[libvirt] [PATCH 2/4] util: add functions to keep capabilities

[Daniel P. Berrange]

On Mon, Jan 30, 2012 at 06:09:44PM +0900, Taku Izumi wrote:
> 
> This patch introduces virKeepCapabilities() function and implements
> virCommandAllowCap() function.
> 
> Existing virClearCapabilities() is function to clear all capabilities.
> Instead virKeepCapabilities() is function to keep arbitrary capabilities.
> 
> 
> Signed-off-by: Taku Izumi <izumi.taku at jp.fujitsu.com>
> Signed-off-by: Shota Hirae <m11g1401 at hibikino.ne.jp>
> ---
>  src/util/command.c |   45 ++++++++++++++++++++++++++++++++++++++-------
>  src/util/command.h |    4 +---
>  2 files changed, 39 insertions(+), 10 deletions(-)
> 
> Index: libvirt/src/util/command.c
> ===================================================================
> --- libvirt.orig/src/util/command.c
> +++ libvirt/src/util/command.c
> @@ -103,6 +103,8 @@ struct _virCommand {
>      pid_t pid;
>      char *pidfile;
>      bool reap;
> +
> +    unsigned long long capabilities;
>  };
>  
>  /*
> @@ -182,6 +184,33 @@ static int virClearCapabilities(void)
>  
>      return 0;
>  }
> +
> +/**
> + * virKeepCapabilities:
> + *  @capabilities - capability flag to keep.
> + *                  In case of 0, this function is identical to
> + *                  virClearCapabilities()
> + *
> + */
> +static int virKeepCapabilities(unsigned long long capabilities)
> +{
> +    int ret, i;
> +
> +    capng_clear(CAPNG_SELECT_BOTH);
> +
> +    for (i = 0; i <= CAP_LAST_CAP; i++) {
> +        if (capabilities & (1ULL << i))
> +            capng_update(CAPNG_ADD, CAPNG_BOUNDING_SET, i);
> +    }
> +
> +    if (ret = capng_apply(CAPNG_SELECT_BOTH) < 0) {
> +        virCommandError(VIR_ERR_INTERNAL_ERROR,
> +                        _("cannot apply process capabilities %d"), ret);
> +        return -1;
> +    }
> +
> +    return 0;
> +}
>  # else
>  static int virClearCapabilities(void)
>  {
> @@ -189,6 +218,11 @@ static int virClearCapabilities(void)
>  //             "capabilities");
>      return 0;
>  }
> +
> +static int virKeepCapabilities(unsigned long long capabilities)
> +{
> +    return 0;
> +}
>  # endif


I suggest calling this 'virSetCapabilities' instead,
since it is possible this is called with no capabilities
to be kept.

>  
>  /**
> @@ -883,26 +917,23 @@ virCommandClearCaps(virCommandPtr cmd)
>      cmd->flags |= VIR_EXEC_CLEAR_CAPS;
>  }
>  
> -#if 0 /* XXX Enable if we have a need for capability management.  */
> -
>  /**
>   * virCommandAllowCap:
>   * @cmd: the command to modify
> - * @capability: what to allow
> + * @capabilities: what to allow
>   *
> - * Re-allow a specific capability
> + * Allow specific capabilities
>   */
>  void
>  virCommandAllowCap(virCommandPtr cmd,
> -                   int capability ATTRIBUTE_UNUSED)
> +                   unsigned long long capabilities)

IMHO this shouldn't be changed.

>  {
>      if (!cmd || cmd->has_error)
>          return;
>  
> -    /* XXX ? */
> +    cmd->capabilities = capabilities;

I'd prefer to see

    cmd->capabilities  |= capability;


Daniel
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