summaryrefslogtreecommitdiff
path: root/convert.c
blob: 5fdaee75714fa6a42601fbb366aeafb18f3334fb (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
#include "cache.h"
#include "attr.h"
#include "run-command.h"

/*
 * convert.c - convert a file when checking it out and checking it in.
 *
 * This should use the pathname to decide on whether it wants to do some
 * more interesting conversions (automatic gzip/unzip, general format
 * conversions etc etc), but by default it just does automatic CRLF<->LF
 * translation when the "auto_crlf" option is set.
 */

#define CRLF_GUESS	(-1)
#define CRLF_BINARY	0
#define CRLF_TEXT	1
#define CRLF_INPUT	2

struct text_stat {
	/* CR, LF and CRLF counts */
	unsigned cr, lf, crlf;

	/* These are just approximations! */
	unsigned printable, nonprintable;
};

static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
{
	unsigned long i;

	memset(stats, 0, sizeof(*stats));

	for (i = 0; i < size; i++) {
		unsigned char c = buf[i];
		if (c == '\r') {
			stats->cr++;
			if (i+1 < size && buf[i+1] == '\n')
				stats->crlf++;
			continue;
		}
		if (c == '\n') {
			stats->lf++;
			continue;
		}
		if (c == 127)
			/* DEL */
			stats->nonprintable++;
		else if (c < 32) {
			switch (c) {
				/* BS, HT, ESC and FF */
			case '\b': case '\t': case '\033': case '\014':
				stats->printable++;
				break;
			default:
				stats->nonprintable++;
			}
		}
		else
			stats->printable++;
	}
}

/*
 * The same heuristics as diff.c::mmfile_is_binary()
 */
static int is_binary(unsigned long size, struct text_stat *stats)
{

	if ((stats->printable >> 7) < stats->nonprintable)
		return 1;
	/*
	 * Other heuristics? Average line length might be relevant,
	 * as might LF vs CR vs CRLF counts..
	 *
	 * NOTE! It might be normal to have a low ratio of CRLF to LF
	 * (somebody starts with a LF-only file and edits it with an editor
	 * that adds CRLF only to lines that are added..). But do  we
	 * want to support CR-only? Probably not.
	 */
	return 0;
}

static char *crlf_to_git(const char *path, const char *src, unsigned long *sizep, int action)
{
	char *buffer, *dst;
	unsigned long size, nsize;
	struct text_stat stats;

	if ((action == CRLF_BINARY) || (action == CRLF_GUESS && !auto_crlf))
		return NULL;

	size = *sizep;
	if (!size)
		return NULL;

	gather_stats(src, size, &stats);

	/* No CR? Nothing to convert, regardless. */
	if (!stats.cr)
		return NULL;

	if (action == CRLF_GUESS) {
		/*
		 * We're currently not going to even try to convert stuff
		 * that has bare CR characters. Does anybody do that crazy
		 * stuff?
		 */
		if (stats.cr != stats.crlf)
			return NULL;

		/*
		 * And add some heuristics for binary vs text, of course...
		 */
		if (is_binary(size, &stats))
			return NULL;
	}

	/*
	 * Ok, allocate a new buffer, fill it in, and return it
	 * to let the caller know that we switched buffers.
	 */
	nsize = size - stats.crlf;
	buffer = xmalloc(nsize);
	*sizep = nsize;

	dst = buffer;
	if (action == CRLF_GUESS) {
		/*
		 * If we guessed, we already know we rejected a file with
		 * lone CR, and we can strip a CR without looking at what
		 * follow it.
		 */
		do {
			unsigned char c = *src++;
			if (c != '\r')
				*dst++ = c;
		} while (--size);
	} else {
		do {
			unsigned char c = *src++;
			if (! (c == '\r' && (1 < size && *src == '\n')))
				*dst++ = c;
		} while (--size);
	}

	return buffer;
}

static char *crlf_to_worktree(const char *path, const char *src, unsigned long *sizep, int action)
{
	char *buffer, *dst;
	unsigned long size, nsize;
	struct text_stat stats;
	unsigned char last;

	if ((action == CRLF_BINARY) || (action == CRLF_INPUT) ||
	    (action == CRLF_GUESS && auto_crlf <= 0))
		return NULL;

	size = *sizep;
	if (!size)
		return NULL;

	gather_stats(src, size, &stats);

	/* No LF? Nothing to convert, regardless. */
	if (!stats.lf)
		return NULL;

	/* Was it already in CRLF format? */
	if (stats.lf == stats.crlf)
		return NULL;

	if (action == CRLF_GUESS) {
		/* If we have any bare CR characters, we're not going to touch it */
		if (stats.cr != stats.crlf)
			return NULL;

		if (is_binary(size, &stats))
			return NULL;
	}

	/*
	 * Ok, allocate a new buffer, fill it in, and return it
	 * to let the caller know that we switched buffers.
	 */
	nsize = size + stats.lf - stats.crlf;
	buffer = xmalloc(nsize);
	*sizep = nsize;
	last = 0;

	dst = buffer;
	do {
		unsigned char c = *src++;
		if (c == '\n' && last != '\r')
			*dst++ = '\r';
		*dst++ = c;
		last = c;
	} while (--size);

