Re: [Qemu-devel] [PATCH] linux-user: added fake open() for /proc/self/cmdline

[Riku Voipio <riku.voipio@iki.fi>]

On Wed, Jun 18, 2014 at 11:02:39AM +0200, lists@fixnum.org wrote:
> From: Wim Vander Schelden <wim@fixnum.org>

Seems to work,
applied to linux-user updates 

> Signed-off-by: Wim Vander Schelden <wim@fixnum.org>
> ---
>  linux-user/syscall.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 46 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index c134c32..1be0f09 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -4947,6 +4947,51 @@ int host_to_target_waitstatus(int status)
>      return status;
>  }
>  
> +static int open_self_cmdline(void *cpu_env, int fd)
> +{
> +    int fd_orig = -1;
> +    bool word_skipped = false;
> +
> +    fd_orig = open("/proc/self/cmdline", O_RDONLY);
> +    if (fd_orig < 0) {
> +        return fd_orig;
> +    }
> +
> +    while (true) {
> +        ssize_t nb_read;
> +        char buf[128];
> +        char *cp_buf = buf;
> +
> +        nb_read = read(fd_orig, buf, sizeof(buf));
> +        if (nb_read < 0) {
> +            fd_orig = close(fd_orig);
> +            return -1;
> +        } else if (nb_read == 0) {
> +            break;
> +        }
> +
> +        if (!word_skipped) {
> +            /* Skip the first string, which is the path to qemu-*-static
> +               instead of the actual command. */
> +            cp_buf = memchr(buf, 0, sizeof(buf));
> +            if (cp_buf) {
> +                /* Null byte found, skip one string */
> +                cp_buf++;
> +                nb_read -= cp_buf - buf;
> +                word_skipped = true;
> +            }
> +        }
> +
> +        if (word_skipped) {
> +            if (write(fd, cp_buf, nb_read) != nb_read) {
> +                return -1;
> +            }
> +        }
> +    }
> +
> +    return close(fd_orig);
> +}
> +
>  static int open_self_maps(void *cpu_env, int fd)
>  {
>  #if defined(TARGET_ARM) || defined(TARGET_M68K) || defined(TARGET_UNICORE32)
> @@ -5148,6 +5193,7 @@ static int do_open(void *cpu_env, const char *pathname, int flags, mode_t mode)
>          { "maps", open_self_maps, is_proc_myself },
>          { "stat", open_self_stat, is_proc_myself },
>          { "auxv", open_self_auxv, is_proc_myself },
> +        { "cmdline", open_self_cmdline, is_proc_myself },
>  #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN)
>          { "/proc/net/route", open_net_route, is_proc },
>  #endif
> -- 
> 1.9.1
>