[systemd-devel] [RFC 1/4] use libmount to enumerate /proc/self/mountinfo

Chris Leech cleech at redhat.com
Thu Nov 6 21:11:00 PST 2014


This lets libmount add in user options from /run/mount/utab, like
_netdev which is needed to get proper ordering against remote-fs.target
---
 .travis.yml      |  2 +-
 Makefile.am      |  4 +++-
 README           |  1 +
 configure.ac     | 13 ++++++++++++
 src/core/build.h |  7 +++++++
 src/core/mount.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 87 insertions(+), 2 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 7e5251c..4ea2bc2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@ compiler:
   - gcc
 before_install:
  - sudo apt-get update -qq
- - sudo apt-get install autotools-dev automake autoconf libtool libdbus-1-dev libcap-dev libblkid-dev libpam-dev libcryptsetup-dev libaudit-dev libacl1-dev libattr1-dev libselinux-dev liblzma-dev libgcrypt-dev libqrencode-dev libmicrohttpd-dev gtk-doc-tools gperf python2.7-dev
+ - sudo apt-get install autotools-dev automake autoconf libtool libdbus-1-dev libcap-dev libblkid-dev libmount-dev libpam-dev libcryptsetup-dev libaudit-dev libacl1-dev libattr1-dev libselinux-dev liblzma-dev libgcrypt-dev libqrencode-dev libmicrohttpd-dev gtk-doc-tools gperf python2.7-dev
 script: ./autogen.sh && ./configure --enable-gtk-doc --enable-gtk-doc-pdf && make V=1 && sudo ./systemd-machine-id-setup && make check && make distcheck
 after_failure: cat test-suite.log
 notifications:
diff --git a/Makefile.am b/Makefile.am
index 461ffa9..3deffe8 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1163,6 +1163,7 @@ libsystemd_core_la_CFLAGS = \
 	$(KMOD_CFLAGS) \
 	$(APPARMOR_CFLAGS) \
 	$(SECCOMP_CFLAGS) \
+	$(MOUNT_CFLAGS) \
 	-pthread
 
 libsystemd_core_la_LIBADD = \
@@ -1177,7 +1178,8 @@ libsystemd_core_la_LIBADD = \
 	$(CAP_LIBS) \
 	$(KMOD_LIBS) \
 	$(APPARMOR_LIBS) \
-	$(SECCOMP_LIBS)
+	$(SECCOMP_LIBS) \
+	$(MOUNT_LIBS)
 
 if HAVE_SECCOMP
 libsystemd_core_la_LIBADD += \
diff --git a/README b/README
index aefb349..89abc3e 100644
--- a/README
+++ b/README
@@ -108,6 +108,7 @@ REQUIREMENTS:
         libcap
         libseccomp >= 1.0.0 (optional)
         libblkid >= 2.20 (from util-linux) (optional)
+        libmount >= 2.20 (from util-linux) (optional)
         libkmod >= 15 (optional)
         PAM >= 1.1.2 (optional)
         libcryptsetup (optional)
diff --git a/configure.ac b/configure.ac
index 05fc00d..85ff053 100644
--- a/configure.ac
+++ b/configure.ac
@@ -426,6 +426,18 @@ fi
 AM_CONDITIONAL(HAVE_BLKID, [test "$have_blkid" = "yes"])
 
 # ------------------------------------------------------------------------------
+have_libmount=no
+AC_ARG_ENABLE(libmount, AS_HELP_STRING([--disable-libmount], [disable libmount support]))
+if test "x$enable_libmount" != "xno"; then
+        PKG_CHECK_MODULES(MOUNT, [ mount >= 2.20 ],
+                [AC_DEFINE(HAVE_LIBMOUNT, 1, [Define if libmount is available]) have_libmount=yes], have_libmount=no)
+        if test "x$have_libmount" = xno -a "x$enable_libmount" = xyes; then
+                AC_MSG_ERROR([*** libmount support requested but libraries not found])
+        fi
+fi
+AM_CONDITIONAL(HAVE_LIBMOUNT, [test "$have_libmount" = "yes"])
+
+# ------------------------------------------------------------------------------
 have_seccomp=no
 AC_ARG_ENABLE(seccomp, AS_HELP_STRING([--disable-seccomp], [Disable optional SECCOMP support]))
 if test "x$enable_seccomp" != "xno"; then
@@ -1374,6 +1386,7 @@ AC_MSG_RESULT([
         efi:                     ${have_efi}
         kmod:                    ${have_kmod}
         blkid:                   ${have_blkid}
+        libmount:                ${have_libmount}
         dbus:                    ${have_dbus}
         nss-myhostname:          ${have_myhostname}
         gudev:                   ${enable_gudev}
diff --git a/src/core/build.h b/src/core/build.h
index d5e5550..5644693 100644
--- a/src/core/build.h
+++ b/src/core/build.h
@@ -117,6 +117,12 @@
 #define _BLKID_FEATURE_ "-BLKID"
 #endif
 
