[Libguestfs] [PATCH] p2v: improve error message for sudo with password

[Richard W.M. Jones]

On Thu, Jun 23, 2016 at 11:09:23AM +0200, Pino Toscano wrote:
> Print a better error message when the non-root user on the conversion
> server requires a password to use sudo, and p2v is told to use sudo.
> 
> See also RHZ#1340809.
> ---
>  p2v/ssh.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/p2v/ssh.c b/p2v/ssh.c
> index 76a6827..97d76ae 100644
> --- a/p2v/ssh.c
> +++ b/p2v/ssh.c
> @@ -97,6 +97,7 @@ static void free_regexps (void) __attribute__((destructor));
>  
>  static pcre *password_re;
>  static pcre *ssh_message_re;
> +static pcre *sudo_password_re;
>  static pcre *prompt_re;
>  static pcre *version_re;
>  static pcre *feature_libguestfs_rewrite_re;
> @@ -140,6 +141,7 @@ compile_regexps (void)
>  
>    COMPILE (password_re, "password:", 0);
>    COMPILE (ssh_message_re, "(ssh: .*)", 0);
> +  COMPILE (sudo_password_re, "sudo: a password is required", 0);
>    /* The magic synchronization strings all match this expression.  See
>     * start_ssh function below.
>     */
> @@ -160,6 +162,7 @@ free_regexps (void)
>  {
>    pcre_free (password_re);
>    pcre_free (ssh_message_re);
> +  pcre_free (sudo_password_re);
>    pcre_free (prompt_re);
>    pcre_free (version_re);
>    pcre_free (feature_libguestfs_rewrite_re);
> @@ -532,6 +535,7 @@ test_connection (struct config *config)
>                           (mexp_regexp[]) {
>                             { 100, .re = version_re },
>                             { 101, .re = prompt_re },
> +                           { 102, .re = sudo_password_re },
>                             { 0 }
>                           }, ovector, ovecsize)) {
>      case 100:                   /* Got version string. */
> @@ -546,6 +550,11 @@ test_connection (struct config *config)
>      case 101:             /* Got the prompt. */
>        goto end_of_version;
>  
> +    case 102:
> +      mexp_close (h);
> +      set_ssh_error ("sudo for user '%s' requires a password", config->username);
> +      return -1;
> +
>      case MEXP_EOF:
>        mexp_close (h);
>        set_ssh_error ("unexpected end of file waiting virt-v2v --version output");
> -- 
> 2.5.5
> 

This is pretty much the same as my patch, so ACK.

However it did lead me to think that if we're matching on error
messages now, we need to also send a "LANG=C" command (which is not so
simple).

And from there I wondered if we can rely on people using bash (or
other Bourne-like shell).  Currently we send 'export PS1=...' which
will totally fail for anyone using csh/tcsh (I'm not sure about ksh
and zsh).

So I'm still looking at this.  However please push the above patch
anyway.

Rich.

-- 
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