compress: Allow uncompress -c with multiple pathnames, as required by…

… POSIX.

Per POSIX, allow passing multiple pathnames to uncompress -c, concatenating
the uncompressed data.

Passing multiple pathnames to compress -c remains disallowed, since the
result cannot be decompressed.

PR:		219387
Reported by:	Jörg Schilling

usr.bin/compress/compress.c

@@ -129,7 +129,7 @@ main(int argc, char *argv[])
 		exit (eval);
 	}
 
-	if (cat == 1 && argc > 1)
+	if (cat == 1 && style == COMPRESS && argc > 1)
 		errx(1, "the -c option permits only a single file argument");
 
 	for (; *argv; ++argv)

usr.bin/compress/tests/compress_test.sh

@@ -161,6 +161,27 @@ compress_uncompress_file_2_body()
 	atf_check cmp file2 expectfile2
 }
 
+atf_test_case compress_uncompress_file_minusc_1
+compress_uncompress_file_minusc_1_head()
+{
+	atf_set "descr" \
+	    "Test compressing and uncompressing some data, passing two filenames to uncompress -c"
+}
+compress_uncompress_file_minusc_1_body()
+{
+	printf '%01000d\n' 7 8 >expectfile1
+	printf '%01000d\n' 8 7 >expectfile2
+	cp expectfile1 file1
+	cp expectfile2 file2
+	atf_check compress file1 file2
+	atf_check -s exit:1 cmp -s file1.Z expectfile1
+	atf_check -s exit:1 cmp -s file2.Z expectfile2
+	atf_check -s exit:1 cmp -s file1.Z file2.Z
+	atf_check -x 'uncompress -c file1.Z file2.Z >all'
+	atf_check -x 'cat expectfile1 expectfile2 >expectall'
+	atf_check cmp all expectall
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case uncompress_file_1
@@ -171,4 +192,5 @@ atf_init_test_cases()
 	atf_add_test_case compress_uncompress_minusc_1
 	atf_add_test_case compress_uncompress_file_1
 	atf_add_test_case compress_uncompress_file_2
+	atf_add_test_case compress_uncompress_file_minusc_1
 }