Introduce common `strcasecmp` and `strncasecmp` implementations (#23840)

1 files changed, 64 insertions, 0 deletions

diff --git a/lib/c/string.zig b/lib/c/string.zig
index 0633f7e654..e846c4d960 100644
--- a/lib/c/string.zig
+++ b/lib/c/string.zig
@@ -6,6 +6,12 @@ comptime {
     @export(&strcmp, .{ .name = "strcmp", .linkage = common.linkage, .visibility = common.visibility });
     @export(&strlen, .{ .name = "strlen", .linkage = common.linkage, .visibility = common.visibility });
     @export(&strncmp, .{ .name = "strncmp", .linkage = common.linkage, .visibility = common.visibility });
+    @export(&strcasecmp, .{ .name = "strcasecmp", .linkage = common.linkage, .visibility = common.visibility });
+    @export(&strncasecmp, .{ .name = "strncasecmp", .linkage = common.linkage, .visibility = common.visibility });
+    @export(&__strcasecmp_l, .{ .name = "__strcasecmp_l", .linkage = common.linkage, .visibility = common.visibility });
+    @export(&__strncasecmp_l, .{ .name = "__strncasecmp_l", .linkage = common.linkage, .visibility = common.visibility });
+    @export(&__strcasecmp_l, .{ .name = "strcasecmp_l", .linkage = .weak, .visibility = common.visibility });
+    @export(&__strncasecmp_l, .{ .name = "strncasecmp_l", .linkage = .weak, .visibility = common.visibility });
 }
 
 fn strcmp(s1: [*:0]const c_char, s2: [*:0]const c_char) callconv(.c) c_int {
@@ -33,6 +39,64 @@ fn strncmp(s1: [*:0]const c_char, s2: [*:0]const c_char, n: usize) callconv(.c)
     return @as(c_int, l[0]) - @as(c_int, r[0]);
 }
 
+fn strcasecmp(s1: [*:0]const c_char, s2: [*:0]const c_char) callconv(.c) c_int {
+    const toLower = std.ascii.toLower;
+    var l: [*:0]const u8 = @ptrCast(s1);
+    var r: [*:0]const u8 = @ptrCast(s2);
+
+    while (l[0] != 0 and r[0] != 0 and (l[0] == r[0] or toLower(l[0]) == toLower(r[0]))) {
+        l += 1;
+        r += 1;
+    }
+
+    return @as(c_int, toLower(l[0])) - @as(c_int, toLower(r[0]));
+}
+
+fn __strcasecmp_l(s1: [*:0]const c_char, s2: [*:0]const c_char, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return strcasecmp(s1, s2);
+}
+
+fn strncasecmp(s1: [*:0]const c_char, s2: [*:0]const c_char, n: usize) callconv(.c) c_int {
+    const toLower = std.ascii.toLower;
+    var l: [*:0]const u8 = @ptrCast(s1);
+    var r: [*:0]const u8 = @ptrCast(s2);
+    var i = n - 1;
+
+    while (l[0] != 0 and r[0] != 0 and i != 0 and (l[0] == r[0] or toLower(l[0]) == toLower(r[0]))) {
+        l += 1;
+        r += 1;
+        i -= 1;
+    }
+
+    return @as(c_int, toLower(l[0])) - @as(c_int, toLower(r[0]));
+}
+
+fn __strncasecmp_l(s1: [*:0]const c_char, s2: [*:0]const c_char, n: usize, locale: *anyopaque) callconv(.c) c_int {
+    _ = locale;
+    return strncasecmp(s1, s2, n);
+}
+
+test strcasecmp {
+    try std.testing.expect(strcasecmp(@ptrCast("a"), @ptrCast("b")) < 0);
+    try std.testing.expect(strcasecmp(@ptrCast("b"), @ptrCast("a")) > 0);
+    try std.testing.expect(strcasecmp(@ptrCast("A"), @ptrCast("b")) < 0);
+    try std.testing.expect(strcasecmp(@ptrCast("b"), @ptrCast("A")) > 0);
+    try std.testing.expect(strcasecmp(@ptrCast("A"), @ptrCast("A")) == 0);
+    try std.testing.expect(strcasecmp(@ptrCast("B"), @ptrCast("b")) == 0);
+    try std.testing.expect(strcasecmp(@ptrCast("bb"), @ptrCast("AA")) > 0);
+}
+
+test strncasecmp {
+    try std.testing.expect(strncasecmp(@ptrCast("a"), @ptrCast("b"), 1) < 0);
+    try std.testing.expect(strncasecmp(@ptrCast("b"), @ptrCast("a"), 1) > 0);
+    try std.testing.expect(strncasecmp(@ptrCast("A"), @ptrCast("b"), 1) < 0);
+    try std.testing.expect(strncasecmp(@ptrCast("b"), @ptrCast("A"), 1) > 0);
+    try std.testing.expect(strncasecmp(@ptrCast("A"), @ptrCast("A"), 1) == 0);
+    try std.testing.expect(strncasecmp(@ptrCast("B"), @ptrCast("b"), 1) == 0);
+    try std.testing.expect(strncasecmp(@ptrCast("bb"), @ptrCast("AA"), 2) > 0);
+}
+
 test strncmp {
     try std.testing.expect(strncmp(@ptrCast("a"), @ptrCast("b"), 1) < 0);
     try std.testing.expect(strncmp(@ptrCast("a"), @ptrCast("c"), 1) < 0);