[Libguestfs] [nbdkit PATCH] data: don't ignore SIGPIPE

[Eric Blake]

On Fri, Jan 13, 2023 at 05:57:35AM +0000, Thomas Weißschuh wrote:
> If all of the requested data has been read, the call to popen_close will
> close the scripts output pipe and on the next write a SIGPIPE is
> delivered.
> When the scripts inherited signalhandler is ignoring the singal, it
> won't be aborted by default.

s/scripts/script's/2

> 
> This happens in the test suite, as make 4.4 seems to ignore this signal.
> Therefore the executed scripts never stop and the testsuite never
> finishes.

That's a bug in make:
https://savannah.gnu.org/bugs/index.php?63307

but one we may indeed need to work around (along with every other
impacted program).

> ---
>  plugins/data/format.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/plugins/data/format.c b/plugins/data/format.c
> index 3667ead6790f..2319ea09475c 100644
> --- a/plugins/data/format.c
> +++ b/plugins/data/format.c
> @@ -40,6 +40,7 @@
>  #include <stdarg.h>
>  #include <string.h>
>  #include <assert.h>
> +#include <signal.h>
>  
>  #define NBDKIT_API_VERSION 2
>  #include <nbdkit-plugin.h>
> @@ -1951,6 +1952,9 @@ store_script_len (struct allocator *a,
>    char buf[BUFSIZ];
>    size_t n;
>  
> +  /* Restore SIGPIPE back to SIG_DFL, since shell can't undo SIG_IGN */
> +  signal (SIGPIPE, SIG_DFL);
> +
>    pp = popen (script, "r");
>    if (pp == NULL) {
>      nbdkit_error ("popen: %m");

ACK from my end, even if make ends up fixing their regression.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org