[PATCH] fstests: fix compilation error in splice2pipe on old (<C99) compilers

[PATCH] fstests: fix compilation error in splice2pipe on old (<C99) compilers

[Andrey Albershteyn]

Compilation fails on system with compiler which uses older C dialect
(e.g. RHEL7; gcc with gnu90) with:

splice2pipe.c: In function 'prepare_pipe':
splice2pipe.c:54:2: error: 'for' loop initial declarations are only allowed in C99 mode
  for (unsigned r = pipe_size; r > 0;) {

Fix it by declaring 'r' outside of the loop.

Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
---
 src/splice2pipe.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/splice2pipe.c b/src/splice2pipe.c
index bd33ff67..00b3a23a 100644
--- a/src/splice2pipe.c
+++ b/src/splice2pipe.c
@@ -41,6 +41,7 @@
  */
 static void prepare_pipe(int p[2])
 {
+	unsigned int r = 0;
 	if (pipe(p)) {
 		perror("pipe failed");
 		abort();
@@ -51,7 +52,7 @@ static void prepare_pipe(int p[2])
 
 	/* fill the pipe completely; each pipe_buffer will now have
 	   the PIPE_BUF_FLAG_CAN_MERGE flag */
-	for (unsigned r = pipe_size; r > 0;) {
+	for (r = pipe_size; r > 0;) {
 		unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;
 		write(p[1], buffer, n);
 		r -= n;
@@ -59,7 +60,7 @@ static void prepare_pipe(int p[2])
 
 	/* drain the pipe, freeing all pipe_buffer instances (but
 	   leaving the flags initialized) */
-	for (unsigned r = pipe_size; r > 0;) {
+	for (r = pipe_size; r > 0;) {
 		unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;
 		read(p[0], buffer, n);
 		r -= n;
-- 
2.31.1

Re: [PATCH] fstests: fix compilation error in splice2pipe on old (<C99) compilers

[Darrick J. Wong]

On Tue, May 16, 2023 at 12:23:03PM +0200, Andrey Albershteyn wrote:
> Compilation fails on system with compiler which uses older C dialect
> (e.g. RHEL7; gcc with gnu90) with:
> 
> splice2pipe.c: In function 'prepare_pipe':
> splice2pipe.c:54:2: error: 'for' loop initial declarations are only allowed in C99 mode
>   for (unsigned r = pipe_size; r > 0;) {
> 
> Fix it by declaring 'r' outside of the loop.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>

Not sure if you need to zero-init the variable, but eh looks good to me

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  src/splice2pipe.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/src/splice2pipe.c b/src/splice2pipe.c
> index bd33ff67..00b3a23a 100644
> --- a/src/splice2pipe.c
> +++ b/src/splice2pipe.c
> @@ -41,6 +41,7 @@
>   */
>  static void prepare_pipe(int p[2])
>  {
> +	unsigned int r = 0;
>  	if (pipe(p)) {
>  		perror("pipe failed");
>  		abort();
> @@ -51,7 +52,7 @@ static void prepare_pipe(int p[2])
>  
>  	/* fill the pipe completely; each pipe_buffer will now have
>  	   the PIPE_BUF_FLAG_CAN_MERGE flag */
> -	for (unsigned r = pipe_size; r > 0;) {
> +	for (r = pipe_size; r > 0;) {
>  		unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;
>  		write(p[1], buffer, n);
>  		r -= n;
> @@ -59,7 +60,7 @@ static void prepare_pipe(int p[2])
>  
>  	/* drain the pipe, freeing all pipe_buffer instances (but
>  	   leaving the flags initialized) */
> -	for (unsigned r = pipe_size; r > 0;) {
> +	for (r = pipe_size; r > 0;) {
>  		unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;
>  		read(p[0], buffer, n);
>  		r -= n;
> -- 
> 2.31.1
>