alternates: provide helper for adding to alternates list
[git] / mailinfo.c
1 #include "cache.h"
2 #include "utf8.h"
3 #include "strbuf.h"
4 #include "mailinfo.h"
5
6 static void cleanup_space(struct strbuf *sb)
7 {
8         size_t pos, cnt;
9         for (pos = 0; pos < sb->len; pos++) {
10                 if (isspace(sb->buf[pos])) {
11                         sb->buf[pos] = ' ';
12                         for (cnt = 0; isspace(sb->buf[pos + cnt + 1]); cnt++);
13                         strbuf_remove(sb, pos + 1, cnt);
14                 }
15         }
16 }
17
18 static void get_sane_name(struct strbuf *out, struct strbuf *name, struct strbuf *email)
19 {
20         struct strbuf *src = name;
21         if (name->len < 3 || 60 < name->len || strchr(name->buf, '@') ||
22                 strchr(name->buf, '<') || strchr(name->buf, '>'))
23                 src = email;
24         else if (name == out)
25                 return;
26         strbuf_reset(out);
27         strbuf_addbuf(out, src);
28 }
29
30 static void parse_bogus_from(struct mailinfo *mi, const struct strbuf *line)
31 {
32         /* John Doe <johndoe> */
33
34         char *bra, *ket;
35         /* This is fallback, so do not bother if we already have an
36          * e-mail address.
37          */
38         if (mi->email.len)
39                 return;
40
41         bra = strchr(line->buf, '<');
42         if (!bra)
43                 return;
44         ket = strchr(bra, '>');
45         if (!ket)
46                 return;
47
48         strbuf_reset(&mi->email);
49         strbuf_add(&mi->email, bra + 1, ket - bra - 1);
50
51         strbuf_reset(&mi->name);
52         strbuf_add(&mi->name, line->buf, bra - line->buf);
53         strbuf_trim(&mi->name);
54         get_sane_name(&mi->name, &mi->name, &mi->email);
55 }
56
57 static const char *unquote_comment(struct strbuf *outbuf, const char *in)
58 {
59         int c;
60         int take_next_litterally = 0;
61
62         strbuf_addch(outbuf, '(');
63
64         while ((c = *in++) != 0) {
65                 if (take_next_litterally == 1) {
66                         take_next_litterally = 0;
67                 } else {
68                         switch (c) {
69                         case '\\':
70                                 take_next_litterally = 1;
71                                 continue;
72                         case '(':
73                                 in = unquote_comment(outbuf, in);
74                                 continue;
75                         case ')':
76                                 strbuf_addch(outbuf, ')');
77                                 return in;
78                         }
79                 }
80
81                 strbuf_addch(outbuf, c);
82         }
83
84         return in;
85 }
86
87 static const char *unquote_quoted_string(struct strbuf *outbuf, const char *in)
88 {
89         int c;
90         int take_next_litterally = 0;
91
92         while ((c = *in++) != 0) {
93                 if (take_next_litterally == 1) {
94                         take_next_litterally = 0;
95                 } else {
96                         switch (c) {
97                         case '\\':
98                                 take_next_litterally = 1;
99                                 continue;
100                         case '"':
101                                 return in;
102                         }
103                 }
104
105                 strbuf_addch(outbuf, c);
106         }
107
108         return in;
109 }
110
111 static void unquote_quoted_pair(struct strbuf *line)
112 {
113         struct strbuf outbuf;
114         const char *in = line->buf;
115         int c;
116
117         strbuf_init(&outbuf, line->len);
118
119         while ((c = *in++) != 0) {
120                 switch (c) {
121                 case '"':
122                         in = unquote_quoted_string(&outbuf, in);
123                         continue;
124                 case '(':
125                         in = unquote_comment(&outbuf, in);
126                         continue;
127                 }
128
129                 strbuf_addch(&outbuf, c);
130         }
131
132         strbuf_swap(&outbuf, line);
133         strbuf_release(&outbuf);
134
135 }
136
137 static void handle_from(struct mailinfo *mi, const struct strbuf *from)
138 {
139         char *at;
140         size_t el;
141         struct strbuf f;
142
143         strbuf_init(&f, from->len);
144         strbuf_addbuf(&f, from);
145
146         unquote_quoted_pair(&f);
147
148         at = strchr(f.buf, '@');
149         if (!at) {
150                 parse_bogus_from(mi, from);
151                 return;
152         }
153
154         /*
155          * If we already have one email, don't take any confusing lines
156          */
157         if (mi->email.len && strchr(at + 1, '@')) {
158                 strbuf_release(&f);
159                 return;
160         }
161
162         /* Pick up the string around '@', possibly delimited with <>
163          * pair; that is the email part.
