From 0d1e6960af35ab4aa289e4e0c2443320e2a3adb0 Mon Sep 17 00:00:00 2001
From: Craig Barnes <craigbarnes@protonmail.com>
Date: Wed, 6 Apr 2022 01:24:34 +0100
Subject: [PATCH] osc: avoid unnecessary calls to strlen(3)

Checking for specific strings of length 0 or 1 can be done with e.g.:

    if (str[0] == '\0') {...}
    if (str[0] == '?' && str[1] == '\0') {...}

Doing it this way instead of using strlen(3) means we avoid the
function call overhead and also avoid scanning through more of the
string than is neceessary.

A compiler could perhaps optimize away calls to strlen(3) when the
result is compared to a small constant, but GCC 11.2 only seems to
actually do this[1] for lengths of 0.

[1]: https://godbolt.org/z/qxoW8qqW6
---
 osc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/osc.c b/osc.c
index 5d04910b..2abd3e86 100644
--- a/osc.c
+++ b/osc.c
@@ -252,7 +252,7 @@ osc_selection(struct terminal *term, char *string)
 
     LOG_DBG("clipboard: target = %s data = %s", string, p);
 
-    if (strlen(p) == 1 && p[0] == '?')
+    if (p[0] == '?' && p[1] == '\0')
         osc_from_clipboard(term, string);
     else
         osc_to_clipboard(term, string, p);
@@ -587,7 +587,7 @@ osc_dispatch(struct terminal *term)
             }
 
             /* Client queried for current value */
-            if (strlen(s_color) == 1 && s_color[0] == '?') {
+            if (s_color[0] == '?' && s_color[1] == '\0') {
                 uint32_t color = term->colors.table[idx];
                 uint8_t r = (color >> 16) & 0xff;
                 uint8_t g = (color >>  8) & 0xff;
@@ -683,7 +683,7 @@ osc_dispatch(struct terminal *term)
         /* Set default foreground/background/highlight-bg/highlight-fg color */
 
         /* Client queried for current value */
-        if (strlen(string) == 1 && string[0] == '?') {
+        if (string[0] == '?' && string[1] == '\0') {
             uint32_t color = param == 10 ? term->colors.fg : term->colors.bg;
             uint8_t r = (color >> 16) & 0xff;
             uint8_t g = (color >>  8) & 0xff;
@@ -752,7 +752,7 @@ osc_dispatch(struct terminal *term)
     case 12: /* Set cursor color */
 
         /* Client queried for current value */
-        if (strlen(string) == 1 && string[0] == '?') {
+        if (string[0] == '?' && string[1] == '\0') {
             uint8_t r = (term->cursor_color.cursor >> 16) & 0xff;
             uint8_t g = (term->cursor_color.cursor >>  8) & 0xff;
             uint8_t b = (term->cursor_color.cursor >>  0) & 0xff;
@@ -800,7 +800,7 @@ osc_dispatch(struct terminal *term)
     case 104: {
         /* Reset Color Number 'c' (whole table if no parameter) */
 
-        if (strlen(string) == 0) {
+        if (string[0] == '\0') {
             LOG_DBG("resetting all colors");
             for (size_t i = 0; i < ALEN(term->colors.table); i++)
                 term->colors.table[i] = term->conf->colors.table[i];