git-am.txt: add an 'a', say what 'it' is, simplify a sentence
[git] / builtin-mailinfo.c
1 /*
2  * Another stupid program, this one parsing the headers of an
3  * email to figure out authorship and subject
4  */
5 #include "cache.h"
6 #include "builtin.h"
7 #include "utf8.h"
8 #include "strbuf.h"
9
10 static FILE *cmitmsg, *patchfile, *fin, *fout;
11
12 static int keep_subject;
13 static const char *metainfo_charset;
14 static struct strbuf line = STRBUF_INIT;
15 static struct strbuf name = STRBUF_INIT;
16 static struct strbuf email = STRBUF_INIT;
17
18 static enum  {
19         TE_DONTCARE, TE_QP, TE_BASE64,
20 } transfer_encoding;
21 static enum  {
22         TYPE_TEXT, TYPE_OTHER,
23 } message_type;
24
25 static struct strbuf charset = STRBUF_INIT;
26 static int patch_lines;
27 static struct strbuf **p_hdr_data, **s_hdr_data;
28
29 #define MAX_HDR_PARSED 10
30 #define MAX_BOUNDARIES 5
31
32 static void cleanup_space(struct strbuf *sb);
33
34
35 static void get_sane_name(struct strbuf *out, struct strbuf *name, struct strbuf *email)
36 {
37         struct strbuf *src = name;
38         if (name->len < 3 || 60 < name->len || strchr(name->buf, '@') ||
39                 strchr(name->buf, '<') || strchr(name->buf, '>'))
40                 src = email;
41         else if (name == out)
42                 return;
43         strbuf_reset(out);
44         strbuf_addbuf(out, src);
45 }
46
47 static void parse_bogus_from(const struct strbuf *line)
48 {
49         /* John Doe <johndoe> */
50
51         char *bra, *ket;
52         /* This is fallback, so do not bother if we already have an
53          * e-mail address.
54          */
55         if (email.len)
56                 return;
57
58         bra = strchr(line->buf, '<');
59         if (!bra)
60                 return;
61         ket = strchr(bra, '>');
62         if (!ket)
63                 return;
64
65         strbuf_reset(&email);
66         strbuf_add(&email, bra + 1, ket - bra - 1);
67
68         strbuf_reset(&name);
69         strbuf_add(&name, line->buf, bra - line->buf);
70         strbuf_trim(&name);
71         get_sane_name(&name, &name, &email);
72 }
73
74 static void handle_from(const struct strbuf *from)
75 {
76         char *at;
77         size_t el;
78         struct strbuf f;
79
80         strbuf_init(&f, from->len);
81         strbuf_addbuf(&f, from);
82
83         at = strchr(f.buf, '@');
84         if (!at) {
85                 parse_bogus_from(from);
86                 return;
87         }
88
89         /*
90          * If we already have one email, don't take any confusing lines
91          */
92         if (email.len && strchr(at + 1, '@')) {
93                 strbuf_release(&f);
94                 return;
95         }
96
97         /* Pick up the string around '@', possibly delimited with <>
98          * pair; that is the email part.
99          */
100         while (at > f.buf) {
101                 char c = at[-1];
102                 if (isspace(c))
103                         break;
104                 if (c == '<') {
105                         at[-1] = ' ';
106                         break;
107                 }
108                 at--;
109         }
110         el = strcspn(at, " \n\t\r\v\f>");
111         strbuf_reset(&email);
112         strbuf_add(&email, at, el);
113         strbuf_remove(&f, at - f.buf, el + (at[el] ? 1 : 0));
114
115         /* The remainder is name.  It could be
116          *
117          * - "John Doe <john.doe@xz>"                   (a), or
118          * - "john.doe@xz (John Doe)"                   (b), or
119          * - "John (zzz) Doe <john.doe@xz> (Comment)"   (c)
120          *
121          * but we have removed the email part, so
122          *
123          * - remove extra spaces which could stay after email (case 'c'), and
124          * - trim from both ends, possibly removing the () pair at the end
125          *   (cases 'a' and 'b').
