Merge branch 'lt/deepen-builtin-source'

* lt/deepen-builtin-source:
  Move 'builtin-*' into a 'builtin/' subdirectory

Conflicts:
	Makefile

1 files changed, 1063 insertions, 0 deletions

diff --git a/builtin/mailinfo.c b/builtin/mailinfo.c
new file mode 100644
index 0000000000..ce2ef6bede
--- /dev/null
+++ b/builtin/mailinfo.c
@@ -0,0 +1,1063 @@
+/*
+ * Another stupid program, this one parsing the headers of an
+ * email to figure out authorship and subject
+ */
+#include "cache.h"
+#include "builtin.h"
+#include "utf8.h"
+#include "strbuf.h"
+
+static FILE *cmitmsg, *patchfile, *fin, *fout;
+
+static int keep_subject;
+static int keep_non_patch_brackets_in_subject;
+static const char *metainfo_charset;
+static struct strbuf line = STRBUF_INIT;
+static struct strbuf name = STRBUF_INIT;
+static struct strbuf email = STRBUF_INIT;
+
+static enum  {
+	TE_DONTCARE, TE_QP, TE_BASE64,
+} transfer_encoding;
+static enum  {
+	TYPE_TEXT, TYPE_OTHER,
+} message_type;
+
+static struct strbuf charset = STRBUF_INIT;
+static int patch_lines;
+static struct strbuf **p_hdr_data, **s_hdr_data;
+static int use_scissors;
+static int use_inbody_headers = 1;
+
+#define MAX_HDR_PARSED 10
+#define MAX_BOUNDARIES 5
+
+static void cleanup_space(struct strbuf *sb);
+
+
+static void get_sane_name(struct strbuf *out, struct strbuf *name, struct strbuf *email)
+{
+	struct strbuf *src = name;
+	if (name->len < 3 || 60 < name->len || strchr(name->buf, '@') ||
+		strchr(name->buf, '<') || strchr(name->buf, '>'))
+		src = email;
+	else if (name == out)
+		return;
+	strbuf_reset(out);
+	strbuf_addbuf(out, src);
+}
+
+static void parse_bogus_from(const struct strbuf *line)
+{
+	/* John Doe <johndoe> */
+
+	char *bra, *ket;
+	/* This is fallback, so do not bother if we already have an
+	 * e-mail address.
+	 */
+	if (email.len)
+		return;
+
+	bra = strchr(line->buf, '<');
+	if (!bra)
+		return;
+	ket = strchr(bra, '>');
+	if (!ket)
+		return;
+
+	strbuf_reset(&email);
+	strbuf_add(&email, bra + 1, ket - bra - 1);
+
+	strbuf_reset(&name);
+	strbuf_add(&name, line->buf, bra - line->buf);
+	strbuf_trim(&name);
+	get_sane_name(&name, &name, &email);
+}
+
+static void handle_from(const struct strbuf *from)
+{
+	char *at;
+	size_t el;
+	struct strbuf f;
+
+	strbuf_init(&f, from->len);
+	strbuf_addbuf(&f, from);
+
+	at = strchr(f.buf, '@');
+	if (!at) {
+		parse_bogus_from(from);
+		return;
+	}
+
+	/*
+	 * If we already have one email, don't take any confusing lines
+	 */
+	if (email.len && strchr(at + 1, '@')) {
+		strbuf_release(&f);
+		return;
+	}
+
+	/* Pick up the string around '@', possibly delimited with <>
+	 * pair; that is the email part.
+	 */
+	while (at > f.buf) {
+		char c = at[-1];
+		if (isspace(c))
+			break;
+		if (c == '<') {
+			at[-1] = ' ';
+			break;
+		}
+		at--;
+	}
+	el = strcspn(at, " \n\t\r\v\f>");
+	strbuf_reset(&email);
+	strbuf_add(&email, at, el);
+	strbuf_remove(&f, at - f.buf, el + (at[el] ? 1 : 0));
+
+	/* The remainder is name.  It could be
+	 *
+	 * - "John Doe <john.doe@xz>"			(a), or
+	 * - "john.doe@xz (John Doe)"			(b), or
+	 * - "John (zzz) Doe <john.doe@xz> (Comment)"	(c)
+	 *
+	 * but we have removed the email part, so
+	 *
+	 * - remove extra spaces which could stay after email (case 'c'), and
+	 * - trim from both ends, possibly removing the () pair at the end
+	 *   (cases 'a' and 'b').
