Support RFC 2822 date parsing in fast-import.

Since some frontends may be working with source material where
the dates are only readily available as RFC 2822 strings, it is
more friendly if fast-import exposes Git's parse_date() function
to handle the conversion.  This way the frontend doesn't need
to perform the parsing itself.

The new --date-format option to fast-import can be used by a
frontend to select which format it will supply date strings in.
The default is the standard `raw` Git format, which fast-import
has always supported.  Format rfc2822 can be used to activate the
parse_date() function instead.

Because fast-import could also be useful for creating new, current
commits, the format `now` is also supported to generate the current
system timestamp.  The implementation of `now` is a trivial call
to datestamp(), but is actually a whole whopping 3 lines so that
fast-import can verify the frontend really meant `now`.

As part of this change I have added validation of the `raw` date
format.  Prior to this change fast-import would accept anything
in a `committer` command, even if it was seriously malformed.
Now fast-import requires the '> ' near the end of the string and
verifies the timestamp is formatted properly.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

3 files changed, 214 insertions, 24 deletions

diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
index 6fc78bff3..08450de9a 100644
--- a/Documentation/git-fast-import.txt
+++ b/Documentation/git-fast-import.txt
@@ -32,6 +32,12 @@ the frontend program in use.
 
 OPTIONS
 -------
+--date-format=<fmt>::
+	Specify the type of dates the frontend will supply to
+	gfi within `author`, `committer` and `tagger` commands.
+	See ``Date Formats'' below for details about which formats
+	are supported, and their syntax.
+
 --max-pack-size=<n>::
 	Maximum size of each output packfile, expressed in MiB.
 	The default is 4096 (4 GiB) as that is the maximum allowed
@@ -53,7 +59,6 @@ OPTIONS
 	Frontends can use this file to validate imports after they
 	have been completed.
 
-
 Performance
 -----------
 The design of gfi allows it to import large projects in a minimum
@@ -127,6 +132,78 @@ results, such as branch names or file names with leading or trailing
 spaces in their name, or early termination of gfi when it encounters
 unexpected input.
 
