ident: move commit_rewrite_person() to ident.c

commit_rewrite_person() and rewrite_ident_line() are static functions
defined in revision.c.

Their usages are as follows:
- commit_rewrite_person() takes a commit buffer and replaces the author
  and committer idents with their canonical versions using the mailmap
  mechanism
- rewrite_ident_line() takes author/committer header lines from the
  commit buffer and replaces the idents with their canonical versions
  using the mailmap mechanism.

This patch moves commit_rewrite_person() and rewrite_ident_line() to
ident.c which contains many other functions related to idents like
split_ident_line(). By moving commit_rewrite_person() to ident.c, we
also intend to use it in git-cat-file to replace committer and author
idents from the headers to their canonical versions using the mailmap
mechanism. The function is moved as is for now to make it clear that
there are no other changes, but it will be renamed in a following
commit.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: John Cai <johncai86@gmail.com>
Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 74 insertions, 0 deletions

diff --git a/ident.c b/ident.c
index 89ca5b4700..1eee4fd0e3 100644
--- a/ident.c
+++ b/ident.c
@@ -8,6 +8,7 @@
 #include "cache.h"
 #include "config.h"
 #include "date.h"
+#include "mailmap.h"
 
 static struct strbuf git_default_name = STRBUF_INIT;
 static struct strbuf git_default_email = STRBUF_INIT;
@@ -346,6 +347,79 @@ person_only:
 	return 0;
 }
 
+/*
+ * Returns the difference between the new and old length of the ident line.
+ */
+static ssize_t rewrite_ident_line(const char *person, size_t len,
+				   struct strbuf *buf,
+				   struct string_list *mailmap)
+{
+	size_t namelen, maillen;
+	const char *name;
+	const char *mail;
+	struct ident_split ident;
+
+	if (split_ident_line(&ident, person, len))
+		return 0;
+
+	mail = ident.mail_begin;
+	maillen = ident.mail_end - ident.mail_begin;
+	name = ident.name_begin;
+	namelen = ident.name_end - ident.name_begin;
+
+	if (map_user(mailmap, &mail, &maillen, &name, &namelen)) {
+		struct strbuf namemail = STRBUF_INIT;
+		size_t newlen;
+
+		strbuf_addf(&namemail, "%.*s <%.*s>",
+			    (int)namelen, name, (int)maillen, mail);
+
+		strbuf_splice(buf, ident.name_begin - buf->buf,
+			      ident.mail_end - ident.name_begin + 1,
+			      namemail.buf, namemail.len);
+		newlen = namemail.len;
+
+		strbuf_release(&namemail);
+
+		return newlen - (ident.mail_end - ident.name_begin);
+	}
+
+	return 0;
+}
+
+void commit_rewrite_person(struct strbuf *buf, const char **header,
+			    struct string_list *mailmap)
+{
+	size_t buf_offset = 0;
+
+	if (!mailmap)
+		return;
+
+	for (;;) {
+		const char *person, *line;
+		size_t i;
+		int found_header = 0;
+
+		line = buf->buf + buf_offset;
+		if (!*line || *line == '\n')
+			return; /* End of headers */
+
+		for (i = 0; header[i]; i++)
+			if (skip_prefix(line, header[i], &person)) {
+				const char *endp = strchrnul(person, '\n');
+				found_header = 1;
+				buf_offset += endp - line;
+				buf_offset += rewrite_ident_line(person, endp - person, buf, mailmap);
+				break;
+			}
+
+		if (!found_header) {
+			buf_offset = strchrnul(line, '\n') - buf->buf;
+			if (buf->buf[buf_offset] == '\n')
+				buf_offset++;
+		}
+	}
+}
 
 static void ident_env_hint(enum want_ident whose_ident)
 {