[v2,1/2] linux-user: fix the errno value in print_syscall_err()
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Message ID 20200708152435.706070-2-laurent@vivier.eu
State New
Headers show
Series
  • [v2,1/2] linux-user: fix the errno value in print_syscall_err()
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Commit Message

Laurent Vivier July 8, 2020, 3:24 p.m. UTC
errno of the target is returned as a negative value by the syscall,
not in the host errno variable.

The emulation of the target syscall can return an error while the
host doesn't set an errno value. Target errnos and host errnos can
also differ in some cases.

Fixes: c84be71f6854 ("linux-user: Extend strace support to enable argument printing after syscall execution")
Cc: Filip.Bozuta@syrmia.com
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/strace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Richard Henderson July 8, 2020, 3:49 p.m. UTC | #1
On 7/8/20 8:24 AM, Laurent Vivier wrote:
> errno of the target is returned as a negative value by the syscall,
> not in the host errno variable.
> 
> The emulation of the target syscall can return an error while the
> host doesn't set an errno value. Target errnos and host errnos can
> also differ in some cases.
> 
> Fixes: c84be71f6854 ("linux-user: Extend strace support to enable argument printing after syscall execution")
> Cc: Filip.Bozuta@syrmia.com
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> ---
>  linux-user/strace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~
Philippe Mathieu-Daudé July 8, 2020, 4:47 p.m. UTC | #2
On 7/8/20 5:24 PM, Laurent Vivier wrote:
> errno of the target is returned as a negative value by the syscall,
> not in the host errno variable.
> 
> The emulation of the target syscall can return an error while the
> host doesn't set an errno value. Target errnos and host errnos can
> also differ in some cases.
> 
> Fixes: c84be71f6854 ("linux-user: Extend strace support to enable argument printing after syscall execution")
> Cc: Filip.Bozuta@syrmia.com
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> ---
>  linux-user/strace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index 5235b2260cdd..b42664bbd180 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -731,7 +731,7 @@ print_syscall_err(abi_long ret)
>  
>      qemu_log(" = ");
>      if (ret < 0) {
> -        qemu_log("-1 errno=%d", errno);
> +        qemu_log("-1 errno=%d", (int)-ret);
>          errstr = target_strerror(-ret);
>          if (errstr) {
>              qemu_log(" (%s)", errstr);
> 

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Filip Bozuta July 10, 2020, 1:48 p.m. UTC | #3
On 8.7.20. 17:24, Laurent Vivier wrote:
> errno of the target is returned as a negative value by the syscall,
> not in the host errno variable.
>
> The emulation of the target syscall can return an error while the
> host doesn't set an errno value. Target errnos and host errnos can
> also differ in some cases.
>
> Fixes: c84be71f6854 ("linux-user: Extend strace support to enable argument printing after syscall execution")
> Cc: Filip.Bozuta@syrmia.com
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> ---
>   linux-user/strace.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index 5235b2260cdd..b42664bbd180 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -731,7 +731,7 @@ print_syscall_err(abi_long ret)
>   
>       qemu_log(" = ");
>       if (ret < 0) {
> -        qemu_log("-1 errno=%d", errno);
> +        qemu_log("-1 errno=%d", (int)-ret);
>           errstr = target_strerror(-ret);
>           if (errstr) {
>               qemu_log(" (%s)", errstr);
Reviewed-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Laurent Vivier July 13, 2020, 7:29 p.m. UTC | #4
Le 08/07/2020 à 17:24, Laurent Vivier a écrit :
> errno of the target is returned as a negative value by the syscall,
> not in the host errno variable.
> 
> The emulation of the target syscall can return an error while the
> host doesn't set an errno value. Target errnos and host errnos can
> also differ in some cases.
> 
> Fixes: c84be71f6854 ("linux-user: Extend strace support to enable argument printing after syscall execution")
> Cc: Filip.Bozuta@syrmia.com
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> ---
>  linux-user/strace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index 5235b2260cdd..b42664bbd180 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -731,7 +731,7 @@ print_syscall_err(abi_long ret)
>  
>      qemu_log(" = ");
>      if (ret < 0) {
> -        qemu_log("-1 errno=%d", errno);
> +        qemu_log("-1 errno=%d", (int)-ret);
>          errstr = target_strerror(-ret);
>          if (errstr) {
>              qemu_log(" (%s)", errstr);
> 

Applied to my linux-user-for-5.1 branch.

Thanks,
Laurent

Patch
diff mbox series

diff --git a/linux-user/strace.c b/linux-user/strace.c
index 5235b2260cdd..b42664bbd180 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -731,7 +731,7 @@  print_syscall_err(abi_long ret)
 
     qemu_log(" = ");
     if (ret < 0) {
-        qemu_log("-1 errno=%d", errno);
+        qemu_log("-1 errno=%d", (int)-ret);
         errstr = target_strerror(-ret);
         if (errstr) {
             qemu_log(" (%s)", errstr);