126          */
127         cleanup_space(&f);
128         strbuf_trim(&f);
129         if (f.buf[0] == '(' && f.len && f.buf[f.len - 1] == ')') {
130                 strbuf_remove(&f, 0, 1);
131                 strbuf_setlen(&f, f.len - 1);
132         }
133
134         get_sane_name(&name, &f, &email);
135         strbuf_release(&f);
136 }
137
138 static void handle_header(struct strbuf **out, const struct strbuf *line)
139 {
140         if (!*out) {
141                 *out = xmalloc(sizeof(struct strbuf));
142                 strbuf_init(*out, line->len);
143         } else
144                 strbuf_reset(*out);
145
146         strbuf_addbuf(*out, line);
147 }
148
149 /* NOTE NOTE NOTE.  We do not claim we do full MIME.  We just attempt
150  * to have enough heuristics to grok MIME encoded patches often found
151  * on our mailing lists.  For example, we do not even treat header lines
152  * case insensitively.
153  */
154
155 static int slurp_attr(const char *line, const char *name, struct strbuf *attr)
156 {
157         const char *ends, *ap = strcasestr(line, name);
158         size_t sz;
159
160         if (!ap) {
161                 strbuf_setlen(attr, 0);
162                 return 0;
163         }
164         ap += strlen(name);
165         if (*ap == '"') {
166                 ap++;
167                 ends = "\"";
168         }
169         else
170                 ends = "; \t";
171         sz = strcspn(ap, ends);
172         strbuf_add(attr, ap, sz);
173         return 1;
174 }
175
176 static struct strbuf *content[MAX_BOUNDARIES];
177
178 static struct strbuf **content_top = content;
179
180 static void handle_content_type(struct strbuf *line)
181 {
182         struct strbuf *boundary = xmalloc(sizeof(struct strbuf));
183         strbuf_init(boundary, line->len);
184
185         if (!strcasestr(line->buf, "text/"))
186                  message_type = TYPE_OTHER;
187         if (slurp_attr(line->buf, "boundary=", boundary)) {
188                 strbuf_insert(boundary, 0, "--", 2);
189                 if (++content_top > &content[MAX_BOUNDARIES]) {
190                         fprintf(stderr, "Too many boundaries to handle\n");
191                         exit(1);
192                 }
193                 *content_top = boundary;
194                 boundary = NULL;
195         }
196         if (slurp_attr(line->buf, "charset=", &charset))
197                 strbuf_tolower(&charset);
198
199         if (boundary) {
200                 strbuf_release(boundary);
201                 free(boundary);
202         }
203 }
204
205 static void handle_content_transfer_encoding(const struct strbuf *line)
206 {
207         if (strcasestr(line->buf, "base64"))
208                 transfer_encoding = TE_BASE64;
209         else if (strcasestr(line->buf, "quoted-printable"))
210                 transfer_encoding = TE_QP;
211         else
212                 transfer_encoding = TE_DONTCARE;
213 }
214
215 static int is_multipart_boundary(const struct strbuf *line)
216 {
217         return (((*content_top)->len <= line->len) &&
218                 !memcmp(line->buf, (*content_top)->buf, (*content_top)->len));
219 }
220
221 static void cleanup_subject(struct strbuf *subject)
222 {
223         char *pos;
224         size_t remove;
225         while (subject->len) {
226                 switch (*subject->buf) {
227                 case 'r': case 'R':
228                         if (subject->len <= 3)
229                                 break;
230                         if (!memcmp(subject->buf + 1, "e:", 2)) {
231                                 strbuf_remove(subject, 0, 3);
232                                 continue;
233                         }
234                         break;
235                 case ' ': case '\t': case ':':
236                         strbuf_remove(subject, 0, 1);
237                         continue;
238                 case '[':
239                         if ((pos = strchr(subject->buf, ']'))) {
240                                 remove = pos - subject->buf;
