aboutsummaryrefslogtreecommitdiff
path: root/builtin-tar-tree.c
blob: f6310b9032374d6fd262b807d85987465887cdbf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
/*
 * Copyright (c) 2005, 2006 Rene Scharfe
 */
#include <time.h>
#include "cache.h"
#include "tree-walk.h"
#include "commit.h"
#include "strbuf.h"
#include "tar.h"
#include "builtin.h"
#include "pkt-line.h"

#define RECORDSIZE	(512)
#define BLOCKSIZE	(RECORDSIZE * 20)

static const char tar_tree_usage[] =
"git-tar-tree [--remote=<repo>] <ent> [basedir]";

static char block[BLOCKSIZE];
static unsigned long offset;

static time_t archive_time;

/* tries hard to write, either succeeds or dies in the attempt */
static void reliable_write(void *buf, unsigned long size)
{
	while (size > 0) {
		long ret = xwrite(1, buf, size);
		if (ret < 0) {
			if (errno == EPIPE)
				exit(0);
			die("git-tar-tree: %s", strerror(errno));
		} else if (!ret) {
			die("git-tar-tree: disk full?");
		}
		size -= ret;
		buf += ret;
	}
}

/* writes out the whole block, but only if it is full */
static void write_if_needed(void)
{
	if (offset == BLOCKSIZE) {
		reliable_write(block, BLOCKSIZE);
		offset = 0;
	}
}

/* acquire the next record from the buffer; user must call write_if_needed() */
static char *get_record(void)
{
	char *p = block + offset;
	memset(p, 0, RECORDSIZE);
	offset += RECORDSIZE;
	return p;
}

/*
 * The end of tar archives is marked by 1024 nul bytes and after that
 * follows the rest of the block (if any).
 */
static void write_trailer(void)
{
	get_record();
	write_if_needed();
	get_record();
	write_if_needed();
	while (offset) {
		get_record();
		write_if_needed();
	}
}

/*
 * queues up writes, so that all our write(2) calls write exactly one
 * full block; pads writes to RECORDSIZE
 */
static void write_blocked(void *buf, unsigned long size)
{
	unsigned long tail;

	if (offset) {
		unsigned long chunk = BLOCKSIZE - offset;
		if (size < chunk)
			chunk = size;
		memcpy(block + offset, buf, chunk);
		size -= chunk;
		offset += chunk;
		buf += chunk;
		write_if_needed();
	}
	while (size >= BLOCKSIZE) {
		reliable_write(buf, BLOCKSIZE);
		size -= BLOCKSIZE;
		buf += BLOCKSIZE;
	}
	if (size) {
		memcpy(block + offset, buf, size);
		offset += size;
	}
	tail = offset % RECORDSIZE;
	if (tail)  {
		memset(block + offset, 0, RECORDSIZE - tail);
		offset += RECORDSIZE - tail;
	}
	write_if_needed();
}

static void strbuf_append_string(struct strbuf *sb, const char *s)
{
	int slen = strlen(s);
	int total = sb->len + slen;
	if (total > sb->alloc) {
		sb->buf = xrealloc(sb->buf, total);
		sb->alloc = total;
	}
	memcpy(sb->buf + sb->len, s, slen);
	sb->len = total;
}

/*
 * pax extended header records have the format "%u %s=%s\n".  %u contains
 * the size of the whole string (including the %u), the first %s is the
 * keyword, the second one is the value.  This function constructs such a
 * string and appends it to a struct strbuf.
 */
static void strbuf_append_ext_header(struct strbuf *sb, const char *keyword,
                                     const char *value, unsigned int valuelen)
{
	char *p;
	int len, total, tmp;

	/* "%u %s=%s\n" */
	len = 1 + 1 + strlen(keyword) + 1 + valuelen + 1;
	for (tmp = len; tmp > 9; tmp /= 10)
		len++;

	total = sb->len + len;
	if (total > sb->alloc) {
		sb->buf = xrealloc(sb->buf, total);
		sb->alloc = total;
	}

	p = sb->buf;
	p += sprintf(p, "%u %s=", len, keyword);
	memcpy(p, value, valuelen);
	p += valuelen;
	*p = '\n';
	sb->len = total;
}

static unsigned int ustar_header_chksum(const struct ustar_header *header)
{
	char *p = (char *)header;
	unsigned int chksum = 0;
	while (p < header->chksum)
		chksum += *p++;
	chksum += sizeof(header->chksum) * ' ';
	p += sizeof(header->chksum);
	while (p < (char *)header + sizeof(struct ustar_header))
		chksum += *p++;
	return chksum;
}

