From a7bae1b8579475eaf4a25907405d85b98d29977d Mon Sep 17 00:00:00 2001
From: Jakub Konka <kubkon@jakubkonka.com>
Date: Sun, 27 Dec 2020 10:23:44 +0100
Subject: [PATCH] macho: write matching UUID to dSym bundle

---
 src/link/MachO.zig              |  2 +-
 src/link/MachO/DebugSymbols.zig | 35 ++++++++++++++++++++++++++++++++-
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/link/MachO.zig b/src/link/MachO.zig
index c8449fbe1a..510d7b74fb 100644
--- a/src/link/MachO.zig
+++ b/src/link/MachO.zig
@@ -355,7 +355,7 @@ pub fn flushModule(self: *MachO, comp: *Compilation) !void {
 
             if (self.d_sym) |*ds| {
                 // Flush debug symbols bundle.
-                try ds.flush();
+                try ds.flush(self.base.allocator);
             }
 
             if (target.cpu.arch == .aarch64) {
diff --git a/src/link/MachO/DebugSymbols.zig b/src/link/MachO/DebugSymbols.zig
index b485e391af..3882eaca69 100644
--- a/src/link/MachO/DebugSymbols.zig
+++ b/src/link/MachO/DebugSymbols.zig
@@ -58,18 +58,51 @@ pub fn populateMissingMetadata(self: *DebugSymbols, allocator: *Allocator) !void
         self.header = header;
         self.header_dirty = true;
     }
+    if (self.uuid_cmd_index == null) {
+        const base_cmd = self.base.load_commands.items[self.base.uuid_cmd_index.?];
+        self.uuid_cmd_index = @intCast(u16, self.load_commands.items.len);
+        try self.load_commands.append(allocator, base_cmd);
+        self.header_dirty = true;
+        self.load_commands_dirty = true;
+    }
 }
 
-pub fn flush(self: *DebugSymbols) !void {
+pub fn flush(self: *DebugSymbols, allocator: *Allocator) !void {
+    try self.writeLoadCommands(allocator);
     try self.writeHeader();
     assert(!self.header_dirty);
     assert(!self.load_commands_dirty);
 }
 
 pub fn deinit(self: *DebugSymbols, allocator: *Allocator) void {
+    for (self.load_commands.items) |*lc| {
+        lc.deinit(allocator);
+    }
     self.file.close();
 }
 
+/// Writes all load commands and section headers.
+fn writeLoadCommands(self: *DebugSymbols, allocator: *Allocator) !void {
+    if (!self.load_commands_dirty) return;
+
+    var sizeofcmds: usize = 0;
+    for (self.load_commands.items) |lc| {
+        sizeofcmds += lc.cmdsize();
+    }
+
+    var buffer = try allocator.alloc(u8, sizeofcmds);
+    defer allocator.free(buffer);
+    var writer = std.io.fixedBufferStream(buffer).writer();
+    for (self.load_commands.items) |lc| {
+        try lc.write(writer);
+    }
+
+    const off = @sizeOf(macho.mach_header_64);
+    log.debug("writing {} dSym load commands from 0x{x} to 0x{x}", .{ self.load_commands.items.len, off, off + sizeofcmds });
+    try self.file.pwriteAll(buffer, off);
+    self.load_commands_dirty = false;
+}
+
 fn writeHeader(self: *DebugSymbols) !void {
     if (!self.header_dirty) return;