[PATCH] tools: kwboot: Replace fstat()+st_size by lseek()+SEEK_END

[PATCH] tools: kwboot: Replace fstat()+st_size by lseek()+SEEK_END

[Pali Rohár]

fstat()'s st_size works only for regular files. lseek() with SEEK_END works
also for block or MTD devices. This replacement allows kwboot to load
kwbimage from /dev/mtd0 for booting another device over /dev/ttyS0.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 tools/kwboot.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/tools/kwboot.c b/tools/kwboot.c
index 9f2dd2de4ef5..b697d3b60e6a 100644
--- a/tools/kwboot.c
+++ b/tools/kwboot.c
@@ -1591,8 +1591,8 @@ static void *
 kwboot_read_image(const char *path, size_t *size, size_t reserve)
 {
 	int rc, fd;
-	struct stat st;
 	void *img;
+	off_t len;
 	off_t tot;
 
 	rc = -1;
@@ -1602,31 +1602,34 @@ kwboot_read_image(const char *path, size_t *size, size_t reserve)
 	if (fd < 0)
 		goto out;
 
-	rc = fstat(fd, &st);
-	if (rc)
+	len = lseek(fd, 0, SEEK_END);
+	if (len == (off_t)-1)
+		goto out;
+
+	if (lseek(fd, 0, SEEK_SET) == (off_t)-1)
 		goto out;
 
-	img = malloc(st.st_size + reserve);
+	img = malloc(len + reserve);
 	if (!img)
 		goto out;
 
 	tot = 0;
-	while (tot < st.st_size) {
-		ssize_t rd = read(fd, img + tot, st.st_size - tot);
+	while (tot < len) {
+		ssize_t rd = read(fd, img + tot, len - tot);
 
 		if (rd < 0)
 			goto out;
 
 		tot += rd;
 
-		if (!rd && tot < st.st_size) {
+		if (!rd && tot < len) {
 			errno = EIO;
 			goto out;
 		}
 	}
 
 	rc = 0;
-	*size = st.st_size;
+	*size = len;
 out:
 	if (rc && img) {
 		free(img);
-- 
2.20.1

Re: [PATCH] tools: kwboot: Replace fstat()+st_size by lseek()+SEEK_END

[Marek Behún]

On Wed,  6 Apr 2022 15:18:59 +0200
Pali Rohár <pali@kernel.org> wrote:

> fstat()'s st_size works only for regular files. lseek() with SEEK_END works
> also for block or MTD devices. This replacement allows kwboot to load
> kwbimage from /dev/mtd0 for booting another device over /dev/ttyS0.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>

Nice.

Reviewed-by: Marek Behún <marek.behun@nic.cz>

Re: [PATCH] tools: kwboot: Replace fstat()+st_size by lseek()+SEEK_END

[Stefan Roese]

On 4/6/22 15:18, Pali Rohár wrote:
> fstat()'s st_size works only for regular files. lseek() with SEEK_END works
> also for block or MTD devices. This replacement allows kwboot to load
> kwbimage from /dev/mtd0 for booting another device over /dev/ttyS0.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>

Applied to u-boot-marvell/master

Thanks,
Stefan

> ---
>   tools/kwboot.c | 19 +++++++++++--------
>   1 file changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/tools/kwboot.c b/tools/kwboot.c
> index 9f2dd2de4ef5..b697d3b60e6a 100644
> --- a/tools/kwboot.c
> +++ b/tools/kwboot.c
> @@ -1591,8 +1591,8 @@ static void *
>   kwboot_read_image(const char *path, size_t *size, size_t reserve)
>   {
>   	int rc, fd;
> -	struct stat st;
>   	void *img;
> +	off_t len;
>   	off_t tot;
>   
>   	rc = -1;
> @@ -1602,31 +1602,34 @@ kwboot_read_image(const char *path, size_t *size, size_t reserve)
>   	if (fd < 0)
>   		goto out;
>   
> -	rc = fstat(fd, &st);
> -	if (rc)
> +	len = lseek(fd, 0, SEEK_END);
> +	if (len == (off_t)-1)
> +		goto out;
> +
> +	if (lseek(fd, 0, SEEK_SET) == (off_t)-1)
>   		goto out;
>   
> -	img = malloc(st.st_size + reserve);
> +	img = malloc(len + reserve);
>   	if (!img)
>   		goto out;
>   
>   	tot = 0;
> -	while (tot < st.st_size) {
> -		ssize_t rd = read(fd, img + tot, st.st_size - tot);
> +	while (tot < len) {
> +		ssize_t rd = read(fd, img + tot, len - tot);
>   
>   		if (rd < 0)
>   			goto out;
>   
>   		tot += rd;
>   
> -		if (!rd && tot < st.st_size) {
> +		if (!rd && tot < len) {
>   			errno = EIO;
>   			goto out;
>   		}
>   	}
>   
>   	rc = 0;
> -	*size = st.st_size;
> +	*size = len;
>   out:
>   	if (rc && img) {
>   		free(img);

Viele Grüße,
Stefan Roese

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