static int get_path_prefix(const struct strbuf *path, int maxlen)
{
	int i = path->len;
	if (i > maxlen)
		i = maxlen;
	do {
		i--;
	} while (i > 0 && path->buf[i] != '/');
	return i;
}

static void write_entry(const unsigned char *sha1, struct strbuf *path,
                        unsigned int mode, void *buffer, unsigned long size)
{
	struct ustar_header header;
	struct strbuf ext_header;

	memset(&header, 0, sizeof(header));
	ext_header.buf = NULL;
	ext_header.len = ext_header.alloc = 0;

	if (!sha1) {
		*header.typeflag = TYPEFLAG_GLOBAL_HEADER;
		mode = 0100666;
		strcpy(header.name, "pax_global_header");
	} else if (!path) {
		*header.typeflag = TYPEFLAG_EXT_HEADER;
		mode = 0100666;
		sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
	} else {
		if (S_ISDIR(mode)) {
			*header.typeflag = TYPEFLAG_DIR;
			mode |= 0777;
		} else if (S_ISLNK(mode)) {
			*header.typeflag = TYPEFLAG_LNK;
			mode |= 0777;
		} else if (S_ISREG(mode)) {
			*header.typeflag = TYPEFLAG_REG;
			mode |= (mode & 0100) ? 0777 : 0666;
		} else {
			error("unsupported file mode: 0%o (SHA1: %s)",
			      mode, sha1_to_hex(sha1));
			return;
		}
		if (path->len > sizeof(header.name)) {
			int plen = get_path_prefix(path, sizeof(header.prefix));
			int rest = path->len - plen - 1;
			if (plen > 0 && rest <= sizeof(header.name)) {
				memcpy(header.prefix, path->buf, plen);
				memcpy(header.name, path->buf + plen + 1, rest);
			} else {
				sprintf(header.name, "%s.data",
				        sha1_to_hex(sha1));
				strbuf_append_ext_header(&ext_header, "path",
				                         path->buf, path->len);
			}
		} else
			memcpy(header.name, path->buf, path->len);
	}

	if (S_ISLNK(mode) && buffer) {
		if (size > sizeof(header.linkname)) {
			sprintf(header.linkname, "see %s.paxheader",
			        sha1_to_hex(sha1));
			strbuf_append_ext_header(&ext_header, "linkpath",
			                         buffer, size);
		} else
			memcpy(header.linkname, buffer, size);
	}

	sprintf(header.mode, "%07o", mode & 07777);
	sprintf(header.size, "%011lo", S_ISREG(mode) ? size : 0);
	sprintf(header.mtime, "%011lo", archive_time);

	/* XXX: should we provide more meaningful info here? */
	sprintf(header.uid, "%07o", 0);
	sprintf(header.gid, "%07o", 0);
	safe_strncpy(header.uname, "git", sizeof(header.uname));
	safe_strncpy(header.gname, "git", sizeof(header.gname));
	sprintf(header.devmajor, "%07o", 0);
	sprintf(header.devminor, "%07o", 0);

	memcpy(header.magic, "ustar", 6);
	memcpy(header.version, "00", 2);

	sprintf(header.chksum, "%07o", ustar_header_chksum(&header));

	if (ext_header.len > 0) {
		write_entry(sha1, NULL, 0, ext_header.buf, ext_header.len);
		free(ext_header.buf);
	}
	write_blocked(&header, sizeof(header));
	if (S_ISREG(mode) && buffer && size > 0)
		write_blocked(buffer, size);
}

static void write_global_extended_header(const unsigned char *sha1)
{
	struct strbuf ext_header;
	ext_header.buf = NULL;
	ext_header.len = ext_header.alloc = 0;
	strbuf_append_ext_header(&ext_header, "comment", sha1_to_hex(sha1), 40);
	write_entry(NULL, NULL, 0, ext_header.buf, ext_header.len);
	free(ext_header.buf);
}

static void traverse_tree(struct tree_desc *tree, struct strbuf *path)
{
	int pathlen = path->len;
	struct name_entry entry;

	while (tree_entry(tree, &entry)) {
		void *eltbuf;
		char elttype[20];
		unsigned long eltsize;

		eltbuf = read_sha1_file(entry.sha1, elttype, &eltsize);
		if (!eltbuf)
			die("cannot read %s", sha1_to_hex(entry.sha1));

