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