Fixes for -L command line switch

1) Bug fix for issue ggreer#238 where a file (call it test.txt) of contents
  "foo\n\n" will be invert matched by this command:

      ag -L foo test.txt

2) If user specifies both -L and -v on command line, that's a conflict.
   Resolve by suppressing -v .

3) Added test cases for 1 and 2.

src/options.c

@@ -410,7 +410,7 @@ void parse_options(int argc, char **argv, char **base_paths[], char **paths[]) {
                 opts.casing = CASE_INSENSITIVE;
                 break;
             case 'L':
-                opts.invert_match = 1;
+                opts.invert_match_filename = 1;
             /* fall through */
             case 'l':
                 needs_query = 0;
@@ -454,7 +454,7 @@ void parse_options(int argc, char **argv, char **base_paths[], char **paths[]) {
                 opts.skip_vcs_ignores = 1;
                 break;
             case 'v':
-                opts.invert_match = 1;
+                opts.invert_match_listing = 1;
                 /* Color highlighting doesn't make sense when inverting matches */
                 opts.color = 0;
                 break;
@@ -540,6 +540,16 @@ void parse_options(int argc, char **argv, char **base_paths[], char **paths[]) {
         }
     }
 
+    if (opts.invert_match_listing && opts.invert_match_filename) {
+        /* 
+         * User specified -L and -v at same time on the command line.
+         * These two options are inherently at conflict with each other.
+         * Opt to make -L the higher precedence option, which seems to give
+         * the least surprising results.
+         */
+        opts.invert_match_listing = FALSE;
+    }
+    opts.invert_match = (opts.invert_match_listing || opts.invert_match_filename);
 
     if (ext_index[0]) {
         num_exts = combine_file_extensions(ext_index, lang_num, &extensions);

src/options.h

@@ -45,7 +45,9 @@ typedef struct {
     int column;
     int context;
     int follow_symlinks;
-    int invert_match;
+    int invert_match_listing;   /* list inverted matches */
+    int invert_match_filename;  /* list only filename    */
+    int invert_match;           /* semi-logical OR of previous 2 fields */
     int literal;
     int literal_starts_wordchar;
     int literal_ends_wordchar;

src/search.c

@@ -118,8 +118,18 @@ void search_buf(const char *buf, const size_t buf_len,
         }
     }
 
+    size_t inverted_matches = 0;
+    int    invert_L = FALSE;      /* -L conditions met */
+    int    invert_v = FALSE;      /* -v conditions met */
     if (opts.invert_match) {
-        matches_len = invert_matches(buf, buf_len, matches, matches_len);
+        int all_inverted;         /* T => nothing in buffer matches PATTERN */
+
+        all_inverted = (matches_len == 0);
+        matches_len = inverted_matches = invert_matches(
+                                         buf, buf_len, matches, matches_len
+                                                       );
+        invert_v = (inverted_matches != 0 && opts.invert_match_listing);
+        invert_L = (all_inverted && opts.invert_match_filename);
     }
 
     if (opts.stats) {
@@ -133,29 +143,38 @@ void search_buf(const char *buf, const size_t buf_len,
         pthread_mutex_unlock(&stats_mtx);
     }
 
-    if (matches_len > 0) {
+    if (opts.invert_match) {
+        /*
+         * now that stats are recorded, whack "matches_len" so that it's
+         * not used for listing decisions in the next "if"
+         */
+
+        matches_len = 0;
+    }
+
+    if (matches_len > 0 || invert_L || invert_v) {
         if (binary == -1 && !opts.print_filename_only) {
             binary = is_binary((const void *)buf, buf_len);
         }
         pthread_mutex_lock(&print_mtx);
         if (opts.print_filename_only) {
-            /* If the --files-without-matches or -L option is passed we should
-             * not print a matching line. This option currently sets
-             * opts.print_filename_only and opts.invert_match. Unfortunately
-             * setting the latter has the side effect of making matches.len = 1
-             * on a file-without-matches which is not desired behaviour. See
-             * GitHub issue 206 for the consequences if this behaviour is not
-             * checked. */
-            if (!opts.invert_match || matches_len < 2) {
-                if (opts.print_count) {
-                    print_path_count(dir_full_path, opts.path_sep, (size_t)matches_len);
-                } else {
-                    print_path(dir_full_path, opts.path_sep);
-                }
+            if (opts.print_count) {
+                print_path_count(dir_full_path, opts.path_sep, (size_t)matches_len);
+            } else {
+                print_path(dir_full_path, opts.path_sep);
             }
         } else if (binary) {
             print_binary_file_matches(dir_full_path);
         } else {
+            if (opts.invert_match) {
+                /*
+                 * Restore the correct value of "matches_len" (which was
+                 * whacked up above) so that print_file_matches() works
+                 * correctly.
+                 */
+
+                matches_len = inverted_matches;
+            }
             print_file_matches(dir_full_path, buf, buf_len, matches, matches_len);
         }
         pthread_mutex_unlock(&print_mtx);

tests/files_without_matches.t

@@ -0,0 +1,29 @@
+Setup:
+
+  $ . $TESTDIR/setup.sh
+  $ echo 'foo' > ./blah.txt
+  $ echo       >> ./blah.txt
+
+This file structure caused older versions of ag to falsely report an
+inverted match for "foo"
+
+  $ ag -L 'foo' ./blah.txt
+  [1]
+
+Run a few more tests....
+
+  $ echo 'stuff for a test'    >  ./blah2.txt
+  $ echo 'There you go'        >> ./blah2.txt
+  $ echo 'Down Goes Frazier'   >> ./blah2.txt
+  $ echo 'There it is'         >  ./blah3.txt
+  $ echo '.........'           >> ./blah3.txt
+  $ echo 'Was it there'        >> ./blah3.txt
+
+  $ ag -L 'there' ./blah.txt ./blah2.txt ./blah3.txt
+  blah.txt
+
+If -v and -L are both specified, -L wins ...
+
+  $ ag -v -L 'stuff' ./blah.txt ./blah2.txt ./blah3.txt
+  blah.txt
+  blah3.txt