Source

git / path.c

  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
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
/*
 * I'm tired of doing "vsnprintf()" etc just to open a
 * file, so here's a "return static buffer with printf"
 * interface for paths.
 *
 * It's obviously not thread-safe. Sue me. But it's quite
 * useful for doing things like
 *
 *   f = open(mkpath("%s/%s.git", base, name), O_RDONLY);
 *
 * which is what it's designed for.
 */
#include "cache.h"

static char bad_path[] = "/bad-path/";

static char *get_pathname(void)
{
	static char pathname_array[4][PATH_MAX];
	static int index;
	return pathname_array[3 & ++index];
}

static char *cleanup_path(char *path)
{
	/* Clean it up */
	if (!memcmp(path, "./", 2)) {
		path += 2;
		while (*path == '/')
			path++;
	}
	return path;
}

char *mksnpath(char *buf, size_t n, const char *fmt, ...)
{
	va_list args;
	unsigned len;

	va_start(args, fmt);
	len = vsnprintf(buf, n, fmt, args);
	va_end(args);
	if (len >= n) {
		strlcpy(buf, bad_path, n);
		return buf;
	}
	return cleanup_path(buf);
}

static char *git_vsnpath(char *buf, size_t n, const char *fmt, va_list args)
{
	const char *git_dir = get_git_dir();
	size_t len;

	len = strlen(git_dir);
	if (n < len + 1)
		goto bad;
	memcpy(buf, git_dir, len);
	if (len && !is_dir_sep(git_dir[len-1]))
		buf[len++] = '/';
	len += vsnprintf(buf + len, n - len, fmt, args);
	if (len >= n)
		goto bad;
	return cleanup_path(buf);
bad:
	strlcpy(buf, bad_path, n);
	return buf;
}

char *git_snpath(char *buf, size_t n, const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	(void)git_vsnpath(buf, n, fmt, args);
	va_end(args);
	return buf;
}

char *git_pathdup(const char *fmt, ...)
{
	char path[PATH_MAX];
	va_list args;
	va_start(args, fmt);
	(void)git_vsnpath(path, sizeof(path), fmt, args);
	va_end(args);
	return xstrdup(path);
}

char *mkpath(const char *fmt, ...)
{
	va_list args;
	unsigned len;
	char *pathname = get_pathname();

	va_start(args, fmt);
	len = vsnprintf(pathname, PATH_MAX, fmt, args);
	va_end(args);
	if (len >= PATH_MAX)
		return bad_path;
	return cleanup_path(pathname);
}

char *git_path(const char *fmt, ...)
{
	const char *git_dir = get_git_dir();
	char *pathname = get_pathname();
	va_list args;
	unsigned len;

	len = strlen(git_dir);
	if (len > PATH_MAX-100)
		return bad_path;
	memcpy(pathname, git_dir, len);
	if (len && git_dir[len-1] != '/')
		pathname[len++] = '/';
	va_start(args, fmt);
	len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
	va_end(args);
	if (len >= PATH_MAX)
		return bad_path;
	return cleanup_path(pathname);
}


/* git_mkstemp() - create tmp file honoring TMPDIR variable */
int git_mkstemp(char *path, size_t len, const char *template)
{
	const char *tmp;
	size_t n;

	tmp = getenv("TMPDIR");
	if (!tmp)
		tmp = "/tmp";
	n = snprintf(path, len, "%s/%s", tmp, template);
	if (len <= n) {
		errno = ENAMETOOLONG;
		return -1;
	}
	return mkstemp(path);
}


int validate_headref(const char *path)
{
	struct stat st;
	char *buf, buffer[256];
	unsigned char sha1[20];
	int fd;
	ssize_t len;

	if (lstat(path, &st) < 0)
		return -1;

	/* Make sure it is a "refs/.." symlink */
	if (S_ISLNK(st.st_mode)) {
		len = readlink(path, buffer, sizeof(buffer)-1);
		if (len >= 5 && !memcmp("refs/", buffer, 5))
			return 0;
		return -1;
	}

