From b4e1921916a3db8fe5053d89b7a4189a40ccc3d7 Mon Sep 17 00:00:00 2001
From: Giuliano Belinassi <gbelinassi@suse.de>
Date: Wed, 26 Jun 2024 00:17:11 -0300
Subject: [PATCH] Replace strlen upper bound with checks for '\0'
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Strings in C are always terminated by the '\0' character. We can
explore this to avoid sweeping through the string twice.

Constructs like `for (i = 0; i < strlen(str); i++)` are even worse, as
it will call strlen **for each character of the string**, which is
O(n²) instead of O(n). Replace those cases as well.

Signed-off-by: Giuliano Belinassi <gbelinassi@suse.de>
---
 common/wwstd.h       | 21 ++++++++++++---------
 redalert/session.cpp |  5 +++--
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/common/wwstd.h b/common/wwstd.h
index ab99bcc1..03c7d170 100644
--- a/common/wwstd.h
+++ b/common/wwstd.h
@@ -250,18 +250,22 @@ inline static void _splitpath(const char* path, char* drive, char* dir, char* fn
         return;
     }
 
-    for (int i = 0; i < strlen(path); i++) {
-        if (path[i] == '.') {
-            strcpy(ext, path + i + 1);
+    while (*path != '\0') {
+        if (*path == '.') {
+            strcpy(ext, path + 1);
             break;
         }
+
+        ++path;
     }
 }
 
 inline static char* strupr(char* str)
 {
-    for (int i = 0; i < strlen(str); i++)
-        str[i] = toupper(str[i]);
+    while (*str != '\0') {
+        *str = toupper(*str);
+        ++str;
+    }
     return str;
 }
 
@@ -278,10 +282,9 @@ inline static void strrev(char* str)
 
 inline static void _strlwr(char* str)
 {
-    int len = strlen(str);
-
-    for (int i = 0; i < len; i++) {
-        str[i] = tolower(str[i]);
+    while (*str != '\0') {
+        *str = tolower(*str);
+        ++str;
     }
 }
 
diff --git a/redalert/session.cpp b/redalert/session.cpp
index 3a575f86..5057ca55 100644
--- a/redalert/session.cpp
+++ b/redalert/session.cpp
@@ -1089,8 +1089,9 @@ uint32_t SessionClass::Compute_Unique_ID(void)
     //------------------------------------------------------------------------
     path = getenv("PATH");
     if (path) {
-        for (i = 0; i < strlen(path); i++) {
-            Add_CRC(&id, (unsigned int)path[i]);
+        while (*path != '\0') {
+            Add_CRC(&id, (unsigned int)(*path));
+            ++path;
         }
     }