zgrep: fix "binary file matches" mislabeling

Problem reported by Jim Avera (Bug#31280).
This became more of an issue when GNU grep 3.5 (2020) started sending
"binary file matches" diagnostics to stderr instead of to stdout.
* tests/Makefile.am (TESTS): Add zgrep-binary.
* tests/zgrep-binary: New test.
* zgrep.in (args): New var, to accumulate args separately
from grep command, so we can prepend args if need be.
Most uses of 'grep' changed to use 'args' instead, or also.
(with_filename): Set to 1 if more than one file and -h not given;
this simplifies later code.
(gnuish_grep): New var; evaluates to true if grep supports
-H and --label options, as is true for GNU and FreeBSD grep.
Append -H to 'grep' if outputting file names with GNUish grep,
and use --label with GNUish grep unless reading from stdin,
as that’s safer and more efficient than relabeling with 'sed'.

4 files changed, 53 insertions, 9 deletions

diff --git a/NEWS b/NEWS
index 6f83b6a..c15d2e0 100644
--- a/NEWS
+++ b/NEWS
@@ -20,6 +20,9 @@ GNU gzip NEWS                                    -*- outline -*-
   can no longer overwrite an arbitrary, attacker-selected file.
   [bug introduced in gzip-1.3.10]
 
+  zgrep now names input file on error instead of mislabeling it as
+  "(standard input)", if grep supports the GNU -H and --label options.
+
   'zdiff -C 5' no longer misbehaves by treating '5' as a file name.
   [bug present since the beginning]
 
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 5f148d6..b116b03 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -37,6 +37,7 @@ TESTS =					\
   zdiff					\
   zgrep-f				\
   zgrep-abuse				\
+  zgrep-binary				\
   zgrep-context				\
   zgrep-signal				\
   znew-k
diff --git a/tests/zgrep-binary b/tests/zgrep-binary
new file mode 100755
index 0000000..6c00cef
--- /dev/null
+++ b/tests/zgrep-binary
@@ -0,0 +1,30 @@
+#!/bin/sh
+# 'zgrep PATTERN FILE' would output "(standard input): binary file matches"
+# without mentioning FILE.  Fixed in gzip-1.12.
+
+# Copyright (C) 2022 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+# limit so don't run it by default.
+
+. "${srcdir=.}/init.sh"; path_prepend_ ..
+
+fail=0
+
+unset GREP_OPTIONS
+
+printf 'foo\0\n' >f || framework_failure_
+LC_ALL=C zgrep foo f >out 2>err && grep '(standard input)' out err && fail=1
+
+Exit $fail
diff --git a/zgrep.in b/zgrep.in
index 2cb2426..25c2782 100644
--- a/zgrep.in
+++ b/zgrep.in
@@ -23,6 +23,7 @@
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
 grep='${GREP-'\''@GREP@'\''}'
+args=
 
 version='zgrep (gzip) @VERSION@
 Copyright (C) 2010-2018 Free Software Foundation, Inc.
@@ -178,7 +179,7 @@ while test $# -ne 0; do
     option="'$option'";;
   esac
 
-  grep="$grep $option$optarg"
+  args="$args $option$optarg"
 done
 
 eval "set -- $operands "'${1+"$@"}'
@@ -186,15 +187,23 @@ eval "set -- $operands "'${1+"$@"}'
 if test $have_pat -eq 0; then
   case ${1?"missing pattern; try \`$0 --help' for help"} in
   (*\'*)
-    grep="$grep -- '"$(printf '%s\n' "$1" | LC_ALL=C sed "$escape");;
+    args="$args -- '"$(printf '%s\n' "$1" | LC_ALL=C sed "$escape");;
   (*)
-    grep="$grep -- '$1'";;
+    args="$args -- '$1'";;
   esac
   shift
 fi
 
 if test $# -eq 0; then
   set -- -
+elif test 1 -lt $# && test $no_filename -eq 0; then
+  with_filename=1
+fi
+
+l_e=$(eval "(echo e | $grep -H --label=l e) 2>/dev/null") && test "$l_e" = l:e
+gnuish_grep="test $? -eq 0"
+if $gnuish_grep && test $with_filename -eq 1; then
+  grep="$grep -H"
 fi
 
 exec 3>&1
@@ -207,9 +216,9 @@ do
     exec 5>&1
     ('gzip' -cdfq -- "$i" 5>&-; echo $? >&5) 3>&- |
     if test $files_with_matches -eq 1; then
-      eval "$grep" >/dev/null && { printf '%s\n' "$i" || exit 2; }
+      eval "$grep$args" >/dev/null && { printf '%s\n' "$i" || exit 2; }
     elif test $files_without_matches -eq 1; then
-      eval "$grep" >/dev/null || {
+      eval "$grep$args" >/dev/null || {
         r=$?
         if test $r -eq 1; then
           printf '%s\n' "$i" || r=2
@@ -217,9 +226,10 @@ do
         test 256 -le $r && r=$(expr 128 + $r % 128)
         exit $r
       }
-    elif test $with_filename -eq 0 &&
-         { test $# -eq 1 || test $no_filename -eq 1; }; then
-      eval "$grep"
+    elif $gnuish_grep && test "$i" != -; then
+      eval "$grep --label \"\$i\"$args"
+    elif $gnuish_grep || test $with_filename -eq 0; then
+      eval "$grep$args"
     else
       case $i in
       (*'
@@ -233,7 +243,7 @@ do
       # Fail if grep or sed fails.
       r=$(
         exec 4>&1
-        (eval "$grep" 4>&-; echo $? >&4) 3>&- |
+        (eval "$grep$args" 4>&-; echo $? >&4) 3>&- |
            LC_ALL=C sed "$sed_script" >&3 4>&-
       ) || { r=$?; test $r -lt 2 && r=2; }
       test 256 -le $r && r=$(expr 128 + $r % 128)