cmdlib: fix broken Q_strcasecmp and Q_strncasecmp

string_view isn't null terminated, can't use C string functions

common/cmdlib.cc

@@ -41,34 +41,47 @@
 #include <algorithm>
 #include <string>
 
-#if defined(__has_include) && __has_include(<strings.h>)
-#include <strings.h>
-#endif
+char Q_tolower(char x)
+{
+    if (x >= 'A' && x <= 'Z') {
+        x += 'a' - 'A';
+    }
+    return x;
+}
 
 int32_t Q_strncasecmp(std::string_view a, std::string_view b, size_t maxcount)
 {
-    return
-#ifdef _WIN32
-        _strnicmp
-#elif defined(__has_include) && __has_include(<strings.h>)
-        strncasecmp
-#else
-        strnicmp
-#endif
-        (a.data(), b.data(), maxcount);
+    return Q_strcasecmp(
+        a.substr(0, maxcount),
+        b.substr(0, maxcount));
 }
 
 int32_t Q_strcasecmp(std::string_view a, std::string_view b)
 {
-    return
-#ifdef _WIN32
-        _stricmp
-#elif defined(__has_include) && __has_include(<strings.h>)
-        strcasecmp
-#else
-        stricmp
-#endif
-        (a.data(), b.data());
+    const char *a_ptr = a.data();
+    const char *b_ptr = b.data();
+    const size_t common_size = std::min(a.size(), b.size());
+
+    for (size_t i = 0; i < common_size; ++i) {
+        char achar = Q_tolower(a_ptr[i]);
+        char bchar = Q_tolower(b_ptr[i]);
+
+        if (achar < bchar) {
+            return -1;
+        }
+        if (achar > bchar) {
+            return 1;
+        }
+    }
+
+    // the first common_size chars are the same
+    if (a.size() < b.size()) {
+        return -1;
+    }
+    if (a.size() > b.size()) {
+        return 1;
+    }
+    return 0;
 }
 
 void // mxd

include/common/cmdlib.hh

@@ -30,6 +30,7 @@
 #include <ostream>
 #include <tuple> // for std::apply()
 
+char Q_tolower(char x);
 int32_t Q_strncasecmp(std::string_view a, std::string_view b, size_t maxcount);
 int32_t Q_strcasecmp(std::string_view a, std::string_view b);
 bool string_iequals(std::string_view a, std::string_view b); // mxd

tests/test_common.cc

@@ -382,3 +382,33 @@ TEST(qmat, transpose)
 
     EXPECT_EQ(in.transpose(), exp);
 }
+
+TEST(string, strcasecmp)
+{
+    EXPECT_EQ('x', Q_tolower('X'));
+    EXPECT_EQ('"', Q_tolower('"'));
+
+    const char *test = "abcA**";
+
+    // lhs < rhs
+    EXPECT_LT(Q_strcasecmp("a", "aa"), 0);
+    EXPECT_LT(Q_strcasecmp("aaa", "BBB"), 0);
+    EXPECT_LT(Q_strcasecmp("AAA", "bbb"), 0);
+
+    // lhs == rhs
+    EXPECT_EQ(Q_strcasecmp(std::string_view(&test[0], 1), std::string_view(&test[3], 1)), 0);
+    EXPECT_EQ(Q_strcasecmp("test", "TEST"), 0);
+    EXPECT_EQ(Q_strcasecmp("test", "test"), 0);
+
+    // lhs > rhs
+    EXPECT_GT(Q_strcasecmp("test", "aaaa"), 0);
+    EXPECT_GT(Q_strcasecmp("test", "AAAA"), 0);
+    EXPECT_GT(Q_strcasecmp("test", "tes"), 0);
+    EXPECT_GT(Q_strcasecmp("TEST", "T"), 0);
+}
+
+TEST(string, strncasecmp)
+{
+    EXPECT_EQ(Q_strncasecmp("*lava123", "*LAVA", 5), 0);
+    EXPECT_EQ(Q_strncasecmp("*lava123", "*LAVA", 8), 1);
+}