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

[Eric Blake <eblake@redhat.com>]

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On 06/16/2014 09:16 PM, lists@fixnum.org wrote:
> From: Wim Vander Schelden <wim@fixnum.org>
> 
> ---

Missing a Signed-off-by declaration; without that legal hurdle, we are
unwilling to take the patch.

For more details: http://wiki.qemu.org/Contribute/SubmitAPatch

>  linux-user/syscall.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)

Run your patch through scripts/checkpatch.pl to flag many of the
complaints below.

> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index c134c32..f9fed3e 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -4947,6 +4947,54 @@ 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);

Why a double space?

> +    if(fd_orig < 0) {

Wrong style - we use space after 'if'

> +        return fd_orig;
> +    }
> +
> +    while(true) {

and space after 'while'

> +        if(! word_skipped) {
> +            // Skip the first string, which is the path to qemu-*-static instead of the actual command.

/* */ comments instead of //; fit 80 columns.

> +            size_t command_length = strnlen(buf, sizeof(buf));
> +            if(command_length != sizeof(buf)) {
> +                // Null byte found, skip one string
> +                nb_read -= command_length + 1;
> +                cp_buf += command_length + 1;
> +                word_skipped = true;

This feels a bit complicated.  Why not just use memchr() to locate the
first NUL byte, rather than messing with strnlen()?

> @@ -5148,6 +5196,7 @@ 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},

Match the style of the lines nearby (space before '}')

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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