gzip: Fix silent fallback to decompression

Bug-Debian: https://bugs.debian.org/355809
Forwarded: http://www.zytor.com/pipermail/klibc/2016-January/003892.html

If the gzip utilities are built without support for compression,
they will always attempt to carry out decompression even if the
command name and options don't imply that.  Instead they should
fail with an explicit error in this case.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Gbp-Pq: Name gzip-fix-silent-fallback-to-decompression.patch

diff --git a/usr/gzip/gzip.c b/usr/gzip/gzip.c
index ab73de01a875fb76d6b2a08c862646bd8cb3c44a..d0c7e002a287e42fd9ba7f2b0791b3792c5d9658 100644 (file)
--- a/usr/gzip/gzip.c
+++ b/usr/gzip/gzip.c
@@ -90,8 +90,11 @@ int level = 6;        /* compression level */
 #endif
 
 int to_stdout;        /* output to stdout (-c) */
-#ifndef decompress
+#ifdef decompress
+int decompress_wanted;
+#else
 int decompress;       /* decompress (-d) */
+#define decompress_wanted decompress
 #endif
 int force;            /* don't ask questions, compress links (-f) */
 int no_name = -1;     /* don't save or restore the original file name */
@@ -259,17 +262,13 @@ int main (argc, argv)
      * Systems which do not support links can still use -d or -dc.
      * Ignore an .exe extension for MSDOS, OS/2 and VMS.
      */
-#ifndef decompress
     if (  strncmp(progname, "un",  2) == 0     /* ungzip, uncompress */
        || strncmp(progname, "gun", 3) == 0) {  /* gunzip */
-       decompress = 1;
+       decompress_wanted = 1;
     }
-#endif
     if (strequ(progname+1, "cat")       /* zcat, pcat, gcat */
        || strequ(progname, "gzcat")) {    /* gzcat */
-#ifndef decompress
-       decompress = 1;
-#endif
+       decompress_wanted = 1;
        to_stdout = 1;
     }
 #endif
@@ -282,9 +281,7 @@ int main (argc, argv)
        case 'c':
            to_stdout = 1; break;
        case 'd':
-#ifndef decompress
-           decompress = 1;
-#endif
+           decompress_wanted = 1;
            break;
        case 'f':
            force++; break;
@@ -308,9 +305,7 @@ int main (argc, argv)
             break;
        case 't':
            test = to_stdout = 1;
-#ifndef decompress
-           decompress = 1;
-#endif
+           decompress_wanted = 1;
            break;
        case 'v':
            verbose++; quiet = 0; break;
@@ -329,6 +324,14 @@ int main (argc, argv)
        }
     } /* loop on all arguments */
 
+#ifndef SUPPORT_ZIP
+    if (!decompress_wanted) {
+       fprintf(stderr, "%s: this version does not support compression\n",
+               progname);
+       do_exit(ERROR);
+    }
+#endif
+
     /* By default, save name and timestamp on compression but do not
      * restore them on decompression.
      */