1 files changed, 94 insertions, 0 deletions
diff --git a/lib/std/cstr.zig b/lib/std/cstr.zig
new file mode 100644
index 0000000000..dd28e50449
--- /dev/null
+++ b/lib/std/cstr.zig
@@ -0,0 +1,94 @@
+const std = @import("std.zig");
+const builtin = @import("builtin");
+const debug = std.debug;
+const mem = std.mem;
+const testing = std.testing;
+
+pub const line_sep = switch (builtin.os) {
+    builtin.Os.windows => "\r\n",
+    else => "\n",
+};
+
+pub fn cmp(a: [*]const u8, b: [*]const u8) i8 {
+    var index: usize = 0;
+    while (a[index] == b[index] and a[index] != 0) : (index += 1) {}
+    if (a[index] > b[index]) {
+        return 1;
+    } else if (a[index] < b[index]) {
+        return -1;
+    } else {
+        return 0;
+    }
+}
+
+test "cstr fns" {
+    comptime testCStrFnsImpl();
+    testCStrFnsImpl();
+}
+
+fn testCStrFnsImpl() void {
+    testing.expect(cmp(c"aoeu", c"aoez") == -1);
+    testing.expect(mem.len(u8, c"123456789") == 9);
+}
+
+/// Returns a mutable slice with 1 more byte of length which is a null byte.
+/// Caller owns the returned memory.
+pub fn addNullByte(allocator: *mem.Allocator, slice: []const u8) ![]u8 {
+    const result = try allocator.alloc(u8, slice.len + 1);
+    mem.copy(u8, result, slice);
+    result[slice.len] = 0;
+    return result;
+}
+
+pub const NullTerminated2DArray = struct {
+    allocator: *mem.Allocator,
+    byte_count: usize,
+    ptr: ?[*]?[*]u8,
+
+    /// Takes N lists of strings, concatenates the lists together, and adds a null terminator
+    /// Caller must deinit result
+    pub fn fromSlices(allocator: *mem.Allocator, slices: []const []const []const u8) !NullTerminated2DArray {
+        var new_len: usize = 1; // 1 for the list null
+        var byte_count: usize = 0;
+        for (slices) |slice| {
+            new_len += slice.len;
+            for (slice) |inner| {
+                byte_count += inner.len;
+            }
+            byte_count += slice.len; // for the null terminators of inner
+        }
+
+        const index_size = @sizeOf(usize) * new_len; // size of the ptrs
+        byte_count += index_size;
+
+        const buf = try allocator.alignedAlloc(u8, @alignOf(?*u8), byte_count);
+        errdefer allocator.free(buf);
+
+        var write_index = index_size;
+        const index_buf = @bytesToSlice(?[*]u8, buf);
+
+        var i: usize = 0;
+        for (slices) |slice| {
+            for (slice) |inner| {
+                index_buf[i] = buf.ptr + write_index;
+                i += 1;
+                mem.copy(u8, buf[write_index..], inner);
+                write_index += inner.len;
+                buf[write_index] = 0;
+                write_index += 1;
+            }
+        }
+        index_buf[i] = null;
+
+        return NullTerminated2DArray{
+            .allocator = allocator,
+            .byte_count = byte_count,
+            .ptr = @ptrCast(?[*]?[*]u8, buf.ptr),
+        };
+    }
+
+    pub fn deinit(self: *NullTerminated2DArray) void {
+        const buf = @ptrCast([*]u8, self.ptr);
+        self.allocator.free(buf[0..self.byte_count]);
+    }
+};