1 files changed, 93 insertions, 0 deletions
diff --git a/lib/backup-find.c b/lib/backup-find.c
new file mode 100644
index 0000000..e5af21f
--- /dev/null
+++ b/lib/backup-find.c
@@ -0,0 +1,93 @@
+/* backupfile.c -- make Emacs style backup file names
+
+   Copyright 2017-2022 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include "backup-internal.h"
+
+#include "argmatch.h"
+#include "xalloc.h"
+
+#include <stdlib.h>
+
+/* Relative to DIR_FD, return the name of a backup file for the
+   existing file FILE, allocated with malloc.  Report an error and
+   exit if out of memory.  Do not call this function if
+   backup_type == no_backups.  */
+
+char *
+find_backup_file_name (int dir_fd, char const *file,
+                       enum backup_type backup_type)
+{
+  char *result = backupfile_internal (dir_fd, file, backup_type, false);
+  if (!result)
+    xalloc_die ();
+  return result;
+}
+
+static char const *const backup_args[] =
+{
+  /* In a series of synonyms, present the most meaningful first, so
+     that argmatch_valid be more readable. */
+  "none", "off",
+  "simple", "never",
+  "existing", "nil",
+  "numbered", "t",
+  NULL
+};
+
+static const enum backup_type backup_types[] =
+{
+  no_backups, no_backups,
+  simple_backups, simple_backups,
+  numbered_existing_backups, numbered_existing_backups,
+  numbered_backups, numbered_backups
+};
+
+/* Ensure that these two vectors have the same number of elements,
+   not counting the final NULL in the first one.  */
+ARGMATCH_VERIFY (backup_args, backup_types);
+
+/* Return the type of backup specified by VERSION.
+   If VERSION is NULL or the empty string, return numbered_existing_backups.
+   If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
+   for the specified CONTEXT.  Unambiguous abbreviations are accepted.  */
+
+enum backup_type
+get_version (char const *context, char const *version)
+{
+  if (version == 0 || *version == 0)
+    return numbered_existing_backups;
+  else
+    return XARGMATCH (context, version, backup_args, backup_types);
+}
+
+
+/* Return the type of backup specified by VERSION.
+   If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
+   If the specified string is invalid or ambiguous, fail with a diagnostic
+   appropriate for the specified CONTEXT.
+   Unambiguous abbreviations are accepted.  */
+
+enum backup_type
+xget_version (char const *context, char const *version)
+{
+  if (version && *version)
+    return get_version (context, version);
+  else
+    return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));
+}