grep: tune -f /dev/null

* src/grep.c (main): Do the -f /dev/null early-exit checks before
more-expensive tests that involve syscalls.

1 files changed, 40 insertions, 40 deletions

diff --git a/src/grep.c b/src/grep.c
index 317a0d5d..066df8cb 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -2761,6 +2761,28 @@ main (int argc, char **argv)
   if (show_help)
     usage (EXIT_SUCCESS);
 
+  if (keys)
+    {
+      if (keycc == 0)
+        {
+          /* No keys were specified (e.g. -f /dev/null).  Match nothing.  */
+          out_invert ^= true;
+          match_lines = match_words = false;
+        }
+      else
+        /* Strip trailing newline. */
+        --keycc;
+    }
+  else if (optind < argc)
+    {
+      /* Make a copy so that it can be reallocated or freed later.  */
+      keycc = strlen (argv[optind]);
+      keys = xmemdup (argv[optind++], keycc + 1);
+      fl_add (keys, 0, keycc, "");
+    }
+  else
+    usage (EXIT_TROUBLE);
+
   bool possibly_tty = false;
   struct stat tmp_stat;
   if (! exit_on_match && fstat (STDOUT_FILENO, &tmp_stat) == 0)
@@ -2778,21 +2800,6 @@ main (int argc, char **argv)
         }
     }
 
-  if (color_option == 2)
-    color_option = possibly_tty && should_colorize () && isatty (STDOUT_FILENO);
-  init_colorize ();
-
-  if (color_option)
-    {
-      /* Legacy.  */
-      char *userval = getenv ("GREP_COLOR");
-      if (userval != NULL && *userval != '\0')
-        selected_match_color = context_match_color = userval;
-
-      /* New GREP_COLORS has priority.  */
-      parse_grep_colors ();
-    }
-
   /* POSIX says -c, -l and -q are mutually exclusive.  In this
      implementation, -q overrides -l and -L, which in turn override -c.  */
   if (exit_on_match | dev_null_output)
@@ -2809,27 +2816,26 @@ main (int argc, char **argv)
   if (out_before < 0)
     out_before = default_context;
 
-  if (keys)
-    {
-      if (keycc == 0)
-        {
-          /* No keys were specified (e.g. -f /dev/null).  Match nothing.  */
-          out_invert ^= true;
-          match_lines = match_words = false;
-        }
-      else
-        /* Strip trailing newline. */
-        --keycc;
-    }
-  else if (optind < argc)
+  /* If it is easy to see that matching cannot succeed (e.g., 'grep -f
+     /dev/null'), fail without reading the input.  */
+  if (max_count == 0
+      || (keycc == 0 && out_invert && !match_lines && !match_words))
+    return EXIT_FAILURE;
+
+  if (color_option == 2)
+    color_option = possibly_tty && should_colorize () && isatty (STDOUT_FILENO);
+  init_colorize ();
+
+  if (color_option)
     {
-      /* Make a copy so that it can be reallocated or freed later.  */
-      keycc = strlen (argv[optind]);
-      keys = xmemdup (argv[optind++], keycc + 1);
-      fl_add (keys, 0, keycc, "");
+      /* Legacy.  */
+      char *userval = getenv ("GREP_COLOR");
+      if (userval != NULL && *userval != '\0')
+        selected_match_color = context_match_color = userval;
+
+      /* New GREP_COLORS has priority.  */
+      parse_grep_colors ();
     }
-  else
-    usage (EXIT_TROUBLE);
 
   initialize_unibyte_mask ();
 
@@ -2866,12 +2872,6 @@ main (int argc, char **argv)
   if (O_BINARY && !isatty (STDOUT_FILENO))
     set_binary_mode (STDOUT_FILENO, O_BINARY);
 
-  /* If it is easy to see that matching cannot succeed (e.g., 'grep -f
-     /dev/null'), fail without reading the input.  */
-  if (max_count == 0
-      || (keycc == 0 && out_invert && !match_lines && !match_words))
-    return EXIT_FAILURE;
-
   /* Prefer sysconf for page size, as getpagesize typically returns int.  */
 #ifdef _SC_PAGESIZE
   long psize = sysconf (_SC_PAGESIZE);