[PATCH 0/1] tools: env: Handle shorter read calls

[PATCH 0/1] tools: env: Handle shorter read calls

[Thibault Ferrante]

On specific devices, read can return less bytes than expected.
I noticed this problem on a EEPROM chip with 16Kbyte of memory. Defining
an environment with more than 4Kbyte leads to less bytes read than expected
and failures from fw_printenv/fw_setenv.
This patch target to handle this issue by doing multiple reads instead
of exiting directly.


Thibault Ferrante (1):
  tools: env: Handle shorter read calls

 tools/env/fw_env.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

-- 
2.25.1

[PATCH 1/1] tools: env: Handle shorter read calls

[Thibault Ferrante]

On some cases, the actual number of bytes read can be shorter
than what was requested. This can be handled gracefully by
taking this difference into account instead of exiting.

Signed-off-by: Thibault Ferrante <thibault.ferrante@gmail.com>
---

 tools/env/fw_env.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index 2a61a5d6f0..e39c39e23a 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -951,21 +951,23 @@ static int flash_read_buf(int dev, int fd, void *buf, size_t count,
 				DEVNAME(dev), strerror(errno));
 			return -1;
 		}
-		if (rc != readlen) {
-			fprintf(stderr,
-				"Read error on %s: Attempted to read %zd 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,
 			DEVNAME(dev));
 #endif
-		processed += readlen;
-		readlen = min(blocklen, count - processed);
-		block_seek = 0;
-		blockstart += blocklen;
+		processed += rc;
+		if (rc != readlen) {
+			fprintf(stderr,
+				"Warning on %s: Attempted to read %zd bytes but got %d\n",
+				DEVNAME(dev), readlen, rc);
+			readlen -= rc;
+			block_seek += rc;
+		} else {
+			blockstart += blocklen;
+			readlen = min(blocklen, count - processed);
+			block_seek = 0;
+		}
 	}
 
 	return processed;
-- 
2.25.1

Re: [PATCH 1/1] tools: env: Handle shorter read calls

[Tom Rini]

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On Tue, Aug 24, 2021 at 05:29:50PM +0200, Thibault Ferrante wrote:

> On some cases, the actual number of bytes read can be shorter
> than what was requested. This can be handled gracefully by
> taking this difference into account instead of exiting.
> 
> Signed-off-by: Thibault Ferrante <thibault.ferrante@gmail.com>

Applied to u-boot/next, thanks!

-- 
Tom

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