Merge master.kernel.org:/pub/scm/gitk/gitk
[git/git.git] / unpack-objects.c
1 #include "cache.h"
2 #include "object.h"
3 #include "delta.h"
4 #include "pack.h"
5
6 static int dry_run;
7 static const char unpack_usage[] = "git-unpack-objects < pack-file";
8
9 /* We always read in 4kB chunks. */
10 static unsigned char buffer[4096];
11 static unsigned long offset, len, eof;
12 static SHA_CTX ctx;
13
14 /*
15 * Make sure at least "min" bytes are available in the buffer, and
16 * return the pointer to the buffer.
17 */
18 static void * fill(int min)
19 {
20 if (min <= len)
21 return buffer + offset;
22 if (eof)
23 die("unable to fill input");
24 if (min > sizeof(buffer))
25 die("cannot fill %d bytes", min);
26 if (offset) {
27 SHA1_Update(&ctx, buffer, offset);
28 memcpy(buffer, buffer + offset, len);
29 offset = 0;
30 }
31 do {
32 int ret = read(0, buffer + len, sizeof(buffer) - len);
33 if (ret <= 0) {
34 if (!ret)
35 die("early EOF");
36 if (errno == EAGAIN || errno == EINTR)
37 continue;
38 die("read error on input: %s", strerror(errno));
39 }
40 len += ret;
41 } while (len < min);
42 return buffer;
43 }
44
45 static void use(int bytes)
46 {
47 if (bytes > len)
48 die("used more bytes than were available");
49 len -= bytes;
50 offset += bytes;
51 }
52
53 static void *get_data(unsigned long size)
54 {
55 z_stream stream;
56 void *buf = xmalloc(size);
57
58 memset(&stream, 0, sizeof(stream));
59
60 stream.next_out = buf;
61 stream.avail_out = size;
62 stream.next_in = fill(1);
63 stream.avail_in = len;
64 inflateInit(&stream);
65
66 for (;;) {
67 int ret = inflate(&stream, 0);
68 use(len - stream.avail_in);
69 if (stream.total_out == size && ret == Z_STREAM_END)
70 break;
71 if (ret != Z_OK)
72 die("inflate returned %d\n", ret);
73 stream.next_in = fill(1);
74 stream.avail_in = len;
75 }
76 return buf;
77 }
78
79 struct delta_info {
80 unsigned char base_sha1[20];
81 unsigned long size;
82 void *delta;
83 struct delta_info *next;
84 };
85
86 static struct delta_info *delta_list;
87
88 static void add_delta_to_list(unsigned char *base_sha1, void *delta, unsigned long size)
89 {
90 struct delta_info *info = xmalloc(sizeof(*info));
91
92 memcpy(info->base_sha1, base_sha1, 20);
93 info->size = size;
94 info->delta = delta;
95 info->next = delta_list;
96 delta_list = info;
97 }
98
99 static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size);
100
101 static void write_object(void *buf, unsigned long size, const char *type)
102 {
103 unsigned char sha1[20];
104 if (write_sha1_file(buf, size, type, sha1) < 0)
105 die("failed to write object");
106 added_object(sha1, type, buf, size);
107 }
108
109 static int resolve_delta(const char *type,
110 void *base, unsigned long base_size,
111 void *delta, unsigned long delta_size)
112 {
113 void *result;
114 unsigned long result_size;
115
116 result = patch_delta(base, base_size,
117 delta, delta_size,
118 &result_size);
119 if (!result)
120 die("failed to apply delta");
121 free(delta);
122 write_object(result, result_size, type);
123 free(result);
124 return 0;
125 }
126
127 static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size)
128 {
129 struct delta_info **p = &delta_list;
130 struct delta_info *info;
131
132 while ((info = *p) != NULL) {
133 if (!memcmp(info->base_sha1, sha1, 20)) {
134 *p = info->next;
135 p = &delta_list;
136 resolve_delta(type, data, size, info->delta, info->size);
137 free(info);
138 continue;
139 }
140 p = &info->next;
141 }
142 }
143