164          */
165         while (at > f.buf) {
166                 char c = at[-1];
167                 if (isspace(c))
168                         break;
169                 if (c == '<') {
170                         at[-1] = ' ';
171                         break;
172                 }
173                 at--;
174         }
175         el = strcspn(at, " \n\t\r\v\f>");
176         strbuf_reset(&mi->email);
177         strbuf_add(&mi->email, at, el);
178         strbuf_remove(&f, at - f.buf, el + (at[el] ? 1 : 0));
179
180         /* The remainder is name.  It could be
181          *
182          * - "John Doe <john.doe@xz>"                   (a), or
183          * - "john.doe@xz (John Doe)"                   (b), or
184          * - "John (zzz) Doe <john.doe@xz> (Comment)"   (c)
185          *
186          * but we have removed the email part, so
187          *
188          * - remove extra spaces which could stay after email (case 'c'), and
189          * - trim from both ends, possibly removing the () pair at the end
190          *   (cases 'a' and 'b').
191          */
192         cleanup_space(&f);
193         strbuf_trim(&f);
194         if (f.buf[0] == '(' && f.len && f.buf[f.len - 1] == ')') {
195                 strbuf_remove(&f, 0, 1);
196                 strbuf_setlen(&f, f.len - 1);
197         }
198
199         get_sane_name(&mi->name, &f, &mi->email);
200         strbuf_release(&f);
201 }
202
203 static void handle_header(struct strbuf **out, const struct strbuf *line)
204 {
205         if (!*out) {
206                 *out = xmalloc(sizeof(struct strbuf));
207                 strbuf_init(*out, line->len);
208         } else
209                 strbuf_reset(*out);
210
211         strbuf_addbuf(*out, line);
212 }
213
214 /* NOTE NOTE NOTE.  We do not claim we do full MIME.  We just attempt
215  * to have enough heuristics to grok MIME encoded patches often found
216  * on our mailing lists.  For example, we do not even treat header lines
217  * case insensitively.
218  */
219
220 static int slurp_attr(const char *line, const char *name, struct strbuf *attr)
221 {
222         const char *ends, *ap = strcasestr(line, name);
223         size_t sz;
224
225         strbuf_setlen(attr, 0);
226         if (!ap)
227                 return 0;
228         ap += strlen(name);
229         if (*ap == '"') {
230                 ap++;
231                 ends = "\"";
232         }
233         else
234                 ends = "; \t";
235         sz = strcspn(ap, ends);
236         strbuf_add(attr, ap, sz);
237         return 1;
238 }
239
240 static void handle_content_type(struct mailinfo *mi, struct strbuf *line)
241 {
242         struct strbuf *boundary = xmalloc(sizeof(struct strbuf));
243         strbuf_init(boundary, line->len);
244
245         if (slurp_attr(line->buf, "boundary=", boundary)) {
246                 strbuf_insert(boundary, 0, "--", 2);
247                 if (++mi->content_top >= &mi->content[MAX_BOUNDARIES]) {
248                         error("Too many boundaries to handle");
249                         mi->input_error = -1;
250                         mi->content_top = &mi->content[MAX_BOUNDARIES] - 1;
251                         return;
252                 }
253                 *(mi->content_top) = boundary;
254                 boundary = NULL;
255         }
256         slurp_attr(line->buf, "charset=", &mi->charset);
257
258         if (boundary) {
259                 strbuf_release(boundary);
260                 free(boundary);
261         }
262 }
263
264 static void handle_content_transfer_encoding(struct mailinfo *mi,
265                                              const struct strbuf *line)
266 {
267         if (strcasestr(line->buf, "base64"))
268                 mi->transfer_encoding = TE_BASE64;
269         else if (strcasestr(line->buf, "quoted-printable"))
270                 mi->transfer_encoding = TE_QP;
271         else
272                 mi->transfer_encoding = TE_DONTCARE;
273 }
274
275 static int is_multipart_boundary(struct mailinfo *mi, const struct strbuf *line)
276 {
277         struct strbuf *content_top = *(mi->content_top);
278
279         return ((content_top->len <= line->len) &&
280                 !memcmp(line->buf, content_top->buf, content_top->len));
281 }
282
283 static void cleanup_subject(struct mailinfo *mi, struct strbuf *subject)
284 {
285         size_t at = 0;
286
287         while (at < subject->len) {
288                 char *pos;
289                 size_t remove;
290
291                 switch (subject->buf[at]) {
292                 case 'r': case 'R':
293                         if (subject->len <= at + 3)
294                                 break;
295                         if ((subject->buf[at + 1] == 'e' ||
296                              subject->buf[at + 1] == 'E') &&
297                             subject->buf[at + 2] == ':') {
298                                 strbuf_remove(subject, at, 3);
299                                 continue;
300                         }
301                         at++;
302                         break;
303                 case ' ': case '\t': case ':':
304                         strbuf_remove(subject, at, 1);
305                         continue;
306                 case '[':
307                         pos = strchr(subject->buf + at, ']');
308                         if (!pos)
309                                 break;
310                         remove = pos - subject->buf + at + 1;
311                         if (!mi->keep_non_patch_brackets_in_subject ||
312                             (7 <= remove &&
313                              memmem(subject->buf + at, remove, "PATCH", 5)))
314                                 strbuf_remove(subject, at, remove);
315                         else {
316                                 at += remove;
317                                 /*
318                                  * If the input had a space after the ], keep
319                                  * it.  We don't bother with finding the end of
320                                  * the space, since we later normalize it
321                                  * anyway.