+	 */
+	cleanup_space(&f);
+	strbuf_trim(&f);
+	if (f.buf[0] == '(' && f.len && f.buf[f.len - 1] == ')') {
+		strbuf_remove(&f, 0, 1);
+		strbuf_setlen(&f, f.len - 1);
+	}
+
+	get_sane_name(&name, &f, &email);
+	strbuf_release(&f);
+}
+
+static void handle_header(struct strbuf **out, const struct strbuf *line)
+{
+	if (!*out) {
+		*out = xmalloc(sizeof(struct strbuf));
+		strbuf_init(*out, line->len);
+	} else
+		strbuf_reset(*out);
+
+	strbuf_addbuf(*out, line);
+}
+
+/* NOTE NOTE NOTE.  We do not claim we do full MIME.  We just attempt
+ * to have enough heuristics to grok MIME encoded patches often found
+ * on our mailing lists.  For example, we do not even treat header lines
+ * case insensitively.
+ */
+
+static int slurp_attr(const char *line, const char *name, struct strbuf *attr)
+{
+	const char *ends, *ap = strcasestr(line, name);
+	size_t sz;
+
+	if (!ap) {
+		strbuf_setlen(attr, 0);
+		return 0;
+	}
+	ap += strlen(name);
+	if (*ap == '"') {
+		ap++;
+		ends = "\"";
+	}
+	else
+		ends = "; \t";
+	sz = strcspn(ap, ends);
+	strbuf_add(attr, ap, sz);
+	return 1;
+}
+
+static struct strbuf *content[MAX_BOUNDARIES];
+
+static struct strbuf **content_top = content;
+
+static void handle_content_type(struct strbuf *line)
+{
+	struct strbuf *boundary = xmalloc(sizeof(struct strbuf));
+	strbuf_init(boundary, line->len);
+
+	if (!strcasestr(line->buf, "text/"))
+		 message_type = TYPE_OTHER;
+	if (slurp_attr(line->buf, "boundary=", boundary)) {
+		strbuf_insert(boundary, 0, "--", 2);
+		if (++content_top > &content[MAX_BOUNDARIES]) {
+			fprintf(stderr, "Too many boundaries to handle\n");
+			exit(1);
+		}
+		*content_top = boundary;
+		boundary = NULL;
+	}
+	slurp_attr(line->buf, "charset=", &charset);
+
+	if (boundary) {
+		strbuf_release(boundary);
+		free(boundary);
+	}
+}
+
+static void handle_content_transfer_encoding(const struct strbuf *line)
+{
+	if (strcasestr(line->buf, "base64"))
+		transfer_encoding = TE_BASE64;
+	else if (strcasestr(line->buf, "quoted-printable"))
+		transfer_encoding = TE_QP;
+	else
+		transfer_encoding = TE_DONTCARE;
+}
+
+static int is_multipart_boundary(const struct strbuf *line)
+{
+	return (((*content_top)->len <= line->len) &&
+		!memcmp(line->buf, (*content_top)->buf, (*content_top)->len));
+}
+
+static void cleanup_subject(struct strbuf *subject)
+{
+	size_t at = 0;
+
+	while (at < subject->len) {
+		char *pos;
+		size_t remove;
+
+		switch (subject->buf[at]) {
+		case 'r': case 'R':
+			if (subject->len <= at + 3)
+				break;
+			if (!memcmp(subject->buf + at + 1, "e:", 2)) {
+				strbuf_remove(subject, at, 3);
+				continue;
+			}
+			at++;
+			break;
+		case ' ': case '\t': case ':':
+			strbuf_remove(subject, at, 1);
+			continue;
+		case '[':
+			pos = strchr(subject->buf + at, ']');
+			if (!pos)
+				break;
+			remove = pos - subject->buf + at + 1;
+			if (!keep_non_patch_brackets_in_subject ||
+			    (7 <= remove &&
+			     memmem(subject->buf + at, remove, "PATCH", 5)))
+				strbuf_remove(subject, at, remove);
+			else
+				at += remove;
+			continue;
+		}
+		break;
+	}
+	strbuf_trim(subject);
+}
