Add missing call to atexit() to clean up temp files on error.

Use mkstemp() to create the temp file when "sort -o" specifies
the same name as an input file and preserve the original file
mode on the temp file.  Check for write access on the original
file before creating the temporary.
Based on a diff from and OK bluhm@

1 files changed, 21 insertions, 18 deletions

diff --git a/usr.bin/sort/sort.c b/usr.bin/sort/sort.c
index 1d4da6abd7f..9a330d5ada8 100644
--- a/usr.bin/sort/sort.c
+++ b/usr.bin/sort/sort.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sort.c,v 1.50 2015/03/30 22:20:53 millert Exp $	*/
+/*	$OpenBSD: sort.c,v 1.51 2015/03/31 11:46:26 millert Exp $	*/
 
 /*-
  * Copyright (C) 2009 Gabor Kovesdan <gabor@FreeBSD.org>
@@ -861,7 +861,7 @@ main(int argc, char *argv[])
 	    { false, false, false, false, false, false };
 
 	result = 0;
-	outfile = sort_strdup("-");
+	outfile = "-";
 	real_outfile = NULL;
 
 	struct sort_mods *sm = &default_sort_mods_object;
@@ -870,6 +870,8 @@ main(int argc, char *argv[])
 
 	set_signal_handler();
 
+	atexit(clear_tmp_files);
+
 	set_hw_params();
 	set_locale();
 	set_tmpdir();
@@ -923,8 +925,7 @@ main(int argc, char *argv[])
 				sort_opts_vals.mflag = true;
 				break;
 			case 'o':
-				sort_free(outfile);
-				outfile = sort_strdup(optarg);
+				outfile = optarg;
 				break;
 			case 's':
 				sort_opts_vals.sflag = true;
@@ -1098,20 +1099,25 @@ main(int argc, char *argv[])
 	set_random_seed();
 
 	/* Case when the outfile equals one of the input files: */
-	if (strcmp(outfile, "-")) {
-		int i;
+	if (strcmp(outfile, "-") != 0) {
+		struct stat sb;
+		int fd, i;
 
 		for (i = 0; i < argc; ++i) {
 			if (strcmp(argv[i], outfile) == 0) {
-				real_outfile = sort_strdup(outfile);
-				for (;;) {
-					const size_t size = strlen(outfile) + strlen(".tmp") + 1;
-					outfile = sort_realloc(outfile, size);
-					strlcat(outfile, ".tmp", size);
-					if (access(outfile, F_OK) < 0)
-						break;
-				}
+				if (stat(outfile, &sb) == -1)
+					err(2, "%s", outfile);
+				if (access(outfile, W_OK) == -1)
+					err(2, "%s", outfile);
+				real_outfile = outfile;
+				sort_asprintf(&outfile, "%s.XXXXXXXXXX",
+				    real_outfile);
+				if ((fd = mkstemp(outfile)) == -1 ||
+				    fchmod(fd, sb.st_mode & ALLPERMS) == -1)
+					err(2, "%s", outfile);
+				close(fd);
 				tmp_file_atexit(outfile);
+				break;
 			}
 		}
 	}
@@ -1166,13 +1172,10 @@ main(int argc, char *argv[])
 	}
 
 	if (real_outfile) {
-		unlink(real_outfile);
 		if (rename(outfile, real_outfile) < 0)
 			err(2, "%s", real_outfile);
-		sort_free(real_outfile);
+		sort_free(outfile);
 	}
 
-	sort_free(outfile);
-
 	return result;
 }