diff --git a/lib/std/fs/File.zig b/lib/std/fs/File.zig
index 8005dba4ad..6e365a8fd5 100644
--- a/lib/std/fs/File.zig
+++ b/lib/std/fs/File.zig
@@ -1737,9 +1737,10 @@ pub fn writer_writeFile(
         const smaller_len = if (len_int == 0) max_count else @min(len_int, max_count);
         var off: std.os.linux.off_t = undefined;
         const off_ptr: ?*std.os.linux.off_t = if (in_offset.toInt()) |offset| b: {
-            off = try std.math.cast(std.os.linux.off_t, offset);
+            off = std.math.cast(std.os.linux.off_t, offset) orelse return error.Overflow;
             break :b &off;
         } else null;
+        if (true) @panic("TODO");
         const n = std.os.linux.wrapped.sendfile(out_fd, in_fd, off_ptr, smaller_len) catch |err| switch (err) {
             error.UnsupportedOperation => break :sf,
             error.Unseekable => break :sf,
diff --git a/lib/std/io/BufferedReader.zig b/lib/std/io/BufferedReader.zig
index 3c9ddecf63..55fdad5ac3 100644
--- a/lib/std/io/BufferedReader.zig
+++ b/lib/std/io/BufferedReader.zig
@@ -34,7 +34,7 @@ const eof_reader: std.io.Reader.VTable = .{
     .streamReadVec = eof_streamReadVec,
 };
 
-fn eof_writeSplat(context: ?*anyopaque, data: []const []const u8, splat: usize) anyerror!Reader.Status {
+fn eof_writeSplat(context: ?*anyopaque, data: []const []const u8, splat: usize) anyerror!usize {
     _ = context;
     _ = data;
     _ = splat;
@@ -44,11 +44,11 @@ fn eof_writeSplat(context: ?*anyopaque, data: []const []const u8, splat: usize)
 fn eof_writeFile(
     context: ?*anyopaque,
     file: std.fs.File,
-    offset: u64,
-    len: Reader.FileLen,
+    offset: std.io.Writer.Offset,
+    len: std.io.Writer.FileLen,
     headers_and_trailers: []const []const u8,
     headers_len: usize,
-) anyerror!Reader.Status {
+) anyerror!usize {
     _ = context;
     _ = file;
     _ = offset;
@@ -73,14 +73,14 @@ fn eof_posReadVec(ctx: ?*anyopaque, data: []const []u8, offset: u64) anyerror!Re
     return error.EndOfStream;
 }
 
-fn eof_streamRead(ctx: ?*anyopaque, bw: *std.io.BufferedWriter, limit: Reader.Limit) Reader.Status {
+fn eof_streamRead(ctx: ?*anyopaque, bw: *std.io.BufferedWriter, limit: Reader.Limit) anyerror!Reader.Status {
     _ = ctx;
     _ = bw;
     _ = limit;
     return error.EndOfStream;
 }
 
-fn eof_streamReadVec(ctx: ?*anyopaque, data: []const []u8) Reader.Status {
+fn eof_streamReadVec(ctx: ?*anyopaque, data: []const []u8) anyerror!Reader.Status {
     _ = ctx;
     _ = data;
     return error.EndOfStream;
@@ -91,13 +91,16 @@ pub fn initFixed(br: *BufferedReader, buffer: []const u8) void {
     br.* = .{
         .seek = 0,
         .storage = .{
-            .buffer = .initBuffer(@constCast(buffer)),
+            .buffer = .fromOwnedSlice(@constCast(buffer)),
             .unbuffered_writer = .{
                 .context = undefined,
                 .vtable = &eof_writer,
             },
         },
-        .unbuffered_reader = &.{ .context = undefined, .vtable = &eof_reader },
+        .unbuffered_reader = .{
+            .context = undefined,
+            .vtable = &eof_reader,
+        },
     };
 }
 
diff --git a/lib/std/io/BufferedWriter.zig b/lib/std/io/BufferedWriter.zig
index 8bee5d0ed7..96d9ff66b0 100644
--- a/lib/std/io/BufferedWriter.zig
+++ b/lib/std/io/BufferedWriter.zig
@@ -50,7 +50,7 @@ pub fn initFixed(bw: *BufferedWriter, buffer: []u8) void {
             .context = bw,
             .vtable = &fixed_vtable,
         },
-        .buffer = buffer,
+        .buffer = .initBuffer(buffer),
     };
 }
 
diff --git a/lib/std/io/Reader.zig b/lib/std/io/Reader.zig
index 2cc914092b..90193acdc8 100644
--- a/lib/std/io/Reader.zig
+++ b/lib/std/io/Reader.zig
@@ -85,6 +85,11 @@ pub fn posReadAll(r: Reader, w: *std.io.BufferedWriter, start_offset: u64) anyer
     }
 }
 
+/// Returns total number of bytes written to `w`.
+pub fn streamRead(r: Reader, w: *std.io.BufferedWriter, limit: Limit) anyerror!Status {
+    return r.vtable.streamRead.?(r.context, w, limit);
+}
+
 /// Returns total number of bytes written to `w`.
 pub fn streamReadAll(r: Reader, w: *std.io.BufferedWriter) anyerror!usize {
     const vtable_streamRead = r.vtable.streamRead.?;
diff --git a/lib/std/io/Writer.zig b/lib/std/io/Writer.zig
index bdd5de86cc..762c6d3a17 100644
--- a/lib/std/io/Writer.zig
+++ b/lib/std/io/Writer.zig
@@ -96,7 +96,7 @@ pub fn writeFile(
 pub fn unimplemented_writeFile(
     context: ?*anyopaque,
     file: std.fs.File,
-    offset: u64,
+    offset: Offset,
     len: FileLen,
     headers_and_trailers: []const []const u8,
     headers_len: usize,
@@ -136,7 +136,7 @@ fn null_writeSplat(context: ?*anyopaque, data: []const []const u8, splat: usize)
     const pattern = data[headers.len..];
     var written: usize = pattern.len * splat;
     for (headers) |bytes| written += bytes.len;
-    return .{ .len = written };
+    return written;
 }
 
 fn null_writeFile(
@@ -156,12 +156,12 @@ fn null_writeFile(
             const stat = try file.stat();
             n += stat.size - off;
             for (headers_and_trailers[headers_len..]) |bytes| n += bytes.len;
-            return .{ .len = n };
+            return n;
         }
         @panic("TODO stream from file until eof, counting");
     }
     for (headers_and_trailers) |bytes| n += bytes.len;
-    return .{ .len = len.int() + n };
+    return len.int() + n;
 }
 
 test @"null" {