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Junio C Hamano
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Add 'ident' conversion.
The 'ident' attribute set to path squashes "$ident:<any bytes except dollor sign>$" to "$ident$" upon checkin, and expands it to "$ident: <blob SHA-1> $" upon checkout. As we have two conversions that affect checkin/checkout paths, clarify how they interact with each other. Signed-off-by: Junio C Hamano <junkio@cox.net>
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‎Documentation/gitattributes.txt‎

Lines changed: 29 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -78,12 +78,17 @@ are attributes-aware.
7878
Checking-out and checking-in
7979
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
8080

81-
The attribute `crlf` affects how the contents stored in the
81+
These attributes affect how the contents stored in the
8282
repository are copied to the working tree files when commands
83-
such as `git checkout` and `git merge` run. It also affects how
83+
such as `git checkout` and `git merge` run. They also affect how
8484
git stores the contents you prepare in the working tree in the
8585
repository upon `git add` and `git commit`.
8686

87+
`crlf`
88+
^^^^^^
89+
90+
This attribute controls the line-ending convention.
91+
8792
Set::
8893

8994
Setting the `crlf` attribute on a path is meant to mark
@@ -129,6 +134,28 @@ converted to LF upon checkin, but there is no conversion done
129134
upon checkout.
130135

131136

137+
`ident`
138+
^^^^^^^
139+
140+
When the attribute `ident` is set to a path, git replaces
141+
`$ident$` in the blob object with `$ident:`, followed by
142+
40-character hexadecimal blob object name, followed by a dollar
143+
sign `$` upon checkout. Any byte sequence that begins with
144+
`$ident:` and ends with `$` in the worktree file is replaced
145+
with `$ident$` upon check-in.
146+
147+
148+
Interaction between checkin/checkout attributes
149+
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
150+
151+
In the check-in codepath, the worktree file is first converted
152+
with `ident` (if specified), and then with `crlf` (again, if
153+
specified and applicable).
154+
155+
In the check-out codepath, the blob content is first converted
156+
with `crlf`, and then `ident`.
157+
158+
132159
Generating diff text
133160
~~~~~~~~~~~~~~~~~~~~
134161

‎convert.c‎

Lines changed: 184 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,6 @@
11
#include "cache.h"
22
#include "attr.h"
3+
#include "run-command.h"
34

45
/*
56
* convert.c - convert a file when checking it out and checking it in.
@@ -203,10 +204,152 @@ static char *crlf_to_worktree(const char *path, const char *src, unsigned long *
203204
static void setup_convert_check(struct git_attr_check *check)
204205
{
205206
static struct git_attr *attr_crlf;
207+
static struct git_attr *attr_ident;
206208

207-
if (!attr_crlf)
209+
if (!attr_crlf) {
208210
attr_crlf = git_attr("crlf", 4);
209-
check->attr = attr_crlf;
211+
attr_ident = git_attr("ident", 5);
212+
}
213+
check[0].attr = attr_crlf;
214+
check[1].attr = attr_ident;
215+
}
216+
217+
static int count_ident(const char *cp, unsigned long size)
218+
{
219+
/*
220+
* "$ident: 0000000000000000000000000000000000000000 $" <=> "$ident$"
221+
*/
222+
int cnt = 0;
223+
char ch;
224+
225+
while (size) {
226+
ch = *cp++;
227+
size--;
228+
if (ch != '$')
229+
continue;
230+
if (size < 6)
231+
break;
232+
if (memcmp("ident", cp, 5))
233+
continue;
234+
ch = cp[5];
235+
cp += 6;
236+
size -= 6;
237+
if (ch == '$')
238+
cnt++; /* $ident$ */
239+
if (ch != ':')
240+
continue;
241+
242+
/*
243+
* "$ident: ... "; scan up to the closing dollar sign and discard.
244+
*/
245+
while (size) {
246+
ch = *cp++;
247+
size--;
248+
if (ch == '$') {
249+
cnt++;
250+
break;
251+
}
252+
}
253+
}
254+
return cnt;
255+
}
256+
257+
static char *ident_to_git(const char *path, const char *src, unsigned long *sizep, int ident)
258+
{
259+
int cnt;
260+
unsigned long size;
261+
char *dst, *buf;
262+
263+
if (!ident)
264+
return NULL;
265+
size = *sizep;
266+
cnt = count_ident(src, size);
267+
if (!cnt)
268+
return NULL;
269+
buf = xmalloc(size);
270+
271+
for (dst = buf; size; size--) {
272+
char ch = *src++;
273+
*dst++ = ch;
274+
if ((ch == '$') && (6 <= size) &&
275+
!memcmp("ident:", src, 6)) {
276+
unsigned long rem = size - 6;
277+
const char *cp = src + 6;
278+
do {
279+
ch = *cp++;
280+
if (ch == '$')
281+
break;
282+
rem--;
283+
} while (rem);