+Date Formats
+~~~~~~~~~~~~
+The following date formats are supported.  A frontend should select
+the format it will use for this import by passing the format name
+in the `--date-format=<fmt>` command line option.
+
+`raw`::
+	This is the Git native format and is `<time> SP <tz>`.
+	It is also gfi's default format, if `--date-format` was
+	not specified.
++
+The time of the event is specified by `<time>` as the number of
+seconds since the UNIX epoch (midnight, Jan 1, 1970, UTC) and is
+written as an ASCII decimal integer.
++
+The timezone is specified by `<tz>` as a positive or negative offset
+from UTC.  For example EST (which is typically 5 hours behind GMT)
+would be expressed in `<tz>` by ``-0500'' while GMT is ``+0000''.
++
+If the timezone is not available in the source material, use
+``+0000'', or the most common local timezone.  For example many
+organizations have a CVS repository which has only ever been accessed
+by users who are located in the same location and timezone.  In this
+case the user's timezone can be easily assumed.
++
+Unlike the `rfc2822` format, this format is very strict.  Any
+variation in formatting will cause gfi to reject the value.
+
+`rfc2822`::
+	This is the standard email format as described by RFC 2822.
++
+An example value is ``Tue Feb 6 11:22:18 2007 -0500''.  The Git
+parser is accurate, but a little on the lenient side.  Its the
+same parser used by gitlink:git-am[1] when applying patches
+received from email.
++
+Some malformed strings may be accepted as valid dates.  In some of
+these cases Git will still be able to obtain the correct date from
+the malformed string.  There are also some types of malformed
+strings which Git will parse wrong, and yet consider valid.
+Seriously malformed strings will be rejected.
++
+If the source material is formatted in RFC 2822 style dates,
+the frontend should let gfi handle the parsing and conversion
+(rather than attempting to do it itself) as the Git parser has
+been well tested in the wild.
++
+Frontends should prefer the `raw` format if the source material
+is already in UNIX-epoch format, or is easily convertible to
+that format, as there is no ambiguity in parsing.
+
+`now`::
+	Always use the current time and timezone.  The literal
+	`now` must always be supplied for `<when>`.
++
+This is a toy format.  The current time and timezone of this system
+is always copied into the identity string at the time it is being
+created by gfi.  There is no way to specify a different time or
+timezone.
++
+This particular format is supplied as its short to implement and
+may be useful to a process that wants to create a new commit
+right now, without needing to use a working directory or
+gitlink:git-update-index[1].
++
+If separate `author` and `committer` commands are used in a `commit`
+the timestamps may not match, as the system clock will be polled
+twice (once for each command).  The only way to ensure that both
+author and committer identity information has the same timestamp
+is to omit `author` (thus copying from `committer`) or to use a
+date format other than `now`.
+
 Commands
 ~~~~~~~~
 gfi accepts several commands to update the current repository
@@ -168,8 +245,8 @@ change to the project.
 ....
 	'commit' SP <ref> LF
 	mark?
-	('author' SP <name> SP LT <email> GT SP <time> SP <tz> LF)?
-	'committer' SP <name> SP LT <email> GT SP <time> SP <tz> LF
+	('author' SP <name> SP LT <email> GT SP <when> LF)?
+	'committer' SP <name> SP LT <email> GT SP <when> LF
 	data
 	('from' SP <committish> LF)?
 	('merge' SP <committish> LF)?
@@ -222,12 +299,10 @@ the email address from the other fields in the line.  Note that
 `<name>` is free-form and may contain any sequence of bytes, except
 `LT` and `LF`.  It is typically UTF-8 encoded.
 
-The time of the change is specified by `<time>` as the number of
-seconds since the UNIX epoc (midnight, Jan 1, 1970, UTC) and is
-written as an ASCII decimal integer.  The committer's
