
315 if (*endp != ' ')
316 result = 0;
317 break;
318 }
319 size -= endp - p - 1;
320 p = endp + 1;
321 }
322 free(buffer);
323 }
324 return result;
325 }
326
327 int main(int argc, char **argv)
328 {
329 unsigned char sha1[20];
330 void *buffer;
331 unsigned long size;
332 unsigned char tree_sha1[20];
333
334 switch (argc) {
335 case 3:
336 basedir = argv[2];
337 /* FALLTHROUGH */
338 case 2:
339 if (get_sha1_hex(argv[1], sha1) < 0)
340 usage(tar_tree_usage);
341 break;
342 default:
343 usage(tar_tree_usage);
344 }
345
346 sha1_file_directory = getenv(DB_ENVIRONMENT);
347 if (!sha1_file_directory)
348 sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
349
350 buffer = read_tree_with_tree_or_commit_sha1(sha1, &size, tree_sha1);
351 if (!buffer)
352 die("unable to read sha1 file");
353 if (memcmp(sha1, tree_sha1, 20)) /* is sha1 a commit object? */
354 archive_time = commit_time(sha1);
355 if (!archive_time)
356 archive_time = time(NULL);
357 if (basedir)
358 write_header("0", NULL, NULL, basedir, 040755, 0);
359 traverse_tree(buffer, size, NULL);
360 free(buffer);
361 write_trailer();
362 return 0;
363 }