Reduce number of `#ifdef`s

1 files changed, 65 insertions, 67 deletions

diff --git a/vespalib/src/vespa/vespalib/util/memory_trap.cpp b/vespalib/src/vespa/vespalib/util/memory_trap.cpp
index 113af0de35a..f17a0221246 100644
--- a/vespalib/src/vespa/vespalib/util/memory_trap.cpp
+++ b/vespalib/src/vespa/vespalib/util/memory_trap.cpp
@@ -1,9 +1,5 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
-#ifdef __linux__
-#  define VESPA_HAS_MPROTECT
-#endif
-
 #include "memory_trap.h"
 #include <string_view>
 #include <cassert>
@@ -12,7 +8,8 @@
 #include <cstdlib>
 #include <cstring>
 #include <malloc.h>
-#ifdef VESPA_HAS_MPROTECT
+#ifdef __linux__
+#  define VESPA_HAS_MPROTECT
 #  include <unistd.h>
 #  include <sys/mman.h>
 #endif
@@ -26,36 +23,6 @@ namespace vespalib {
 
 namespace {
 
-#ifdef VESPA_HAS_MPROTECT
-
-bool has_4k_pages() noexcept {
-    return (sysconf(_SC_PAGESIZE) == 4096);
-}
-
-constexpr bool is_4k_aligned(size_t v) noexcept {
-    return (v % 4096) == 0;
-}
-
-constexpr size_t align_up_4k(size_t v) noexcept {
-    return (v + 4095) & ~4095ULL;
-}
-
-constexpr size_t align_down_4k(size_t v) noexcept {
-    return v & ~4095ULL;
-}
-
-bool env_var_is_yes(const char* env_var) noexcept {
-    const char* ev = getenv(env_var);
-    return ((ev != nullptr) && ("yes"sv == ev));
-}
-
-bool mprotect_trapping_is_enabled() noexcept {
-    static const bool enabled = (has_4k_pages() && env_var_is_yes("VESPA_USE_MPROTECT_TRAP"));
-    return enabled;
-}
-
-#endif
-
 // Have some symbols that provide immediate context in a crash backtrace
 [[noreturn]] void abort_due_to_guard_bits_tampered_with() __attribute__((noinline));
 [[noreturn]] void abort_due_to_guard_bits_tampered_with() {
@@ -85,8 +52,62 @@ MemoryRangeTrapper::~MemoryRangeTrapper() {
     check_and_release();
 }
 
-void MemoryRangeTrapper::rw_protect_buffer_if_possible() {
+void MemoryRangeTrapper::check_and_release() noexcept {
+    unprotect_buffer_to_read_only(); // Make sure sanity check can't race with writes
+    verify_buffer_is_all_zeros();
+    unprotect_buffer_to_read_and_write();
+    _trap_len = _buf_len = 0;
+}
+
+void MemoryRangeTrapper::verify_buffer_is_all_zeros() {
+    for (size_t i = 0; i < _buf_len; ++i) {
+        if (_trap_buf[i] != 0) {
+            const bool in_protected_area = ((i >= _trap_offset) && (i < _trap_offset + _trap_len));
+            LOG(error, "Memory corruption detected! Offset %zu into buffer %p: 0x%.2x != 0x00%s",
+                i, _trap_buf, static_cast<unsigned int>(_trap_buf[i]),
+                in_protected_area ? ". CORRUPTION IN R/W PROTECTED MEMORY!" : "");
+            if (in_protected_area) {
+                abort_due_to_PROTECTED_guard_bits_tampered_with();
+            } else {
+                abort_due_to_guard_bits_tampered_with();
+            }
+        }
+    }
+}
+
 #ifdef VESPA_HAS_MPROTECT
+
+namespace {
+
+bool has_4k_pages() noexcept {
+    return (sysconf(_SC_PAGESIZE) == 4096);
+}
+
+constexpr bool is_4k_aligned(size_t v) noexcept {
+    return (v % 4096) == 0;
+}
+
+constexpr size_t align_up_4k(size_t v) noexcept {
+    return (v + 4095) & ~4095ULL;
+}
+
+constexpr size_t align_down_4k(size_t v) noexcept {
+    return v & ~4095ULL;
+}
+
+bool env_var_is_yes(const char *env_var) noexcept {
+    const char *ev = getenv(env_var);
+    return ((ev != nullptr) && ("yes"sv == ev));
+}
+
+bool mprotect_trapping_is_enabled() noexcept {
+    static const bool enabled = (has_4k_pages() && env_var_is_yes("VESPA_USE_MPROTECT_TRAP"));
+    return enabled;
+}
+
+} // anon ns
+
+void MemoryRangeTrapper::rw_protect_buffer_if_possible() {
     static_assert(std::is_same_v<size_t, uintptr_t>);
     const auto aligned_start = align_up_4k(reinterpret_cast<uintptr_t>(_trap_buf));
     const auto aligned_end   = align_down_4k(reinterpret_cast<uintptr_t>(_trap_buf + _buf_len));
@@ -105,57 +126,34 @@ void MemoryRangeTrapper::rw_protect_buffer_if_possible() {
             _trap_offset = _trap_len = 0;
         }
     }
-#endif
 }
 