+
+static void cleanup_space(struct strbuf *sb)
+{
+	size_t pos, cnt;
+	for (pos = 0; pos < sb->len; pos++) {
+		if (isspace(sb->buf[pos])) {
+			sb->buf[pos] = ' ';
+			for (cnt = 0; isspace(sb->buf[pos + cnt + 1]); cnt++);
+			strbuf_remove(sb, pos + 1, cnt);
+		}
+	}
+}
+
+static void decode_header(struct strbuf *line);
+static const char *header[MAX_HDR_PARSED] = {
+	"From","Subject","Date",
+};
+
+static inline int cmp_header(const struct strbuf *line, const char *hdr)
+{
+	int len = strlen(hdr);
+	return !strncasecmp(line->buf, hdr, len) && line->len > len &&
+			line->buf[len] == ':' && isspace(line->buf[len + 1]);
+}
+
+static int check_header(const struct strbuf *line,
+				struct strbuf *hdr_data[], int overwrite)
+{
+	int i, ret = 0, len;
+	struct strbuf sb = STRBUF_INIT;
+	/* search for the interesting parts */
+	for (i = 0; header[i]; i++) {
+		int len = strlen(header[i]);
+		if ((!hdr_data[i] || overwrite) && cmp_header(line, header[i])) {
+			/* Unwrap inline B and Q encoding, and optionally
+			 * normalize the meta information to utf8.
+			 */
+			strbuf_add(&sb, line->buf + len + 2, line->len - len - 2);
+			decode_header(&sb);
+			handle_header(&hdr_data[i], &sb);
+			ret = 1;
+			goto check_header_out;
+		}
+	}
+
+	/* Content stuff */
+	if (cmp_header(line, "Content-Type")) {
+		len = strlen("Content-Type: ");
+		strbuf_add(&sb, line->buf + len, line->len - len);
+		decode_header(&sb);
+		strbuf_insert(&sb, 0, "Content-Type: ", len);
+		handle_content_type(&sb);
+		ret = 1;
+		goto check_header_out;
+	}
+	if (cmp_header(line, "Content-Transfer-Encoding")) {
+		len = strlen("Content-Transfer-Encoding: ");
+		strbuf_add(&sb, line->buf + len, line->len - len);
+		decode_header(&sb);
+		handle_content_transfer_encoding(&sb);
+		ret = 1;
+		goto check_header_out;
+	}
+
+	/* for inbody stuff */
+	if (!prefixcmp(line->buf, ">From") && isspace(line->buf[5])) {
+		ret = 1; /* Should this return 0? */
+		goto check_header_out;
+	}
+	if (!prefixcmp(line->buf, "[PATCH]") && isspace(line->buf[7])) {
+		for (i = 0; header[i]; i++) {
+			if (!memcmp("Subject", header[i], 7)) {
+				handle_header(&hdr_data[i], line);
+				ret = 1;
+				goto check_header_out;
+			}
+		}
+	}
+
+check_header_out:
+	strbuf_release(&sb);
+	return ret;
+}
+
+static int is_rfc2822_header(const struct strbuf *line)
+{
+	/*
+	 * The section that defines the loosest possible
+	 * field name is "3.6.8 Optional fields".
+	 *
+	 * optional-field = field-name ":" unstructured CRLF
+	 * field-name = 1*ftext
+	 * ftext = %d33-57 / %59-126
+	 */
+	int ch;
+	char *cp = line->buf;
+
+	/* Count mbox From headers as headers */
+	if (!prefixcmp(cp, "From ") || !prefixcmp(cp, ">From "))
+		return 1;
+
+	while ((ch = *cp++)) {
+		if (ch == ':')
+			return 1;
+		if ((33 <= ch && ch <= 57) ||
+		    (59 <= ch && ch <= 126))
+			continue;
+		break;
+	}
+	return 0;
+}
+
+static int read_one_header_line(struct strbuf *line, FILE *in)
+{
+	/* Get the first part of the line. */
+	if (strbuf_getline(line, in, '\n'))
+		return 0;
+
+	/*
+	 * Is it an empty line or not a valid rfc2822 header?