241                                 if (remove <= (subject->len - remove) * 2) {
242                                         strbuf_remove(subject, 0, remove + 1);
243                                         continue;
244                                 }
245                         } else
246                                 strbuf_remove(subject, 0, 1);
247                         break;
248                 }
249                 strbuf_trim(subject);
250                 return;
251         }
252 }
253
254 static void cleanup_space(struct strbuf *sb)
255 {
256         size_t pos, cnt;
257         for (pos = 0; pos < sb->len; pos++) {
258                 if (isspace(sb->buf[pos])) {
259                         sb->buf[pos] = ' ';
260                         for (cnt = 0; isspace(sb->buf[pos + cnt + 1]); cnt++);
261                         strbuf_remove(sb, pos + 1, cnt);
262                 }
263         }
264 }
265
266 static void decode_header(struct strbuf *line);
267 static const char *header[MAX_HDR_PARSED] = {
268         "From","Subject","Date",
269 };
270
271 static inline int cmp_header(const struct strbuf *line, const char *hdr)
272 {
273         int len = strlen(hdr);
274         return !strncasecmp(line->buf, hdr, len) && line->len > len &&
275                         line->buf[len] == ':' && isspace(line->buf[len + 1]);
276 }
277
278 static int check_header(const struct strbuf *line,
279                                 struct strbuf *hdr_data[], int overwrite)
280 {
281         int i, ret = 0, len;
282         struct strbuf sb = STRBUF_INIT;
283         /* search for the interesting parts */
284         for (i = 0; header[i]; i++) {
285                 int len = strlen(header[i]);
286                 if ((!hdr_data[i] || overwrite) && cmp_header(line, header[i])) {
287                         /* Unwrap inline B and Q encoding, and optionally
288                          * normalize the meta information to utf8.
289                          */
290                         strbuf_add(&sb, line->buf + len + 2, line->len - len - 2);
291                         decode_header(&sb);
292                         handle_header(&hdr_data[i], &sb);
293                         ret = 1;
294                         goto check_header_out;
295                 }
296         }
297
298         /* Content stuff */
299         if (cmp_header(line, "Content-Type")) {
300                 len = strlen("Content-Type: ");
301                 strbuf_add(&sb, line->buf + len, line->len - len);
302                 decode_header(&sb);
303                 strbuf_insert(&sb, 0, "Content-Type: ", len);
304                 handle_content_type(&sb);
305                 ret = 1;
306                 goto check_header_out;
307         }
308         if (cmp_header(line, "Content-Transfer-Encoding")) {
309                 len = strlen("Content-Transfer-Encoding: ");
310                 strbuf_add(&sb, line->buf + len, line->len - len);
311                 decode_header(&sb);
312                 handle_content_transfer_encoding(&sb);
313                 ret = 1;
314                 goto check_header_out;
315         }
316
317         /* for inbody stuff */
318         if (!prefixcmp(line->buf, ">From") && isspace(line->buf[5])) {
319                 ret = 1; /* Should this return 0? */
320                 goto check_header_out;
321         }
322         if (!prefixcmp(line->buf, "[PATCH]") && isspace(line->buf[7])) {
323                 for (i = 0; header[i]; i++) {
324                         if (!memcmp("Subject", header[i], 7)) {
325                                 handle_header(&hdr_data[i], line);
326                                 ret = 1;
327                                 goto check_header_out;
328                         }
329                 }
330         }
331
332 check_header_out:
333         strbuf_release(&sb);
334         return ret;
335 }
336
337 static int is_rfc2822_header(const struct strbuf *line)
338 {
339         /*
340          * The section that defines the loosest possible
341          * field name is "3.6.8 Optional fields".
