Rename src/ to lib/

lib/private-data.c

@@ -0,0 +1,158 @@
+/* libguestfs
+ * Copyright (C) 2009-2017 Red Hat Inc.
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * Implement a private data area where libguestfs C API users can
+ * attach arbitrary pieces of data to a C<guestfs_h> handle.
+ *
+ * For more information see L<guestfs(3)/PRIVATE DATA AREA>.
+ *
+ * Language bindings do not generally expose this, largely because in
+ * non-C languages it is easy to associate data with handles in other
+ * ways (using hash tables or maps).
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include "hash.h"
+#include "hash-pjw.h"
+
+#include "guestfs.h"
+#include "guestfs-internal.h"
+
+/**
+ * The private data area is internally stored as a gnulib hash
+ * table containing C<pda_entry> structures.
+ *
+ * Note the private data area is allocated lazily, since the vast
+ * majority of callers will never use it.  This means C<g-E<gt>pda> is
+ * likely to be C<NULL>.
+ */
+struct pda_entry {
+  char *key;                    /* key */
+  void *data;                   /* opaque user data pointer */
+};
+
+static size_t
+hasher (void const *x, size_t table_size)
+{
+  struct pda_entry const *p = x;
+  return hash_pjw (p->key, table_size);
+}
+
+static bool
+comparator (void const *x, void const *y)
+{
+  struct pda_entry const *a = x;
+  struct pda_entry const *b = y;
+  return STREQ (a->key, b->key);
+}
+
+static void
+freer (void *x)
+{
+  if (x) {
+    struct pda_entry *p = x;
+    free (p->key);
+    free (p);
+  }
+}
+
+void
+guestfs_set_private (guestfs_h *g, const char *key, void *data)
+{
+  struct pda_entry *new_entry, *old_entry, *entry;
+
+  if (g->pda == NULL) {
+    g->pda = hash_initialize (16, NULL, hasher, comparator, freer);
+    if (g->pda == NULL)
+      g->abort_cb ();
+  }
+
+  new_entry = safe_malloc (g, sizeof *new_entry);
+  new_entry->key = safe_strdup (g, key);
+  new_entry->data = data;
+
+  old_entry = hash_delete (g->pda, new_entry);
+  freer (old_entry);
+
+  entry = hash_insert (g->pda, new_entry);
+  if (entry == NULL)
+    g->abort_cb ();
+  assert (entry == new_entry);
+}
+
+void *
+guestfs_get_private (guestfs_h *g, const char *key)
+{
+  if (g->pda == NULL)
+    return NULL;                /* no keys have been set */
+
+  const struct pda_entry k = { .key = (char *) key };
+  struct pda_entry *entry = hash_lookup (g->pda, &k);
+  if (entry)
+    return entry->data;
+  else
+    return NULL;
+}
+
+/* Iterator. */
+void *
+guestfs_first_private (guestfs_h *g, const char **key_rtn)
+{
+  if (g->pda == NULL)
+    return NULL;
+
+  g->pda_next = hash_get_first (g->pda);
+
+  /* Ignore any keys with NULL data pointers. */
+  while (g->pda_next && g->pda_next->data == NULL)
+    g->pda_next = hash_get_next (g->pda, g->pda_next);
+
+  if (g->pda_next == NULL)
+    return NULL;
+
+  *key_rtn = g->pda_next->key;
+  return g->pda_next->data;
+}
+
+void *
+guestfs_next_private (guestfs_h *g, const char **key_rtn)
+{
+  if (g->pda == NULL)
+    return NULL;
+
+  if (g->pda_next == NULL)
+    return NULL;
+
+  /* Walk to the next key with a non-NULL data pointer. */
+  do {
+    g->pda_next = hash_get_next (g->pda, g->pda_next);
+  } while (g->pda_next && g->pda_next->data == NULL);
+
+  if (g->pda_next == NULL)
+    return NULL;
+
+  *key_rtn = g->pda_next->key;
+  return g->pda_next->data;
+}