	return buffer;
}

static void setup_convert_check(struct git_attr_check *check)
{
	static struct git_attr *attr_crlf;
	static struct git_attr *attr_ident;

	if (!attr_crlf) {
		attr_crlf = git_attr("crlf", 4);
		attr_ident = git_attr("ident", 5);
	}
	check[0].attr = attr_crlf;
	check[1].attr = attr_ident;
}

static int count_ident(const char *cp, unsigned long size)
{
	/*
	 * "$ident: 0000000000000000000000000000000000000000 $" <=> "$ident$"
	 */
	int cnt = 0;
	char ch;

	while (size) {
		ch = *cp++;
		size--;
		if (ch != '$')
			continue;
		if (size < 6)
			break;
		if (memcmp("ident", cp, 5))
			continue;
		ch = cp[5];
		cp += 6;
		size -= 6;
		if (ch == '$')
			cnt++; /* $ident$ */
		if (ch != ':')
			continue;

		/*
		 * "$ident: ... "; scan up to the closing dollar sign and discard.
		 */
		while (size) {
			ch = *cp++;
			size--;
			if (ch == '$') {
				cnt++;
				break;
			}
		}
	}
	return cnt;
}

static char *ident_to_git(const char *path, const char *src, unsigned long *sizep, int ident)
{
	int cnt;
	unsigned long size;
	char *dst, *buf;

	if (!ident)
		return NULL;
	size = *sizep;
	cnt = count_ident(src, size);
	if (!cnt)
		return NULL;
	buf = xmalloc(size);

	for (dst = buf; size; size--) {
		char ch = *src++;
		*dst++ = ch;
		if ((ch == '$') && (6 <= size) &&
		    !memcmp("ident:", src, 6)) {
			unsigned long rem = size - 6;
			const char *cp = src + 6;
			do {
				ch = *cp++;
				if (ch == '$')
					break;
				rem--;
			} while (rem);
			if (!rem)
				continue;
			memcpy(dst, "ident$", 6);
			dst += 6;
			size -= (cp - src);
			src = cp;
		}
	}

	*sizep = dst - buf;
	return buf;
}

static char *ident_to_worktree(const char *path, const char *src, unsigned long *sizep, int ident)
{
	int cnt;
	unsigned long size;
	char *dst, *buf;
	unsigned char sha1[20];

	if (!ident)
		return NULL;

	size = *sizep;
	cnt = count_ident(src, size);
	if (!cnt)
		return NULL;

	hash_sha1_file(src, size, "blob", sha1);
	buf = xmalloc(size + cnt * 43);

	for (dst = buf; size; size--) {
		const char *cp;
		char ch = *src++;
		*dst++ = ch;
		if ((ch != '$') || (size < 6) || memcmp("ident", src, 5))
			continue;

		if (src[5] == ':') {
			/* discard up to but not including the closing $ */
			unsigned long rem = size - 6;
			cp = src + 6;
			do {
				ch = *cp++;
				if (ch == '$')
					break;
				rem--;
			} while (rem);
			if (!rem)
				continue;
			size -= (cp - src);
		} else if (src[5] == '$')
			cp = src + 5;
		else
			continue;

		memcpy(dst, "ident: ", 7);
		dst += 7;
		memcpy(dst, sha1_to_hex(sha1), 40);
		dst += 40;
		*dst++ = ' ';
		size -= (cp - src);
		src = cp;
		*dst++ = *src++;
		size--;
	}

	*sizep = dst - buf;
	return buf;
}

static int git_path_check_crlf(const char *path, struct git_attr_check *check)
{
	const char *value = check->value;

	if (ATTR_TRUE(value))
		return CRLF_TEXT;
	else if (ATTR_FALSE(value))
		return CRLF_BINARY;
	else if (ATTR_UNSET(value))
		;
	else if (!strcmp(value, "input"))
		return CRLF_INPUT;
	return CRLF_GUESS;
}

static int git_path_check_ident(const char *path, struct git_attr_check *check)
{
	const char *value = check->value;

	return !!ATTR_TRUE(value);
}

char *convert_to_git(const char *path, const char *src, unsigned long *sizep)
{
	struct git_attr_check check[2];
	int crlf = CRLF_GUESS;
	int ident = 0;
	char *buf, *buf2;

	setup_convert_check(check);
	if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
		crlf = git_path_check_crlf(path, check + 0);
		ident = git_path_check_ident(path, check + 1);
	}

	buf = crlf_to_git(path, src, sizep, crlf);

	buf2 = ident_to_git(path, buf ? buf : src, sizep, ident);
	if (buf2) {
		free(buf);
		buf = buf2;
	}

	return buf;
}

char *convert_to_working_tree(const char *path, const char *src, unsigned long *sizep)
{
	struct git_attr_check check[2];
	int crlf = CRLF_GUESS;
	int ident = 0;
	char *buf, *buf2;

	setup_convert_check(check);
	if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
		crlf = git_path_check_crlf(path, check + 0);
		ident = git_path_check_ident(path, check + 1);
	}

	buf = ident_to_worktree(path, src, sizep, ident);

	buf2 = crlf_to_worktree(path, buf ? buf : src, sizep, crlf);
	if (buf2) {
		free(buf);
		buf = buf2;
	}

	return buf;
}