fixups for the previous commit

* std.fs.File.copyRange and copyRangeAll return u64 instead of usize -
   the returned value is how much of the `len` is transferred, so the
   types should match. This removes the need for an `@intCast`.
 * fix typo that removed a subtraction
 * Fix the size of codegen.AnyMCValue which gave me a compile error when
   I tried to build self-hosted for i386-linux.
 * restore the coercion to u64 of syms_sect.sh_info. We want to make
   sure the multiplication happens with 64 bits and not the smaller type
   used by the ELF format.
 * fix another offset parameter in link/Elf.zig to be u64 instead of usize
 * add a nice little TODO note to help out Jakub
 * FmtError already has FileTooBig in it; we just need to return it.

lib/std/fs/file.zig

@@ -652,25 +652,26 @@ pub const File = struct {
 
     pub const CopyRangeError = os.CopyFileRangeError;
 
-    pub fn copyRange(in: File, in_offset: u64, out: File, out_offset: u64, len: u64) CopyRangeError!usize {
+    pub fn copyRange(in: File, in_offset: u64, out: File, out_offset: u64, len: u64) CopyRangeError!u64 {
         const adjusted_len = math.cast(usize, len) catch math.maxInt(usize);
-        return os.copy_file_range(in.handle, in_offset, out.handle, out_offset, adjusted_len, 0);
+        const result = try os.copy_file_range(in.handle, in_offset, out.handle, out_offset, adjusted_len, 0);
+        return result;
     }
 
     /// Returns the number of bytes copied. If the number read is smaller than `buffer.len`, it
     /// means the in file reached the end. Reaching the end of a file is not an error condition.
-    pub fn copyRangeAll(in: File, in_offset: u64, out: File, out_offset: u64, len: u64) CopyRangeError!usize {
+    pub fn copyRangeAll(in: File, in_offset: u64, out: File, out_offset: u64, len: u64) CopyRangeError!u64 {
         var total_bytes_copied: u64 = 0;
         var in_off = in_offset;
         var out_off = out_offset;
         while (total_bytes_copied < len) {
-            const amt_copied = try copyRange(in, in_off, out, out_off, len);
+            const amt_copied = try copyRange(in, in_off, out, out_off, len - total_bytes_copied);
-            if (amt_copied == 0) return @intCast(usize, total_bytes_copied);
+            if (amt_copied == 0) return total_bytes_copied;
             total_bytes_copied += amt_copied;
             in_off += amt_copied;
             out_off += amt_copied;
         }
-        return @intCast(usize, total_bytes_copied);
+        return total_bytes_copied;
     }
 
     pub const WriteFileOptions = struct {

src/codegen.zig

@@ -32,7 +32,7 @@ pub const BlockData = struct {
 /// comptime assert that makes sure we guessed correctly about the size. This only
 /// exists so that we can bitcast an arch-independent field to and from the real MCValue.
 pub const AnyMCValue = extern struct {
-    a: u64,
+    a: usize,
     b: u64,
 };
 

src/link/Elf.zig

@@ -2757,7 +2757,7 @@ fn writeSymbol(self: *Elf, index: usize) !void {
         if (needed_size > self.allocatedSize(syms_sect.sh_offset)) {
             // Move all the symbols to a new file location.
             const new_offset = self.findFreeSpace(needed_size, sym_align);
-            const existing_size = syms_sect.sh_info * sym_size;
+            const existing_size = @as(u64, syms_sect.sh_info) * sym_size;
             const amt = try self.base.file.?.copyRangeAll(syms_sect.sh_offset, self.base.file.?, new_offset, existing_size);
             if (amt != existing_size) return error.InputOutput;
             syms_sect.sh_offset = new_offset;
@@ -2990,7 +2990,7 @@ fn pwriteDbgInfoNops(
     buf: []const u8,
     next_padding_size: usize,
     trailing_zero: bool,
-    offset: usize,
+    offset: u64,
 ) !void {
     const tracy = trace(@src());
     defer tracy.end();

src/link/MachO.zig

@@ -1264,6 +1264,10 @@ fn updateString(self: *MachO, old_str_off: u32, new_name: []const u8) !u32 {
     return self.makeString(new_name);
 }
 
+/// TODO This should not heap allocate, instead it should utilize a fixed size, statically allocated
+/// global const array. You could even use pwritev to write the same buffer multiple times with only
+/// 1 syscall if you needed to, for example, write 8192 bytes using a buffer of only 4096 bytes.
+/// This size parameter should probably be a usize not u64.
 fn addPadding(self: *MachO, size: u64, file_offset: u64) !void {
     if (size == 0) return;
 

src/main.zig

@@ -2541,7 +2541,7 @@ fn fmtPathFile(
     check_mode: bool,
     dir: fs.Dir,
     sub_path: []const u8,
-) (FmtError || error{Overflow})!void {
+) FmtError!void {
     const source_file = try dir.openFile(sub_path, .{});
     var file_closed = false;
     errdefer if (!file_closed) source_file.close();
@@ -2554,7 +2554,7 @@ fn fmtPathFile(
     const source_code = source_file.readToEndAllocOptions(
         fmt.gpa,
         max_src_size,
-        try std.math.cast(usize, stat.size),
+        std.math.cast(usize, stat.size) catch return error.FileTooBig,
         @alignOf(u8),
         null,
     ) catch |err| switch (err) {