+	 * If so, stop here, and return false ("not a header")
+	 */
+	strbuf_rtrim(line);
+	if (!line->len || !is_rfc2822_header(line)) {
+		/* Re-add the newline */
+		strbuf_addch(line, '\n');
+		return 0;
+	}
+
+	/*
+	 * Now we need to eat all the continuation lines..
+	 * Yuck, 2822 header "folding"
+	 */
+	for (;;) {
+		int peek;
+		struct strbuf continuation = STRBUF_INIT;
+
+		peek = fgetc(in); ungetc(peek, in);
+		if (peek != ' ' && peek != '\t')
+			break;
+		if (strbuf_getline(&continuation, in, '\n'))
+			break;
+		continuation.buf[0] = '\n';
+		strbuf_rtrim(&continuation);
+		strbuf_addbuf(line, &continuation);
+	}
+
+	return 1;
+}
+
+static struct strbuf *decode_q_segment(const struct strbuf *q_seg, int rfc2047)
+{
+	const char *in = q_seg->buf;
+	int c;
+	struct strbuf *out = xmalloc(sizeof(struct strbuf));
+	strbuf_init(out, q_seg->len);
+
+	while ((c = *in++) != 0) {
+		if (c == '=') {
+			int d = *in++;
+			if (d == '\n' || !d)
+				break; /* drop trailing newline */
+			strbuf_addch(out, (hexval(d) << 4) | hexval(*in++));
+			continue;
+		}
+		if (rfc2047 && c == '_') /* rfc2047 4.2 (2) */
+			c = 0x20;
+		strbuf_addch(out, c);
+	}
+	return out;
+}
+
+static struct strbuf *decode_b_segment(const struct strbuf *b_seg)
+{
+	/* Decode in..ep, possibly in-place to ot */
+	int c, pos = 0, acc = 0;
+	const char *in = b_seg->buf;
+	struct strbuf *out = xmalloc(sizeof(struct strbuf));
+	strbuf_init(out, b_seg->len);
+
+	while ((c = *in++) != 0) {
+		if (c == '+')
+			c = 62;
+		else if (c == '/')
+			c = 63;
+		else if ('A' <= c && c <= 'Z')
+			c -= 'A';
+		else if ('a' <= c && c <= 'z')
+			c -= 'a' - 26;
+		else if ('0' <= c && c <= '9')
+			c -= '0' - 52;
+		else
+			continue; /* garbage */
+		switch (pos++) {
+		case 0:
+			acc = (c << 2);
+			break;
+		case 1:
+			strbuf_addch(out, (acc | (c >> 4)));
+			acc = (c & 15) << 4;
+			break;
+		case 2:
+			strbuf_addch(out, (acc | (c >> 2)));
+			acc = (c & 3) << 6;
+			break;
+		case 3:
+			strbuf_addch(out, (acc | c));
+			acc = pos = 0;
+			break;
+		}
+	}
+	return out;
+}
+
+/*
+ * When there is no known charset, guess.
+ *
+ * Right now we assume that if the target is UTF-8 (the default),
+ * and it already looks like UTF-8 (which includes US-ASCII as its
+ * subset, of course) then that is what it is and there is nothing
+ * to do.
+ *
+ * Otherwise, we default to assuming it is Latin1 for historical
+ * reasons.
+ */
+static const char *guess_charset(const struct strbuf *line, const char *target_charset)
+{
+	if (is_encoding_utf8(target_charset)) {
+		if (is_utf8(line->buf))
+			return NULL;
+	}
+	return "ISO8859-1";
+}
+
+static void convert_to_utf8(struct strbuf *line, const char *charset)
+{
+	char *out;
+
+	if (!charset || !*charset) {
+		charset = guess_charset(line, metainfo_charset);
+		if (!charset)
+			return;
+	}
+
+	if (!strcasecmp(metainfo_charset, charset))
+		return;
+	out = reencode_string(line->buf, metainfo_charset, charset);
+	if (!out)
+		die("cannot convert from %s to %s",
+		    charset, metainfo_charset);
+	strbuf_attach(line, out, strlen(out), strlen(out));
+}
+
+static int decode_header_bq(struct strbuf *it)
+{
+	char *in, *ep, *cp;
+	struct strbuf outbuf = STRBUF_INIT, *dec;
+	struct strbuf charset_q = STRBUF_INIT, piecebuf = STRBUF_INIT;
+	int rfc2047 = 0;
+
+	in = it->buf;
+	while (in - it->buf <= it->len && (ep = strstr(in, "=?")) != NULL) {
+		int encoding;
+		strbuf_reset(&charset_q);
+		strbuf_reset(&piecebuf);
+		rfc2047 = 1;
+
+		if (in != ep) {
+			/*
+			 * We are about to process an encoded-word
+			 * that begins at ep, but there is something
+			 * before the encoded word.