322                                  */
323                                 if (isspace(subject->buf[at]))
324                                         at += 1;
325                         }
326                         continue;
327                 }
328                 break;
329         }
330         strbuf_trim(subject);
331 }
332
333 #define MAX_HDR_PARSED 10
334 static const char *header[MAX_HDR_PARSED] = {
335         "From","Subject","Date",
336 };
337
338 static inline int cmp_header(const struct strbuf *line, const char *hdr)
339 {
340         int len = strlen(hdr);
341         return !strncasecmp(line->buf, hdr, len) && line->len > len &&
342                         line->buf[len] == ':' && isspace(line->buf[len + 1]);
343 }
344
345 static int is_format_patch_separator(const char *line, int len)
346 {
347         static const char SAMPLE[] =
348                 "From e6807f3efca28b30decfecb1732a56c7db1137ee Mon Sep 17 00:00:00 2001\n";
349         const char *cp;
350
351         if (len != strlen(SAMPLE))
352                 return 0;
353         if (!skip_prefix(line, "From ", &cp))
354                 return 0;
355         if (strspn(cp, "0123456789abcdef") != 40)
356                 return 0;
357         cp += 40;
358         return !memcmp(SAMPLE + (cp - line), cp, strlen(SAMPLE) - (cp - line));
359 }
360
361 static struct strbuf *decode_q_segment(const struct strbuf *q_seg, int rfc2047)
362 {
363         const char *in = q_seg->buf;
364         int c;
365         struct strbuf *out = xmalloc(sizeof(struct strbuf));
366         strbuf_init(out, q_seg->len);
367
368         while ((c = *in++) != 0) {
369                 if (c == '=') {
370                         int d = *in++;
371                         if (d == '\n' || !d)
372                                 break; /* drop trailing newline */
373                         strbuf_addch(out, (hexval(d) << 4) | hexval(*in++));
374                         continue;
375                 }
376                 if (rfc2047 && c == '_') /* rfc2047 4.2 (2) */
377                         c = 0x20;
378                 strbuf_addch(out, c);
379         }
380         return out;
381 }
382
383 static struct strbuf *decode_b_segment(const struct strbuf *b_seg)
384 {
385         /* Decode in..ep, possibly in-place to ot */
386         int c, pos = 0, acc = 0;
387         const char *in = b_seg->buf;
388         struct strbuf *out = xmalloc(sizeof(struct strbuf));
389         strbuf_init(out, b_seg->len);
390
391         while ((c = *in++) != 0) {
392                 if (c == '+')
393                         c = 62;
394                 else if (c == '/')
395                         c = 63;
396                 else if ('A' <= c && c <= 'Z')
397                         c -= 'A';
398                 else if ('a' <= c && c <= 'z')
399                         c -= 'a' - 26;
400                 else if ('0' <= c && c <= '9')
401                         c -= '0' - 52;
402                 else
403                         continue; /* garbage */
404                 switch (pos++) {
405                 case 0:
406                         acc = (c << 2);
407                         break;
408                 case 1:
409                         strbuf_addch(out, (acc | (c >> 4)));
410                         acc = (c & 15) << 4;
411                         break;
412                 case 2:
413                         strbuf_addch(out, (acc | (c >> 2)));
414                         acc = (c & 3) << 6;
415                         break;
416                 case 3:
417                         strbuf_addch(out, (acc | c));
418                         acc = pos = 0;
419                         break;
420                 }
421         }
422         return out;
423 }
424
425 static int convert_to_utf8(struct mailinfo *mi,
426                            struct strbuf *line, const char *charset)
427 {
428         char *out;
429
430         if (!mi->metainfo_charset || !charset || !*charset)
431                 return 0;
432
433         if (same_encoding(mi->metainfo_charset, charset))
434                 return 0;
435         out = reencode_string(line->buf, mi->metainfo_charset, charset);
436         if (!out) {
437                 mi->input_error = -1;
438                 return error("cannot convert from %s to %s",
439                              charset, mi->metainfo_charset);
440         }
441         strbuf_attach(line, out, strlen(out), strlen(out));
442         return 0;
443 }
444
445 static void decode_header(struct mailinfo *mi, struct strbuf *it)
446 {
447         char *in, *ep, *cp;
448         struct strbuf outbuf = STRBUF_INIT, *dec;
449         struct strbuf charset_q = STRBUF_INIT, piecebuf = STRBUF_INIT;
450         int found_error = 1; /* pessimism */
451
452         in = it->buf;
453         while (in - it->buf <= it->len && (ep = strstr(in, "=?")) != NULL) {
454                 int encoding;
455                 strbuf_reset(&charset_q);
456                 strbuf_reset(&piecebuf);
457
458                 if (in != ep) {
459                         /*
460                          * We are about to process an encoded-word
461                          * that begins at ep, but there is something
462                          * before the encoded word.
