Let read_file return the actual data size

Let read_file return the actual data size to the caller. This gives
the caller the possibility to check that the data size is as expected
and large enough for the purpose, and report to the user if not.

1 files changed, 7 insertions, 4 deletions

diff --git a/util.c b/util.c
index f97ac0d..52ed413 100644
--- a/util.c
+++ b/util.c
@@ -94,10 +94,11 @@ int checksum(const u8 *buf, size_t len)
  * needs to be freed by the caller.
  * This provides a similar usage model to mem_chunk()
  *
- * Returns pointer to buffer of max_len bytes, or NULL on error
+ * Returns pointer to buffer of max_len bytes, or NULL on error, and
+ * sets max_len to the length actually read.
  *
  */
-void *read_file(size_t max_len, const char *filename)
+void *read_file(size_t *max_len, const char *filename)
 {
 	int fd;
 	size_t r2 = 0;
@@ -115,7 +116,7 @@ void *read_file(size_t max_len, const char *filename)
 		return(NULL);
 	}
 
-	if ((p = malloc(max_len)) == NULL)
+	if ((p = malloc(*max_len)) == NULL)
 	{
 		perror("malloc");
 		return NULL;
@@ -123,7 +124,7 @@ void *read_file(size_t max_len, const char *filename)
 
 	do
 	{
-		r = read(fd, p + r2, max_len - r2);
+		r = read(fd, p + r2, *max_len - r2);
 		if (r == -1)
 		{
 			if (errno != EINTR)
@@ -140,6 +141,8 @@ void *read_file(size_t max_len, const char *filename)
 	while (r != 0);
 
 	close(fd);
+	*max_len = r2;
+
 	return p;
 }