+			 */
+			char *scan;
+			for (scan = in; scan < ep; scan++)
+				if (!isspace(*scan))
+					break;
+
+			if (scan != ep || in == it->buf) {
+				/*
+				 * We should not lose that "something",
+				 * unless we have just processed an
+				 * encoded-word, and there is only LWS
+				 * before the one we are about to process.
+				 */
+				strbuf_add(&outbuf, in, ep - in);
+			}
+		}
+		/* E.g.
+		 * ep : "=?iso-2022-jp?B?GyR...?= foo"
+		 * ep : "=?ISO-8859-1?Q?Foo=FCbar?= baz"
+		 */
+		ep += 2;
+
+		if (ep - it->buf >= it->len || !(cp = strchr(ep, '?')))
+			goto decode_header_bq_out;
+
+		if (cp + 3 - it->buf > it->len)
+			goto decode_header_bq_out;
+		strbuf_add(&charset_q, ep, cp - ep);
+
+		encoding = cp[1];
+		if (!encoding || cp[2] != '?')
+			goto decode_header_bq_out;
+		ep = strstr(cp + 3, "?=");
+		if (!ep)
+			goto decode_header_bq_out;
+		strbuf_add(&piecebuf, cp + 3, ep - cp - 3);
+		switch (tolower(encoding)) {
+		default:
+			goto decode_header_bq_out;
+		case 'b':
+			dec = decode_b_segment(&piecebuf);
+			break;
+		case 'q':
+			dec = decode_q_segment(&piecebuf, 1);
+			break;
+		}
+		if (metainfo_charset)
+			convert_to_utf8(dec, charset_q.buf);
+
+		strbuf_addbuf(&outbuf, dec);
+		strbuf_release(dec);
+		free(dec);
+		in = ep + 2;
+	}
+	strbuf_addstr(&outbuf, in);
+	strbuf_reset(it);
+	strbuf_addbuf(it, &outbuf);
+decode_header_bq_out:
+	strbuf_release(&outbuf);
+	strbuf_release(&charset_q);
+	strbuf_release(&piecebuf);
+	return rfc2047;
+}
+
+static void decode_header(struct strbuf *it)
+{
+	if (decode_header_bq(it))
+		return;
+	/* otherwise "it" is a straight copy of the input.
+	 * This can be binary guck but there is no charset specified.
+	 */
+	if (metainfo_charset)
+		convert_to_utf8(it, "");
+}
+
+static void decode_transfer_encoding(struct strbuf *line)
+{
+	struct strbuf *ret;
+
+	switch (transfer_encoding) {
+	case TE_QP:
+		ret = decode_q_segment(line, 0);
+		break;
+	case TE_BASE64:
+		ret = decode_b_segment(line);
+		break;
+	case TE_DONTCARE:
+	default:
+		return;
+	}
+	strbuf_reset(line);
+	strbuf_addbuf(line, ret);
+	strbuf_release(ret);
+	free(ret);
+}
+
+static void handle_filter(struct strbuf *line);
+
+static int find_boundary(void)
+{
+	while (!strbuf_getline(&line, fin, '\n')) {
+		if (*content_top && is_multipart_boundary(&line))
+			return 1;
+	}
+	return 0;
+}
+
+static int handle_boundary(void)
+{
+	struct strbuf newline = STRBUF_INIT;
+
+	strbuf_addch(&newline, '\n');
+again:
+	if (line.len >= (*content_top)->len + 2 &&
+	    !memcmp(line.buf + (*content_top)->len, "--", 2)) {
+		/* we hit an end boundary */
+		/* pop the current boundary off the stack */
+		strbuf_release(*content_top);
+		free(*content_top);
+		*content_top = NULL;
+
+		/* technically won't happen as is_multipart_boundary()
+		   will fail first.  But just in case..
