[PATCH 2/2] Make sha1_to_hex thread-safe

[Fredrik Kuivinen <frekui@gmail.com>]

Signed-off-by: Fredrik Kuivinen <frekui@gmail.com>
---

 hex.c |   53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 53 insertions(+), 0 deletions(-)

diff --git a/hex.c b/hex.c
index bb402fb..fe1d302 100644
--- a/hex.c
+++ b/hex.c
@@ -1,5 +1,9 @@
 #include "cache.h"
 
+#ifndef NO_PTHREADS
+#include <pthread.h>
+#endif
+
 const signed char hexval_table[256] = {
 	 -1, -1, -1, -1, -1, -1, -1, -1,		/* 00-07 */
 	 -1, -1, -1, -1, -1, -1, -1, -1,		/* 08-0f */
@@ -48,6 +52,7 @@ int get_sha1_hex(const char *hex, unsigned char *sha1)
 	return 0;
 }
 
+#ifdef NO_PTHREADS
 char *sha1_to_hex(const unsigned char *sha1)
 {
 	static int bufno;
@@ -65,3 +70,51 @@ char *sha1_to_hex(const unsigned char *sha1)
 
 	return buffer;
 }
+#else
+static pthread_once_t sha1_to_hex_once = PTHREAD_ONCE_INIT;
+static pthread_key_t sha1_to_hex_key;
+
+static void sha1_to_hex_init(void)
+{
+	int err = pthread_key_create(&sha1_to_hex_key, free);
+	if (err)
+		die("pthread_key_create failed: %s", strerror(err));
+}
+
+struct sha1_to_hex_buf
+{
+	int no;
+	char hex[4][50];
+};
+
+char *sha1_to_hex(const unsigned char *sha1)
+{
+	static const char hex[] = "0123456789abcdef";
+	struct sha1_to_hex_buf *hexbuf;
+	int i;
+	char *buffer, *buf;
+
+	pthread_once(&sha1_to_hex_once, sha1_to_hex_init);
+
+	hexbuf = pthread_getspecific(sha1_to_hex_key);
+	if (!hexbuf) {
+		int err;
+		hexbuf = xmalloc(sizeof(struct sha1_to_hex_buf));
+		hexbuf->no = 0;
+		err = pthread_setspecific(sha1_to_hex_key, hexbuf);
+		if (err)
+			die("pthread_getspecific failed: %s", strerror(err));
+	}
+
+	buffer = hexbuf->hex[3 & ++hexbuf->no], buf = buffer;
+
+	for (i = 0; i < 20; i++) {
+		unsigned int val = *sha1++;
+		*buf++ = hex[val >> 4];
+		*buf++ = hex[val & 0xf];
+	}
+	*buf = '\0';
+
+	return buffer;
+}
+#endif