342          *
343          * optional-field = field-name ":" unstructured CRLF
344          * field-name = 1*ftext
345          * ftext = %d33-57 / %59-126
346          */
347         int ch;
348         char *cp = line->buf;
349
350         /* Count mbox From headers as headers */
351         if (!prefixcmp(cp, "From ") || !prefixcmp(cp, ">From "))
352                 return 1;
353
354         while ((ch = *cp++)) {
355                 if (ch == ':')
356                         return 1;
357                 if ((33 <= ch && ch <= 57) ||
358                     (59 <= ch && ch <= 126))
359                         continue;
360                 break;
361         }
362         return 0;
363 }
364
365 static int read_one_header_line(struct strbuf *line, FILE *in)
366 {
367         /* Get the first part of the line. */
368         if (strbuf_getline(line, in, '\n'))
369                 return 0;
370
371         /*
372          * Is it an empty line or not a valid rfc2822 header?
373          * If so, stop here, and return false ("not a header")
374          */
375         strbuf_rtrim(line);
376         if (!line->len || !is_rfc2822_header(line)) {
377                 /* Re-add the newline */
378                 strbuf_addch(line, '\n');
379                 return 0;
380         }
381
382         /*
383          * Now we need to eat all the continuation lines..
384          * Yuck, 2822 header "folding"
385          */
386         for (;;) {
387                 int peek;
388                 struct strbuf continuation = STRBUF_INIT;
389
390                 peek = fgetc(in); ungetc(peek, in);
391                 if (peek != ' ' && peek != '\t')
392                         break;
393                 if (strbuf_getline(&continuation, in, '\n'))
394                         break;
395                 continuation.buf[0] = '\n';
396                 strbuf_rtrim(&continuation);
397                 strbuf_addbuf(line, &continuation);
398         }
399
400         return 1;
401 }
402
403 static struct strbuf *decode_q_segment(const struct strbuf *q_seg, int rfc2047)
404 {
405         const char *in = q_seg->buf;
406         int c;
407         struct strbuf *out = xmalloc(sizeof(struct strbuf));
408         strbuf_init(out, q_seg->len);
409
410         while ((c = *in++) != 0) {
411                 if (c == '=') {
412                         int d = *in++;
413                         if (d == '\n' || !d)
414                                 break; /* drop trailing newline */
415                         strbuf_addch(out, (hexval(d) << 4) | hexval(*in++));
416                         continue;
417                 }
418                 if (rfc2047 && c == '_') /* rfc2047 4.2 (2) */
419                         c = 0x20;
420                 strbuf_addch(out, c);
421         }
422         return out;
423 }
424
425 static struct strbuf *decode_b_segment(const struct strbuf *b_seg)
426 {
427         /* Decode in..ep, possibly in-place to ot */
428         int c, pos = 0, acc = 0;
429         const char *in = b_seg->buf;
430         struct strbuf *out = xmalloc(sizeof(struct strbuf));
431         strbuf_init(out, b_seg->len);
432
433         while ((c = *in++) != 0) {
434                 if (c == '+')
435                         c = 62;
436                 else if (c == '/')
437                         c = 63;
438                 else if ('A' <= c && c <= 'Z')
439                         c -= 'A';
440                 else if ('a' <= c && c <= 'z')
441                         c -= 'a' - 26;
442                 else if ('0' <= c && c <= '9')
443                         c -= '0' - 52;
444                 else
445                         continue; /* garbage */
446                 switch (pos++) {
447                 case 0:
448                         acc = (c << 2);
449                         break;
450                 case 1:
451                         strbuf_addch(out, (acc | (c >> 4)));
452                         acc = (c & 15) << 4;
453                         break;
454                 case 2:
455                         strbuf_addch(out, (acc | (c >> 2)));
456                         acc = (c & 3) << 6;
457                         break;
458                 case 3:
459                         strbuf_addch(out, (acc | c));
460                         acc = pos = 0;
461                         break;
462                 }
463         }
464         return out;
465 }
466
467 /*
468  * When there is no known charset, guess.