463                          */
464                         char *scan;
465                         for (scan = in; scan < ep; scan++)
466                                 if (!isspace(*scan))
467                                         break;
468
469                         if (scan != ep || in == it->buf) {
470                                 /*
471                                  * We should not lose that "something",
472                                  * unless we have just processed an
473                                  * encoded-word, and there is only LWS
474                                  * before the one we are about to process.
475                                  */
476                                 strbuf_add(&outbuf, in, ep - in);
477                         }
478                 }
479                 /* E.g.
480                  * ep : "=?iso-2022-jp?B?GyR...?= foo"
481                  * ep : "=?ISO-8859-1?Q?Foo=FCbar?= baz"
482                  */
483                 ep += 2;
484
485                 if (ep - it->buf >= it->len || !(cp = strchr(ep, '?')))
486                         goto release_return;
487
488                 if (cp + 3 - it->buf > it->len)
489                         goto release_return;
490                 strbuf_add(&charset_q, ep, cp - ep);
491
492                 encoding = cp[1];
493                 if (!encoding || cp[2] != '?')
494                         goto release_return;
495                 ep = strstr(cp + 3, "?=");
496                 if (!ep)
497                         goto release_return;
498                 strbuf_add(&piecebuf, cp + 3, ep - cp - 3);
499                 switch (tolower(encoding)) {
500                 default:
501                         goto release_return;
502                 case 'b':
503                         dec = decode_b_segment(&piecebuf);
504                         break;
505                 case 'q':
506                         dec = decode_q_segment(&piecebuf, 1);
507                         break;
508                 }
509                 if (convert_to_utf8(mi, dec, charset_q.buf))
510                         goto release_return;
511
512                 strbuf_addbuf(&outbuf, dec);
513                 strbuf_release(dec);
514                 free(dec);
515                 in = ep + 2;
516         }
517         strbuf_addstr(&outbuf, in);
518         strbuf_reset(it);
519         strbuf_addbuf(it, &outbuf);
520         found_error = 0;
521 release_return:
522         strbuf_release(&outbuf);
523         strbuf_release(&charset_q);
524         strbuf_release(&piecebuf);
525
526         if (found_error)
527                 mi->input_error = -1;
528 }
529
530 static int check_header(struct mailinfo *mi,
531                         const struct strbuf *line,
532                         struct strbuf *hdr_data[], int overwrite)
533 {
534         int i, ret = 0, len;
535         struct strbuf sb = STRBUF_INIT;
536
537         /* search for the interesting parts */
538         for (i = 0; header[i]; i++) {
539                 int len = strlen(header[i]);
540                 if ((!hdr_data[i] || overwrite) && cmp_header(line, header[i])) {
541                         /* Unwrap inline B and Q encoding, and optionally
542                          * normalize the meta information to utf8.
543                          */
544                         strbuf_add(&sb, line->buf + len + 2, line->len - len - 2);
545                         decode_header(mi, &sb);
546                         handle_header(&hdr_data[i], &sb);
547                         ret = 1;
548                         goto check_header_out;
549                 }
550         }
551
552         /* Content stuff */
553         if (cmp_header(line, "Content-Type")) {
554                 len = strlen("Content-Type: ");
555                 strbuf_add(&sb, line->buf + len, line->len - len);
556                 decode_header(mi, &sb);
557                 strbuf_insert(&sb, 0, "Content-Type: ", len);
558                 handle_content_type(mi, &sb);
559                 ret = 1;
560                 goto check_header_out;
561         }
562         if (cmp_header(line, "Content-Transfer-Encoding")) {
563                 len = strlen("Content-Transfer-Encoding: ");
564                 strbuf_add(&sb, line->buf + len, line->len - len);
565                 decode_header(mi, &sb);
566                 handle_content_transfer_encoding(mi, &sb);
567                 ret = 1;
568                 goto check_header_out;
569         }
570         if (cmp_header(line, "Message-Id")) {
571                 len = strlen("Message-Id: ");
572                 strbuf_add(&sb, line->buf + len, line->len - len);
573                 decode_header(mi, &sb);
574                 if (mi->add_message_id)
575                         mi->message_id = strbuf_detach(&sb, NULL);
576                 ret = 1;
577                 goto check_header_out;
578         }
579
580 check_header_out:
581         strbuf_release(&sb);
582         return ret;
583 }
584
585 /*
586  * Returns 1 if the given line or any line beginning with the given line is an
587  * in-body header (that is, check_header will succeed when passed
588  * mi->s_hdr_data).
