libmount: add mnt_table_uniq_fs()

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/docs/libmount-sections.txt b/libmount/docs/libmount-sections.txt
index 6affbfbb6e3d02432e8be1a46e143538ccaac602..2220cf158853500d42d788df10b87915075de488 100644 (file)
--- a/libmount/docs/libmount-sections.txt
+++ b/libmount/docs/libmount-sections.txt
@@ -331,6 +331,7 @@ mnt_table_set_parser_errcb
 mnt_table_set_trailing_comment
 mnt_table_set_userdata
 mnt_table_with_comments
+mnt_table_uniq_fs
 </SECTION>
 
 <SECTION>

diff --git a/libmount/src/libmount.h.in b/libmount/src/libmount.h.in
index 8c8e739c9a81d9e5005c1361438769666aac2d27..08ddd659600d99ddd69985b2e2a5ef5a489a47f8 100644 (file)
--- a/libmount/src/libmount.h.in
+++ b/libmount/src/libmount.h.in
@@ -449,6 +449,15 @@ extern int mnt_table_get_root_fs(struct libmnt_table *tb, struct libmnt_fs **roo
 extern int mnt_table_set_iter(struct libmnt_table *tb, struct libmnt_iter *itr,
                              struct libmnt_fs *fs);
 
+enum {
+       MNT_UNIQ_FORWARD  = (1 << 1),   /* default is backward */
+       MNT_UNIQ_KEEPTREE = (1 << 2)
+};
+extern int mnt_table_uniq_fs(struct libmnt_table *tb, int flags,
+                               int (*cmp)(struct libmnt_table *,
+                                          struct libmnt_fs *,
+                                          struct libmnt_fs *));
+
 extern struct libmnt_fs *mnt_table_find_mountpoint(struct libmnt_table *tb,
                                const char *path, int direction);
 extern struct libmnt_fs *mnt_table_find_target(struct libmnt_table *tb,

diff --git a/libmount/src/libmount.sym b/libmount/src/libmount.sym
index d1180d35b5a4ded2bd6a345114fc6f588b1de358..088db77494343e1e40fa6714020067c57ff7a8d8 100644 (file)
--- a/libmount/src/libmount.sym
+++ b/libmount/src/libmount.sym
@@ -289,5 +289,6 @@ global:
 } MOUNT_2.23;
 
 MOUNT_2.25 {
+       mnt_table_uniq_fs;
        mnt_tag_is_valid;
 } MOUNT_2.24;

diff --git a/libmount/src/tab.c b/libmount/src/tab.c
index 3633b6aa08b04ebd4e3d76c3199f0dabf5149a28..8ae49c8dfe4767d322f25b227eb0e84833d9f131 100644 (file)
--- a/libmount/src/tab.c
+++ b/libmount/src/tab.c
@@ -47,6 +47,20 @@
 #include "strutils.h"
 #include "loopdev.h"
 
+static int is_mountinfo(struct libmnt_table *tb)
+{
+       struct libmnt_fs *fs;
+
+       if (!tb)
+               return 0;
+
+       fs = list_first_entry(&tb->ents, struct libmnt_fs, ents);
+       if (fs && mnt_fs_is_kernel(fs) && mnt_fs_get_root(fs))
+               return 1;
+
+       return 0;
+}
+
 /**
  * mnt_new_table:
  *
@@ -697,6 +711,98 @@ int mnt_table_find_next_fs(struct libmnt_table *tb, struct libmnt_iter *itr,
        return 1;
 }
 
