1 files changed, 19 insertions, 9 deletions

diff --git a/gunzip.c b/gunzip.c
index b29bdf7c1..330dee335 100644
--- a/gunzip.c
+++ b/gunzip.c
@@ -569,19 +569,20 @@ local int get_method (int in);
 int gunzip_main(int argc, char **argv)
 {
         int file_count;                         /* number of files to precess */
-        int to_stdout = 0;
+        int tostdout = 0;
         int fromstdin = 0;
         int result;
         int inFileNum;
         int outFileNum;
         int delInputFile = 0;
+        int force = 0;
         struct stat statBuf;
         char *delFileName;
         char ifname[MAX_PATH_LEN + 1];  /* input file name */
         char ofname[MAX_PATH_LEN + 1];  /* output file name */
 
         if (strcmp(applet_name, "zcat") == 0) {
-                to_stdout = 1;
+                tostdout = 1;
                 if (argc == 1) {
                         fromstdin = 1;
                 }
@@ -590,23 +591,32 @@ int gunzip_main(int argc, char **argv)
         /* Parse any options */
         while (--argc > 0 && **(++argv) == '-') {
                 if (*((*argv) + 1) == '\0') {
-                        fromstdin = 1;
-                        to_stdout = 1;
+                        tostdout = 1;
                 }
                 while (*(++(*argv))) {
                         switch (**argv) {
                         case 'c':
-                                to_stdout = 1;
+                                tostdout = 1;
                                 break;
                         case 't':
                                 test_mode = 1;
                                 break;
-
+                        case 'f':
+                                force = 1;
+                                break;
                         default:
                                 usage(gunzip_usage);
                         }
                 }
         }
+        if (argc <= 0)
+                fromstdin = 1;
+
+        if (isatty(fileno(stdin)) && fromstdin==1 && force==0)
+                fatalError( "data not read from terminal. Use -f to force it.\n");
+        if (isatty(fileno(stdout)) && tostdout==1 && force==0)
+                fatalError( "data not written to terminal. Use -f to force it.\n");
+
 
         foreground = signal(SIGINT, SIG_IGN) != SIG_IGN;
         if (foreground) {
@@ -644,7 +654,7 @@ int gunzip_main(int argc, char **argv)
                 ifile_size = -1L;               /* convention for unknown size */
         } else {
                 /* Open up the input file */
-                if (*argv == '\0')
+                if (argc <= 0)
                         usage(gunzip_usage);
                 if (strlen(*argv) > MAX_PATH_LEN) {
                         errorMsg(name_too_long);
@@ -667,7 +677,7 @@ int gunzip_main(int argc, char **argv)
                 ifile_size = statBuf.st_size;
         }
 
-        if (to_stdout == 1) {
+        if (tostdout == 1) {
                 /* And get to work */
                 strcpy(ofname, "stdout");
                 outFileNum = fileno(stdout);
@@ -741,7 +751,7 @@ int gunzip_main(int argc, char **argv)
 
 /* ========================================================================
  * Check the magic number of the input file and update ofname if an
- * original name was given and to_stdout is not set.
+ * original name was given and tostdout is not set.
  * Return the compression method, -1 for error, -2 for warning.
  * Set inptr to the offset of the next byte to be processed.
  * Updates time_stamp if there is one and --no-time is not used.