589  */
590 static int is_inbody_header(const struct mailinfo *mi,
591                             const struct strbuf *line)
592 {
593         int i;
594         for (i = 0; header[i]; i++)
595                 if (!mi->s_hdr_data[i] && cmp_header(line, header[i]))
596                         return 1;
597         return 0;
598 }
599
600 static void decode_transfer_encoding(struct mailinfo *mi, struct strbuf *line)
601 {
602         struct strbuf *ret;
603
604         switch (mi->transfer_encoding) {
605         case TE_QP:
606                 ret = decode_q_segment(line, 0);
607                 break;
608         case TE_BASE64:
609                 ret = decode_b_segment(line);
610                 break;
611         case TE_DONTCARE:
612         default:
613                 return;
614         }
615         strbuf_reset(line);
616         strbuf_addbuf(line, ret);
617         strbuf_release(ret);
618         free(ret);
619 }
620
621 static inline int patchbreak(const struct strbuf *line)
622 {
623         size_t i;
624
625         /* Beginning of a "diff -" header? */
626         if (starts_with(line->buf, "diff -"))
627                 return 1;
628
629         /* CVS "Index: " line? */
630         if (starts_with(line->buf, "Index: "))
631                 return 1;
632
633         /*
634          * "--- <filename>" starts patches without headers
635          * "---<sp>*" is a manual separator
636          */
637         if (line->len < 4)
638                 return 0;
639
640         if (starts_with(line->buf, "---")) {
641                 /* space followed by a filename? */
642                 if (line->buf[3] == ' ' && !isspace(line->buf[4]))
643                         return 1;
644                 /* Just whitespace? */
645                 for (i = 3; i < line->len; i++) {
646                         unsigned char c = line->buf[i];
647                         if (c == '\n')
648                                 return 1;
649                         if (!isspace(c))
650                                 break;
651                 }
652                 return 0;
653         }
654         return 0;
655 }
656
657 static int is_scissors_line(const char *line)
658 {
659         const char *c;
660         int scissors = 0, gap = 0;
661         const char *first_nonblank = NULL, *last_nonblank = NULL;
662         int visible, perforation = 0, in_perforation = 0;
663
664         for (c = line; *c; c++) {
665                 if (isspace(*c)) {
666                         if (in_perforation) {
667                                 perforation++;
668                                 gap++;
669                         }
670                         continue;
671                 }
672                 last_nonblank = c;
673                 if (first_nonblank == NULL)
674                         first_nonblank = c;
675                 if (*c == '-') {
676                         in_perforation = 1;
677                         perforation++;
678                         continue;
679                 }
680                 if ((!memcmp(c, ">8", 2) || !memcmp(c, "8<", 2) ||
681                      !memcmp(c, ">%", 2) || !memcmp(c, "%<", 2))) {
682                         in_perforation = 1;
683                         perforation += 2;
684                         scissors += 2;
685                         c++;
686                         continue;
687                 }
688                 in_perforation = 0;
689         }
690
691         /*
692          * The mark must be at least 8 bytes long (e.g. "-- >8 --").
693          * Even though there can be arbitrary cruft on the same line
694          * (e.g. "cut here"), in order to avoid misidentification, the
695          * perforation must occupy more than a third of the visible
696          * width of the line, and dashes and scissors must occupy more
697          * than half of the perforation.
698          */
699
700         if (first_nonblank && last_nonblank)
701                 visible = last_nonblank - first_nonblank + 1;
702         else
703                 visible = 0;
704         return (scissors && 8 <= visible &&
705                 visible < perforation * 3 &&
706                 gap * 2 < perforation);
707 }
708
709 static void flush_inbody_header_accum(struct mailinfo *mi)
710 {
711         if (!mi->inbody_header_accum.len)
712                 return;
713         assert(check_header(mi, &mi->inbody_header_accum, mi->s_hdr_data, 0));
714         strbuf_reset(&mi->inbody_header_accum);
715 }
716
717 static int check_inbody_header(struct mailinfo *mi, const struct strbuf *line)
718 {
719         if (mi->inbody_header_accum.len &&
720             (line->buf[0] == ' ' || line->buf[0] == '\t')) {
721                 if (mi->use_scissors && is_scissors_line(line->buf)) {
722                         /*
723                          * This is a scissors line; do not consider this line
724                          * as a header continuation line.
