Do not delete files immediately

Fixes the bug that more than one numbered backup would be created when a patch
file deletes and recreates a file.
* bootstrap.conf (gnulib_modules): Add linked-list and xlist modules.
* src/util.h (file_id_type): Add DELETE_LATER and OVERWRITTEN types.
(create_backup, set_file_attributes): Update prototype.
(insert_file_id): Add prototype.
* src/util.c (insert_file_id): Export.
(set_file_attributes, create_backup_copy): Make the st argument const.
(create_backup): Pass in to_st instead of returning it from create_backup().
This obsoletes the to_errno argument.
(move_file): Determine to_st here and pass it to create_backup().  Remember
when a file is overwritten.
* src/patch.c (output_file): Add to_st parameter.  Remember files to delete
instead of deleting them immediately.  Pass from-st to create_backup().
(file_to_delete): New struct.
(init_files_to_delete, delete_file_later, delete_files): New functions.
(main): Use init_files_to_delete() and delete_files().  Pass to_st to
output_file() where we already have it.
* src/pch.c (intuit_diff_type): Assume that files which are marked for deletion
don't exist.

6 files changed, 105 insertions, 38 deletions

diff --git a/bootstrap.conf b/bootstrap.conf
index 7024323..a549668 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -37,6 +37,7 @@ hash
 ignore-value
 largefile
 lchmod
+linked-list
 lstat
 maintainer-makefile
 malloc
@@ -66,6 +67,7 @@ update-copyright
 utimens
 verror
 xalloc
+xlist
 "
 
 gnulib_tool_option_extras='--symlink --makefile-name=gnulib.mk'
diff --git a/m4/.gitignore b/m4/.gitignore
index 45e6333..b112934 100644
--- a/m4/.gitignore
+++ b/m4/.gitignore
@@ -244,3 +244,4 @@ xsize.m4
 xstrndup.m4
 xvasprintf.m4
 /close.m4
+/gl_list.m4
diff --git a/src/patch.c b/src/patch.c
index 3bd7472..09ae41c 100644
--- a/src/patch.c
+++ b/src/patch.c
@@ -31,6 +31,8 @@
 #include <util.h>
 #include <version.h>
 #include <xalloc.h>
+#include <gl_linked_list.h>
+#include <gl_xlist.h>
 
 /* procedures */
 
@@ -54,7 +56,10 @@ static void abort_hunk_context (bool, bool);
 static void abort_hunk_unified (bool, bool);
 
 static void output_file (char const *, int *, const struct stat *, char const *,
-			 mode_t, bool);
+			 const struct stat *, mode_t, bool);
+
+static void init_files_to_delete (void);
+static void delete_files (void);
 
 #ifdef ENABLE_MERGE
 static bool merge;
@@ -153,6 +158,8 @@ main (int argc, char **argv)
       backup_type = get_version (version_control_context, version_control);
 
     init_backup_hash_table ();
+    init_files_to_delete ();
+
     init_output (&outstate);
     if (outfile)
       outstate.ofp = open_outfile (outfile);
@@ -442,7 +449,9 @@ main (int argc, char **argv)
 		  || S_ISLNK (file_type)))
 	    {
 	      if (! dry_run)
-		output_file (NULL, NULL, NULL, outname, file_type | 0, backup);
+		output_file (NULL, NULL, NULL, outname,
+			     (inname == outname) ? &instat : NULL,
+			     file_type | 0, backup);
 	    }
 	  else
 	    {
@@ -502,13 +511,15 @@ main (int argc, char **argv)
 			}
 
 		      output_file (TMPOUTNAME, &TMPOUTNAME_needs_removal,
-				   &outst, outname, mode, backup);
+				   &outst, outname, NULL, mode, backup);
 
 		      if (pch_rename ())
-			output_file (NULL, NULL, NULL, inname, mode, backup);
+			output_file (NULL, NULL, NULL, inname, &instat,
+				     mode, backup);
 		    }
 		  else
-		    output_file (outname, NULL, &outst, NULL, file_type | 0, backup);
+		    output_file (outname, NULL, &outst, NULL, NULL,
+				 file_type | 0, backup);
 		}
 	    }
       }
@@ -574,6 +585,7 @@ main (int argc, char **argv)
     }
     if (outstate.ofp && (ferror (outstate.ofp) || fclose (outstate.ofp) != 0))
       write_fatal ();
+    delete_files ();
     cleanup ();
     if (somefailed)
       exit (1);
@@ -1608,26 +1620,82 @@ similar (char const *a, size_t alen, char const *b, size_t blen)
     }
 }
 