144 static int unpack_non_delta_entry(enum object_type kind, unsigned long size)
145 {
146 void *buf = get_data(size);
147 const char *type;
148
149 switch (kind) {
150 case OBJ_COMMIT: type = "commit"; break;
151 case OBJ_TREE: type = "tree"; break;
152 case OBJ_BLOB: type = "blob"; break;
153 case OBJ_TAG: type = "tag"; break;
154 default: die("bad type %d", kind);
155 }
156 if (!dry_run)
157 write_object(buf, size, type);
158 free(buf);
159 return 0;
160 }
161
162 static int unpack_delta_entry(unsigned long delta_size)
163 {
164 void *delta_data, *base;
165 unsigned long base_size;
166 char type[20];
167 unsigned char base_sha1[20];
168
169 memcpy(base_sha1, fill(20), 20);
170 use(20);
171
172 delta_data = get_data(delta_size);
173 if (dry_run) {
174 free(delta_data);
175 return 0;
176 }
177
178 if (!has_sha1_file(base_sha1)) {
179 add_delta_to_list(base_sha1, delta_data, delta_size);
180 return 0;
181 }
182 base = read_sha1_file(base_sha1, type, &base_size);
183 if (!base)
184 die("failed to read delta-pack base object %s", sha1_to_hex(base_sha1));
185 return resolve_delta(type, base, base_size, delta_data, delta_size);
186 }
187
188 static void unpack_one(void)
189 {
190 unsigned shift;
191 unsigned char *pack, c;
192 unsigned long size;
193 enum object_type type;
194
195 pack = fill(1);
196 c = *pack;
197 use(1);
198 type = (c >> 4) & 7;
199 size = (c & 15);
200 shift = 4;
201 while (c & 0x80) {
202 pack = fill(1);
203 c = *pack++;
204 use(1);
205 size += (c & 0x7f) << shift;
206 shift += 7;
207 }
208 switch (type) {
209 case OBJ_COMMIT:
210 case OBJ_TREE:
211 case OBJ_BLOB:
212 case OBJ_TAG:
213 unpack_non_delta_entry(type, size);
214 return;
215 case OBJ_DELTA:
216 unpack_delta_entry(size);
217 return;
218 default:
219 die("bad object type %d", type);
220 }
221 }
222
223 /*
224 * We unpack from the end, older files first. Now, usually
225 * there are deltas etc, so we'll not actually write the
226 * objects in that order, but we might as well try..
227 */
228 static void unpack_all(void)
229 {
230 int i;
231 struct pack_header *hdr = fill(sizeof(struct pack_header));
232 unsigned version = ntohl(hdr->hdr_version);
233 unsigned nr_objects = ntohl(hdr->hdr_entries);
234
235 if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
236 die("bad pack file");
237 if (version != PACK_VERSION)
238 die("unable to handle pack file version %d", version);
239 fprintf(stderr, "Unpacking %d objects\n", nr_objects);
240
241 use(sizeof(struct pack_header));
242 for (i = 0; i < nr_objects; i++)
243 unpack_one();
244 if (delta_list)
245 die("unresolved deltas left after unpacking");
246 }
247
248 int main(int argc, char **argv)
249 {
250 int i;
251 unsigned char sha1[20];
252
253 for (i = 1 ; i < argc; i++) {
254 const char *arg = argv[i];
255
256 if (*arg == '-') {
257 if (!strcmp(arg, "-n")) {
258 dry_run = 1;
259 continue;
260 }
261 usage(unpack_usage);
262 }
263
264 /* We don't take any non-flag arguments now.. Maybe some day */
265 usage(unpack_usage);
266 }
267 SHA1_Init(&ctx);
268 unpack_all();
269 SHA1_Update(&ctx, buffer, offset);
270 SHA1_Final(sha1, &ctx);
271 if (memcmp(fill(20), sha1, 20))
272 die("final sha1 did not match");
273 use(20);
274
275 /* Write the last part of the buffer to stdout */
276 while (len) {
277 int ret = write(1, buffer + offset, len);
278 if (!ret)
279 break;
280 if (ret < 0) {
281 if (errno == EAGAIN || errno == EINTR)
282 continue;
283 break;
284 }
285 len -= ret;
286 offset += ret;
287 }
288
289 /* All done */
290 return 0;
291 }