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-rw-r--r--libmount/src/tab_diff.c377
1 files changed, 377 insertions, 0 deletions
diff --git a/libmount/src/tab_diff.c b/libmount/src/tab_diff.c
new file mode 100644
index 0000000..81694bc
--- /dev/null
+++ b/libmount/src/tab_diff.c
@@ -0,0 +1,377 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * This file is part of libmount from util-linux project.
+ *
+ * Copyright (C) 2011-2018 Karel Zak <kzak@redhat.com>
+ *
+ * libmount is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ */
+
+/**
+ * SECTION: tabdiff
+ * @title: Compare changes in mount tables
+ * @short_description: compare changes in the list of the mounted filesystems
+ */
+#include "mountP.h"
+
+struct tabdiff_entry {
+ int oper; /* MNT_TABDIFF_* flags; */
+
+ struct libmnt_fs *old_fs; /* pointer to the old FS */
+ struct libmnt_fs *new_fs; /* pointer to the new FS */
+
+ struct list_head changes;
+};
+
+struct libmnt_tabdiff {
+ int nchanges; /* number of changes */
+
+ struct list_head changes; /* list with modified entries */
+ struct list_head unused; /* list with unused entries */
+};
+
+/**
+ * mnt_new_tabdiff:
+ *
+ * Allocates a new table diff struct.
+ *
+ * Returns: new diff handler or NULL.
+ */
+struct libmnt_tabdiff *mnt_new_tabdiff(void)
+{
+ struct libmnt_tabdiff *df = calloc(1, sizeof(*df));
+
+ if (!df)
+ return NULL;
+
+ DBG(DIFF, ul_debugobj(df, "alloc"));
+
+ INIT_LIST_HEAD(&df->changes);
+ INIT_LIST_HEAD(&df->unused);
+ return df;
+}
+
+static void free_tabdiff_entry(struct tabdiff_entry *de)
+{
+ if (!de)
+ return;
+ list_del(&de->changes);
+ mnt_unref_fs(de->new_fs);
+ mnt_unref_fs(de->old_fs);
+ free(de);
+}
+
+/**
+ * mnt_free_tabdiff:
+ * @df: tab diff
+ *
+ * Deallocates tab diff struct and all entries.
+ */
+void mnt_free_tabdiff(struct libmnt_tabdiff *df)
+{
+ if (!df)
+ return;
+
+ DBG(DIFF, ul_debugobj(df, "free"));
+
+ while (!list_empty(&df->changes)) {
+ struct tabdiff_entry *de = list_entry(df->changes.next,
+ struct tabdiff_entry, changes);
+ free_tabdiff_entry(de);
+ }
+
+ free(df);
+}
+
+/**
+ * mnt_tabdiff_next_change:
+ * @df: tabdiff pointer
+ * @itr: iterator
+ * @old_fs: returns the old entry or NULL if new entry added
+ * @new_fs: returns the new entry or NULL if old entry removed
+ * @oper: MNT_TABDIFF_{MOVE,UMOUNT,REMOUNT,MOUNT} flags
+ *
+ * The options @old_fs, @new_fs and @oper are optional.
+ *
+ * Returns: 0 on success, negative number in case of error or 1 at the end of list.