469  *
470  * Right now we assume that if the target is UTF-8 (the default),
471  * and it already looks like UTF-8 (which includes US-ASCII as its
472  * subset, of course) then that is what it is and there is nothing
473  * to do.
474  *
475  * Otherwise, we default to assuming it is Latin1 for historical
476  * reasons.
477  */
478 static const char *guess_charset(const struct strbuf *line, const char *target_charset)
479 {
480         if (is_encoding_utf8(target_charset)) {
481                 if (is_utf8(line->buf))
482                         return NULL;
483         }
484         return "latin1";
485 }
486
487 static void convert_to_utf8(struct strbuf *line, const char *charset)
488 {
489         char *out;
490
491         if (!charset || !*charset) {
492                 charset = guess_charset(line, metainfo_charset);
493                 if (!charset)
494                         return;
495         }
496
497         if (!strcmp(metainfo_charset, charset))
498                 return;
499         out = reencode_string(line->buf, metainfo_charset, charset);
500         if (!out)
501                 die("cannot convert from %s to %s",
502                     charset, metainfo_charset);
503         strbuf_attach(line, out, strlen(out), strlen(out));
504 }
505
506 static int decode_header_bq(struct strbuf *it)
507 {
508         char *in, *ep, *cp;
509         struct strbuf outbuf = STRBUF_INIT, *dec;
510         struct strbuf charset_q = STRBUF_INIT, piecebuf = STRBUF_INIT;
511         int rfc2047 = 0;
512
513         in = it->buf;
514         while (in - it->buf <= it->len && (ep = strstr(in, "=?")) != NULL) {
515                 int encoding;
516                 strbuf_reset(&charset_q);
517                 strbuf_reset(&piecebuf);
518                 rfc2047 = 1;
519
520                 if (in != ep) {
521                         /*
522                          * We are about to process an encoded-word
523                          * that begins at ep, but there is something
524                          * before the encoded word.
525                          */
526                         char *scan;
527                         for (scan = in; scan < ep; scan++)
528                                 if (!isspace(*scan))
529                                         break;
530
531                         if (scan != ep || in == it->buf) {
532                                 /*
533                                  * We should not lose that "something",
534                                  * unless we have just processed an
535                                  * encoded-word, and there is only LWS
536                                  * before the one we are about to process.
537                                  */
538                                 strbuf_add(&outbuf, in, ep - in);
539                         }
540                         in = ep;
541                 }
542                 /* E.g.
543                  * ep : "=?iso-2022-jp?B?GyR...?= foo"
544                  * ep : "=?ISO-8859-1?Q?Foo=FCbar?= baz"
545                  */
546                 ep += 2;
547
548                 if (ep - it->buf >= it->len || !(cp = strchr(ep, '?')))
549                         goto decode_header_bq_out;
550
551                 if (cp + 3 - it->buf > it->len)
552                         goto decode_header_bq_out;
553                 strbuf_add(&charset_q, ep, cp - ep);
554                 strbuf_tolower(&charset_q);
555
556                 encoding = cp[1];
557                 if (!encoding || cp[2] != '?')
558                         goto decode_header_bq_out;
559                 ep = strstr(cp + 3, "?=");
560                 if (!ep)
561                         goto decode_header_bq_out;
562                 strbuf_add(&piecebuf, cp + 3, ep - cp - 3);
563                 switch (tolower(encoding)) {
564                 default:
565                         goto decode_header_bq_out;
566                 case 'b':
567                         dec = decode_b_segment(&piecebuf);
568                         break;
569                 case 'q':
570                         dec = decode_q_segment(&piecebuf, 1);
571                         break;
572                 }
573                 if (metainfo_charset)
574                         convert_to_utf8(dec, charset_q.buf);
575
576                 strbuf_addbuf(&outbuf, dec);
577                 strbuf_release(dec);
578                 free(dec);
579                 in = ep + 2;
580         }
581         strbuf_addstr(&outbuf, in);
582         strbuf_reset(it);
583         strbuf_addbuf(it, &outbuf);
584 decode_header_bq_out:
585         strbuf_release(&outbuf);
586         strbuf_release(&charset_q);
587         strbuf_release(&piecebuf);
588         return rfc2047;
589 }
590
591 static void decode_header(struct strbuf *it)
592 {
593         if (decode_header_bq(it))
594                 return;
595         /* otherwise "it" is a straight copy of the input.