+/* Deferred deletion of files. */
+
+struct file_to_delete {
+  char *name;
+  struct stat st;
+  bool backup;
+};
+
+static gl_list_t files_to_delete;
+
+static void
+init_files_to_delete (void)
+{
+  files_to_delete = gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
+}
+
+static void
+delete_file_later (const char *name, const struct stat *st, bool backup)
+{
+  struct file_to_delete *file_to_delete;
+  struct stat st_tmp;
+
+  if (! st)
+    {
+      if (lstat (name, &st_tmp) != 0)
+	pfatal ("Can't get file attributes of %s %s", "file", name);
+      st = &st_tmp;
+    }
+  file_to_delete = xmalloc (sizeof *file_to_delete);
+  file_to_delete->name = xstrdup (name);
+  file_to_delete->st = *st;
+  file_to_delete->backup = backup;
+  gl_list_add_last (files_to_delete, file_to_delete);
+  insert_file_id (st, DELETE_LATER);
+}
+
+static void
+delete_files (void)
+{
+  gl_list_iterator_t iter;
+  const void *elt;
+
+  iter = gl_list_iterator (files_to_delete);
+  while (gl_list_iterator_next (&iter, &elt, NULL))
+    {
+      const struct file_to_delete *file_to_delete = elt;
+
+      if (lookup_file_id (&file_to_delete->st) == DELETE_LATER)
+	{
+	  mode_t mode = file_to_delete->st.st_mode;
+
+	  if (verbosity == VERBOSE)
+	    say ("Removing %s %s\n",
+		 S_ISLNK (mode) ? "symbolic link" : "file",
+		 quotearg (file_to_delete->name));
+	    move_file (0, 0, 0, file_to_delete->name, mode,
+		       file_to_delete->backup);
+	    removedirs (file_to_delete->name);
+	}
+    }
+  gl_list_iterator_free (&iter);
+}
+
 /* Putting output files into place and removing them. */
 
 static void
 output_file (char const *from, int *from_needs_removal,
 	     const struct stat *from_st, char const *to,
-	     mode_t mode, bool backup)
+	     const struct stat *to_st, mode_t mode, bool backup)
 {
   if (from == NULL)
-    {
-      if (verbosity == VERBOSE)
-	say ("Removing %s %s\n",
-	     S_ISLNK (mode) ? "symbolic link" : "file",
-	     quotearg (to));
-	move_file (0, 0, 0, to, mode, backup);
-	removedirs (to);
-    }
+    delete_file_later (to, to_st, backup);
   else if (to == NULL)
     {
       if (backup)
-	create_backup (from, 0, 0, true, false);
+	create_backup (from, from_st, true, false);
     }
   else
     {
diff --git a/src/pch.c b/src/pch.c
index a1e2839..ab4ebc6 100644
--- a/src/pch.c
+++ b/src/pch.c
@@ -869,6 +869,8 @@ intuit_diff_type (bool need_header, mode_t *p_file_type)
 		}
 	      else if (lstat (p_name[i], &st[i]) != 0)
 		stat_errno[i] = errno;
+	      else if (lookup_file_id (&st[i]) == DELETE_LATER)
+		stat_errno[i] = ENOENT;
 	      else
 		{
 		  stat_errno[i] = 0;
diff --git a/src/util.c b/src/util.c
index acd8d1b..bb1e7b1 100644
--- a/src/util.c
+++ b/src/util.c
@@ -96,7 +96,7 @@ init_backup_hash_table (void)
 /* Insert a file with status ST and type TYPE into the hash table.
    The type of an existing entry can be changed by re-inserting it.  */
 
