4 files changed, 146 insertions, 0 deletions
diff --git a/gl/lib/file-set.c b/gl/lib/file-set.c
new file mode 100644
index 000000000..ad03f90ce
--- /dev/null
+++ b/gl/lib/file-set.c
@@ -0,0 +1,56 @@
+#include <config.h>
+#include "file-set.h"
+
+#include "hash-triple.h"
+#include "xalloc.h"
+
+/* Record destination file, FILE, and dev/ino from *STATS,
+   in the hash table, HT.  If HT is NULL, return immediately.
+   If memory allocation fails, exit immediately.  */
+void
+record_file (Hash_table *ht, char const *file, struct stat const *stats)
+{
+  struct F_triple *ent;
+
+  if (ht == NULL)
+    return;
+
+  ent = xmalloc (sizeof *ent);
+  ent->name = xstrdup (file);
+  ent->st_ino = stats->st_ino;
+  ent->st_dev = stats->st_dev;
+
+  {
+    struct F_triple *ent_from_table = hash_insert (ht, ent);
+    if (ent_from_table == NULL)
+      {
+	/* Insertion failed due to lack of memory.  */
+	xalloc_die ();
+      }
+
+    if (ent_from_table != ent)
+      {
+	/* There was alread a matching entry in the table, so ENT was
+	   not inserted.  Free it.  */
+	triple_free (ent);
+      }
+  }
+}
+
+/* Return true if there is an entry in hash table, HT,
+   for the file described by FILE and STATS.  */
+bool
+seen_file (Hash_table const *ht, char const *file,
+	   struct stat const *stats)
+{
+  struct F_triple new_ent;
+
+  if (ht == NULL)
+    return false;
+
+  new_ent.name = (char *) file;
+  new_ent.st_ino = stats->st_ino;
+  new_ent.st_dev = stats->st_dev;
+
+  return !!hash_lookup (ht, &new_ent);
+}
diff --git a/gl/lib/file-set.h b/gl/lib/file-set.h
new file mode 100644
index 000000000..a5a159e94
--- /dev/null
+++ b/gl/lib/file-set.h
@@ -0,0 +1,12 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdbool.h>
+
+#include "hash.h"
+
+extern void record_file (Hash_table *ht, char const *file,
+			 struct stat const *stats)
+  __attribute__((nonnull(2, 3)));
+
+extern bool seen_file (Hash_table const *ht, char const *file,
+		       struct stat const *stats);
diff --git a/gl/lib/hash-triple.c b/gl/lib/hash-triple.c
new file mode 100644
index 000000000..dfe2a592d
--- /dev/null
+++ b/gl/lib/hash-triple.c
@@ -0,0 +1,57 @@
+#include <config.h>
+
+#include "hash-triple.h"
+
+#include <stdlib.h>
+
+#include "hash-pjw.h"
+#include "same.h"
+#include "same-inode.h"
+
+/* Hash an F_triple.  */
+size_t
+triple_hash (void const *x, size_t table_size)
+{
+  struct F_triple const *p = x;
+
+  /* Also take the name into account, so that when moving N hard links to the
+     same file (all listed on the command line) all into the same directory,
+     we don't experience any N^2 behavior.  */
+  /* FIXME-maybe: is it worth the overhead of doing this
+     just to avoid N^2 in such an unusual case?  N would have
+     to be very large to make the N^2 factor noticable, and
+     one would probably encounter a limit on the length of
+     a command line before it became a problem.  */
+  size_t tmp = hash_pjw (p->name, table_size);
+
+  /* Ignoring the device number here should be fine.  */
+  return (tmp | p->st_ino) % table_size;
+}
+
+/* Hash an F_triple.  */
+size_t
+triple_hash_no_name (void const *x, size_t table_size)
+{
+  struct F_triple const *p = x;
+
+  /* Ignoring the device number here should be fine.  */
+  return p->st_ino % table_size;
+}
+
+/* Compare two F_triple structs.  */
+bool
+triple_compare (void const *x, void const *y)
+{
+  struct F_triple const *a = x;
+  struct F_triple const *b = y;
+  return (SAME_INODE (*a, *b) && same_name (a->name, b->name)) ? true : false;
+}
+
+/* Free an F_triple.  */
+void
+triple_free (void *x)
+{
+  struct F_triple *a = x;
+  free (a->name);
+  free (a);
+}
diff --git a/gl/lib/hash-triple.h b/gl/lib/hash-triple.h
new file mode 100644
index 000000000..7abe97044
--- /dev/null
+++ b/gl/lib/hash-triple.h
@@ -0,0 +1,21 @@
+#ifndef HASH_TRIPLE_H
+#define HASH_TRIPLE_H
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdbool.h>
+
+/* Describe a just-created or just-renamed destination file.  */
+struct F_triple
+{
+  char *name;
+  ino_t st_ino;
+  dev_t st_dev;
+};
+
+extern size_t triple_hash (void const *x, size_t table_size);
+extern size_t triple_hash_no_name (void const *x, size_t table_size);
+extern bool triple_compare (void const *x, void const *y);
+extern void triple_free (void *x);
+
+#endif