596          * This can be binary guck but there is no charset specified.
597          */
598         if (metainfo_charset)
599                 convert_to_utf8(it, "");
600 }
601
602 static void decode_transfer_encoding(struct strbuf *line)
603 {
604         struct strbuf *ret;
605
606         switch (transfer_encoding) {
607         case TE_QP:
608                 ret = decode_q_segment(line, 0);
609                 break;
610         case TE_BASE64:
611                 ret = decode_b_segment(line);
612                 break;
613         case TE_DONTCARE:
614         default:
615                 return;
616         }
617         strbuf_reset(line);
618         strbuf_addbuf(line, ret);
619         strbuf_release(ret);
620         free(ret);
621 }
622
623 static void handle_filter(struct strbuf *line);
624
625 static int find_boundary(void)
626 {
627         while (!strbuf_getline(&line, fin, '\n')) {
628                 if (*content_top && is_multipart_boundary(&line))
629                         return 1;
630         }
631         return 0;
632 }
633
634 static int handle_boundary(void)
635 {
636         struct strbuf newline = STRBUF_INIT;
637
638         strbuf_addch(&newline, '\n');
639 again:
640         if (line.len >= (*content_top)->len + 2 &&
641             !memcmp(line.buf + (*content_top)->len, "--", 2)) {
642                 /* we hit an end boundary */
643                 /* pop the current boundary off the stack */
644                 strbuf_release(*content_top);
645                 free(*content_top);
646                 *content_top = NULL;
647
648                 /* technically won't happen as is_multipart_boundary()
649                    will fail first.  But just in case..
650                  */
651                 if (--content_top < content) {
652                         fprintf(stderr, "Detected mismatched boundaries, "
653                                         "can't recover\n");
654                         exit(1);
655                 }
656                 handle_filter(&newline);
657                 strbuf_release(&newline);
658
659                 /* skip to the next boundary */
660                 if (!find_boundary())
661                         return 0;
662                 goto again;
663         }
664
665         /* set some defaults */
666         transfer_encoding = TE_DONTCARE;
667         strbuf_reset(&charset);
668         message_type = TYPE_TEXT;
669
670         /* slurp in this section's info */
671         while (read_one_header_line(&line, fin))
672                 check_header(&line, p_hdr_data, 0);
673
674         strbuf_release(&newline);
675         /* replenish line */
676         if (strbuf_getline(&line, fin, '\n'))
677                 return 0;
678         strbuf_addch(&line, '\n');
679         return 1;
680 }
681
682 static inline int patchbreak(const struct strbuf *line)
683 {
684         size_t i;
685
686         /* Beginning of a "diff -" header? */
687         if (!prefixcmp(line->buf, "diff -"))
688                 return 1;
689
690         /* CVS "Index: " line? */
691         if (!prefixcmp(line->buf, "Index: "))
692                 return 1;
693
694         /*
695          * "--- <filename>" starts patches without headers
696          * "---<sp>*" is a manual separator
697          */
698         if (line->len < 4)
699                 return 0;
700
701         if (!prefixcmp(line->buf, "---")) {
702                 /* space followed by a filename? */
703                 if (line->buf[3] == ' ' && !isspace(line->buf[4]))
704                         return 1;
705                 /* Just whitespace? */
706                 for (i = 3; i < line->len; i++) {
707                         unsigned char c = line->buf[i];
708                         if (c == '\n')
709                                 return 1;
710                         if (!isspace(c))
711                                 break;
712                 }
713                 return 0;
714         }
715         return 0;
716 }
717
718 static int handle_commit_msg(struct strbuf *line)
719 {
720         static int still_looking = 1;
