[Skiboot] [PATCH] libflash/file: Handle short read()s and write()s correctly

[Cyril Bur]

Currently we don't move the buffer along for a short read() or write()
and nor do we request only the remaining amount.

Fixes: c7c3a4cd53d libflash/file: Add a file access backend to for the blocklevel interface.
Signed-off-by: Cyril Bur <cyril.bur at au1.ibm.com>
---
 libflash/file.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libflash/file.c b/libflash/file.c
index 7065eb4f..49f61778 100644
--- a/libflash/file.c
+++ b/libflash/file.c
@@ -72,11 +72,12 @@ static int file_read(struct blocklevel_device *bl, uint64_t pos, void *buf, uint
 		return FLASH_ERR_PARM_ERROR;
 
 	while (count < len) {
-		rc = read(file_data->fd, buf, len);
+		rc = read(file_data->fd, buf, len - count);
 		/* errno should remain set */
 		if (rc == -1 || rc == 0)
 			return FLASH_ERR_BAD_READ;
 
+		buf += rc;
 		count += rc;
 	}
 
@@ -95,11 +96,12 @@ static int file_write(struct blocklevel_device *bl, uint64_t dst, const void *sr
 		return FLASH_ERR_PARM_ERROR;
 
 	while (count < len) {
-		rc = write(file_data->fd, src, len);
+		rc = write(file_data->fd, src, len - count);
 		/* errno should remain set */
 		if (rc == -1)
 			return FLASH_ERR_VERIFY_FAILURE;
 
+		src += rc;
 		count += rc;
 	}
 
-- 
2.14.1