725                          */
726                         flush_inbody_header_accum(mi);
727                         return 0;
728                 }
729                 strbuf_strip_suffix(&mi->inbody_header_accum, "\n");
730                 strbuf_addbuf(&mi->inbody_header_accum, line);
731                 return 1;
732         }
733
734         flush_inbody_header_accum(mi);
735
736         if (starts_with(line->buf, ">From") && isspace(line->buf[5]))
737                 return is_format_patch_separator(line->buf + 1, line->len - 1);
738         if (starts_with(line->buf, "[PATCH]") && isspace(line->buf[7])) {
739                 int i;
740                 for (i = 0; header[i]; i++)
741                         if (!strcmp("Subject", header[i])) {
742                                 handle_header(&mi->s_hdr_data[i], line);
743                                 return 1;
744                         }
745                 return 0;
746         }
747         if (is_inbody_header(mi, line)) {
748                 strbuf_addbuf(&mi->inbody_header_accum, line);
749                 return 1;
750         }
751         return 0;
752 }
753
754 static int handle_commit_msg(struct mailinfo *mi, struct strbuf *line)
755 {
756         assert(!mi->filter_stage);
757
758         if (mi->header_stage) {
759                 if (!line->len || (line->len == 1 && line->buf[0] == '\n'))
760                         return 0;
761         }
762
763         if (mi->use_inbody_headers && mi->header_stage) {
764                 mi->header_stage = check_inbody_header(mi, line);
765                 if (mi->header_stage)
766                         return 0;
767         } else
768                 /* Only trim the first (blank) line of the commit message
769                  * when ignoring in-body headers.
770                  */
771                 mi->header_stage = 0;
772
773         /* normalize the log message to UTF-8. */
774         if (convert_to_utf8(mi, line, mi->charset.buf))
775                 return 0; /* mi->input_error already set */
776
777         if (mi->use_scissors && is_scissors_line(line->buf)) {
778                 int i;
779
780                 strbuf_setlen(&mi->log_message, 0);
781                 mi->header_stage = 1;
782
783                 /*
784                  * We may have already read "secondary headers"; purge
785                  * them to give ourselves a clean restart.
786                  */
787                 for (i = 0; header[i]; i++) {
788                         if (mi->s_hdr_data[i])
789                                 strbuf_release(mi->s_hdr_data[i]);
790                         mi->s_hdr_data[i] = NULL;
791                 }
792                 return 0;
793         }
794
795         if (patchbreak(line)) {
796                 if (mi->message_id)
797                         strbuf_addf(&mi->log_message,
798                                     "Message-Id: %s\n", mi->message_id);
799                 return 1;
800         }
801
802         strbuf_addbuf(&mi->log_message, line);
803         return 0;
804 }
805
806 static void handle_patch(struct mailinfo *mi, const struct strbuf *line)
807 {
808         fwrite(line->buf, 1, line->len, mi->patchfile);
809         mi->patch_lines++;
810 }
811
812 static void handle_filter(struct mailinfo *mi, struct strbuf *line)
813 {
814         switch (mi->filter_stage) {
815         case 0:
816                 if (!handle_commit_msg(mi, line))
817                         break;
818                 mi->filter_stage++;
819         case 1:
820                 handle_patch(mi, line);
821                 break;
822         }
823 }
824
825 static int is_rfc2822_header(const struct strbuf *line)
826 {
827         /*
828          * The section that defines the loosest possible
829          * field name is "3.6.8 Optional fields".
830          *
831          * optional-field = field-name ":" unstructured CRLF
832          * field-name = 1*ftext
833          * ftext = %d33-57 / %59-126
834          */
835         int ch;
836         char *cp = line->buf;
837
838         /* Count mbox From headers as headers */
839         if (starts_with(cp, "From ") || starts_with(cp, ">From "))
840                 return 1;
841
842         while ((ch = *cp++)) {
843                 if (ch == ':')
844                         return 1;
845                 if ((33 <= ch && ch <= 57) ||
846                     (59 <= ch && ch <= 126))
847                         continue;
848                 break;
849         }
850         return 0;
851 }
852
853 static int read_one_header_line(struct strbuf *line, FILE *in)
854 {
855         struct strbuf continuation = STRBUF_INIT;
856
857         /* Get the first part of the line. */
858         if (strbuf_getline_lf(line, in))
859                 return 0;
860
861         /*
862          * Is it an empty line or not a valid rfc2822 header?
863          * If so, stop here, and return false ("not a header")
864          */
865         strbuf_rtrim(line);
866         if (!line->len || !is_rfc2822_header(line)) {
867                 /* Re-add the newline */
868                 strbuf_addch(line, '\n');
869                 return 0;
870         }
871
872         /*
873          * Now we need to eat all the continuation lines..
