Initial revision

1 files changed, 224 insertions, 0 deletions

diff --git a/lib/backupfile.c b/lib/backupfile.c
new file mode 100644
index 000000000..c6d7914a6
--- /dev/null
+++ b/lib/backupfile.c
@@ -0,0 +1,224 @@
+/* backupfile.c -- make Emacs style backup file names
+   Copyright (C) 1990 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 2, 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, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* David MacKenzie <djm@ai.mit.edu>.
+   Some algorithms adapted from GNU Emacs. */
+
+#include <stdio.h>
+#include <ctype.h>
+#include <sys/types.h>
+#include "backupfile.h"
+#if defined(USG) || defined(STDC_HEADERS)
+#include <string.h>
+#define index strchr
+#define rindex strrchr
+#else
+#include <strings.h>
+#endif
+
+#ifdef DIRENT
+#include <dirent.h>
+#ifdef direct
+#undef direct
+#endif
+#define direct dirent
+#define NLENGTH(direct) (strlen((direct)->d_name))
+#else /* !DIRENT */
+#define NLENGTH(direct) ((direct)->d_namlen)
+#ifdef USG
+#ifdef SYSNDIR
+#include <sys/ndir.h>
+#else /* !SYSNDIR */
+#include <ndir.h>
+#endif /* !SYSNDIR */
+#else /* !USG */
+#include <sys/dir.h>
+#endif /* !USG */
+#endif /* !DIRENT */
+
+#ifdef VOID_CLOSEDIR
+/* Fake a return value. */
+#define CLOSEDIR(d) (closedir (d), 0)
+#else
+#define CLOSEDIR(d) closedir (d)
+#endif
+
+#ifdef STDC_HEADERS
+#include <stdlib.h>
+#else
+char *malloc ();
+#endif
+
+#ifndef isascii
+#define ISDIGIT(c) (isdigit ((unsigned char) (c)))
+#else
+#define ISDIGIT(c) (isascii (c) && isdigit (c))
+#endif
+
+#if defined (HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
+
+#if defined (_POSIX_VERSION)
+/* POSIX does not require that the d_ino field be present, and some
+   systems do not provide it. */
+#define REAL_DIR_ENTRY(dp) 1
+#else
+#define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
+#endif
+
+/* Which type of backup file names are generated. */
+enum backup_type backup_type = none;
+
+/* The extension added to file names to produce a simple (as opposed
+   to numbered) backup file name. */
+char *simple_backup_suffix = "~";
+
+char *basename ();
+char *dirname ();
+static char *concat ();
+char *find_backup_file_name ();
+static char *make_version_name ();
+static int max_backup_version ();
+static int version_number ();
+
+/* Return the name of the new backup file for file FILE,
+   allocated with malloc.  Return 0 if out of memory.
+   FILE must not end with a '/' unless it is the root directory.
+   Do not call this function if backup_type == none. */
+
+char *
+find_backup_file_name (file)
+     char *file;
+{
+  char *dir;
+  char *base_versions;
+  int highest_backup;
+
+  if (backup_type == simple)
+    return concat (file, simple_backup_suffix);
+  base_versions = concat (basename (file), ".~");
+  if (base_versions == 0)
+    return 0;
+  dir = dirname (file);
+  if (dir == 0)
+    {
+      free (base_versions);
+      return 0;
+    }
+  highest_backup = max_backup_version (base_versions, dir);
+  free (base_versions);
+  free (dir);
+  if (backup_type == numbered_existing && highest_backup == 0)
+    return concat (file, simple_backup_suffix);
+  return make_version_name (file, highest_backup + 1);
+}
+
+/* Return the number of the highest-numbered backup file for file
+   FILE in directory DIR.  If there are no numbered backups
+   of FILE in DIR, or an error occurs reading DIR, return 0.
+   FILE should already have ".~" appended to it. */
+
+static int
+max_backup_version (file, dir)
+     char *file, *dir;
+{
+  DIR *dirp;
+  struct direct *dp;
+  int highest_version;
+  int this_version;
+  int file_name_length;
+  
+  dirp = opendir (dir);
+  if (!dirp)
+    return 0;
+  
+  highest_version = 0;
+  file_name_length = strlen (file);
+
+  while ((dp = readdir (dirp)) != 0)
+    {
+      if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) <= file_name_length)
+	continue;
+      
+      this_version = version_number (file, dp->d_name, file_name_length);
+      if (this_version > highest_version)
+	highest_version = this_version;
+    }
+  if (CLOSEDIR (dirp))
+    return 0;
+  return highest_version;
+}
+
+/* Return a string, allocated with malloc, containing
+   "FILE.~VERSION~".  Return 0 if out of memory. */
+
+static char *
+make_version_name (file, version)
+     char *file;
+     int version;
+{
+  char *backup_name;
+
+  backup_name = malloc (strlen (file) + 16);
+  if (backup_name == 0)
+    return 0;
+  sprintf (backup_name, "%s.~%d~", file, version);
+  return backup_name;
+}
+
+/* If BACKUP is a numbered backup of BASE, return its version number;
+   otherwise return 0.  BASE_LENGTH is the length of BASE.
+   BASE should already have ".~" appended to it. */
+
+static int
+version_number (base, backup, base_length)
+     char *base;
+     char *backup;
+     int base_length;
+{
+  int version;
+  char *p;
+  
+  version = 0;
+  if (!strncmp (base, backup, base_length) && ISDIGIT (backup[base_length]))
+    {
+      for (p = &backup[base_length]; ISDIGIT (*p); ++p)
+	version = version * 10 + *p - '0';
+      if (p[0] != '~' || p[1])
+	version = 0;
+    }
+  return version;
+}
+
+/* Return the newly-allocated concatenation of STR1 and STR2.
+   If out of memory, return 0. */
+
+static char *
+concat (str1, str2)
+     char *str1, *str2;
+{
+  char *newstr;
+  char str1_length = strlen (str1);
+
+  newstr = malloc (str1_length + strlen (str2) + 1);
+  if (newstr == 0)
+    return 0;
+  strcpy (newstr, str1);
+  strcpy (newstr + str1_length, str2);
+  return newstr;
+}