[vlc-devel] [PATCH 5/6] spawn: provide fallback implementation using fork() & exec()

[Steve Lhomme]

This broke the tvOS build
https://code.videolan.org/videolan/vlc/-/jobs/450328

On 2020-09-19 12:29, Rémi Denis-Courmont wrote:
> ---
>   src/posix/spawn.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 64 insertions(+), 1 deletion(-)
> 
> diff --git a/src/posix/spawn.c b/src/posix/spawn.c
> index 774c6cb6cb..233bb01047 100644
> --- a/src/posix/spawn.c
> +++ b/src/posix/spawn.c
> @@ -115,11 +115,74 @@ out:
>   
>   #else /* _POSIX_SPAWN */
>   
> +#include <vlc_fs.h>
> +
>   static int vlc_spawn_inner(pid_t *restrict pid, const char *path,
>                              const int *fdv, const char *const *argv,
>                              bool search)
>   {
> -    (void) pid; (void) path; (void) fdv; (void) argv; (void) search;
> +    size_t argc = 0;
> +
> +    assert(pid != NULL);
> +    assert(path != NULL);
> +    assert(fdv != NULL);
> +    assert(argv != NULL);
> +
> +    int nulfd = vlc_open("/dev/null", O_RDWR);
> +    if (unlikely(nulfd == -1))
> +        return errno;
> +
> +    while (argv[argc++] != NULL);
> +
> +    char **vargv = malloc(sizeof (*argv) * argc);
> +    if (unlikely(vargv == NULL)) {
> +        vlc_close(nulfd);
> +        return errno;
> +    }
> +
> +    for (size_t i = 0; i < argc; i++)
> +        vargv[i] = (char *)argv[i];
> +
> +    *pid = fork();
> +
> +    switch (*pid) {
> +         case -1:
> +             return errno;
> +
> +         case 0:
> +             break;
> +
> +         default:
> +             free(vargv);
> +             vlc_close(nulfd);
> +             return 0;
> +    }
> +
> +    for (int newfd = 0; newfd < 3 || fdv[newfd] != -1; newfd++) {
> +        int oldfd = fdv[newfd];
> +
> +        if (oldfd == -1)
> +            oldfd = nulfd;
> +
> +        if (oldfd == newfd)
> +            fcntl(oldfd, F_SETFD, fcntl(oldfd, F_GETFD) & ~FD_CLOEXEC);
> +        else
> +        if (dup2(oldfd, newfd) < 0)
> +            _exit(1);
> +    }
> +
> +    sigset_t set;
> +
> +    sigemptyset(&set);
> +    pthread_sigmask(SIG_SETMASK, &set, NULL);
> +    signal(SIGPIPE, SIG_DFL);
> +
> +    if (search)
> +        execvp(path, vargv);
> +    else
> +        execv(path, vargv);
> +
> +    _exit(1);
>   }
>   
>   #endif /* _POSIX_SPAWN */
> -- 
> 2.28.0
> 
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