[Libguestfs] [PATCH 2/4] febootstrap: Cope with non-existing insmod.static

[Richard W.M. Jones]

On Wed, Jun 01, 2011 at 12:43:10AM +0200, Hilko Bengen wrote:
> Add module loading functionality into init.c, make copying insmod.static to initrd optional.
> ---
>  configure.ac        |   14 +++++---------
>  helper/ext2initrd.c |    2 ++
>  helper/init.c       |   37 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 44 insertions(+), 9 deletions(-)
> 
> diff --git a/configure.ac b/configure.ac
> index 7606bca..382e270 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -71,17 +71,13 @@ dnl Required programs, libraries.
>  AC_PATH_PROG([INSMODSTATIC],[insmod.static],[no],
>               [$PATH$PATH_SEPARATOR/sbin$PATH_SEPARATOR])
>  if test "x$INSMODSTATIC" = "xno" ; then
> -  AC_MSG_FAILURE([insmod.static program not found
> -
> -Is /sbin in your current path?
> -
> -Note that Debian/Ubuntu do not package this file from module-init-tools.
> -Sorry, please fix your distribution.  In the meantime you can copy
> -/sbin/insmod.static from a Fedora machine.
> +  AC_MSG_WARN([insmod.static program not found
> +Compiling insmod functionality directly into init program.
>  ])
> +else
> +  AC_DEFINE_UNQUOTED([INSMODSTATIC],["$INSMODSTATIC"],
> +    [Full path to the insmod.static program.])
>  fi
> -AC_DEFINE_UNQUOTED([INSMODSTATIC],["$INSMODSTATIC"],
> -  [Full path to the insmod.static program.])
>  
>  AC_PATH_PROG([MKE2FS],[mke2fs],[no],
>               [$PATH$PATH_SEPARATOR/sbin$PATH_SEPARATOR])
> diff --git a/helper/ext2initrd.c b/helper/ext2initrd.c
> index 3d765ca..c65ecf8 100644
> --- a/helper/ext2initrd.c
> +++ b/helper/ext2initrd.c
> @@ -155,6 +155,7 @@ ext2_make_initrd (const char *modpath, const char *initrd)
>    free (cmd);
>    free_module_deps ();
>  
> +#ifdef INSMODSTATIC
>    /* Copy in insmod static binary. */
>    cmd = xasprintf ("cp %s %s", INSMODSTATIC, dir);
>    if (verbose >= 2) fprintf (stderr, "%s\n", cmd);
> @@ -163,6 +164,7 @@ ext2_make_initrd (const char *modpath, const char *initrd)
>      error (EXIT_FAILURE, 0,
>             "ext2_make_initrd: copy %s failed", INSMODSTATIC);
>    free (cmd);
> +#endif
>  
>    /* Copy in the init program, linked into this program as a data blob. */
>    char *init = xasprintf ("%s/init", dir);
> diff --git a/helper/init.c b/helper/init.c
> index 7b6b94e..ac71018 100644
> --- a/helper/init.c
> +++ b/helper/init.c
> @@ -36,6 +36,12 @@
>  #include <sys/stat.h>
>  #include <sys/wait.h>
>  
> +#ifndef INSMODSTATIC
> +#include <fcntl.h>
> +#include <asm/unistd.h>
> +extern long init_module(void *, unsigned long, const char *);
> +#endif
> +
>  /* Leave this enabled for now.  When we get more confident in the boot
>   * process we can turn this off or make it configurable.
>   */
> @@ -70,7 +76,9 @@ main ()
>     * executable.  Just make it executable.  It's easier than fixing
>     * everyone's distro.
>     */
> +#ifdef INSMODSTATIC
>    chmod ("/sbin/insmod.static", 0755);
> +#endif
>  
>    FILE *fp = fopen ("/modules", "r");
>    if (fp == NULL) {
> @@ -184,9 +192,38 @@ insmod (const char *filename)
>    }
>  
>    if (pid == 0) { /* Child. */
> +#ifdef INSMODSTATIC
>      execl ("/insmod.static", "insmod.static", filename, NULL);
>      perror ("insmod: execl");
>      _exit (EXIT_FAILURE);
> +#else
> +    int fd = open (filename, O_RDONLY);
> +    if (fd == -1) {
> +      fprintf (stderr, "insmod: open: %s: %s\n", filename, strerror(errno));
> +      _exit (EXIT_FAILURE);
> +    }
> +    struct stat st;
> +    if (fstat (fd, &st) == -1) {
> +      perror ("insmod: fstat");
> +      _exit (EXIT_FAILURE);
> +    }
> +    char buf[st.st_size];
> +    long offset = 0;
> +    do {
> +      long rc = read (fd, buf + offset, st.st_size - offset);
> +      if (rc == -1) {
> +        perror ("insmod: read");
> +        _exit (EXIT_FAILURE);
> +      }
> +      offset += rc;
> +    } while (offset < st.st_size);
> +    if (init_module (buf, st.st_size, "") != 0) {
> +      fprintf (stderr, "insmod: init_module: %s: %s\n", filename, strerror(errno));
> +      _exit (EXIT_FAILURE);
> +    }
> +    close (fd);
> +    _exit (EXIT_SUCCESS);
> +#endif
>    }
>  
>    /* Parent. */
> -- 

ACK, but once I properly test it I think I'll just make !INSMODSTATIC
the default and only choice.  It doesn't seem like there's any reason
to call out to an external program when it's so easy to do this way.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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