libfile: Document that read_file() returns a terminated buffer

read_file() and read_file_2() return a '\0' terminated buffer to make
sure the buffer is usable as a string. Other code like read_file_line()
depends on this behaviour, so document it explicitly.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/libfile.c b/lib/libfile.c
index 3f3ec21fdb..02078dd43d 100644
--- a/lib/libfile.c
+++ b/lib/libfile.c
@@ -158,7 +158,9 @@ EXPORT_SYMBOL_GPL(read_file_line);
  * bytes are read. The actual read size is returned in @size. -EFBIG is
  * returned if the file is bigger than @max_size, but the buffer is read
  * anyway up to @max_size in this case. Free the buffer with free() after
- * usage.
+ * usage. The allocated buffer is actually one byte bigger than the file
+ * and the extra byte is initialized to '\0' so that the returned buffer
+ * can safely be interpreted as a string.
  *
  * Return: 0 for success, or negative error code. -EFBIG is returned
  * when the file has been bigger than max_size.