[systemd-devel] [RFC 1/4] use libmount to enumerate /proc/self/mountinfo
Tom Gundersen
teg at jklm.no
Sat Nov 15 05:09:26 PST 2014
Usually we don't do this kind of fallback, but rather disable the relevant
functionality if the lib is not available.
In this case I guess it means making support for .mount units optional. I
could imagine someone doing that in very specialised use cases, but maybe
it makes more sense to make the library a hard dependency for now...
Cheers,
Tom
On 7 Nov 2014 06:11, "Chris Leech" <cleech at redhat.com> wrote:
> 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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>
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