874          * Yuck, 2822 header "folding"
875          */
876         for (;;) {
877                 int peek;
878
879                 peek = fgetc(in); ungetc(peek, in);
880                 if (peek != ' ' && peek != '\t')
881                         break;
882                 if (strbuf_getline_lf(&continuation, in))
883                         break;
884                 continuation.buf[0] = ' ';
885                 strbuf_rtrim(&continuation);
886                 strbuf_addbuf(line, &continuation);
887         }
888         strbuf_release(&continuation);
889
890         return 1;
891 }
892
893 static int find_boundary(struct mailinfo *mi, struct strbuf *line)
894 {
895         while (!strbuf_getline_lf(line, mi->input)) {
896                 if (*(mi->content_top) && is_multipart_boundary(mi, line))
897                         return 1;
898         }
899         return 0;
900 }
901
902 static int handle_boundary(struct mailinfo *mi, struct strbuf *line)
903 {
904         struct strbuf newline = STRBUF_INIT;
905
906         strbuf_addch(&newline, '\n');
907 again:
908         if (line->len >= (*(mi->content_top))->len + 2 &&
909             !memcmp(line->buf + (*(mi->content_top))->len, "--", 2)) {
910                 /* we hit an end boundary */
911                 /* pop the current boundary off the stack */
912                 strbuf_release(*(mi->content_top));
913                 free(*(mi->content_top));
914                 *(mi->content_top) = NULL;
915
916                 /* technically won't happen as is_multipart_boundary()
917                    will fail first.  But just in case..
918                  */
919                 if (--mi->content_top < mi->content) {
920                         error("Detected mismatched boundaries, can't recover");
921                         mi->input_error = -1;
922                         mi->content_top = mi->content;
923                         return 0;
924                 }
925                 handle_filter(mi, &newline);
926                 strbuf_release(&newline);
927                 if (mi->input_error)
928                         return 0;
929
930                 /* skip to the next boundary */
931                 if (!find_boundary(mi, line))
932                         return 0;
933                 goto again;
934         }
935
936         /* set some defaults */
937         mi->transfer_encoding = TE_DONTCARE;
938         strbuf_reset(&mi->charset);
939
940         /* slurp in this section's info */
941         while (read_one_header_line(line, mi->input))
942                 check_header(mi, line, mi->p_hdr_data, 0);
943
944         strbuf_release(&newline);
945         /* replenish line */
946         if (strbuf_getline_lf(line, mi->input))
947                 return 0;
948         strbuf_addch(line, '\n');
949         return 1;
950 }
951
952 static void handle_body(struct mailinfo *mi, struct strbuf *line)
953 {
954         struct strbuf prev = STRBUF_INIT;
955
956         /* Skip up to the first boundary */
957         if (*(mi->content_top)) {
958                 if (!find_boundary(mi, line))
959                         goto handle_body_out;
960         }
961
962         do {
963                 /* process any boundary lines */
964                 if (*(mi->content_top) && is_multipart_boundary(mi, line)) {
965                         /* flush any leftover */
966                         if (prev.len) {
967                                 handle_filter(mi, &prev);
968                                 strbuf_reset(&prev);
969                         }
970                         if (!handle_boundary(mi, line))
971                                 goto handle_body_out;
972                 }
973
974                 /* Unwrap transfer encoding */
975                 decode_transfer_encoding(mi, line);
976
977                 switch (mi->transfer_encoding) {
978                 case TE_BASE64:
979                 case TE_QP:
980                 {
981                         struct strbuf **lines, **it, *sb;
982
983                         /* Prepend any previous partial lines */
984                         strbuf_insert(line, 0, prev.buf, prev.len);
985                         strbuf_reset(&prev);
986
987                         /*
988                          * This is a decoded line that may contain
989                          * multiple new lines.  Pass only one chunk
990                          * at a time to handle_filter()
991                          */
992                         lines = strbuf_split(line, '\n');
993                         for (it = lines; (sb = *it); it++) {
994                                 if (*(it + 1) == NULL) /* The last line */
995                                         if (sb->buf[sb->len - 1] != '\n') {
996                                                 /* Partial line, save it for later. */
997                                                 strbuf_addbuf(&prev, sb);
998                                                 break;
999                                         }
1000                                 handle_filter(mi, sb);
1001                         }
1002                         /*
1003                          * The partial chunk is saved in "prev" and will be
1004                          * appended by the next iteration of read_line_with_nul().
