[git commit] less: implement -F

[Denys Vlasenko]

commit: https://git.busybox.net/busybox/commit/?id=36941503bd8e28a1fac13edffc3ffc84346b32c5
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master

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 at iki.fi>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 miscutils/less.c | 20 +++++++++++++-------
 1 file 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;