 bool MemoryRangeTrapper::hw_trapping_enabled() noexcept {
-#ifdef VESPA_HAS_MPROTECT
     return mprotect_trapping_is_enabled();
-#else
-    return false;
-#endif
-}
-
-void MemoryRangeTrapper::check_and_release() noexcept {
-    unprotect_buffer_to_read_only(); // Make sure sanity check can't race with writes
-    verify_buffer_is_all_zeros();
-    unprotect_buffer_to_read_and_write();
-    _trap_len = _buf_len = 0;
 }
 
 void MemoryRangeTrapper::unprotect_buffer_to_read_only() {
-#ifdef VESPA_HAS_MPROTECT
     if (_trap_len > 0) {
         int ret = mprotect(_trap_buf + _trap_offset, _trap_len, PROT_READ);
         assert(ret == 0 && "failed to un-protect memory region to PROT_READ");
     }
-#endif
 }
 
 void MemoryRangeTrapper::unprotect_buffer_to_read_and_write() {
-#ifdef VESPA_HAS_MPROTECT
     if (_trap_len > 0) {
         int ret = mprotect(_trap_buf + _trap_offset, _trap_len, PROT_READ | PROT_WRITE);
         assert(ret == 0 && "failed to un-protect memory region to PROT_READ | PROT_WRITE");
     }
-#endif
 }
 
-void MemoryRangeTrapper::verify_buffer_is_all_zeros() {
-    for (size_t i = 0; i < _buf_len; ++i) {
-        if (_trap_buf[i] != 0) {
-            const bool in_protected_area = ((i >= _trap_offset) && (i < _trap_offset + _trap_len));
-            LOG(error, "Memory corruption detected! Offset %zu into buffer %p: 0x%.2x != 0x00%s",
-                i, _trap_buf, static_cast<unsigned int>(_trap_buf[i]),
-                in_protected_area ? ". CORRUPTION IN R/W PROTECTED MEMORY!" : "");
-            if (in_protected_area) {
-                abort_due_to_PROTECTED_guard_bits_tampered_with();
-            } else {
-                abort_due_to_guard_bits_tampered_with();
-            }
-        }
-    }
-}
+#else // VESPA_HAS_MPROTECT not defined, fall back to no-ops
+
+void MemoryRangeTrapper::rw_protect_buffer_if_possible() { /* no-op */ }
+bool MemoryRangeTrapper::hw_trapping_enabled() noexcept { return false; }
+void MemoryRangeTrapper::unprotect_buffer_to_read_only() { /* no-op */ }
+void MemoryRangeTrapper::unprotect_buffer_to_read_and_write() { /* no-op */ }
+
+#endif
 
 HeapMemoryTrap::HeapMemoryTrap(size_t trap_4k_pages)
     : _trap_buf(static_cast<char*>(memalign(4096, trap_4k_pages * 4096))),