grep: be GNU compatible with -f EMPTY_FILE

Signed-off-by: Lauri Kasanen <curaga@operamail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 30 insertions, 10 deletions

diff --git a/findutils/grep.c b/findutils/grep.c
index 3acfa9197..5f4224203 100644
--- a/findutils/grep.c
+++ b/findutils/grep.c
@@ -562,20 +562,20 @@ static char *add_grep_list_data(char *pattern)
 
 static void load_regexes_from_file(llist_t *fopt)
 {
-        char *line;
-        FILE *f;
-
         while (fopt) {
+                char *line;
+                FILE *fp;
                 llist_t *cur = fopt;
                 char *ffile = cur->data;
 
                 fopt = cur->link;
                 free(cur);
-                f = xfopen_stdin(ffile);
-                while ((line = xmalloc_fgetline(f)) != NULL) {
+                fp = xfopen_stdin(ffile);
+                while ((line = xmalloc_fgetline(fp)) != NULL) {
                         llist_add_to(&pattern_head,
                                 new_grep_list_data(line, ALLOCATED));
                 }
+                fclose_if_not_stdin(fp);
         }
 }
 
@@ -659,15 +659,19 @@ int grep_main(int argc UNUSED_PARAM, char **argv)
 #endif
         invert_search = ((option_mask32 & OPT_v) != 0); /* 0 | 1 */
 
-        if (pattern_head != NULL) {
-                /* convert char **argv to grep_list_data_t */
+        {       /* convert char **argv to grep_list_data_t */
                 llist_t *cur;
-
                 for (cur = pattern_head; cur; cur = cur->link)
                         cur->data = new_grep_list_data(cur->data, 0);
         }
-        if (option_mask32 & OPT_f)
+        if (option_mask32 & OPT_f) {
                 load_regexes_from_file(fopt);
+                if (!pattern_head) { /* -f EMPTY_FILE? */
+                        /* GNU grep treats it as "nothing matches" */
+                        llist_add_to(&pattern_head, new_grep_list_data((char*) "", 0));
+                        invert_search ^= 1;
+                }
+        }
 
         if (ENABLE_FEATURE_GREP_FGREP_ALIAS && applet_name[0] == 'f')
                 option_mask32 |= OPT_F;
diff --git a/testsuite/grep.tests b/testsuite/grep.tests
index ffce033e6..006a215e1 100755
--- a/testsuite/grep.tests
+++ b/testsuite/grep.tests
@@ -7,7 +7,7 @@
 
 . ./testing.sh
 
-# testing "test name" "options" "expected result" "file input" "stdin"
+# testing "test name" "commands" "expected result" "file input" "stdin"
 #   file input will be file called "input"
 #   test can create a file "actual" instead of writing to stdout
 
@@ -103,4 +103,20 @@ testing "grep -o does not loop forever on zero-length match" \
         "" \
         "" "test\n"
 
+testing "grep -f EMPTY_FILE" \
+        "grep -f input" \
+        "" \
+        "" \
+        "test\n"
+
+testing "grep -v -f EMPTY_FILE" \
+        "grep -v -f input" \
+        "test\n" \
+        "" \
+        "test\n"
+
+# testing "test name" "commands" "expected result" "file input" "stdin"
+#   file input will be file called "input"
+#   test can create a file "actual" instead of writing to stdout
+
 exit $FAILCOUNT