build: add build opts for enabling sanitizers

INSTALL.md

@@ -33,6 +33,22 @@ pro hand -p true -s false -n false SIGBUS
 pro hand -p true -s false -n false SIGSEGV
 ```
 
+### Sanitizers
+
+Sanitizers are supported for native builds only and you need to have `llvm-18` (and `clang-18` on linux) installed on your machine.
+
+For native linux builds this is the only situation where we actually build against the native abi. Normally we build agains musl even on native gnu machines.
+
+macOS:
+```terminal
+brew install llvm@18
+```
+
+Debian/Ubuntu:
+```terminal
+apt-get install llvm-18 clang-18
+```
+
 ## Build
 
 Once you install `zig`, you're ready to build:
@@ -79,6 +95,12 @@ Provide additional compiler flags. These propagate to all build artifacts.
 
 Example: `zig build -Dcopt="-g" -Dcopt="-fno-sanitize=all"`
 
+#### `-Dasan`
+Enable address sanitizer. Only supported nativelly. Requires `llvm@18`, see [prerequisites](#sanitizers).
+
+#### `-Dubsan`
+Enable undefined behavior sanitizer. Only supported nativelly. Requires `llvm@18`, see [prerequisites](#sanitizers).
+
 <!-- ## LSP Integration -->
 
 <!-- ```console -->

build.zig

@@ -26,6 +26,8 @@ const BuildCfg = struct {
     mem_dbg: bool = false,
     c3dbg: bool = false,
     snapshot_validation: bool = false,
+    ubsan: bool = false,
+    asan: bool = false,
 };
 
 pub fn build(b: *std.Build) !void {
@@ -84,6 +86,24 @@ pub fn build(b: *std.Build) !void {
         "Binary name (Default: urbit)",
     ) orelse "urbit";
 
+    const asan = if (target.query.isNative())
+        b.option(
+            bool,
+            "asan",
+            "Enable address sanitizer (native only, requires llvm@18)",
+        ) orelse false
+    else
+        false;
+
+    const ubsan = if (target.query.isNative())
+        b.option(
+            bool,
+            "ubsan",
+            "Enable undefined behavior sanitizer (native only, requires llvm@18)",
+        ) orelse false
+    else
+        false;
+
     // Parse short git rev
     var file = try std.fs.cwd().openFile(".git/logs/HEAD", .{});
     defer file.close();
@@ -116,6 +136,8 @@ pub fn build(b: *std.Build) !void {
         .mem_dbg = mem_dbg,
         .c3dbg = c3dbg,
         .snapshot_validation = snapshot_validation,
+        .asan = asan,
+        .ubsan = ubsan,
         .include_test_steps = !all,
     };
 
@@ -127,7 +149,9 @@ pub fn build(b: *std.Build) !void {
         const t = target.result;
         try buildBinary(
             b,
-            if (t.os.tag == .linux and target.query.isNative())
+            if (t.os.tag == .linux and
+                target.query.isNative() and
+                !asan and !ubsan)
                 b.resolveTargetQuery(.{ .abi = .musl })
             else
                 target,
@@ -155,12 +179,38 @@ fn buildBinary(
 
     try global_flags.appendSlice(cfg.flags);
     try global_flags.appendSlice(&.{
-        "-fno-sanitize=all",
         "-g",
         "-Wall",
         "-Werror",
     });
 
+    if (!cfg.asan and !cfg.ubsan)
+        try global_flags.appendSlice(&.{
+            "-fno-sanitize=all",
+        });
+
+    if (cfg.asan and !cfg.ubsan)
+        try global_flags.appendSlice(&.{
+            "-Wno-deprecated",
+            "-fsanitize=address",
+            "-fno-sanitize=undefined",
+            "-fno-sanitize-trap=undefined",
+        });
+
+    if (!cfg.asan and cfg.ubsan)
+        try global_flags.appendSlice(&.{
+            "-fsanitize=undefined",
+            "-fno-sanitize-trap=undefined",
+        });
+
+    if (cfg.asan and cfg.ubsan)
+        try global_flags.appendSlice(&.{
+            "-Wno-deprecated",
