less: implement -F

Implement -F option: Exit if entire file fits on first screen.

function                                             old     new   delta
buffer_print                                         622     633     +11
less_main                                           2446    2449      +3
buffer_fill_and_print                                169     172      +3
packed_usage                                       32258   32236     -22
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/1 up/down: 17/-22)             Total: -5 bytes

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 13 insertions, 7 deletions

diff --git a/miscutils/less.c b/miscutils/less.c
index 51ef2a59d..3bce93247 100644
--- a/miscutils/less.c
+++ b/miscutils/less.c
@@ -121,11 +121,12 @@
 //kbuild:lib-$(CONFIG_LESS) += less.o
 
 //usage:#define less_trivial_usage
-//usage:       "[-E" IF_FEATURE_LESS_REGEXP("I")IF_FEATURE_LESS_FLAGS("Mm")
+//usage:       "[-EF" IF_FEATURE_LESS_REGEXP("I")IF_FEATURE_LESS_FLAGS("Mm")
 //usage:       "N" IF_FEATURE_LESS_TRUNCATE("S") IF_FEATURE_LESS_RAW("R") "h~] [FILE]..."
 //usage:#define less_full_usage "\n\n"
 //usage:       "View FILE (or stdin) one screenful at a time\n"
 //usage:     "\n        -E      Quit once the end of a file is reached"
+//usage:     "\n        -F      Quit if entire file fits on first screen"
 //usage:        IF_FEATURE_LESS_REGEXP(
 //usage:     "\n        -I      Ignore case in all searches"
 //usage:        )
@@ -175,8 +176,9 @@ enum {
         FLAG_N = 1 << 3,
         FLAG_TILDE = 1 << 4,
         FLAG_I = 1 << 5,
-        FLAG_S = (1 << 6) * ENABLE_FEATURE_LESS_TRUNCATE,
-        FLAG_R = (1 << 7) * ENABLE_FEATURE_LESS_RAW,
+        FLAG_F = 1 << 6,
+        FLAG_S = (1 << 7) * ENABLE_FEATURE_LESS_TRUNCATE,
+        FLAG_R = (1 << 8) * ENABLE_FEATURE_LESS_RAW,
 /* hijack command line options variable for internal state vars */
         LESS_STATE_MATCH_BACKWARDS = 1 << 15,
 };
@@ -906,11 +908,12 @@ static void buffer_print(void)
                 else
                         print_ascii(buffer[i]);
         }
-        if ((option_mask32 & FLAG_E)
+        if ((option_mask32 & (FLAG_E|FLAG_F))
          && eof_error <= 0
-         && (max_fline - cur_fline) <= max_displayed_line
         ) {
-                less_exit(EXIT_SUCCESS);
+                i = option_mask32 & FLAG_F ? 0 : cur_fline;
+                if (max_fline - i <= max_displayed_line)
+                        less_exit(EXIT_SUCCESS);
         }
         status_print();
 }
@@ -1814,7 +1817,7 @@ int less_main(int argc, char **argv)
          * -s: condense many empty lines to one
          *     (used by some setups for manpage display)
          */
-        getopt32(argv, "EMmN~I"
+        getopt32(argv, "EMmN~IF"
                 IF_FEATURE_LESS_TRUNCATE("S")
                 IF_FEATURE_LESS_RAW("R")
                 /*ignored:*/"s"
@@ -1828,6 +1831,9 @@ int less_main(int argc, char **argv)
         if (ENABLE_FEATURE_LESS_ENV) {
                 char *c = getenv("LESS");
                 if (c) while (*c) switch (*c++) {
+                case 'F':
+                        option_mask32 |= FLAG_F;
+                        break;
                 case 'M':
                         option_mask32 |= FLAG_M;
                         break;