+ */
+int mnt_tabdiff_next_change(struct libmnt_tabdiff *df, struct libmnt_iter *itr,
+ struct libmnt_fs **old_fs, struct libmnt_fs **new_fs, int *oper)
+{
+ int rc = 1;
+ struct tabdiff_entry *de = NULL;
+
+ if (!df || !itr)
+ return -EINVAL;
+
+ if (!itr->head)
+ MNT_ITER_INIT(itr, &df->changes);
+ if (itr->p != itr->head) {
+ MNT_ITER_ITERATE(itr, de, struct tabdiff_entry, changes);
+ rc = 0;
+ }
+
+ if (old_fs)
+ *old_fs = de ? de->old_fs : NULL;
+ if (new_fs)
+ *new_fs = de ? de->new_fs : NULL;
+ if (oper)
+ *oper = de ? de->oper : 0;
+
+ return rc;
+}
+
+static int tabdiff_reset(struct libmnt_tabdiff *df)
+{
+ assert(df);
+
+ DBG(DIFF, ul_debugobj(df, "resetting"));
+
+ /* zeroize all entries and move them to the list of unused
+ */
+ while (!list_empty(&df->changes)) {
+ struct tabdiff_entry *de = list_entry(df->changes.next,
+ struct tabdiff_entry, changes);
+
+ list_del_init(&de->changes);
+ list_add_tail(&de->changes, &df->unused);
+
+ mnt_unref_fs(de->new_fs);
+ mnt_unref_fs(de->old_fs);
+
+ de->new_fs = de->old_fs = NULL;
+ de->oper = 0;
+ }
+
+ df->nchanges = 0;
+ return 0;
+}
+
+static int tabdiff_add_entry(struct libmnt_tabdiff *df, struct libmnt_fs *old,
+ struct libmnt_fs *new, int oper)
+{
+ struct tabdiff_entry *de;
+
+ assert(df);
+
+ DBG(DIFF, ul_debugobj(df, "add change on %s",
+ mnt_fs_get_target(new ? new : old)));
+
+ if (!list_empty(&df->unused)) {
+ de = list_entry(df->unused.next, struct tabdiff_entry, changes);
+ list_del(&de->changes);
+ } else {
+ de = calloc(1, sizeof(*de));
+ if (!de)
+ return -ENOMEM;
+ }
+
+ INIT_LIST_HEAD(&de->changes);
+
+ mnt_ref_fs(new);
+ mnt_ref_fs(old);
+
+ mnt_unref_fs(de->new_fs);
+ mnt_unref_fs(de->old_fs);
+
+ de->old_fs = old;
+ de->new_fs = new;
+ de->oper = oper;
+
+ list_add_tail(&de->changes, &df->changes);
+ df->nchanges++;
+ return 0;
+}
+
+static struct tabdiff_entry *tabdiff_get_mount(struct libmnt_tabdiff *df,
+ const char *src,
+ int id)
+{
+ struct list_head *p;
+
+ assert(df);
+
+ list_for_each(p, &df->changes) {
+ struct tabdiff_entry *de;
+
+ de = list_entry(p, struct tabdiff_entry, changes);
+
+ if (de->oper == MNT_TABDIFF_MOUNT && de->new_fs &&
+ mnt_fs_get_id(de->new_fs) == id) {
+
+ const char *s = mnt_fs_get_source(de->new_fs);
+
+ if (s == NULL && src == NULL)
+ return de;
+ if (s && src && strcmp(s, src) == 0)
+ return de;
+ }
+ }
+ return NULL;
+}
+
+/**
+ * mnt_diff_tables:
+ * @df: diff handler
+ * @old_tab: old table
+ * @new_tab: new table
+ *
+ * Compares @old_tab and @new_tab, the result is stored in @df and accessible by
+ * mnt_tabdiff_next_change().
+ *
+ * Returns: number of changes, negative number in case of error.
+ */
+int mnt_diff_tables(struct libmnt_tabdiff *df, struct libmnt_table *old_tab,
+ struct libmnt_table *new_tab)
+{
+ struct libmnt_fs *fs;
+ struct libmnt_iter itr;
+ int no, nn;
+
+ if (!df || !old_tab || !new_tab)
+ return -EINVAL;
+
+ tabdiff_reset(df);
+
+ no = mnt_table_get_nents(old_tab);
+ nn = mnt_table_get_nents(new_tab);
+
+ if (!no && !nn) /* both tables are empty */
+ return 0;
+
+ DBG(DIFF, ul_debugobj(df, "analyze new (%d entries), "
+ "old (%d entries)",
+ nn, no));
+
+ mnt_reset_iter(&itr, MNT_ITER_FORWARD);
+