+            "-fsanitize=address",
+            "-fsanitize=undefined",
+            "-fno-sanitize-trap=undefined",
+        });
+
     //
     //  C Opts for Urbit PKGs And Binary
     //
@@ -367,6 +417,34 @@ fn buildBinary(
     urbit.linkLibrary(urcrypt.artifact("urcrypt"));
     urbit.linkLibrary(whereami.artifact("whereami"));
 
+    if (t.isDarwin()) {
+        // Requires llvm@18 homebrew installation
+        if (cfg.asan or cfg.ubsan)
+            urbit.addLibraryPath(.{
+                .cwd_relative = "/opt/homebrew/opt/llvm@18/lib/clang/18/lib/darwin",
+            });
+        if (cfg.asan) urbit.linkSystemLibrary("clang_rt.asan_osx_dynamic");
+        if (cfg.ubsan) urbit.linkSystemLibrary("clang_rt.ubsan_osx_dynamic");
+    }
+
+    if (t.os.tag == .linux) {
+        // Requires llvm-18 and clang-18 installation
+        if (cfg.asan or cfg.ubsan)
+            urbit.addLibraryPath(.{
+                .cwd_relative = "/usr/lib/clang/18/lib/linux",
+            });
+        if (t.cpu.arch == .x86_64) {
+            if (cfg.asan) urbit.linkSystemLibrary("clang_rt.asan-x86_64");
+            if (cfg.ubsan)
+                urbit.linkSystemLibrary("clang_rt.ubsan_standalone-x86_64");
+        }
+        if (t.cpu.arch == .aarch64) {
+            if (cfg.asan) urbit.linkSystemLibrary("clang_rt.asan-aarch64");
+            if (cfg.ubsan)
+                urbit.linkSystemLibrary("clang_rt.ubsan_standalone-aarch64");
+        }
+    }
+
     urbit.addCSourceFiles(.{
         .root = b.path("pkg/vere"),
         .files = &.{

pkg/c3/portable.h

@@ -128,7 +128,11 @@
 #       define U3_OS_LoomBits 30
 #   elif defined(U3_OS_osx)
 #     ifdef __LP64__
-#       define U3_OS_LoomBase 0x28000000000
+#       ifdef ASAN_ENABLED
+#         define U3_OS_LoomBase 0x728000000000
+#       else
+#         define U3_OS_LoomBase 0x28000000000
+#       endif
 #     else
 #       define U3_OS_LoomBase 0x4000000
 #     endif

pkg/vere/mdns.c

@@ -80,7 +80,7 @@ static void resolve_cb(DNSServiceRef sref,
   hints.ai_family = AF_INET; // Request only IPv4 addresses
   hints.ai_socktype = SOCK_STREAM; // TCP socket
 
-  uv_getaddrinfo_t* req = (uv_getaddrinfo_t*)c3_malloc(sizeof(uv_getaddrinfo_t));
+  uv_getaddrinfo_t* req = (uv_getaddrinfo_t*)c3_calloc(sizeof(uv_getaddrinfo_t));
   req->data = (void*)payload;
 
   uv_loop_t* loop = uv_default_loop();
@@ -126,7 +126,7 @@ static void browse_cb(DNSServiceRef s,
     // we are leaking payload because we don't know when we are done
     // browsing, luckily we only browse once
     mdns_payload* payload = (mdns_payload*)context;
-    mdns_payload* payload_copy = c3_malloc(sizeof *payload_copy);
+    mdns_payload* payload_copy = c3_calloc(sizeof *payload_copy);
 
     // copy to prevent asynchronous thrashing of payload
     memcpy(payload_copy, payload, sizeof(mdns_payload));
@@ -181,7 +181,7 @@ void mdns_init(uint16_t port, bool fake, char* our, mdns_cb* cb, void* context)
   setenv("DBUS_SYSTEM_BUS_ADDRESS", "unix:path=/var/run/dbus/system_bus_socket", 0);
   #   endif
 
-  mdns_payload* register_payload = (mdns_payload*)c3_malloc(sizeof(mdns_payload));
+  mdns_payload* register_payload = (mdns_payload*)c3_calloc(sizeof(mdns_payload));
 
   DNSServiceRef sref;
   DNSServiceErrorType err;
@@ -215,7 +215,7 @@ void mdns_init(uint16_t port, bool fake, char* our, mdns_cb* cb, void* context)
 
   init_sref_poll(sref, register_payload);
 
-  mdns_payload* browse_payload = (mdns_payload*)c3_malloc(sizeof(mdns_payload));
+  mdns_payload* browse_payload = (mdns_payload*)c3_calloc(sizeof(mdns_payload));
 
   browse_payload->cb = cb;
   browse_payload->context = context;