-static void
+void
 insert_file_id (struct stat const *st, enum file_id_type type)
 {
    file_id *p;
@@ -193,7 +193,7 @@ copy_attr (char const *src_path, char const *dst_path)
 
 void
 set_file_attributes (char const *to, enum file_attributes attr,
-		     char const *from, struct stat *st, mode_t mode,
+		     char const *from, const struct stat *st, mode_t mode,
 		     struct timespec *new_time)
 {
   if (attr & FA_TIMES)
@@ -260,7 +260,7 @@ set_file_attributes (char const *to, enum file_attributes attr,
 }
 
 static void
-create_backup_copy (char const *from, char const *to, struct stat *st,
+create_backup_copy (char const *from, char const *to, const struct stat *st,
 		    bool to_dir_known_to_exist, bool remember_backup)
 {
   struct stat backup_st;
@@ -272,12 +272,9 @@ create_backup_copy (char const *from, char const *to, struct stat *st,
 }
 
 void
-create_backup (char const *to, struct stat *to_st, int *to_errno,
-	       bool leave_original, bool remember_backup)
+create_backup (char const *to, const struct stat *to_st, bool leave_original,
+	       bool remember_backup)
 {
-  struct stat tmp_st;
-  int tmp_errno;
-
   /* When the input to patch modifies the same file more than once, patch only
      backs up the initial version of each file.
 
@@ -294,18 +291,11 @@ create_backup (char const *to, struct stat *to_st, int *to_errno,
      deletes and later recreates a file with numbered backups, two numbered
      backups will be created.  */
 
-  if (! to_st || ! to_errno)
-    {
-      to_st = &tmp_st;
-      to_errno = &tmp_errno;
-    }
-  *to_errno = lstat (to, to_st) == 0 ? 0 : errno;
-
-  if (! to_errno && ! (S_ISREG (to_st->st_mode) || S_ISLNK (to_st->st_mode)))
+  if (to_st && ! (S_ISREG (to_st->st_mode) || S_ISLNK (to_st->st_mode)))
     fatal ("File %s is not a %s -- refusing to create backup",
 	   to, S_ISLNK (to_st->st_mode) ? "symbolic link" : "regular file");
 
-  if (! *to_errno && lookup_file_id (to_st) == CREATED)
+  if (to_st && lookup_file_id (to_st) == CREATED)
     {
       if (debug & 4)
 	say ("File %s already seen\n", quotearg (to));
@@ -354,7 +344,7 @@ create_backup (char const *to, struct stat *to_st, int *to_errno,
 	    xalloc_die ();
 	}
 
-      if (*to_errno)
+      if (! to_st)
 	{
 	  struct stat backup_st;
 	  int fd;
@@ -435,10 +425,13 @@ move_file (char const *from, int *from_needs_removal,
 	   char const *to, mode_t mode, bool backup)
 {
   struct stat to_st;
-  int to_errno = -1;
+  int to_errno;
 
+  to_errno = lstat (to, &to_st) == 0 ? 0 : errno;
   if (backup)
-    create_backup (to, &to_st, &to_errno, false, from == NULL);
+    create_backup (to, to_errno ? NULL : &to_st, false, from == NULL);
+  if (! to_errno)
+    insert_file_id (&to_st, OVERWRITTEN);
 
   if (from)
     {
diff --git a/src/util.h b/src/util.h
index c61a834..97212ed 100644
--- a/src/util.h
+++ b/src/util.h
@@ -27,7 +27,7 @@
    Add one for the sign.  */
 #define LINENUM_LENGTH_BOUND (sizeof (lin) * CHAR_BIT / 3 + 1)
 
-enum file_id_type { UNKNOWN, CREATED };
+enum file_id_type { UNKNOWN, CREATED, DELETE_LATER, OVERWRITTEN };
 
 XTERN enum backup_type backup_type;
 
@@ -57,13 +57,14 @@ void ignore_signals (void);
 void init_backup_hash_table (void);
 void init_time (void);
 void xalloc_die (void) __attribute__ ((noreturn));
-void create_backup (char const *, struct stat *, int *, bool, bool);
+void create_backup (char const *, const struct stat *, bool, bool);
 void move_file (char const *, int *, struct stat const *, char const *, mode_t, bool);
 void read_fatal (void) __attribute__ ((noreturn));
 void remove_prefix (char *, size_t);
 void removedirs (char const *);
 void set_signals (bool);
 void write_fatal (void) __attribute__ ((noreturn));
+void insert_file_id (struct stat const *, enum file_id_type);
 enum file_id_type lookup_file_id (struct stat const *);
 
 enum file_attributes {
@@ -74,7 +75,7 @@ enum file_attributes {
 };
 
 void set_file_attributes (char const *, enum file_attributes, char const *,
-			  struct stat *, mode_t, struct timespec *);
+			  const struct stat *, mode_t, struct timespec *);
 
 static inline char const * _GL_ATTRIBUTE_PURE
 skip_spaces (char const *str)