721
722         if (!cmitmsg)
723                 return 0;
724
725         if (still_looking) {
726                 strbuf_ltrim(line);
727                 if (!line->len)
728                         return 0;
729                 if ((still_looking = check_header(line, s_hdr_data, 0)) != 0)
730                         return 0;
731         }
732
733         /* normalize the log message to UTF-8. */
734         if (metainfo_charset)
735                 convert_to_utf8(line, charset.buf);
736
737         if (patchbreak(line)) {
738                 fclose(cmitmsg);
739                 cmitmsg = NULL;
740                 return 1;
741         }
742
743         fputs(line->buf, cmitmsg);
744         return 0;
745 }
746
747 static void handle_patch(const struct strbuf *line)
748 {
749         fwrite(line->buf, 1, line->len, patchfile);
750         patch_lines++;
751 }
752
753 static void handle_filter(struct strbuf *line)
754 {
755         static int filter = 0;
756
757         /* filter tells us which part we left off on */
758         switch (filter) {
759         case 0:
760                 if (!handle_commit_msg(line))
761                         break;
762                 filter++;
763         case 1:
764                 handle_patch(line);
765                 break;
766         }
767 }
768
769 static void handle_body(void)
770 {
771         int len = 0;
772         struct strbuf prev = STRBUF_INIT;
773
774         /* Skip up to the first boundary */
775         if (*content_top) {
776                 if (!find_boundary())
777                         goto handle_body_out;
778         }
779
780         do {
781                 strbuf_setlen(&line, line.len + len);
782
783                 /* process any boundary lines */
784                 if (*content_top && is_multipart_boundary(&line)) {
785                         /* flush any leftover */
786                         if (prev.len) {
787                                 handle_filter(&prev);
788                                 strbuf_reset(&prev);
789                         }
790                         if (!handle_boundary())
791                                 goto handle_body_out;
792                 }
793
794                 /* Unwrap transfer encoding */
795                 decode_transfer_encoding(&line);
796
797                 switch (transfer_encoding) {
798                 case TE_BASE64:
799                 case TE_QP:
800                 {
801                         struct strbuf **lines, **it, *sb;
802
803                         /* Prepend any previous partial lines */
804                         strbuf_insert(&line, 0, prev.buf, prev.len);
805                         strbuf_reset(&prev);
806
807                         /* binary data most likely doesn't have newlines */
808                         if (message_type != TYPE_TEXT) {
809                                 handle_filter(&line);
810                                 break;
811                         }
812                         /*
813                          * This is a decoded line that may contain
814                          * multiple new lines.  Pass only one chunk
815                          * at a time to handle_filter()
816                          */
817                         lines = strbuf_split(&line, '\n');
818                         for (it = lines; (sb = *it); it++) {
819                                 if (*(it + 1) == NULL) /* The last line */
820                                         if (sb->buf[sb->len - 1] != '\n') {
821                                                 /* Partial line, save it for later. */
822                                                 strbuf_addbuf(&prev, sb);
823                                                 break;
824                                         }
825                                 handle_filter(sb);
826                         }
827                         /*
828                          * The partial chunk is saved in "prev" and will be
829                          * appended by the next iteration of read_line_with_nul().