-timezone is specified by `<tz>` as a positive or negative offset
-from UTC.  For example EST (which is typically 5 hours behind GMT)
-would be expressed in `<tz>` by ``-0500'' while GMT is ``+0000''.
+The time of the change is specified by `<when>` using the date format
+that was selected by the `--date-format=<fmt>` command line option.
+See ``Date Formats'' above for the set of supported formats, and
+their syntax.
 
 `from`
 ^^^^^^
@@ -394,7 +469,7 @@ lightweight (non-annotated) tags see the `reset` command below.
 ....
 	'tag' SP <name> LF
 	'from' SP <committish> LF
-	'tagger' SP <name> SP LT <email> GT SP <time> SP <tz> LF
+	'tagger' SP <name> SP LT <email> GT SP <when> LF
 	data
 	LF
 ....
diff --git a/fast-import.c b/fast-import.c
index 4dcba416e..ee4777fda 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -17,8 +17,8 @@ Format of STDIN stream:
 
   new_commit ::= 'commit' sp ref_str lf
     mark?
-    ('author' sp name '<' email '>' ts tz lf)?
-    'committer' sp name '<' email '>' ts tz lf
+    ('author' sp name '<' email '>' when lf)?
+    'committer' sp name '<' email '>' when lf
     commit_msg
     ('from' sp (ref_str | hexsha1 | sha1exp_str | idnum) lf)?
     ('merge' sp (ref_str | hexsha1 | sha1exp_str | idnum) lf)*
@@ -34,7 +34,7 @@ Format of STDIN stream:
 
   new_tag ::= 'tag' sp tag_str lf
     'from' sp (ref_str | hexsha1 | sha1exp_str | idnum) lf
-	'tagger' sp name '<' email '>' ts tz lf
+	'tagger' sp name '<' email '>' when lf
     tag_msg;
   tag_msg ::= data;
 
@@ -88,6 +88,10 @@ Format of STDIN stream:
   bigint ::= # unsigned integer value, ascii base10 notation;
   binary_data ::= # file content, not interpreted;
 
+  when         ::= raw_when | rfc2822_when;
+  raw_when     ::= ts sp tz;
+  rfc2822_when ::= # Valid RFC 2822 date and time;
+
   sp ::= # ASCII space character;
   lf ::= # ASCII newline (LF) character;
 
@@ -234,6 +238,12 @@ struct hash_list
 	unsigned char sha1[20];
 };
 
+typedef enum {
+	WHENSPEC_RAW = 1,
+	WHENSPEC_RFC2822,
+	WHENSPEC_NOW,
+} whenspec_type;
+
 /* Configured limits on output */
 static unsigned long max_depth = 10;
 static unsigned long max_packsize = (1LL << 32) - 1;
@@ -294,6 +304,7 @@ static struct tag *first_tag;
 static struct tag *last_tag;
 
 /* Input stream parsing */
+static whenspec_type whenspec = WHENSPEC_RAW;
 static struct strbuf command_buf;
 static uintmax_t next_mark;
 static struct dbuf new_data;
@@ -1396,6 +1407,64 @@ static void *cmd_data (size_t *size)
 	return buffer;
 }
 
+static int validate_raw_date(const char *src, char *result, int maxlen)
+{
+	const char *orig_src = src;
+	char *endp, sign;
+
+	strtoul(src, &endp, 10);
+	if (endp == src || *endp != ' ')
+		return -1;
+
+	src = endp + 1;
+	if (*src != '-' && *src != '+')
+		return -1;
+	sign = *src;
+
+	strtoul(src + 1, &endp, 10);
+	if (endp == src || *endp || (endp - orig_src) >= maxlen)
+		return -1;
+
+	strcpy(result, orig_src);
+	return 0;
+}
+
+static char *parse_ident(const char *buf)
+{
+	const char *gt;
+	size_t name_len;
+	char *ident;
+
+	gt = strrchr(buf, '>');
+	if (!gt)
+		die("Missing > in ident string: %s", buf);
+	gt++;
+	if (*gt != ' ')
+		die("Missing space after > in ident string: %s", buf);
+	gt++;
+	name_len = gt - buf;
+	ident = xmalloc(name_len + 24);
+	strncpy(ident, buf, name_len);
+
+	switch (whenspec) {
+	case WHENSPEC_RAW:
+		if (validate_raw_date(gt, ident + name_len, 24) < 0)
+			die("Invalid raw date \"%s\" in ident: %s", gt, buf);
+		break;
+	case WHENSPEC_RFC2822:
+		if (parse_date(gt, ident + name_len, 24) < 0)
+			die("Invalid rfc2822 date \"%s\" in ident: %s", gt, buf);
+		break;
+	case WHENSPEC_NOW:
+		if (strcmp("now", gt))
+			die("Date in ident must be 'now': %s", buf);
+		datestamp(ident + name_len, 24);
+		break;
+	}
+
+	return ident;
+}
+
 static void cmd_new_blob(void)
 {
 	size_t l;
@@ -1655,11 +1724,11 @@ static void cmd_new_commit(void)
 	read_next_command();
 	cmd_mark();
 	if (!strncmp("author ", command_buf.buf, 7)) {