	/*
	 * Anything else, just open it and try to see if it is a symbolic ref.
	 */
	fd = open(path, O_RDONLY);
	if (fd < 0)
		return -1;
	len = read_in_full(fd, buffer, sizeof(buffer)-1);
	close(fd);

	/*
	 * Is it a symbolic ref?
	 */
	if (len < 4)
		return -1;
	if (!memcmp("ref:", buffer, 4)) {
		buf = buffer + 4;
		len -= 4;
		while (len && isspace(*buf))
			buf++, len--;
		if (len >= 5 && !memcmp("refs/", buf, 5))
			return 0;
	}

	/*
	 * Is this a detached HEAD?
	 */
	if (!get_sha1_hex(buffer, sha1))
		return 0;

	return -1;
}

static char *user_path(char *buf, char *path, int sz)
{
	struct passwd *pw;
	char *slash;
	int len, baselen;

	if (!path || path[0] != '~')
		return NULL;
	path++;
	slash = strchr(path, '/');
	if (path[0] == '/' || !path[0]) {
		pw = getpwuid(getuid());
	}
	else {
		if (slash) {
			*slash = 0;
			pw = getpwnam(path);
			*slash = '/';
		}
		else
			pw = getpwnam(path);
	}
	if (!pw || !pw->pw_dir || sz <= strlen(pw->pw_dir))
		return NULL;
	baselen = strlen(pw->pw_dir);
	memcpy(buf, pw->pw_dir, baselen);
	while ((1 < baselen) && (buf[baselen-1] == '/')) {
		buf[baselen-1] = 0;
		baselen--;
	}
	if (slash && slash[1]) {
		len = strlen(slash);
		if (sz <= baselen + len)
			return NULL;
		memcpy(buf + baselen, slash, len + 1);
	}
	return buf;
}

/*
 * First, one directory to try is determined by the following algorithm.
 *
 * (0) If "strict" is given, the path is used as given and no DWIM is
 *     done. Otherwise:
 * (1) "~/path" to mean path under the running user's home directory;
 * (2) "~user/path" to mean path under named user's home directory;
 * (3) "relative/path" to mean cwd relative directory; or
 * (4) "/absolute/path" to mean absolute directory.
 *
 * Unless "strict" is given, we try access() for existence of "%s.git/.git",
 * "%s/.git", "%s.git", "%s" in this order.  The first one that exists is
 * what we try.
 *
 * Second, we try chdir() to that.  Upon failure, we return NULL.
 *
 * Then, we try if the current directory is a valid git repository.
 * Upon failure, we return NULL.
 *
 * If all goes well, we return the directory we used to chdir() (but
 * before ~user is expanded), avoiding getcwd() resolving symbolic
 * links.  User relative paths are also returned as they are given,
 * except DWIM suffixing.
 */
char *enter_repo(char *path, int strict)
{
	static char used_path[PATH_MAX];
	static char validated_path[PATH_MAX];

	if (!path)
		return NULL;

	if (!strict) {
		static const char *suffix[] = {
			".git/.git", "/.git", ".git", "", NULL,
		};
		int len = strlen(path);
		int i;
		while ((1 < len) && (path[len-1] == '/')) {
			path[len-1] = 0;
			len--;
		}
		if (PATH_MAX <= len)
			return NULL;
		if (path[0] == '~') {
			if (!user_path(used_path, path, PATH_MAX))
				return NULL;
			strcpy(validated_path, path);
			path = used_path;
		}
		else if (PATH_MAX - 10 < len)
			return NULL;
		else {
			path = strcpy(used_path, path);
			strcpy(validated_path, path);
		}
		len = strlen(path);
		for (i = 0; suffix[i]; i++) {
			strcpy(path + len, suffix[i]);
			if (!access(path, F_OK)) {
				strcat(validated_path, suffix[i]);
				break;
			}
		}
		if (!suffix[i] || chdir(path))
			return NULL;
		path = validated_path;
	}
	else if (chdir(path))
		return NULL;

	if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
	    validate_headref("HEAD") == 0) {
		setenv(GIT_DIR_ENVIRONMENT, ".", 1);
		check_repository_format();
		return path;
	}

	return NULL;
}

int adjust_shared_perm(const char *path)
{
	struct stat st;
	int mode;

	if (!shared_repository)
		return 0;
	if (lstat(path, &st) < 0)
		return -1;
	mode = st.st_mode;

	if (shared_repository) {
		int tweak = shared_repository;
		if (!(mode & S_IWUSR))
			tweak &= ~0222;
		mode |= tweak;
	} else {
		/* Preserve old PERM_UMASK behaviour */
		if (mode & S_IWUSR)
			mode |= S_IWGRP;
	}

	if (S_ISDIR(mode)) {
		mode |= FORCE_DIR_SET_GID;