+static int mnt_table_move_parent(struct libmnt_table *tb, int oldid, int newid)
+{
+       struct libmnt_iter itr;
+       struct libmnt_fs *fs;
+
+       assert(tb);
+
+       if (!tb)
+               return -EINVAL;
+       if (list_empty(&tb->ents))
+               return 0;
+
+       DBG(TAB, mnt_debug_h(tb, "moving parent ID from %d -> %d", oldid, newid));
+       mnt_reset_iter(&itr, MNT_ITER_FORWARD);
+
+       while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
+               if (fs->parent == oldid)
+                       fs->parent = newid;
+       }
+       return 0;
+}
+
+/**
+ * mnt_table_uniq_fs:
+ * @tb: table
+ * @direction: MNT_UNIQ_*
+ * @cmp: function to compare filesystems
+ *
+ * This function de-duplicate the @tb, but does not change order of the
+ * filesystems. The @cmp function has to return 0 if the filesystems are
+ * equal, otherwise non-zero.
+ *
+ * The default is to keep in the table later mounted filesystems (function uses
+ * backward mode iterator).
+ *
+ * @MNT_UNIQ_FORWARD:  remove later mounted filesystems
+ * @MNT_UNIQ_KEEPTREE: keep parent->id relation ship stil valid
+ *
+ * Returns: negative number in case of error, or 0 o success.
+ */
+int mnt_table_uniq_fs(struct libmnt_table *tb, int flags,
+                               int (*cmp)(struct libmnt_table *,
+                                          struct libmnt_fs *,
+                                          struct libmnt_fs *))
+{
+       struct libmnt_iter itr;
+       struct libmnt_fs *fs;
+       int direction = MNT_ITER_BACKWARD;
+
+       assert(tb);
+       assert(cmp);
+
+       if (!tb || !cmp)
+               return -EINVAL;
+       if (list_empty(&tb->ents))
+               return 0;
+
+       if (flags & MNT_UNIQ_FORWARD)
+               direction = MNT_ITER_FORWARD;
+
+       DBG(TAB, mnt_debug_h(tb, "de-duplicate"));
+       mnt_reset_iter(&itr, direction);
+
+       if ((flags & MNT_UNIQ_KEEPTREE) && !is_mountinfo(tb))
+               flags &= ~MNT_UNIQ_KEEPTREE;
+
+       while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
+               int want = 1;
+               struct libmnt_iter xtr;
+               struct libmnt_fs *x;
+
+               mnt_reset_iter(&xtr, direction);
+               while (want && mnt_table_next_fs(tb, &xtr, &x) == 0) {
+                       if (fs == x)
+                               break;
+                       want = cmp(tb, x, fs) != 0;
+               }
+
+               if (!want) {
+                       if (flags & MNT_UNIQ_KEEPTREE)
+                               mnt_table_move_parent(tb, mnt_fs_get_id(fs),
+                                                         mnt_fs_get_parent_id(fs));
+
+                       DBG(TAB, mnt_debug_h(tb, "remove duplicate %s",
+                                               mnt_fs_get_target(fs)));
+                       mnt_table_remove_fs(tb, fs);
+               }
+       }
+
+       return 0;
+}
+
 /**
  * mnt_table_set_iter:
  * @tb: tab pointer
@@ -1229,20 +1335,6 @@ err:
        return NULL;
 }
 
-static int is_mountinfo(struct libmnt_table *tb)
-{
-       struct libmnt_fs *fs;
-
-       if (!tb)
-               return 0;
-
-       fs = list_first_entry(&tb->ents, struct libmnt_fs, ents);
-       if (fs && mnt_fs_is_kernel(fs) && mnt_fs_get_root(fs))
-               return 1;
-
-       return 0;
-}
-
 /**
  * mnt_table_is_fs__mounted:
  * @tb: /proc/self/mountinfo file
@@ -1633,12 +1725,53 @@ done:
        return rc;
 }
 
+/* returns 0 if @a and @b targets are the same */
+static int test_uniq_cmp(struct libmnt_table *tb __attribute__((__unused__)),
+                        struct libmnt_fs *a,
+                        struct libmnt_fs *b)
+{
+       assert(a);
+       assert(b);
+
+       return mnt_fs_streq_target(a, mnt_fs_get_target(b)) ? 0 : 1;
+}
+
+static int test_uniq(struct libmnt_test *ts, int argc, char *argv[])
+{
+       struct libmnt_table *tb;
+       int rc = -1;
+
+       if (argc != 2) {
+               fprintf(stderr, "try --help\n");
+               return -EINVAL;
+       }
+
+       tb = create_table(argv[1], FALSE);
+       if (!tb)
+               goto done;
+
+       if (mnt_table_uniq_fs(tb, 0, test_uniq_cmp) == 0) {
+               struct libmnt_iter *itr = mnt_new_iter(MNT_ITER_FORWARD);
+               struct libmnt_fs *fs;
+               if (!itr)
+                       goto done;
+               while (mnt_table_next_fs(tb, itr, &fs) == 0)
+                       mnt_fs_print_debug(fs, stdout);
+               mnt_free_iter(itr);
+               rc = 0;
+       }
+done:
+       mnt_unref_table(tb);
+       return rc;
+}
+
 int main(int argc, char *argv[])
 {
        struct libmnt_test tss[] = {
        { "--parse",    test_parse,        "<file> [--comments] parse and print tab" },
        { "--find-forward",  test_find_fw, "<file> <source|target> <string>" },
        { "--find-backward", test_find_bw, "<file> <source|target> <string>" },
+       { "--uniq-target",   test_uniq,    "<file>" },
        { "--find-pair",     test_find_pair, "<file> <source> <target>" },
        { "--find-mountpoint", test_find_mountpoint, "<path>" },
        { "--copy-fs",       test_copy_fs, "<file>  copy root FS from the file" },