Re: [PATCH] On Linux, read partition start offsets from sysfs if possible

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

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Looks good. Go ahead.
On 05.12.2013 13:17, Colin Watson wrote:
> This lets us cope with block device drivers that don't implement
> HDIO_GETGEO.  Fixes Ubuntu bug #1237519.
> 
> * grub-core/osdep/linux/hostdisk.c (sysfs_partition_path): New
> function.
> (sysfs_partition_start): Likewise.
> (grub_util_find_partition_start_os): Try sysfs_partition_start
> before HDIO_GETGEO.
> ---
>  ChangeLog                        | 12 ++++++
>  grub-core/osdep/linux/hostdisk.c | 89 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 101 insertions(+)
> 
> diff --git a/ChangeLog b/ChangeLog
> index d60acab..d08d841 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,15 @@
> +2013-12-05  Colin Watson  <cjwatson@ubuntu.com>
> +
> +	On Linux, read partition start offsets from sysfs if possible, to
> +	cope with block device drivers that don't implement HDIO_GETGEO.
> +	Fixes Ubuntu bug #1237519.
> +
> +	* grub-core/osdep/linux/hostdisk.c (sysfs_partition_path): New
> +	function.
> +	(sysfs_partition_start): Likewise.
> +	(grub_util_find_partition_start_os): Try sysfs_partition_start
> +	before HDIO_GETGEO.
> +
>  2013-12-05  Vladimir Serbinenko  <phcoder@gmail.com>
>  
>  	Handle unaligned .bss on sparc64.
> diff --git a/grub-core/osdep/linux/hostdisk.c b/grub-core/osdep/linux/hostdisk.c
> index a2c80f3..74d87a4 100644
> --- a/grub-core/osdep/linux/hostdisk.c
> +++ b/grub-core/osdep/linux/hostdisk.c
> @@ -27,6 +27,7 @@
>  #include <grub/emu/misc.h>
>  #include <grub/emu/hostdisk.h>
>  #include <grub/emu/getroot.h>
> +#include <grub/emu/exec.h>
>  #include <grub/misc.h>
>  #include <grub/i18n.h>
>  #include <grub/list.h>
> @@ -39,6 +40,7 @@
>  #include <unistd.h>
>  #include <sys/types.h>
>  #include <sys/stat.h>
> +#include <sys/wait.h>
>  #include <fcntl.h>
>  #include <errno.h>
>  #include <limits.h>
> @@ -93,12 +95,99 @@ grub_util_get_fd_size_os (grub_util_fd_t fd, const char *name, unsigned *log_sec
>    return nr;
>  }
>  
> +static char *
> +sysfs_partition_path (const char *dev, const char *entry)
> +{
> +  const char *argv[7];
> +  int fd;
> +  pid_t pid;
> +  FILE *udevadm;
> +  char *buf = NULL;
> +  size_t len = 0;
> +  char *path = NULL;
> +
> +  argv[0] = "udevadm";
> +  argv[1] = "info";
> +  argv[2] = "--query";
> +  argv[3] = "path";
> +  argv[4] = "--name";
> +  argv[5] = dev;
> +  argv[6] = NULL;
> +
> +  pid = grub_util_exec_pipe (argv, &fd);
> +
> +  if (!pid)
> +    return NULL;
> +
> +  /* Parent.  Read udevadm's output.  */
> +  udevadm = fdopen (fd, "r");
> +  if (!udevadm)
> +    {
> +      grub_util_warn (_("Unable to open stream from %s: %s"),
> +		      "udevadm", strerror (errno));
> +      close (fd);
> +      goto out;
> +    }
> +
> +  if (getline (&buf, &len, udevadm) > 0)
> +    {
> +      char *newline;
> +
> +      newline = strchr (buf, '\n');
> +      if (newline)
> +	*newline = '\0';
> +      path = xasprintf ("/sys%s/%s", buf, entry);
> +    }
> +
> +out:
> +  if (udevadm)
> +    fclose (udevadm);
> +  waitpid (pid, NULL, 0);
> +  free (buf);
> +
> +  return path;
> +}
> +
> +static int
> +sysfs_partition_start (const char *dev, grub_disk_addr_t *start)
> +{
> +  char *path;
> +  FILE *fp;
> +  unsigned long long val;
> +  int ret = 0;
> +
> +  path = sysfs_partition_path (dev, "start");
> +  if (!path)
> +    return 0;
> +
> +  fp = grub_util_fopen (path, "r");
> +  if (!fp)
> +    goto out;
> +
> +  if (fscanf (fp, "%llu", &val) == 1)
> +    {
> +      *start = (grub_disk_addr_t) val;
> +      ret = 1;
> +    }
> +
> +out:
> +  free (path);
> +  if (fp)
> +    fclose (fp);
> +
> +  return ret;
> +}
> +
>  grub_disk_addr_t
>  grub_util_find_partition_start_os (const char *dev)
>  {
> +  grub_disk_addr_t start;
>    grub_util_fd_t fd;
>    struct hd_geometry hdg;
>  
> +  if (sysfs_partition_start (dev, &start))
> +    return start;
> +
>    fd = open (dev, O_RDONLY);
>    if (fd == -1)
>      {
> 



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