830                          */
831                         strbuf_list_free(lines);
832                         break;
833                 }
834                 default:
835                         handle_filter(&line);
836                 }
837
838                 strbuf_reset(&line);
839                 if (strbuf_avail(&line) < 100)
840                         strbuf_grow(&line, 100);
841         } while ((len = read_line_with_nul(line.buf, strbuf_avail(&line), fin)));
842
843 handle_body_out:
844         strbuf_release(&prev);
845 }
846
847 static void output_header_lines(FILE *fout, const char *hdr, const struct strbuf *data)
848 {
849         const char *sp = data->buf;
850         while (1) {
851                 char *ep = strchr(sp, '\n');
852                 int len;
853                 if (!ep)
854                         len = strlen(sp);
855                 else
856                         len = ep - sp;
857                 fprintf(fout, "%s: %.*s\n", hdr, len, sp);
858                 if (!ep)
859                         break;
860                 sp = ep + 1;
861         }
862 }
863
864 static void handle_info(void)
865 {
866         struct strbuf *hdr;
867         int i;
868
869         for (i = 0; header[i]; i++) {
870                 /* only print inbody headers if we output a patch file */
871                 if (patch_lines && s_hdr_data[i])
872                         hdr = s_hdr_data[i];
873                 else if (p_hdr_data[i])
874                         hdr = p_hdr_data[i];
875                 else
876                         continue;
877
878                 if (!memcmp(header[i], "Subject", 7)) {
879                         if (!keep_subject) {
880                                 cleanup_subject(hdr);
881                                 cleanup_space(hdr);
882                         }
883                         output_header_lines(fout, "Subject", hdr);
884                 } else if (!memcmp(header[i], "From", 4)) {
885                         cleanup_space(hdr);
886                         handle_from(hdr);
887                         fprintf(fout, "Author: %s\n", name.buf);
888                         fprintf(fout, "Email: %s\n", email.buf);
889                 } else {
890                         cleanup_space(hdr);
891                         fprintf(fout, "%s: %s\n", header[i], hdr->buf);
892                 }
893         }
894         fprintf(fout, "\n");
895 }
896
897 static int mailinfo(FILE *in, FILE *out, int ks, const char *encoding,
898                     const char *msg, const char *patch)
899 {
900         int peek;
901         keep_subject = ks;
902         metainfo_charset = encoding;
903         fin = in;
904         fout = out;
905
906         cmitmsg = fopen(msg, "w");
907         if (!cmitmsg) {
908                 perror(msg);
909                 return -1;
910         }
911         patchfile = fopen(patch, "w");
912         if (!patchfile) {
913                 perror(patch);
914                 fclose(cmitmsg);
915                 return -1;
916         }
917
918         p_hdr_data = xcalloc(MAX_HDR_PARSED, sizeof(*p_hdr_data));
919         s_hdr_data = xcalloc(MAX_HDR_PARSED, sizeof(*s_hdr_data));
920
921         do {
922                 peek = fgetc(in);
923         } while (isspace(peek));
924         ungetc(peek, in);
925
926         /* process the email header */
927         while (read_one_header_line(&line, fin))
928                 check_header(&line, p_hdr_data, 1);
929
930         handle_body();
931         handle_info();
932
933         return 0;
934 }
935
936 static const char mailinfo_usage[] =
937         "git mailinfo [-k] [-u | --encoding=<encoding> | -n] msg patch <mail >info";
938
939 int cmd_mailinfo(int argc, const char **argv, const char *prefix)
940 {
941         const char *def_charset;
942
943         /* NEEDSWORK: might want to do the optional .git/ directory
944          * discovery
945          */
946         git_config(git_default_config, NULL);
947
948         def_charset = (git_commit_encoding ? git_commit_encoding : "utf-8");
949         metainfo_charset = def_charset;
950
951         while (1 < argc && argv[1][0] == '-') {
952                 if (!strcmp(argv[1], "-k"))
953                         keep_subject = 1;
954                 else if (!strcmp(argv[1], "-u"))
955                         metainfo_charset = def_charset;
956                 else if (!strcmp(argv[1], "-n"))
957                         metainfo_charset = NULL;
958                 else if (!prefixcmp(argv[1], "--encoding="))
959                         metainfo_charset = argv[1] + 11;
960                 else
961                         usage(mailinfo_usage);
962                 argc--; argv++;
963         }
964
965         if (argc != 3)
966                 usage(mailinfo_usage);
967
968         return !!mailinfo(stdin, stdout, keep_subject, metainfo_charset, argv[1], argv[2]);
969 }