+#ifdef HAVE_LIBMOUNT
+#define _LIBMOUNT_FEATURE_ "+LIBMOUNT"
+#else
+#define _LIBMOUNT_FEATURE_ "-LIBMOUNT"
+#endif
+
 #ifdef HAVE_ELFUTILS
 #define _ELFUTILS_FEATURE_ "+ELFUTILS"
 #else
@@ -152,6 +158,7 @@
         _LZ4_FEATURE_ " "                                               \
         _SECCOMP_FEATURE_ " "                                           \
         _BLKID_FEATURE_ " "                                             \
+        _LIBMOUNT_FEATURE_ " "                                          \
         _ELFUTILS_FEATURE_ " "                                          \
         _KMOD_FEATURE_ " "                                              \
         _IDN_FEATURE_ " "
diff --git a/src/core/mount.c b/src/core/mount.c
index 8b787f6..a639515 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -25,6 +25,12 @@
 #include <sys/epoll.h>
 #include <signal.h>
 
+#ifdef HAVE_LIBMOUNT
+#include <libmount.h>
+#else
+#define mnt_init_debug(m) do {} while (0)
+#endif
+
 #include "manager.h"
 #include "unit.h"
 #include "mount.h"
@@ -1492,6 +1498,58 @@ fail:
         return r;
 }
 
+#ifdef HAVE_LIBMOUNT
+
+static inline void mnt_free_table_p(struct libmnt_table **tb) {
+        mnt_free_table(*tb);
+}
+
+static inline void mnt_free_iter_p(struct libmnt_iter **itr) {
+        mnt_free_iter(*itr);
+}
+
+static int mount_load_proc_self_mountinfo(Manager *m, bool set_flags) {
+        _cleanup_(mnt_free_table_p) struct libmnt_table *tb = NULL;
+        _cleanup_(mnt_free_iter_p) struct libmnt_iter *itr = NULL;
+        struct libmnt_fs *fs;
+        int r = 0;
+
+        assert(m);
+
+        tb = mnt_new_table();
+        itr = mnt_new_iter(MNT_ITER_FORWARD);
+        if (!tb || !itr)
+                return log_oom();
+
+        mnt_table_parse_mtab(tb, NULL);
+        if (r)
+                return r;
+
+        while (mnt_table_next_fs(tb, itr, &fs) == 0) {
+                const char *device, *path, *options, *fstype;
+                _cleanup_free_ const char *d = NULL, *p = NULL;
+                int k;
+
+                device = mnt_fs_get_source(fs);
+                path = mnt_fs_get_target(fs);
+                options = mnt_fs_get_options(fs);
+                fstype = mnt_fs_get_fstype(fs);
+
+                d = cunescape(device);
+                p = cunescape(path);
+                if (!d || !p)
+                        return log_oom();
+
+                k = mount_add_one(m, d, p, options, fstype, set_flags);
+                if (k < 0)
+                        r = k;
+        }
+
+        return r;
+}
+
+#else
+
 static int mount_load_proc_self_mountinfo(Manager *m, bool set_flags) {
         int r = 0;
         unsigned i;
@@ -1548,6 +1606,8 @@ static int mount_load_proc_self_mountinfo(Manager *m, bool set_flags) {
         return r;
 }
 
+#endif
+
 static void mount_shutdown(Manager *m) {
         assert(m);
 
@@ -1577,6 +1637,8 @@ static int mount_enumerate(Manager *m) {
         int r;
         assert(m);
 
+        mnt_init_debug(0);
+
         if (!m->proc_self_mountinfo) {
                 m->proc_self_mountinfo = fopen("/proc/self/mountinfo", "re");
                 if (!m->proc_self_mountinfo)
-- 
1.9.3



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