Merge pull request #3570 from ziglang/c-sanitize-undef

use -fsanitize=undefined for C code in safe build modes

2 files changed, 12 insertions, 2 deletions

diff --git a/lib/std/build.zig b/lib/std/build.zig
index e54a23d8ab..f7e4756e90 100644
--- a/lib/std/build.zig
+++ b/lib/std/build.zig
@@ -1034,6 +1034,7 @@ pub const LibExeObjStep = struct {
     disable_gen_h: bool,
     bundle_compiler_rt: bool,
     disable_stack_probing: bool,
+    disable_sanitize_c: bool,
     c_std: Builder.CStd,
     override_lib_dir: ?[]const u8,
     main_pkg_path: ?[]const u8,
@@ -1183,6 +1184,7 @@ pub const LibExeObjStep = struct {
             .disable_gen_h = false,
             .bundle_compiler_rt = false,
             .disable_stack_probing = false,
+            .disable_sanitize_c = false,
             .output_dir = null,
             .need_system_paths = false,
             .single_threaded = false,
@@ -1822,6 +1824,9 @@ pub const LibExeObjStep = struct {
         if (self.disable_stack_probing) {
             try zig_args.append("-fno-stack-check");
         }
+        if (self.disable_sanitize_c) {
+            try zig_args.append("-fno-sanitize-c");
+        }
 
         switch (self.target) {
             .Native => {},
diff --git a/lib/std/debug.zig b/lib/std/debug.zig
index 69b9e894bb..9b24e1acd3 100644
--- a/lib/std/debug.zig
+++ b/lib/std/debug.zig
@@ -2404,6 +2404,7 @@ pub fn attachSegfaultHandler() void {
     };
 
     os.sigaction(os.SIGSEGV, &act, null);
+    os.sigaction(os.SIGILL, &act, null);
 }
 
 fn resetSegfaultHandler() void {
@@ -2420,6 +2421,7 @@ fn resetSegfaultHandler() void {
         .flags = 0,
     };
     os.sigaction(os.SIGSEGV, &act, null);
+    os.sigaction(os.SIGILL, &act, null);
 }
 
 extern fn handleSegfaultLinux(sig: i32, info: *const os.siginfo_t, ctx_ptr: *const c_void) noreturn {
@@ -2429,8 +2431,11 @@ extern fn handleSegfaultLinux(sig: i32, info: *const os.siginfo_t, ctx_ptr: *con
     resetSegfaultHandler();
 
     const addr = @ptrToInt(info.fields.sigfault.addr);
-    std.debug.warn("Segmentation fault at address 0x{x}\n", .{addr});
-
+    switch (sig) {
+        os.SIGSEGV => std.debug.warn("Segmentation fault at address 0x{x}\n", .{addr}),
+        os.SIGILL => std.debug.warn("Illegal instruction at address 0x{x}\n", .{addr}),
+        else => unreachable,
+    }
     switch (builtin.arch) {
         .i386 => {
             const ctx = @ptrCast(*const os.ucontext_t, @alignCast(@alignOf(os.ucontext_t), ctx_ptr));