[lvm-devel] dev-mornfall-lvmcache - libdm: introduce dm_mountinfo_read
Petr Rockai
mornfall at fedoraproject.org
Wed Jun 5 12:03:45 UTC 2013
Gitweb: http://git.fedorahosted.org/git/?p=lvm2.git;a=commitdiff;h=1f30e5a0522a69aac0d246d2fb4e5ce2f6872cff
Commit: 1f30e5a0522a69aac0d246d2fb4e5ce2f6872cff
Parent: d96b854ac054aafc8a9981016faefb9f122fccbb
Author: Zdenek Kabelac <zkabelac at redhat.com>
AuthorDate: Thu May 16 11:34:26 2013 +0200
Committer: Zdenek Kabelac <zkabelac at redhat.com>
CommitterDate: Mon May 20 16:28:30 2013 +0200
libdm: introduce dm_mountinfo_read
Add function for parsing /proc/self/mountinfo entries.
This can be used to detected mounted device.
---
WHATS_NEW_DM | 1 +
libdm/libdevmapper.h | 13 ++++++++
libdm/libdm-common.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 91 insertions(+), 0 deletions(-)
diff --git a/WHATS_NEW_DM b/WHATS_NEW_DM
index 39ebcb2..8bdbfab 100644
--- a/WHATS_NEW_DM
+++ b/WHATS_NEW_DM
@@ -1,5 +1,6 @@
Version 1.02.78 -
===================================
+ Add dm_mountinfo_read() for parsing /proc/self/mountinfo.
Report error for nonexisting devices in dmeventd communication.
Prevent double free error after dmeventd call of _fill_device_data().
Update dmevent structure message_data to simplify/fix error path handling.
diff --git a/libdm/libdevmapper.h b/libdm/libdevmapper.h
index b729846..d9cd280 100644
--- a/libdm/libdevmapper.h
+++ b/libdm/libdevmapper.h
@@ -417,6 +417,19 @@ int dm_device_has_mounted_fs(uint32_t major, uint32_t minor);
/*
+ * Callback is invoked for individal mountinfo lines,
+ * minor, major and mount target are parsed and unmangled.
+ */
+typedef int (*dm_mountinfo_line_callback_fn) (char *line, unsigned maj, unsigned min,
+ char *target, void *cb_data);
+
+/*
+ * Read all lines from /proc/self/mountinfo,
+ * for each line calls read_fn callback.
+ */
+int dm_mountinfo_read(dm_mountinfo_line_callback_fn read_fn, void *cb_data);
+
+/*
* Initialise library
*/
void dm_lib_init(void) __attribute__((constructor));
diff --git a/libdm/libdm-common.c b/libdm/libdm-common.c
index 4736b59..9e8ca25 100644
--- a/libdm/libdm-common.c
+++ b/libdm/libdm-common.c
@@ -62,6 +62,7 @@ union semun
static char _dm_dir[PATH_MAX] = DEV_DIR DM_DIR;
static char _sysfs_dir[PATH_MAX] = "/sys/";
static char _path0[PATH_MAX]; /* path buffer, safe 4kB on stack */
+static const char _mountinfo[] = "/proc/self/mountinfo";
#define DM_MAX_UUID_PREFIX_LEN 15
static char _default_uuid_prefix[DM_MAX_UUID_PREFIX_LEN + 1] = "LVM-";
@@ -1571,6 +1572,82 @@ const char *dm_uuid_prefix(void)
return _default_uuid_prefix;
}
+static int _is_octal(int a)
+{
+ return (((a) & ~7) == '0');
+}
+
+/* Convert mangled mountinfo into normal ASCII string */
+static void _unmangle_mountinfo_string(const char *src, char *buf)
+{
+ while (*src) {
+ if ((*src == '\\') &&
+ _is_octal(src[1]) && _is_octal(src[2]) && _is_octal(src[3])) {
+ *buf++ = 64 * (src[1] & 7) + 8 * (src[2] & 7) + (src[3] & 7);
+ src += 4;
+ } else
+ *buf++ = *src++;
+ }
+ *buf = '\0';
+}
+
+/* Macros to make string defines */
+#define TO_STRING_EXP(A) #A
+#define TO_STRING(A) TO_STRING_EXP(A)
+
+/* Parse one line of mountinfo and unmangled target line */
+static int _mountinfo_parse_line(const char *line, unsigned *maj, unsigned *min, char *buf)
+{
+ char root[PATH_MAX + 1];
+ char target[PATH_MAX + 1];
+
+ /* TODO: maybe detect availability of %ms glib support ? */
+ if (sscanf(line, "%*u %*u %u:%u %" TO_STRING(PATH_MAX)
+ "s %" TO_STRING(PATH_MAX) "s",
+ maj, min, root, target) < 4) {
+ log_error("Failed to parse mountinfo line.");
+ return 0;
+ }
+
+ _unmangle_mountinfo_string(target, buf);
+
+ return 1;
+}
+
+/*
+ * Function to operate on individal mountinfo line,
+ * minor, major and mount target are parsed and unmangled
+ */
+int dm_mountinfo_read(dm_mountinfo_line_callback_fn read_fn, void *cb_data)
+{
+ FILE *minfo;
+ char buffer[2 * PATH_MAX];
+ char target[PATH_MAX];
+ unsigned maj, min;
+ int r = 1;
+
+ if (!(minfo = fopen(_mountinfo, "r"))) {
+ if (errno != ENOENT)
+ log_sys_error("fopen", _mountinfo);
+ else
+ log_sys_debug("fopen", _mountinfo);
+ return 0;
+ }
+
+ while (!feof(minfo) && fgets(buffer, sizeof(buffer), minfo))
+ if (!_mountinfo_parse_line(buffer, &maj, &min, target) ||
+ !read_fn(buffer, maj, min, target, cb_data)) {
+ stack;
+ r = 0;
+ break;
+ }
+
+ if (fclose(minfo))
+ log_sys_error("fclose", _mountinfo);
+
+ return r;
+}
+
static int _sysfs_get_dm_name(uint32_t major, uint32_t minor, char *buf, size_t buf_size)
{
char *sysfs_path, *temp_buf = NULL;
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