		path->len = pathlen;
		strbuf_append_string(path, entry.path);
		if (S_ISDIR(entry.mode))
			strbuf_append_string(path, "/");

		write_entry(entry.sha1, path, entry.mode, eltbuf, eltsize);

		if (S_ISDIR(entry.mode)) {
			struct tree_desc subtree;
			subtree.buf = eltbuf;
			subtree.size = eltsize;
			traverse_tree(&subtree, path);
		}
		free(eltbuf);
	}
}

static int generate_tar(int argc, const char **argv, char** envp)
{
	unsigned char sha1[20], tree_sha1[20];
	struct commit *commit;
	struct tree_desc tree;
	struct strbuf current_path;

	current_path.buf = xmalloc(PATH_MAX);
	current_path.alloc = PATH_MAX;
	current_path.len = current_path.eof = 0;

	setup_git_directory();
	git_config(git_default_config);

	switch (argc) {
	case 3:
		strbuf_append_string(&current_path, argv[2]);
		strbuf_append_string(&current_path, "/");
		/* FALLTHROUGH */
	case 2:
		if (get_sha1(argv[1], sha1))
			die("Not a valid object name %s", argv[1]);
		break;
	default:
		usage(tar_tree_usage);
	}

	commit = lookup_commit_reference_gently(sha1, 1);
	if (commit) {
		write_global_extended_header(commit->object.sha1);
		archive_time = commit->date;
	} else
		archive_time = time(NULL);

	tree.buf = read_object_with_reference(sha1, tree_type, &tree.size,
	                                      tree_sha1);
	if (!tree.buf)
		die("not a reference to a tag, commit or tree object: %s",
		    sha1_to_hex(sha1));

	if (current_path.len > 0)
		write_entry(tree_sha1, &current_path, 040777, NULL, 0);
	traverse_tree(&tree, &current_path);
	write_trailer();
	free(current_path.buf);
	return 0;
}

static const char *exec = "git-upload-tar";

static int remote_tar(int argc, const char **argv)
{
	int fd[2], ret, len;
	pid_t pid;
	char buf[1024];
	char *url;

	if (argc < 3 || 4 < argc)
		usage(tar_tree_usage);

	/* --remote=<repo> */
	url = strdup(argv[1]+9);
	pid = git_connect(fd, url, exec);
	if (pid < 0)
		return 1;

	packet_write(fd[1], "want %s\n", argv[2]);
	if (argv[3])
		packet_write(fd[1], "base %s\n", argv[3]);
	packet_flush(fd[1]);

	len = packet_read_line(fd[0], buf, sizeof(buf));
	if (!len)
		die("git-tar-tree: expected ACK/NAK, got EOF");
	if (buf[len-1] == '\n')
		buf[--len] = 0;
	if (strcmp(buf, "ACK")) {
		if (5 < len && !strncmp(buf, "NACK ", 5))
			die("git-tar-tree: NACK %s", buf + 5);
		die("git-tar-tree: protocol error");
	}
	/* expect a flush */
	len = packet_read_line(fd[0], buf, sizeof(buf));
	if (len)
		die("git-tar-tree: expected a flush");

	/* Now, start reading from fd[0] and spit it out to stdout */
	ret = copy_fd(fd[0], 1);
	close(fd[0]);

	ret |= finish_connect(pid);
	return !!ret;
}

int cmd_tar_tree(int argc, const char **argv, char **envp)
{
	if (argc < 2)
		usage(tar_tree_usage);
	if (!strncmp("--remote=", argv[1], 9))
		return remote_tar(argc, argv);
	return generate_tar(argc, argv, envp);
}

/* ustar header + extended global header content */
#define HEADERSIZE (2 * RECORDSIZE)

int cmd_get_tar_commit_id(int argc, const char **argv, char **envp)
{
	char buffer[HEADERSIZE];
	struct ustar_header *header = (struct ustar_header *)buffer;
	char *content = buffer + RECORDSIZE;
	ssize_t n;

	n = xread(0, buffer, HEADERSIZE);
	if (n < HEADERSIZE)
		die("git-get-tar-commit-id: read error");
	if (header->typeflag[0] != 'g')
		return 1;
	if (memcmp(content, "52 comment=", 11))
		return 1;

	n = xwrite(1, content + 11, 41);
	if (n < 41)
		die("git-get-tar-commit-id: write error");

	return 0;
}