[PATCH] tools: fw_env: Fix warning when reading too little

[Harald Seiler]

When using CONFIG_ENV_IS_IN_FAT and the config-file specifies a size
larger than what U-Boot wrote into the env-file, a confusing error
message is shown:

    $ fw_printenv
    Read error on /boot/uboot.env: Success

Fix this by showing a different error message when read returns too
little data.

Signed-off-by: Harald Seiler <hws at denx.de>
---
 tools/env/fw_env.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index 8734663cd4c7..c6378ecf34f6 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -946,11 +946,17 @@ static int flash_read_buf(int dev, int fd, void *buf, size_t count,
 		lseek(fd, blockstart + block_seek, SEEK_SET);
 
 		rc = read(fd, buf + processed, readlen);
-		if (rc != readlen) {
+		if (rc == -1) {
 			fprintf(stderr, "Read error on %s: %s\n",
 				DEVNAME(dev), strerror(errno));
 			return -1;
 		}
+		if (rc != readlen) {
+			fprintf(stderr, "Read error on %s: "
+				"Attempted to read %d bytes but got %d\n",
+				DEVNAME(dev), readlen, rc);
+			return -1;
+		}
 #ifdef DEBUG
 		fprintf(stderr, "Read 0x%x bytes at 0x%llx on %s\n",
 			rc, (unsigned long long)blockstart + block_seek,
-- 
2.25.4