[PATCH v2 3/5] pkt-line: extract and use `set_packet_header` function

[larsxschneider@gmail.com]

From: Lars Schneider <larsxschneider@gmail.com>

`set_packet_header` converts an integer to a 4 byte hex string. Make
this function publicly available so that other parts of Git can easily
generate a pkt-line.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
---
 pkt-line.c | 15 ++++++++++-----
 pkt-line.h |  1 +
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/pkt-line.c b/pkt-line.c
index 62fdb37..6820224 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -98,9 +98,17 @@ void packet_buf_flush(struct strbuf *buf)
 }
 
 #define hex(a) (hexchar[(a) & 15])
-static void format_packet(struct strbuf *out, const char *fmt, va_list args)
+void set_packet_header(char *buf, const int size)
 {
 	static char hexchar[] = "0123456789abcdef";
+	buf[0] = hex(size >> 12);
+	buf[1] = hex(size >> 8);
+	buf[2] = hex(size >> 4);
+	buf[3] = hex(size);
+}
+
+static void format_packet(struct strbuf *out, const char *fmt, va_list args)
+{
 	size_t orig_len, n;
 
 	orig_len = out->len;
@@ -111,10 +119,7 @@ static void format_packet(struct strbuf *out, const char *fmt, va_list args)
 	if (n > LARGE_PACKET_MAX)
 		die("protocol error: impossibly long line");
 
-	out->buf[orig_len + 0] = hex(n >> 12);
-	out->buf[orig_len + 1] = hex(n >> 8);
-	out->buf[orig_len + 2] = hex(n >> 4);
-	out->buf[orig_len + 3] = hex(n);
+	set_packet_header(&out->buf[orig_len], n);
 	packet_trace(out->buf + orig_len + 4, n - 4, 1);
 }
 
diff --git a/pkt-line.h b/pkt-line.h
index 3cb9d91..925c6d3 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -23,6 +23,7 @@ void packet_flush(int fd);
 void packet_write(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 void packet_buf_flush(struct strbuf *buf);
 void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
+void set_packet_header(char *buf, const int size);
 
 /*
  * Read a packetized line into the buffer, which must be at least size bytes
-- 
2.9.0