		/* Copy read bits to execute bits */
		mode |= (shared_repository & 0444) >> 2;
	}

	if ((mode & st.st_mode) != mode && chmod(path, mode) < 0)
		return -2;
	return 0;
}

const char *make_relative_path(const char *abs, const char *base)
{
	static char buf[PATH_MAX + 1];
	int baselen;
	if (!base)
		return abs;
	baselen = strlen(base);
	if (prefixcmp(abs, base))
		return abs;
	if (abs[baselen] == '/')
		baselen++;
	else if (base[baselen - 1] != '/')
		return abs;
	strcpy(buf, abs + baselen);
	return buf;
}

/*
 * path = absolute path
 * buf = buffer of at least max(2, strlen(path)+1) bytes
 * It is okay if buf == path, but they should not overlap otherwise.
 *
 * Performs the following normalizations on path, storing the result in buf:
 * - Removes trailing slashes.
 * - Removes empty components.
 * - Removes "." components.
 * - Removes ".." components, and the components the precede them.
 * "" and paths that contain only slashes are normalized to "/".
 * Returns the length of the output.
 *
 * Note that this function is purely textual.  It does not follow symlinks,
 * verify the existence of the path, or make any system calls.
 */
int normalize_absolute_path(char *buf, const char *path)
{
	const char *comp_start = path, *comp_end = path;
	char *dst = buf;
	int comp_len;
	assert(buf);
	assert(path);

	while (*comp_start) {
		assert(*comp_start == '/');
		while (*++comp_end && *comp_end != '/')
			; /* nothing */
		comp_len = comp_end - comp_start;

		if (!strncmp("/",  comp_start, comp_len) ||
		    !strncmp("/.", comp_start, comp_len))
			goto next;

		if (!strncmp("/..", comp_start, comp_len)) {
			while (dst > buf && *--dst != '/')
				; /* nothing */
			goto next;
		}

		memmove(dst, comp_start, comp_len);
		dst += comp_len;
	next:
		comp_start = comp_end;
	}

	if (dst == buf)
		*dst++ = '/';

	*dst = '\0';
	return dst - buf;
}

/*
 * path = Canonical absolute path
 * prefix_list = Colon-separated list of absolute paths
 *
 * Determines, for each path in prefix_list, whether the "prefix" really
 * is an ancestor directory of path.  Returns the length of the longest
 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 * is an ancestor.  (Note that this means 0 is returned if prefix_list is
 * "/".) "/foo" is not considered an ancestor of "/foobar".  Directories
 * are not considered to be their own ancestors.  path must be in a
 * canonical form: empty components, or "." or ".." components are not
 * allowed.  prefix_list may be null, which is like "".
 */
int longest_ancestor_length(const char *path, const char *prefix_list)
{
	char buf[PATH_MAX+1];
	const char *ceil, *colon;
	int len, max_len = -1;

	if (prefix_list == NULL || !strcmp(path, "/"))
		return -1;

	for (colon = ceil = prefix_list; *colon; ceil = colon+1) {
		for (colon = ceil; *colon && *colon != ':'; colon++);
		len = colon - ceil;
		if (len == 0 || len > PATH_MAX || !is_absolute_path(ceil))
			continue;
		strlcpy(buf, ceil, len+1);
		len = normalize_absolute_path(buf, buf);
		/* Strip "trailing slashes" from "/". */
		if (len == 1)
			len = 0;

		if (!strncmp(path, buf, len) &&
		    path[len] == '/' &&
		    len > max_len) {
			max_len = len;
		}
	}

	return max_len;
}