Re: [Libguestfs] [PATCH RFC] blkid: start using libblkid directly instead

Hi Rich: What do you think about this idea? although this still has some problems like do 'vfs-type /dev/vda'. Can you give some comments about this? Is this a bad idea?

Thanks -Wanlong Gao ----------------------------------------------------------------------------- Use libblkid directly instead of the binary command in blkid. Signed-off-by: Wanlong Gao <gaowanlong(a)cn.fujitsu.com&gt; --- appliance/packagelist.in | 1 + configure.ac | 10 ++++++++ daemon/Makefile.am | 1 + daemon/blkid.c | 55 ++++++++++++++++++++++----------------------- 4 files changed, 39 insertions(+), 28 deletions(-) diff --git a/appliance/packagelist.in b/appliance/packagelist.in index 2ab6b80..575b8dd 100644 --- a/appliance/packagelist.in +++ b/appliance/packagelist.in @@ -45,6 +45,7 @@ vim-minimal xz zfs-fuse + libblkid #endif /* REDHAT */ #ifdef DEBIAN

diff --git a/configure.ac b/configure.ac index cc11b2f..0beef28 100644 --- a/configure.ac +++ b/configure.ac @@ -393,6 +393,16 @@ if test "x$have_libselinux" = "xyes"; then AC_DEFINE([HAVE_LIBSELINUX],[1],[Define to 1 if you have libselinux]) fi AC_SUBST([SELINUX_LIB]) +AC_CHECK_HEADERS([blkid/blkid.h]) +AC_CHECK_LIB([blkid],[blkid_new_probe],[ + have_libblkid="$ac_cv_header_blkid_blkid_h" + LIBBLKID="-lblkid" + LIBS="$LIBS $LIBBLKID" + ],[have_libblkid=no]) +if test "x$have_libblkid" = "xyes"; then + AC_DEFINE([HAVE_LIBBLKID],[1],[Define to 1 if you have libblkid]) +fi +AC_SUBST([LIBBLKID])

dnl Check for systemtap/DTrace userspace probes (optional). dnl http://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps diff --git a/daemon/Makefile.am b/daemon/Makefile.am index 3a698cc..5e4db57 100644 --- a/daemon/Makefile.am +++ b/daemon/Makefile.am @@ -167,6 +167,7 @@ guestfsd_LDADD = \ liberrnostring.a \ libprotocol.a \ $(SELINUX_LIB) \ + $(LIBBLKID) \ $(AUGEAS_LIBS) \ $(top_builddir)/gnulib/lib/.libs/libgnu.a \ $(GETADDRINFO_LIB) \ diff --git a/daemon/blkid.c b/daemon/blkid.c index 8728c29..0c4ca71 100644 --- a/daemon/blkid.c +++ b/daemon/blkid.c @@ -23,6 +23,8 @@ #include <string.h> #include <unistd.h> #include <limits.h> +#include <fcntl.h> +#include <blkid/blkid.h> #include "daemon.h" #include "actions.h" @@ -30,40 +32,37 @@ static char * get_blkid_tag (const char *device, const char *tag) { - char *out, *err; - int r; + int fd, rc; + const char *data = NULL; + blkid_probe blkprobe; - r = commandr (&out, &err, - "blkid", - /* Adding -c option kills all caching, even on RHEL 5. */ - "-c", "/dev/null", - "-o", "value", "-s", tag, device, NULL); - if (r != 0 && r != 2) { - if (r >= 0) - reply_with_error ("%s: %s (blkid returned %d)", device, err, r); - else - reply_with_error ("%s: %s", device, err); - free (out); - free (err); + if (!device || !tag) return NULL; - } - free (err); + fd = open (device, O_RDONLY); + if (fd < 0) + return NULL; - if (r == 2) { /* means UUID etc not found */ - free (out); - out = strdup (""); - if (out == NULL) - reply_with_perror ("strdup"); - return out; - } + blkprobe = blkid_new_probe (); + if (!blkprobe) + goto done; + if (blkid_probe_set_device (blkprobe, fd, 0, 0)) + goto done; + + blkid_probe_enable_superblocks(blkprobe, 1); + + blkid_probe_set_superblocks_flags (blkprobe, BLKID_SUBLKS_LABEL | + BLKID_SUBLKS_UUID | BLKID_SUBLKS_TYPE); - /* Trim trailing \n if present. */ - size_t len = strlen (out); - if (len > 0 && out[len-1] == '\n') - out[len-1] = '\0'; + rc = blkid_do_safeprobe (blkprobe); + if (!rc) + blkid_probe_lookup_value (blkprobe, tag, &data, NULL); - return out; /* caller frees */ +done: + close (fd); + if (blkprobe) + blkid_free_probe (blkprobe); + return data ? strdup ((char *) data) : NULL; } char * -- 1.7.9