+		 */
+		if (--content_top < content) {
+			fprintf(stderr, "Detected mismatched boundaries, "
+					"can't recover\n");
+			exit(1);
+		}
+		handle_filter(&newline);
+		strbuf_release(&newline);
+
+		/* skip to the next boundary */
+		if (!find_boundary())
+			return 0;
+		goto again;
+	}
+
+	/* set some defaults */
+	transfer_encoding = TE_DONTCARE;
+	strbuf_reset(&charset);
+	message_type = TYPE_TEXT;
+
+	/* slurp in this section's info */
+	while (read_one_header_line(&line, fin))
+		check_header(&line, p_hdr_data, 0);
+
+	strbuf_release(&newline);
+	/* replenish line */
+	if (strbuf_getline(&line, fin, '\n'))
+		return 0;
+	strbuf_addch(&line, '\n');
+	return 1;
+}
+
+static inline int patchbreak(const struct strbuf *line)
+{
+	size_t i;
+
+	/* Beginning of a "diff -" header? */
+	if (!prefixcmp(line->buf, "diff -"))
+		return 1;
+
+	/* CVS "Index: " line? */
+	if (!prefixcmp(line->buf, "Index: "))
+		return 1;
+
+	/*
+	 * "--- <filename>" starts patches without headers
+	 * "---<sp>*" is a manual separator
+	 */
+	if (line->len < 4)
+		return 0;
+
+	if (!prefixcmp(line->buf, "---")) {
+		/* space followed by a filename? */
+		if (line->buf[3] == ' ' && !isspace(line->buf[4]))
+			return 1;
+		/* Just whitespace? */
+		for (i = 3; i < line->len; i++) {
+			unsigned char c = line->buf[i];
+			if (c == '\n')
+				return 1;
+			if (!isspace(c))
+				break;
+		}
+		return 0;
+	}
+	return 0;
+}
+
+static int is_scissors_line(const struct strbuf *line)
+{
+	size_t i, len = line->len;
+	int scissors = 0, gap = 0;
+	int first_nonblank = -1;
+	int last_nonblank = 0, visible, perforation = 0, in_perforation = 0;
+	const char *buf = line->buf;
+
+	for (i = 0; i < len; i++) {
+		if (isspace(buf[i])) {
+			if (in_perforation) {
+				perforation++;
+				gap++;
+			}
+			continue;
+		}
+		last_nonblank = i;
+		if (first_nonblank < 0)
+			first_nonblank = i;
+		if (buf[i] == '-') {
+			in_perforation = 1;
+			perforation++;
+			continue;
+		}
+		if (i + 1 < len &&
+		    (!memcmp(buf + i, ">8", 2) || !memcmp(buf + i, "8<", 2))) {
+			in_perforation = 1;
+			perforation += 2;
+			scissors += 2;
+			i++;
+			continue;
+		}
+		in_perforation = 0;
+	}
+
+	/*
+	 * The mark must be at least 8 bytes long (e.g. "-- >8 --").
+	 * Even though there can be arbitrary cruft on the same line
+	 * (e.g. "cut here"), in order to avoid misidentification, the
+	 * perforation must occupy more than a third of the visible
+	 * width of the line, and dashes and scissors must occupy more
+	 * than half of the perforation.
+	 */
+
+	visible = last_nonblank - first_nonblank + 1;
+	return (scissors && 8 <= visible &&
+		visible < perforation * 3 &&
+		gap * 2 < perforation);
+}
+
+static int handle_commit_msg(struct strbuf *line)
+{
+	static int still_looking = 1;
+
+	if (!cmitmsg)
+		return 0;
+
+	if (still_looking) {
+		if (!line->len || (line->len == 1 && line->buf[0] == '\n'))
+			return 0;
+	}
+
+	if (use_inbody_headers && still_looking) {
+		still_looking = check_header(line, s_hdr_data, 0);
+		if (still_looking)
+			return 0;
+	} else
+		/* Only trim the first (blank) line of the commit message
+		 * when ignoring in-body headers.
