Re: [Libguestfs] [PATCH] New API: part_get_part_type for showing partition type

Richard W.M. Jones
2015-03-23T13:28:37Z

On Tue, Mar 17, 2015 at 02:45:46AM -0400, Chen Hanxiao
wrote:
> This patch will add support for getting partition type
> of a partiton numbered device.
>
> Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>
> ---
>  daemon/parted.c      | 112
+++++++++++++++++++++++++++++++++++++++++++++++++++
>  generator/actions.ml |  18 +++++++++
>  src/MAX_PROC_NR      |   2 +-
>  3 files changed, 131 insertions(+), 1 deletion(-)
>
> diff --git a/daemon/parted.c b/daemon/parted.c
> index a7bcb99..0ae6e5c 100644
> --- a/daemon/parted.c
> +++ b/daemon/parted.c
> @@ -33,6 +33,10 @@ GUESTFSD_EXT_CMD(str_parted, parted);
>  GUESTFSD_EXT_CMD(str_sfdisk, sfdisk);
>  GUESTFSD_EXT_CMD(str_sgdisk, sgdisk);
>
> +#ifndef PARTED_NO_M
> +# define PARTED_NO_M 0
> +#endif

What does this bit do?

>  /* Notes:
>   *
>   * Parted 1.9 sends error messages to stdout, hence use of the
> @@ -1022,3 +1026,111 @@ do_part_get_name (const char *device, int partnum)
>    reply_with_error ("cannot get the partition name from '%s'
layouts", parttype);
>    return NULL;
>  }
> +
> +char *
> +do_part_get_part_type (const char *device, int partnum)
> +{
> +  CLEANUP_FREE char *parttype;
> +  char *part_type;
> +
> +  if (partnum <= 0) {
> +    reply_with_error ("partition number must be >= 1");
> +    return NULL;
> +  }
> +
> +  parttype = do_part_get_parttype (device);
> +  if (parttype == NULL)
> +    return NULL;
> +
> +  if (STREQ (parttype, "gpt")) {
> +    part_type = strdup("primary");
> +    if (part_type == NULL) {
> +      reply_with_error ("strdup failed");
> +      return NULL;
> +    }
> +    return part_type;
> +  }
> +
> +  /* machine parseable output by 'parted -m' did not provide
> +   * partition type info.
> +   * Use traditional style.
> +   */
> +  CLEANUP_FREE char *out = print_partition_table (device, PARTED_NO_M);
> +  if (!out)
> +    return NULL;
> +
> +  CLEANUP_FREE_STRING_LIST char **lines = split_lines (out);
> +
> +  if (!lines)
> +    return NULL;
> +
> +  size_t start = 0, end = 0, row;
> +
> +  for (row = 0; lines[row] != NULL; ++row)
> +    if (STRPREFIX (lines[row], "Number")) {
> +      start = row + 1;
> +      break;
> +    }
> +
> +  if (start == 0) {
> +    reply_with_error ("parted output has no \"Number\"
line");
> +    return NULL;
> +  }
> +
> +  for (row = start; lines[row] != NULL; ++row)
> +    if (STREQ (lines[row], "")) {
> +      end = row;
> +      break;
> +    }
> +
> +  if (end == 0) {
> +    reply_with_error ("parted output has no blank after end of
table");
> +    return NULL;
> +  }
> +
> +  /* Now parse the lines. */
> +  size_t i;
> +  int64_t temp_int64;
> +  int part_num;
> +  char temp_type[16];
> +  for (i = 0, row = start;  row < end; ++i, ++row) {
> +    if (sscanf (lines[row], "%d%" SCNi64 "B%" SCNi64
"B%" SCNi64 "B" "%s",
> +                &part_num,
> +                &temp_int64,
> +                &temp_int64,
> +                &temp_int64,
> +                temp_type) != 5) {

We're hoping here that the output of 'parted' never changes and
overflows the 16 byte buffer.

Instead of hoping, you can guarantee that by replacing %s with %15s

> +      reply_with_error ("could not parse row from output of parted
print command: %s", lines[row]);
> +      return NULL;
> +    }
> +
> +    if (part_num != partnum)
> +        continue;
> +
> +    if (STRPREFIX (temp_type, "primary")) {
> +      part_type = strdup("primary");
> +      if (part_type == NULL)
> +          goto error;
> +    } else if (STRPREFIX (temp_type, "logical")) {
> +      part_type = strdup("logical");
> +      if (part_type == NULL)
> +          goto error;
> +    } else if (STRPREFIX (temp_type, "extended")) {
> +      part_type = strdup("extended");
> +      if (part_type == NULL)
> +          goto error;
> +    } else
> +        goto error;
> +
> +    return part_type;
> +  }
> +
> +  if (row == end) {
> +    reply_with_error ("could not find partnum: %d", partnum);
> +    return NULL;
> +  }
> +
> +  error:
> +    reply_with_error ("strdup failed");
> +    return NULL;
> +}
> diff --git a/generator/actions.ml b/generator/actions.ml
> index fb971d3..72418b0 100644
> --- a/generator/actions.ml
> +++ b/generator/actions.ml
> @@ -12522,6 +12522,24 @@ This will Enable extended inode refs." };
>      longdesc = "\
>  This enable skinny metadata extent refs." };
>
> +  { defaults with
> +    name = "part_get_part_type";
> +    style = RString "partitiontype", [Device "device";
Int "partnum"], [];
> +    proc_nr = Some 453;
> +    tests = [
> +      InitEmpty, Always, TestResultString (
> +        [["part_init"; "/dev/sda"; "mbr"];
> +         ["part_add"; "/dev/sda"; "p";
"64"; "204799"];
> +         ["part_add"; "/dev/sda"; "e";
"204800"; "614400"];
> +         ["part_add"; "/dev/sda"; "l";
"204864"; "205988"];
> +         ["part_get_part_type"; "/dev/sda";
"5"]], "logical"), []
> +    ];
> +
> +    shortdesc = "get the partition type";
> +    longdesc = "\
> +This could get the partition type, such as primary, logical,
> +on partition numbered C<partnum> on device C<device>." };
> +
>  ]
>
>  (* Non-API meta-commands available only in guestfish.
> diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
> index 8670c73..534b992 100644
> --- a/src/MAX_PROC_NR
> +++ b/src/MAX_PROC_NR
> @@ -1 +1 @@
> -452
> +453

Rich.

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