+ /* all mounted or umounted */
+ if (!no && nn) {
+ while(mnt_table_next_fs(new_tab, &itr, &fs) == 0)
+ tabdiff_add_entry(df, NULL, fs, MNT_TABDIFF_MOUNT);
+ goto done;
+
+ } else if (no && !nn) {
+ while(mnt_table_next_fs(old_tab, &itr, &fs) == 0)
+ tabdiff_add_entry(df, fs, NULL, MNT_TABDIFF_UMOUNT);
+ goto done;
+ }
+
+ /* search newly mounted or modified */
+ while(mnt_table_next_fs(new_tab, &itr, &fs) == 0) {
+ struct libmnt_fs *o_fs;
+ const char *src = mnt_fs_get_source(fs),
+ *tgt = mnt_fs_get_target(fs);
+
+ o_fs = mnt_table_find_pair(old_tab, src, tgt, MNT_ITER_FORWARD);
+ if (!o_fs)
+ /* 'fs' is not in the old table -- so newly mounted */
+ tabdiff_add_entry(df, NULL, fs, MNT_TABDIFF_MOUNT);
+ else {
+ /* is modified? */
+ const char *v1 = mnt_fs_get_vfs_options(o_fs),
+ *v2 = mnt_fs_get_vfs_options(fs),
+ *f1 = mnt_fs_get_fs_options(o_fs),
+ *f2 = mnt_fs_get_fs_options(fs);
+
+ if ((v1 && v2 && strcmp(v1, v2) != 0) || (f1 && f2 && strcmp(f1, f2) != 0))
+ tabdiff_add_entry(df, o_fs, fs, MNT_TABDIFF_REMOUNT);
+ }
+ }
+
+ /* search umounted or moved */
+ mnt_reset_iter(&itr, MNT_ITER_FORWARD);
+ while(mnt_table_next_fs(old_tab, &itr, &fs) == 0) {
+ const char *src = mnt_fs_get_source(fs),
+ *tgt = mnt_fs_get_target(fs);
+
+ if (!mnt_table_find_pair(new_tab, src, tgt, MNT_ITER_FORWARD)) {
+ struct tabdiff_entry *de;
+
+ de = tabdiff_get_mount(df, src, mnt_fs_get_id(fs));
+ if (de) {
+ mnt_ref_fs(fs);
+ mnt_unref_fs(de->old_fs);
+ de->oper = MNT_TABDIFF_MOVE;
+ de->old_fs = fs;
+ } else
+ tabdiff_add_entry(df, fs, NULL, MNT_TABDIFF_UMOUNT);
+ }
+ }
+done:
+ DBG(DIFF, ul_debugobj(df, "%d changes detected", df->nchanges));
+ return df->nchanges;
+}
+
+#ifdef TEST_PROGRAM
+
+static int test_diff(struct libmnt_test *ts, int argc, char *argv[])
+{
+ struct libmnt_table *tb_old, *tb_new;
+ struct libmnt_tabdiff *diff;
+ struct libmnt_iter *itr;
+ struct libmnt_fs *old, *new;
+ int rc = -1, change;
+
+ tb_old = mnt_new_table_from_file(argv[1]);
+ tb_new = mnt_new_table_from_file(argv[2]);
+ diff = mnt_new_tabdiff();
+ itr = mnt_new_iter(MNT_ITER_FORWARD);
+
+ if (!tb_old || !tb_new || !diff || !itr) {
+ warnx("failed to allocate resources");
+ goto done;
+ }
+
+ rc = mnt_diff_tables(diff, tb_old, tb_new);
+ if (rc < 0)
+ goto done;
+
+ while(mnt_tabdiff_next_change(diff, itr, &old, &new, &change) == 0) {
+
+ printf("%s on %s: ", mnt_fs_get_source(new ? new : old),
+ mnt_fs_get_target(new ? new : old));
+
+ switch(change) {
+ case MNT_TABDIFF_MOVE:
+ printf("MOVED to %s\n", mnt_fs_get_target(new));
+ break;
+ case MNT_TABDIFF_UMOUNT:
+ printf("UMOUNTED\n");
+ break;
+ case MNT_TABDIFF_REMOUNT:
+ printf("REMOUNTED from '%s' to '%s'\n",
+ mnt_fs_get_options(old),
+ mnt_fs_get_options(new));
+ break;
+ case MNT_TABDIFF_MOUNT:
+ printf("MOUNTED\n");
+ break;
+ default:
+ printf("unknown change!\n");
+ }
+ }
+
+ rc = 0;
+done:
+ mnt_unref_table(tb_old);
+ mnt_unref_table(tb_new);
+ mnt_free_tabdiff(diff);
+ mnt_free_iter(itr);
+ return rc;
+}
+
+int main(int argc, char *argv[])
+{
+ struct libmnt_test tss[] = {
+ { "--diff", test_diff, "<old> <new> prints change" },
+ { NULL }
+ };
+
+ return mnt_run_test(tss, argc, argv);
+}
+
+#endif /* TEST_PROGRAM */