+		 */
+		still_looking = 0;
+
+	/* normalize the log message to UTF-8. */
+	if (metainfo_charset)
+		convert_to_utf8(line, charset.buf);
+
+	if (use_scissors && is_scissors_line(line)) {
+		int i;
+		if (fseek(cmitmsg, 0L, SEEK_SET))
+			die_errno("Could not rewind output message file");
+		if (ftruncate(fileno(cmitmsg), 0))
+			die_errno("Could not truncate output message file at scissors");
+		still_looking = 1;
+
+		/*
+		 * We may have already read "secondary headers"; purge
+		 * them to give ourselves a clean restart.
+		 */
+		for (i = 0; header[i]; i++) {
+			if (s_hdr_data[i])
+				strbuf_release(s_hdr_data[i]);
+			s_hdr_data[i] = NULL;
+		}
+		return 0;
+	}
+
+	if (patchbreak(line)) {
+		fclose(cmitmsg);
+		cmitmsg = NULL;
+		return 1;
+	}
+
+	fputs(line->buf, cmitmsg);
+	return 0;
+}
+
+static void handle_patch(const struct strbuf *line)
+{
+	fwrite(line->buf, 1, line->len, patchfile);
+	patch_lines++;
+}
+
+static void handle_filter(struct strbuf *line)
+{
+	static int filter = 0;
+
+	/* filter tells us which part we left off on */
+	switch (filter) {
+	case 0:
+		if (!handle_commit_msg(line))
+			break;
+		filter++;
+	case 1:
+		handle_patch(line);
+		break;
+	}
+}
+
+static void handle_body(void)
+{
+	struct strbuf prev = STRBUF_INIT;
+
+	/* Skip up to the first boundary */
+	if (*content_top) {
+		if (!find_boundary())
+			goto handle_body_out;
+	}
+
+	do {
+		/* process any boundary lines */
+		if (*content_top && is_multipart_boundary(&line)) {
+			/* flush any leftover */
+			if (prev.len) {
+				handle_filter(&prev);
+				strbuf_reset(&prev);
+			}
+			if (!handle_boundary())
+				goto handle_body_out;
+		}
+
+		/* Unwrap transfer encoding */
+		decode_transfer_encoding(&line);
+
+		switch (transfer_encoding) {
+		case TE_BASE64:
+		case TE_QP:
+		{
+			struct strbuf **lines, **it, *sb;
+
+			/* Prepend any previous partial lines */
+			strbuf_insert(&line, 0, prev.buf, prev.len);
+			strbuf_reset(&prev);
+
+			/* binary data most likely doesn't have newlines */
+			if (message_type != TYPE_TEXT) {
+				handle_filter(&line);
+				break;
+			}
+			/*
+			 * This is a decoded line that may contain
+			 * multiple new lines.  Pass only one chunk
+			 * at a time to handle_filter()
+			 */
+			lines = strbuf_split(&line, '\n');
+			for (it = lines; (sb = *it); it++) {
+				if (*(it + 1) == NULL) /* The last line */
+					if (sb->buf[sb->len - 1] != '\n') {
+						/* Partial line, save it for later. */
+						strbuf_addbuf(&prev, sb);
+						break;
+					}
+				handle_filter(sb);
+			}
+			/*
+			 * The partial chunk is saved in "prev" and will be
+			 * appended by the next iteration of read_line_with_nul().
