Re: [Qemu-devel] [PATCH 4/4][RFC] Add logic to QEMU to read command line options from qcow2 images

["andrzej zaborowski" <balrogg@gmail.com>]

On 08/08/07, Jorge Lucángeli Obes <t4m5yn@gmail.com> wrote:
> This patch makes QEMU check for command line options stored in qcow2 images.
>
> Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
> Signed-off-by: Jorge Lucángeli Obes <t4m5yn@gmail.com>
> ---
> diff --git a/qemu/vl.c b/qemu/vl.c
> index 4ad39f1..1d28794 100644
> --- a/qemu/vl.c
> +++ b/qemu/vl.c
> @@ -184,6 +184,11 @@ int time_drift_fix = 0;
>  const char *cpu_vendor_string;
>
>  /***********************************************************/
> +/* Image annotation support */
> +
> +char *img_get_annot(char *filename);
> +
> +/***********************************************************/
>  /* x86 ISA bus support */
>
>  target_phys_addr_t isa_mem_base = 0;
> @@ -6917,6 +6922,13 @@ int main(int argc, char **argv)
>      char usb_devices[MAX_USB_CMDLINE][128];
>      int usb_devices_index;
>      int fds[2];
> +    char *tmpannot;
> +    char annot[1024];
> +    int done = 0;
> +    unsigned int nbtoks = 0;
> +    char *tok;
> +    BlockDriver *drv;
> +    BlockDriverState *bs;
>
>      saved_argc = argc;
>      saved_argv = argv;
> @@ -7000,6 +7012,58 @@ int main(int argc, char **argv)
>      nb_nics = 0;
>      /* default mac address of the first network interface */
>
> +    bdrv_init();
> +
> +    drv = bdrv_find_format("qcow2");
> +
> +    if (argc > 1 && argv[1][0] != '-') {
> +        bs = bdrv_new("");
> +        if (!bs) {
> +            fprintf(stderr, "Not enough memory");
> +            exit(1);
> +        }
> +        if (bdrv_open2(bs, argv[1], 0, drv) < 0) {
> +            fprintf(stderr, "Could not open '%s'", argv[1]);
> +            bdrv_delete(bs);
> +            exit(1);
> +        }
> +
> +        tmpannot = bdrv_get_annot(bs, "commandline_args");
> +        if (tmpannot) {
> +            pstrcpy(annot, 1024, tmpannot);

I thought one of the arguments for storing config options was the
commandline length limit, which is 32k or so characters on most
systems.

> +
> +            do {
> +                tok = strtok(nbtoks == 0? tmpannot : NULL, " ");
> +
> +                if (tok != NULL)
> +                    nbtoks++;
> +                else
> +                    done = 1;
> +            } while (!done);
> +
> +            free(tmpannot);
> +
> +            if (nbtoks > 0) {
> +                char **argvprime = malloc((nbtoks + argc) * sizeof(char*));
> +
> +                for (i = 0; i < argc; i++)
> +                    argvprime[i] = argv[i];
> +
> +                for (i = 0; i < nbtoks; i++)
> +                    argvprime[i + argc] = strtok(i == 0? annot : NULL, " ");
> +
> +                argv = argvprime;
> +                argc = argc + nbtoks;
> +
> +                for (i = 0; i < nbtoks + 2; i++)
> +                    printf("argv[%d] = %s\n", i, argv[i]);
> +
> +            }
> +        }
> +
> +        bdrv_delete(bs);
> +    }
> +
>      optind = 1;
>      for(;;) {
>          if (optind >= argc)
> @@ -7558,7 +7622,6 @@ int main(int argc, char **argv)
>  #endif
>
>      /* we always create the cdrom drive, even if no disk is there */
> -    bdrv_init();
>      if (cdrom_index >= 0) {
>          bs_table[cdrom_index] = bdrv_new("cdrom");
>          bdrv_set_type_hint(bs_table[cdrom_index], BDRV_TYPE_CDROM);
> @@ -7764,5 +7827,8 @@ int main(int argc, char **argv)
>
>      main_loop();
>      quit_timers();
> +
> +    /* was reassigned above so it needs free()ing */
> +    free(argv);
>      return 0;
>  }
>
>

Yes, the file format starting with "#! /path/to/qemu" is a much better
idea, but the commandline length limitation has to be taken care of
separately, perhaps the switches should follow on next lines in the
file while the #! line shouldn't specify the switches.

Regards,
Andrzej (away until mid-September(?))