284+
if (!rem)
285+
continue;
286+
memcpy(dst, "ident$", 6);
287+
dst += 6;
288+
size -= (cp - src);
289+
src = cp;
290+
}
291+
}
292+
293+
*sizep = dst - buf;
294+
return buf;
295+
}
296+
297+
static char *ident_to_worktree(const char *path, const char *src, unsigned long *sizep, int ident)
298+
{
299+
int cnt;
300+
unsigned long size;
301+
char *dst, *buf;
302+
unsigned char sha1[20];
303+
304+
if (!ident)
305+
return NULL;
306+
307+
size = *sizep;
308+
cnt = count_ident(src, size);
309+
if (!cnt)
310+
return NULL;
311+
312+
hash_sha1_file(src, size, "blob", sha1);
313+
buf = xmalloc(size + cnt * 43);
314+
315+
for (dst = buf; size; size--) {
316+
const char *cp;
317+
char ch = *src++;
318+
*dst++ = ch;
319+
if ((ch != '$') || (size < 6) || memcmp("ident", src, 5))
320+
continue;
321+
322+
if (src[5] == ':') {
323+
/* discard up to but not including the closing $ */
324+
unsigned long rem = size - 6;
325+
cp = src + 6;
326+
do {
327+
ch = *cp++;
328+
if (ch == '$')
329+
break;
330+
rem--;
331+
} while (rem);
332+
if (!rem)
333+
continue;
334+
size -= (cp - src);
335+
} else if (src[5] == '$')
336+
cp = src + 5;
337+
else
338+
continue;
339+
340+
memcpy(dst, "ident: ", 7);
341+
dst += 7;
342+
memcpy(dst, sha1_to_hex(sha1), 40);
343+
dst += 40;
344+
*dst++ = ' ';
345+
size -= (cp - src);
346+
src = cp;
347+
*dst++ = *src++;
348+
size--;
349+
}
350+
351+
*sizep = dst - buf;
352+
return buf;
210353
}
211354

212355
static int git_path_check_crlf(const char *path, struct git_attr_check *check)
@@ -224,26 +367,57 @@ static int git_path_check_crlf(const char *path, struct git_attr_check *check)
224367
return CRLF_GUESS;
225368
}
226369

370+
static int git_path_check_ident(const char *path, struct git_attr_check *check)
371+
{
372+
const char *value = check->value;
373+
374+
return !!ATTR_TRUE(value);
375+
}
376+
227377
char *convert_to_git(const char *path, const char *src, unsigned long *sizep)
228378
{
229-
struct git_attr_check check[1];
379+
struct git_attr_check check[2];
230380
int crlf = CRLF_GUESS;
381+
int ident = 0;
382+
char *buf, *buf2;
231383

232384
setup_convert_check(check);
233-
if (!git_checkattr(path, 1, check)) {
234-
crlf = git_path_check_crlf(path, check);
385+
if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
386+
crlf = git_path_check_crlf(path, check + 0);
387+
ident = git_path_check_ident(path, check + 1);
388+
}
389+
390+
buf = crlf_to_git(path, src, sizep, crlf);
391+
392+
buf2 = ident_to_git(path, buf ? buf : src, sizep, ident);
393+
if (buf2) {
394+
free(buf);
395+
buf = buf2;
235396
}
236-
return crlf_to_git(path, src, sizep, crlf);
397+
398+
return buf;
237399
}
238400

239401
char *convert_to_working_tree(const char *path, const char *src, unsigned long *sizep)
240402
{
241-
struct git_attr_check check[1];
403+
struct git_attr_check check[2];
242404
int crlf = CRLF_GUESS;
405+
int ident = 0;
406+
char *buf, *buf2;
243407

244408
setup_convert_check(check);
245-
if (!git_checkattr(path, 1, check)) {
246-
crlf = git_path_check_crlf(path, check);
409+
if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
410+
crlf = git_path_check_crlf(path, check + 0);
411+
ident = git_path_check_ident(path, check + 1);
247412
}
248-
return crlf_to_worktree(path, src, sizep, crlf);
413+
414+
buf = ident_to_worktree(path, src, sizep, ident);
415+
416+
buf2 = crlf_to_worktree(path, buf ? buf : src, sizep, crlf);
417+
if (buf2) {
418+
free(buf);
419+
buf = buf2;
420+
}
421+
422+
return buf;
249423
}

‎t/t0021-conversion.sh‎

Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,39 @@
1+
#!/bin/sh
2+
3+
test_description='blob conversion via gitattributes'
4+
5+
. ./test-lib.sh
6+
7+
test_expect_success setup '
8+
{
9+
echo "*.i ident"
10+
} >.gitattributes &&
11+
12+
{
13+
echo a b c d e f g h i j k l m
14+
echo n o p q r s t u v w x y z
15+
echo '\''$ident$'\''
16+
} >test &&
17+
cat test >test.t &&
18+
cat test >test.o &&
19+
cat test >test.i &&
20+
git add test test.t test.i &&
21+
rm -f test test.t test.i &&
22+
git checkout -- test test.t test.i
23+
'
24+
25+
script='s/^\$ident: \([0-9a-f]*\) \$/\1/p'
26+
27+
test_expect_success check '
28+
29+
cmp test.o test &&
30+
cmp test.o test.t &&
31+
32+
# ident should be stripped in the repository
33+
git diff --raw --exit-code :test :test.i &&
34+
id=$(git rev-parse --verify :test) &&
35+
embedded=$(sed -ne "$script" test.i) &&
36+
test "z$id" = "z$embedded"
37+
'
38+
39+
test_done

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