+			 */
+			strbuf_list_free(lines);
+			break;
+		}
+		default:
+			handle_filter(&line);
+		}
+
+	} while (!strbuf_getwholeline(&line, fin, '\n'));
+
+handle_body_out:
+	strbuf_release(&prev);
+}
+
+static void output_header_lines(FILE *fout, const char *hdr, const struct strbuf *data)
+{
+	const char *sp = data->buf;
+	while (1) {
+		char *ep = strchr(sp, '\n');
+		int len;
+		if (!ep)
+			len = strlen(sp);
+		else
+			len = ep - sp;
+		fprintf(fout, "%s: %.*s\n", hdr, len, sp);
+		if (!ep)
+			break;
+		sp = ep + 1;
+	}
+}
+
+static void handle_info(void)
+{
+	struct strbuf *hdr;
+	int i;
+
+	for (i = 0; header[i]; i++) {
+		/* only print inbody headers if we output a patch file */
+		if (patch_lines && s_hdr_data[i])
+			hdr = s_hdr_data[i];
+		else if (p_hdr_data[i])
+			hdr = p_hdr_data[i];
+		else
+			continue;
+
+		if (!memcmp(header[i], "Subject", 7)) {
+			if (!keep_subject) {
+				cleanup_subject(hdr);
+				cleanup_space(hdr);
+			}
+			output_header_lines(fout, "Subject", hdr);
+		} else if (!memcmp(header[i], "From", 4)) {
+			cleanup_space(hdr);
+			handle_from(hdr);
+			fprintf(fout, "Author: %s\n", name.buf);
+			fprintf(fout, "Email: %s\n", email.buf);
+		} else {
+			cleanup_space(hdr);
+			fprintf(fout, "%s: %s\n", header[i], hdr->buf);
+		}
+	}
+	fprintf(fout, "\n");
+}
+
+static int mailinfo(FILE *in, FILE *out, const char *msg, const char *patch)
+{
+	int peek;
+	fin = in;
+	fout = out;
+
+	cmitmsg = fopen(msg, "w");
+	if (!cmitmsg) {
+		perror(msg);
+		return -1;
+	}
+	patchfile = fopen(patch, "w");
+	if (!patchfile) {
+		perror(patch);
+		fclose(cmitmsg);
+		return -1;
+	}
+
+	p_hdr_data = xcalloc(MAX_HDR_PARSED, sizeof(*p_hdr_data));
+	s_hdr_data = xcalloc(MAX_HDR_PARSED, sizeof(*s_hdr_data));
+
+	do {
+		peek = fgetc(in);
+	} while (isspace(peek));
+	ungetc(peek, in);
+
+	/* process the email header */
+	while (read_one_header_line(&line, fin))
+		check_header(&line, p_hdr_data, 1);
+
+	handle_body();
+	handle_info();
+
+	return 0;
+}
+
+static int git_mailinfo_config(const char *var, const char *value, void *unused)
+{
+	if (prefixcmp(var, "mailinfo."))
+		return git_default_config(var, value, unused);
+	if (!strcmp(var, "mailinfo.scissors")) {
+		use_scissors = git_config_bool(var, value);
+		return 0;
+	}
+	/* perhaps others here */
+	return 0;
+}
+
+static const char mailinfo_usage[] =
+	"git mailinfo [-k|-b] [-u | --encoding=<encoding> | -n] [--scissors | --no-scissors] msg patch < mail >info";
+
+int cmd_mailinfo(int argc, const char **argv, const char *prefix)
+{
+	const char *def_charset;
+
+	/* NEEDSWORK: might want to do the optional .git/ directory
+	 * discovery
+	 */
+	git_config(git_mailinfo_config, NULL);
+
+	def_charset = (git_commit_encoding ? git_commit_encoding : "UTF-8");
+	metainfo_charset = def_charset;
+
+	while (1 < argc && argv[1][0] == '-') {
+		if (!strcmp(argv[1], "-k"))
+			keep_subject = 1;
+		else if (!strcmp(argv[1], "-b"))
+			keep_non_patch_brackets_in_subject = 1;
+		else if (!strcmp(argv[1], "-u"))
+			metainfo_charset = def_charset;
+		else if (!strcmp(argv[1], "-n"))
+			metainfo_charset = NULL;
+		else if (!prefixcmp(argv[1], "--encoding="))
+			metainfo_charset = argv[1] + 11;
+		else if (!strcmp(argv[1], "--scissors"))
+			use_scissors = 1;
+		else if (!strcmp(argv[1], "--no-scissors"))
+			use_scissors = 0;
+		else if (!strcmp(argv[1], "--no-inbody-headers"))
+			use_inbody_headers = 0;
+		else
+			usage(mailinfo_usage);
+		argc--; argv++;
+	}
+
+	if (argc != 3)
+		usage(mailinfo_usage);
+
+	return !!mailinfo(stdin, stdout, argv[1], argv[2]);
+}