-		author = strdup(command_buf.buf);
+		author = parse_ident(command_buf.buf + 7);
 		read_next_command();
 	}
 	if (!strncmp("committer ", command_buf.buf, 10)) {
-		committer = strdup(command_buf.buf);
+		committer = parse_ident(command_buf.buf + 10);
 		read_next_command();
 	}
 	if (!committer)
@@ -1692,7 +1761,7 @@ static void cmd_new_commit(void)
 	store_tree(&b->branch_tree);
 	hashcpy(b->branch_tree.versions[0].sha1,
 		b->branch_tree.versions[1].sha1);
-	size_dbuf(&new_data, 97 + msglen
+	size_dbuf(&new_data, 114 + msglen
 		+ merge_count * 49
 		+ (author
 			? strlen(author) + strlen(committer)
@@ -1708,11 +1777,9 @@ static void cmd_new_commit(void)
 		free(merge_list);
 		merge_list = next;
 	}
-	if (author)
-		sp += sprintf(sp, "%s\n", author);
-	else
-		sp += sprintf(sp, "author %s\n", committer + 10);
-	sp += sprintf(sp, "%s\n\n", committer);
+	sp += sprintf(sp, "author %s\n", author ? author : committer);
+	sp += sprintf(sp, "committer %s\n", committer);
+	*sp++ = '\n';
 	memcpy(sp, msg, msglen);
 	sp += msglen;
 	free(author);
@@ -1780,7 +1847,7 @@ static void cmd_new_tag(void)
 	/* tagger ... */
 	if (strncmp("tagger ", command_buf.buf, 7))
 		die("Expected tagger command, got %s", command_buf.buf);
-	tagger = strdup(command_buf.buf);
+	tagger = parse_ident(command_buf.buf + 7);
 
 	/* tag payload/message */
 	read_next_command();
@@ -1792,7 +1859,8 @@ static void cmd_new_tag(void)
 	sp += sprintf(sp, "object %s\n", sha1_to_hex(sha1));
 	sp += sprintf(sp, "type %s\n", type_names[OBJ_COMMIT]);
 	sp += sprintf(sp, "tag %s\n", t->name);
-	sp += sprintf(sp, "%s\n\n", tagger);
+	sp += sprintf(sp, "tagger %s\n", tagger);
+	*sp++ = '\n';
 	memcpy(sp, msg, msglen);
 	sp += msglen;
 	free(tagger);
@@ -1835,7 +1903,7 @@ static void cmd_checkpoint(void)
 }
 
 static const char fast_import_usage[] =
-"git-fast-import [--depth=n] [--active-branches=n] [--export-marks=marks.file] [--branch-log=log]";
+"git-fast-import [--date-format=f] [--max-pack-size=n] [--depth=n] [--active-branches=n] [--export-marks=marks.file]";
 
 int main(int argc, const char **argv)
 {
@@ -1849,6 +1917,17 @@ int main(int argc, const char **argv)
 
 		if (*a != '-' || !strcmp(a, "--"))
 			break;
+		else if (!strncmp(a, "--date-format=", 14)) {
+			const char *fmt = a + 14;
+			if (!strcmp(fmt, "raw"))
+				whenspec = WHENSPEC_RAW;
+			else if (!strcmp(fmt, "rfc2822"))
+				whenspec = WHENSPEC_RFC2822;
+			else if (!strcmp(fmt, "now"))
+				whenspec = WHENSPEC_NOW;
+			else
+				die("unknown --date-format argument %s", fmt);
+		}
 		else if (!strncmp(a, "--max-pack-size=", 16))
 			max_packsize = strtoumax(a + 16, NULL, 0) * 1024 * 1024;
 		else if (!strncmp(a, "--depth=", 8))
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index a5cc846b3..84b3c12a5 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -240,4 +240,40 @@ test_expect_success \
 	'git-cat-file blob branch:newdir/exec.sh >actual &&
 	 diff -u expect actual'
 
+###
+### series E
+###
+
+cat >input <<INPUT_END
+commit refs/heads/branch
+author $GIT_AUTHOR_NAME <$GIT_AUTHOR_EMAIL> Tue Feb 6 11:22:18 2007 -0500
+committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> Tue Feb 6 12:35:02 2007 -0500
+data <<COMMIT
+RFC 2822 type date
+COMMIT
+
+from refs/heads/branch^0
+
+INPUT_END
+test_expect_failure \
+    'E: rfc2822 date, --date-format=raw' \
+    'git-fast-import --date-format=raw <input'
+test_expect_success \
+    'E: rfc2822 date, --date-format=rfc2822' \
+    'git-fast-import --date-format=rfc2822 <input'
+test_expect_success \
+	'E: verify pack' \
+	'for p in .git/objects/pack/*.pack;do git-verify-pack $p||exit;done'
+
+cat >expect <<EOF
+author $GIT_AUTHOR_NAME <$GIT_AUTHOR_EMAIL> 1170778938 -0500
+committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1170783302 -0500
+
+RFC 2822 type date
+EOF
+test_expect_success \
+	'E: verify commit' \
+	'git-cat-file commit branch | sed 1,2d >actual &&
+	diff -u expect actual'
+
 test_done