configfs: Restructure attribute read to support binary attributes

Modify the attribute_read() function to not add a terminating 0 to the
buffer, and to return the number of bytes read, in order to support
binary attributes. The attribute_read_uint() and attribute_read_str()
functions are modified accordingly to use the new attribute_read()
semantics.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 11 insertions, 9 deletions

diff --git a/configfs.c b/configfs.c
index 38954d5..4c83dca 100644
--- a/configfs.c
+++ b/configfs.c
@@ -53,7 +53,7 @@ static char *path_glob_first_match(const char *g)
  * Attribute handling
  */
 
-static int attribute_read(const char *path, const char *file, char *buf,
+static int attribute_read(const char *path, const char *file, void *buf,
 			  unsigned int len)
 {
 	char *f;
@@ -72,7 +72,7 @@ static int attribute_read(const char *path, const char *file, char *buf,
 		return -ENOENT;
 	}
 
-	ret = read(fd, buf, len - 1);
+	ret = read(fd, buf, len);
 	close(fd);
 
 	if (ret < 0) {
@@ -81,9 +81,7 @@ static int attribute_read(const char *path, const char *file, char *buf,
 		return -ENODATA;
 	}
 
-	buf[ret] = '\0';
-
-	return 0;
+	return len;
 }
 
 static int attribute_read_uint(const char *path, const char *file,
@@ -94,10 +92,12 @@ static int attribute_read_uint(const char *path, const char *file,
 	char *endptr;
 	int ret;
 
-	ret = attribute_read(path, file, buf, sizeof(buf));
-	if (ret)
+	ret = attribute_read(path, file, buf, sizeof(buf) - 1);
+	if (ret < 0)
 		return ret;
 
+	buf[ret] = '\0';
+
 	errno = 0;
 
 	/* base 0: Autodetect hex, octal, decimal. */
@@ -117,10 +117,12 @@ static char *attribute_read_str(const char *path, const char *file)
 	char *p;
 	int ret;
 
-	ret = attribute_read(path, file, buf, sizeof(buf));
-	if (ret)
+	ret = attribute_read(path, file, buf, sizeof(buf) - 1);
+	if (ret < 0)
 		return NULL;
 
+	buf[ret] = '\0';
+
 	p = strrchr(buf, '\n');
 	if (p != buf)
 		*p = '\0';