1005                          */
1006                         strbuf_list_free(lines);
1007                         break;
1008                 }
1009                 default:
1010                         handle_filter(mi, line);
1011                 }
1012
1013                 if (mi->input_error)
1014                         break;
1015         } while (!strbuf_getwholeline(line, mi->input, '\n'));
1016
1017         flush_inbody_header_accum(mi);
1018
1019 handle_body_out:
1020         strbuf_release(&prev);
1021 }
1022
1023 static void output_header_lines(FILE *fout, const char *hdr, const struct strbuf *data)
1024 {
1025         const char *sp = data->buf;
1026         while (1) {
1027                 char *ep = strchr(sp, '\n');
1028                 int len;
1029                 if (!ep)
1030                         len = strlen(sp);
1031                 else
1032                         len = ep - sp;
1033                 fprintf(fout, "%s: %.*s\n", hdr, len, sp);
1034                 if (!ep)
1035                         break;
1036                 sp = ep + 1;
1037         }
1038 }
1039
1040 static void handle_info(struct mailinfo *mi)
1041 {
1042         struct strbuf *hdr;
1043         int i;
1044
1045         for (i = 0; header[i]; i++) {
1046                 /* only print inbody headers if we output a patch file */
1047                 if (mi->patch_lines && mi->s_hdr_data[i])
1048                         hdr = mi->s_hdr_data[i];
1049                 else if (mi->p_hdr_data[i])
1050                         hdr = mi->p_hdr_data[i];
1051                 else
1052                         continue;
1053
1054                 if (!strcmp(header[i], "Subject")) {
1055                         if (!mi->keep_subject) {
1056                                 cleanup_subject(mi, hdr);
1057                                 cleanup_space(hdr);
1058                         }
1059                         output_header_lines(mi->output, "Subject", hdr);
1060                 } else if (!strcmp(header[i], "From")) {
1061                         cleanup_space(hdr);
1062                         handle_from(mi, hdr);
1063                         fprintf(mi->output, "Author: %s\n", mi->name.buf);
1064                         fprintf(mi->output, "Email: %s\n", mi->email.buf);
1065                 } else {
1066                         cleanup_space(hdr);
1067                         fprintf(mi->output, "%s: %s\n", header[i], hdr->buf);
1068                 }
1069         }
1070         fprintf(mi->output, "\n");
1071 }
1072
1073 int mailinfo(struct mailinfo *mi, const char *msg, const char *patch)
1074 {
1075         FILE *cmitmsg;
1076         int peek;
1077         struct strbuf line = STRBUF_INIT;
1078
1079         cmitmsg = fopen(msg, "w");
1080         if (!cmitmsg) {
1081                 perror(msg);
1082                 return -1;
1083         }
1084         mi->patchfile = fopen(patch, "w");
1085         if (!mi->patchfile) {
1086                 perror(patch);
1087                 fclose(cmitmsg);
1088                 return -1;
1089         }
1090
1091         mi->p_hdr_data = xcalloc(MAX_HDR_PARSED, sizeof(*(mi->p_hdr_data)));
1092         mi->s_hdr_data = xcalloc(MAX_HDR_PARSED, sizeof(*(mi->s_hdr_data)));
1093
1094         do {
1095                 peek = fgetc(mi->input);
1096         } while (isspace(peek));
1097         ungetc(peek, mi->input);
1098
1099         /* process the email header */
1100         while (read_one_header_line(&line, mi->input))
1101                 check_header(mi, &line, mi->p_hdr_data, 1);
1102
1103         handle_body(mi, &line);
1104         fwrite(mi->log_message.buf, 1, mi->log_message.len, cmitmsg);
1105         fclose(cmitmsg);
1106         fclose(mi->patchfile);
1107
1108         handle_info(mi);
1109         strbuf_release(&line);
1110         return mi->input_error;
1111 }
1112
1113 static int git_mailinfo_config(const char *var, const char *value, void *mi_)
1114 {
1115         struct mailinfo *mi = mi_;
1116
1117         if (!starts_with(var, "mailinfo."))
1118                 return git_default_config(var, value, NULL);
1119         if (!strcmp(var, "mailinfo.scissors")) {
1120                 mi->use_scissors = git_config_bool(var, value);
1121                 return 0;
1122         }
1123         /* perhaps others here */
1124         return 0;
1125 }
1126
1127 void setup_mailinfo(struct mailinfo *mi)
1128 {
1129         memset(mi, 0, sizeof(*mi));
1130         strbuf_init(&mi->name, 0);
1131         strbuf_init(&mi->email, 0);
1132         strbuf_init(&mi->charset, 0);
1133         strbuf_init(&mi->log_message, 0);
1134         strbuf_init(&mi->inbody_header_accum, 0);
1135         mi->header_stage = 1;
1136         mi->use_inbody_headers = 1;
1137         mi->content_top = mi->content;
1138         git_config(git_mailinfo_config, mi);
1139 }
1140
1141 void clear_mailinfo(struct mailinfo *mi)
1142 {
1143         int i;
1144
1145         strbuf_release(&mi->name);
1146         strbuf_release(&mi->email);
1147         strbuf_release(&mi->charset);
1148         strbuf_release(&mi->inbody_header_accum);
1149         free(mi->message_id);
1150
1151         for (i = 0; mi->p_hdr_data[i]; i++)
1152                 strbuf_release(mi->p_hdr_data[i]);
1153         free(mi->p_hdr_data);
1154         for (i = 0; mi->s_hdr_data[i]; i++)
1155                 strbuf_release(mi->s_hdr_data[i]);
1156         free(mi->s_hdr_data);
1157
1158         while (mi->content < mi->content_top) {
1159                 free(*(mi->content_top));
1160                 mi->content_top--;
1161         }
1162
1163         strbuf_release(&mi->log_message);
1164 }