Using libunwind for mac, since backtrace do not expect thread context (i.e. working just with current thread)

Author: saf-e

src/unwinder/sentry_unwinder_libbacktrace.c

@@ -6,10 +6,115 @@
 #    define HAS_EXECINFO_H
 #endif
 
+#if defined(SENTRY_PLATFORM_MACOS) && defined(MAC_OS_X_VERSION_10_6)
+#    define HAS_LIBUNWIND
+#endif
+
 #ifdef HAS_EXECINFO_H
 #    include <execinfo.h>
 #endif
 
+#ifdef HAS_LIBUNWIND
+#    include <libunwind.h>
+
+#    define ARRAY_SIZE(a) sizeof(a) / sizeof(a[0])
+
+static size_t
+sentry__unwind_stack_libbacktrace_libnuwind(
+    const sentry_ucontext_t *uctx, void **ptrs, size_t max_frames)
+{
+    unw_context_t ctx;
+    if (unw_getcontext(&ctx))
+        return 0;
+
+    unw_cursor_t cursor;
+    if (unw_init_local(&cursor, &ctx))
+        return 0;
+
+#    if defined(__x86_64__)
+    if (unw_set_reg(&cursor, UNW_X86_64_RAX,
+            uctx->user_context->uc_mcontext->__ss.__rax)
+        || unw_set_reg(&cursor, UNW_X86_64_RDX,
+            uctx->user_context->uc_mcontext->__ss.__rdx)
+        || unw_set_reg(&cursor, UNW_X86_64_RCX,
+            uctx->user_context->uc_mcontext->__ss.__rcx)
+        || unw_set_reg(&cursor, UNW_X86_64_RBX,
+            uctx->user_context->uc_mcontext->__ss.__rbx)
+        || unw_set_reg(&cursor, UNW_X86_64_RSI,
+            uctx->user_context->uc_mcontext->__ss.__rsi)
+        || unw_set_reg(&cursor, UNW_X86_64_RDI,
+            uctx->user_context->uc_mcontext->__ss.__rdi)
+        || unw_set_reg(&cursor, UNW_X86_64_RBP,
+            uctx->user_context->uc_mcontext->__ss.__rbp)
+        || unw_set_reg(&cursor, UNW_X86_64_RSP,
+            uctx->user_context->uc_mcontext->__ss.__rsp)
+        || unw_set_reg(
+            &cursor, UNW_X86_64_R8, uctx->user_context->uc_mcontext->__ss.__r8)
+        || unw_set_reg(
+            &cursor, UNW_X86_64_R9, uctx->user_context->uc_mcontext->__ss.__r9)
+        || unw_set_reg(&cursor, UNW_X86_64_R10,
+            uctx->user_context->uc_mcontext->__ss.__r10)
+        || unw_set_reg(&cursor, UNW_X86_64_R11,
+            uctx->user_context->uc_mcontext->__ss.__r11)
+        || unw_set_reg(&cursor, UNW_X86_64_R12,
+            uctx->user_context->uc_mcontext->__ss.__r12)
+        || unw_set_reg(&cursor, UNW_X86_64_R13,
+            uctx->user_context->uc_mcontext->__ss.__r13)
+        || unw_set_reg(&cursor, UNW_X86_64_R14,
+            uctx->user_context->uc_mcontext->__ss.__r14)
+        || unw_set_reg(&cursor, UNW_X86_64_R15,
+            uctx->user_context->uc_mcontext->__ss.__r15)
+        || unw_set_reg(
+            &cursor, UNW_REG_IP, uctx->user_context->uc_mcontext->__ss.__rip))
+        return 0;
+
+#    elif defined(__arm64__)
+    for (size_t i = 0;
+        i < ARRAY_SIZE(uctx->user_context->uc_mcontext->__ss.__x); ++i) {
+        if (unw_set_reg(&cursor, UNW_AARCH64_X0 + i,
+                uctx->user_context->uc_mcontext->__ss.__x[i])) {
+            return 0;
+        }
+    }
+
+    if (unw_set_reg(
+            &cursor, UNW_AARCH64_FP, uctx->user_context->uc_mcontext->__ss.__fp)
+        || unw_set_reg(
+            &cursor, UNW_AARCH64_LR, uctx->user_context->uc_mcontext->__ss.__lr)
+        || unw_set_reg(
+            &cursor, UNW_AARCH64_SP, uctx->user_context->uc_mcontext->__ss.__sp)
+        || unw_set_reg(
+            &cursor, UNW_REG_IP, uctx->user_context->uc_mcontext->__ss.__pc))
+        return 0;
+
+#    endif
+
+    size_t n = 0;
+    for (int err = 1; err >= 0 && n < max_frames; err = unw_step(&cursor)) {
+        unw_word_t ip;
+        if (unw_get_reg(&cursor, UNW_REG_IP, &ip)) {
+            break;
+        }
+
+#    if defined(__arm64__)
+        // Strip pointer authentication, for some reason ptrauth_strip() not
+        // working
+        // https://developer.apple.com/documentation/security/preparing_your_app_to_work_with_pointer_authentication
+        ip &= 0x7fffffffffffull;
+#    endif
+
+        ptrs[n++] = (void *)ip;
+
+        // last frame
+        if (err == 0) {
+            break;
+        }
+    }
+
+    return n;
+}
+#endif
+
 size_t
 sentry__unwind_stack_libbacktrace(
     void *addr, const sentry_ucontext_t *uctx, void **ptrs, size_t max_frames)
@@ -23,7 +128,12 @@ sentry__unwind_stack_libbacktrace(
 #endif
         return 0;
     } else if (uctx) {
+#ifdef HAS_LIBUNWIND
+        return sentry__unwind_stack_libbacktrace_libnuwind(
+            uctx, ptrs, max_frames);
+#else
         return 0;
+#endif
     }
 #ifdef HAS_EXECINFO_H
     return (size_t)backtrace(ptrs, (int)max_frames);