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Date: Tue, 6 May 2014 15:47:03 +0200 (CEST)
From: Lukáš Czerner <lczerner@...hat.com>
To: "Theodore Ts'o" <tytso@....edu>
cc: Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH -v2 3/3] mke2fs: check for a partition table and warn if
present
On Mon, 5 May 2014, Theodore Ts'o wrote:
> Date: Mon, 5 May 2014 21:02:13 -0400
> From: Theodore Ts'o <tytso@....edu>
> To: Ext4 Developers List <linux-ext4@...r.kernel.org>
> Cc: Theodore Ts'o <tytso@....edu>
> Subject: [PATCH -v2 3/3] mke2fs: check for a partition table and warn if
> present
>
> This supercedes the "whole disk" check, since it does a better job and
> there are times when it is quite legitimate to want to use the whole
> disk.
>
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> ---
> configure | 2 +-
> configure.in | 1 +
> lib/config.h.in | 3 +++
> misc/util.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++-------
> 4 files changed, 59 insertions(+), 8 deletions(-)
>
> diff --git a/configure b/configure
> index 44664c3..6fe33f5 100755
> --- a/configure
> +++ b/configure
> @@ -11078,7 +11078,7 @@ if test "$ac_res" != no; then :
> fi
>
> fi
> -for ac_func in __secure_getenv backtrace blkid_probe_get_topology chflags fadvise64 fallocate fallocate64 fchown fdatasync fstat64 ftruncate64 futimes getcwd getdtablesize getmntinfo getpwuid_r getrlimit getrusage jrand48 llseek lseek64 mallinfo mbstowcs memalign mempcpy mmap msync nanosleep open64 pathconf posix_fadvise posix_fadvise64 posix_memalign prctl secure_getenv setmntent setresgid setresuid srandom stpcpy strcasecmp strdup strnlen strptime strtoull sync_file_range sysconf usleep utime valloc
> +for ac_func in __secure_getenv backtrace blkid_probe_get_topology blkid_probe_enable_partitions chflags fadvise64 fallocate fallocate64 fchown fdatasync fstat64 ftruncate64 futimes getcwd getdtablesize getmntinfo getpwuid_r getrlimit getrusage jrand48 llseek lseek64 mallinfo mbstowcs memalign mempcpy mmap msync nanosleep open64 pathconf posix_fadvise posix_fadvise64 posix_memalign prctl secure_getenv setmntent setresgid setresuid srandom stpcpy strcasecmp strdup strnlen strptime strtoull sync_file_range sysconf usleep utime valloc
> do :
> as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
> ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
> diff --git a/configure.in b/configure.in
> index e0e6d48..781b6f5 100644
> --- a/configure.in
> +++ b/configure.in
> @@ -1050,6 +1050,7 @@ AC_CHECK_FUNCS(m4_flatten([
> __secure_getenv
> backtrace
> blkid_probe_get_topology
> + blkid_probe_enable_partitions
> chflags
> fadvise64
> fallocate
> diff --git a/lib/config.h.in b/lib/config.h.in
> index b575a5c..92b3c49 100644
> --- a/lib/config.h.in
> +++ b/lib/config.h.in
> @@ -55,6 +55,9 @@
> /* Define to 1 if you have the `backtrace' function. */
> #undef HAVE_BACKTRACE
>
> +/* Define to 1 if you have the `blkid_probe_enable_partitions' function. */
> +#undef HAVE_BLKID_PROBE_ENABLE_PARTITIONS
> +
> /* Define to 1 if you have the `blkid_probe_get_topology' function. */
> #undef HAVE_BLKID_PROBE_GET_TOPOLOGY
>
> diff --git a/misc/util.c b/misc/util.c
> index d63e21b..ce3c416 100644
> --- a/misc/util.c
> +++ b/misc/util.c
> @@ -139,13 +139,54 @@ static void print_ext2_info(const char *device)
> ext2fs_close(fs);
> }
>
> +/*
> + * return 1 if there is no partition table, 0 if a partition table is
> + * detected, and -1 on an error.
> + */
> +static int check_partition_table(const char *device)
> +{
> +#ifdef HAVE_BLKID_PROBE_ENABLE_PARTITIONS
> + blkid_probe pr;
> + const char *value;
> + int ret;
> +
> + pr = blkid_new_probe_from_filename(device);
> + if (!pr)
> + return -1;
> +
> + ret = blkid_probe_enable_partitions(pr, 1);
> + if (ret < 0)
Wrong indentation (spaces instead of tab), but otherwise it looks
good. Thanks!
Reviewed-by: Lukas Czerner <lczerner@...hat.com>
> + goto errout;
> +
> + ret = blkid_probe_enable_superblocks(pr, 0);
> + if (ret < 0)
> + goto errout;
> +
> + ret = blkid_do_fullprobe(pr);
> + if (ret < 0)
> + goto errout;
> +
> + ret = blkid_probe_lookup_value(pr, "PTTYPE", &value, NULL);
> + if (ret == 0)
> + fprintf(stderr, _("Found a %s partition table in %s\n"),
> + value, device);
> + else
> + ret = 1;
> +
> +errout:
> + blkid_free_probe(pr);
> + return ret;
> +#else
> + return -1;
> +#endif
> +}
>
> /*
> * return 1 if the device looks plausible, creating the file if necessary
> */
> int check_plausibility(const char *device, int flags, int *ret_is_dev)
> {
> - int fd, is_dev = 0;
> + int fd, ret, is_dev = 0;
> ext2fs_struct_stat s;
> int fl = O_RDONLY;
> blkid_cache cache = NULL;
> @@ -189,6 +230,15 @@ int check_plausibility(const char *device, int flags, int *ret_is_dev)
> return 0;
> }
>
> + /*
> + * Note: we use the older-style blkid API's here because we
> + * want as much functionality to be available when using the
> + * internal blkid library, when e2fsprogs is compiled for
> + * non-Linux systems that will probably not have the libraries
> + * from util-linux available. We only use the newer
> + * blkid-probe interfaces to access functionality not
> + * available in the original blkid library.
> + */
> if ((flags & CHECK_FS_EXIST) && blkid_get_cache(&cache, NULL) >= 0) {
> fs_type = blkid_get_tag_value(cache, "TYPE", device);
> if (fs_type)
> @@ -210,12 +260,9 @@ int check_plausibility(const char *device, int flags, int *ret_is_dev)
> return 0;
> }
>
> - /*
> - * We should eventually replace this with a test for the
> - * presence of a partition table. Unfortunately the blkid
> - * library doesn't test for partition tabels, and checking for
> - * valid GPT and MBR and possibly others isn't quite trivial.
> - */
> + ret = check_partition_table(device);
> + if (ret >= 0)
> + return ret;
>
> #ifdef HAVE_LINUX_MAJOR_H
> #ifndef MAJOR
>
--
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