date: use strbufs in date-formatting functions

Many of the date functions write into fixed-size buffers.
This is a minor pain, as we have to take special
precautions, and frequently end up copying the result into a
strbuf or heap-allocated buffer anyway (for which we
sometimes use strcpy!).

Let's instead teach parse_date, datestamp, etc to write to a
strbuf. The obvious downside is that we might need to
perform a heap allocation where we otherwise would not need
to. However, it turns out that the only two new allocations
required are:

  1. In test-date.c, where we don't care about efficiency.

  2. In determine_author_info, which is not performance
     critical (and where the use of a strbuf will help later
     refactoring).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 9 insertions, 11 deletions

diff --git a/fast-import.c b/fast-import.c
index d73f58cbe3..dc9f7a8ccb 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1971,7 +1971,7 @@ static int parse_data(struct strbuf *sb, uintmax_t limit, uintmax_t *len_res)
 	return 1;
 }
 
-static int validate_raw_date(const char *src, char *result, int maxlen)
+static int validate_raw_date(const char *src, struct strbuf *result)
 {
 	const char *orig_src = src;
 	char *endp;
@@ -1989,11 +1989,10 @@ static int validate_raw_date(const char *src, char *result, int maxlen)
 		return -1;
 
 	num = strtoul(src + 1, &endp, 10);
-	if (errno || endp == src + 1 || *endp || (endp - orig_src) >= maxlen ||
-	    1400 < num)
+	if (errno || endp == src + 1 || *endp || 1400 < num)
 		return -1;
 
-	strcpy(result, orig_src);
+	strbuf_addstr(result, orig_src);
 	return 0;
 }
 
@@ -2001,7 +2000,7 @@ static char *parse_ident(const char *buf)
 {
 	const char *ltgt;
 	size_t name_len;
-	char *ident;
+	struct strbuf ident = STRBUF_INIT;
 
 	/* ensure there is a space delimiter even if there is no name */
 	if (*buf == '<')
@@ -2020,26 +2019,25 @@ static char *parse_ident(const char *buf)
 		die("Missing space after > in ident string: %s", buf);
 	ltgt++;
 	name_len = ltgt - buf;
-	ident = xmalloc(name_len + 24);
-	strncpy(ident, buf, name_len);
+	strbuf_add(&ident, buf, name_len);
 
 	switch (whenspec) {
 	case WHENSPEC_RAW:
-		if (validate_raw_date(ltgt, ident + name_len, 24) < 0)
+		if (validate_raw_date(ltgt, &ident) < 0)
 			die("Invalid raw date \"%s\" in ident: %s", ltgt, buf);
 		break;
 	case WHENSPEC_RFC2822:
-		if (parse_date(ltgt, ident + name_len, 24) < 0)
+		if (parse_date(ltgt, &ident) < 0)
 			die("Invalid rfc2822 date \"%s\" in ident: %s", ltgt, buf);
 		break;
 	case WHENSPEC_NOW:
 		if (strcmp("now", ltgt))
 			die("Date in ident must be 'now': %s", buf);
-		datestamp(ident + name_len, 24);
+		datestamp(&ident);
 		break;
 	}
 
-	return ident;
+	return strbuf_detach(&ident, NULL);
 }
 
 static void parse_and_store_blob(