Use make_tempname file descriptor in smart_rename

This patch makes use of the temp file descriptor in smart_rename
rather than reopening the file.  I don't believe there is a security
issue in reopening the file, but this way is one less directory
operation.  The patch also attempts to preserve S_ISUID and S_ISGID.

	PR 27456
	* bucomm.h (smart_rename): Update prototype.
	* rename.c (smart_rename): Add fromfd and preserve_dates params.
	Pass fromfd and target_stat to simple_copy.  Call set_times
	when preserve_dates.
	(simple_copy): Accept fromfd rather than from filename.  Add
	target_stat param.  Rewind fromfd rather than opening.  Open
	"to" file without O_CREAT.  Try to preserve S_ISUID and S_ISGID.
	* ar.c (write_archive): Rename ofd to tmpfd.  Dup tmpfd before
	closing output temp file, and pass tmpfd to smart_rename.
	* arsup.c (temp_fd): Rename from real_fd.
	(ar_save): Dup temp_fd and pass to smart_rename.
	* objcopy.c (strip_main, copy_main): Likewise, and pass
	preserve_dates.

1 files changed, 31 insertions, 11 deletions

diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index abbcb7c..90ae0bd 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -4837,6 +4837,7 @@ strip_main (int argc, char *argv[])
       struct stat statbuf;
       char *tmpname;
       int tmpfd = -1;
+      int copyfd = -1;
 
       if (get_file_size (argv[i]) < 1)
 	{
@@ -4846,7 +4847,11 @@ strip_main (int argc, char *argv[])
 
       if (output_file == NULL
 	  || filename_cmp (argv[i], output_file) == 0)
-	tmpname = make_tempname (argv[i], &tmpfd);
+	{
+	  tmpname = make_tempname (argv[i], &tmpfd);
+	  if (tmpfd >= 0)
+	    copyfd = dup (tmpfd);
+	}
       else
 	tmpname = output_file;
 
@@ -4864,14 +4869,18 @@ strip_main (int argc, char *argv[])
       if (status == 0)
 	{
 	  if (output_file != tmpname)
-	    status = (smart_rename (tmpname,
-				    output_file ? output_file : argv[i],
-				    preserve_dates ? &statbuf : NULL) != 0);
+	    status = smart_rename (tmpname,
+				   output_file ? output_file : argv[i],
+				   copyfd, &statbuf, preserve_dates) != 0;
 	  if (status == 0)
 	    status = hold_status;
 	}
       else
-	unlink_if_ordinary (tmpname);
+	{
+	  if (copyfd >= 0)
+	    close (copyfd);
+	  unlink_if_ordinary (tmpname);
+	}
       if (output_file != tmpname)
 	free (tmpname);
     }
@@ -5078,7 +5087,9 @@ copy_main (int argc, char *argv[])
   bfd_boolean formats_info = FALSE;
   bfd_boolean use_globalize = FALSE;
   bfd_boolean use_keep_global = FALSE;
-  int c, tmpfd = -1;
+  int c;
+  int tmpfd = -1;
+  int copyfd;
   struct stat statbuf;
   const bfd_arch_info_type *input_arch = NULL;
 
@@ -5916,10 +5927,15 @@ copy_main (int argc, char *argv[])
     }
 
   /* If there is no destination file, or the source and destination files
-     are the same, then create a temp and rename the result into the input.  */
+     are the same, then create a temp and copy the result into the input.  */
+  copyfd = -1;
   if (output_filename == NULL
       || filename_cmp (input_filename, output_filename) == 0)
-    tmpname = make_tempname (input_filename, &tmpfd);
+    {
+      tmpname = make_tempname (input_filename, &tmpfd);
+      if (tmpfd >= 0)
+	copyfd = dup (tmpfd);
+    }
   else
     tmpname = output_filename;
 
@@ -5934,11 +5950,15 @@ copy_main (int argc, char *argv[])
   if (status == 0)
     {
       if (tmpname != output_filename)
-	status = (smart_rename (tmpname, input_filename,
-				preserve_dates ? &statbuf : NULL) != 0);
+	status = smart_rename (tmpname, input_filename, copyfd,
+			       &statbuf, preserve_dates) != 0;
     }
   else
-    unlink_if_ordinary (tmpname);
+    {
+      if (copyfd >= 0)
+	close (copyfd);
+      unlink_if_ordinary (tmpname);
+    }
 
   if (tmpname != output_filename)
     free (tmpname);