Split DescribeAddressIfShadow between a function that gets all the information, and one that prints it.

[filcab]

Summary

Replacement for part of D23518
This is the first patch to start reifying information about errors. It deals only with reifying shadow address-related information.
It will allow us to generate structures with all the relevant information for a given error so a debugger can get to them or they can be included in a core dump.

[kcc]

LGTM with one nit.

lib/asan/asan_descriptions.h

31

better name it shadow_byte or shadow_value

lib/asan/CMakeLists.txt

 # Build for the AddressSanitizer runtime support library.
 
 set(ASAN_SOURCES
   asan_allocator.cc
   asan_activation.cc
   asan_debugging.cc
+  asan_descriptions.cc
   asan_fake_stack.cc
   asan_flags.cc
   asan_globals.cc
   asan_interceptors.cc
   asan_linux.cc
   asan_mac.cc
   asan_malloc_linux.cc
   asan_malloc_mac.cc

lib/asan/asan_debugging.cc

 //===-- asan_debugging.cc -------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file is a part of AddressSanitizer, an address sanity checker.
 //
 // This file contains various functions that are generally useful to call when
 // using a debugger (LLDB, GDB).
 //===----------------------------------------------------------------------===//
 
 #include "asan_allocator.h"
+#include "asan_descriptions.h"
 #include "asan_flags.h"
 #include "asan_internal.h"
 #include "asan_mapping.h"
 #include "asan_report.h"
 #include "asan_thread.h"
 
 namespace __asan {
 
void GetInfoForHeapAddress(uptr addr, AddressDescription *descr) {
   }
 
   descr->region_address = chunk.Beg();
   descr->region_size = chunk.UsedSize();
   descr->region_kind = "heap";
 }
 
 void AsanLocateAddress(uptr addr, AddressDescription *descr) {
-  if (DescribeAddressIfShadow(addr, descr, /* print */ false)) {
+  ShadowAddressDescription shadow_descr;
+  if (GetShadowAddressInformation(addr, &shadow_descr)) {
+    descr->region_kind = ShadowNames[shadow_descr.kind];
     return;
   }
   if (GetInfoForAddressIfGlobal(addr, descr)) {
     return;
   }
   asanThreadRegistry().Lock();
   AsanThread *thread = FindThreadByStackAddress(addr);
   asanThreadRegistry().Unlock();

lib/asan/asan_descriptions.h

+//===-- asan_descriptions.h -------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// ASan-private header for asan_descriptions.cc.
+// TODO(filcab): Most struct definitions should move to the interface headers.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_common.h"
+
+namespace __asan {
+
+enum ShadowKind : u8 {
+  kShadowKindLow,
+  kShadowKindGap,
+  kShadowKindHigh,
+};
+static const char *const ShadowNames[] = {"low shadow", "shadow gap",
+                                          "high shadow"};
+
+struct ShadowAddressDescription {
+  uptr addr;
+  ShadowKind kind;
+  u8 byte;
+};
+
+bool GetShadowAddressInformation(uptr addr, ShadowAddressDescription *descr);
+bool DescribeAddressIfShadow(uptr addr);
+
+}  // namespace __asan

lib/asan/asan_descriptions.cc

+//===-- asan_descriptions.cc ------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// ASan functions for getting information about an address and/or printing it.
+//===----------------------------------------------------------------------===//
+
+#include "asan_descriptions.h"
+#include "asan_mapping.h"
+
+namespace __asan {
+
+// Shadow descriptions
+static bool GetShadowKind(uptr addr, ShadowKind *shadow_kind) {
+  CHECK(!AddrIsInMem(addr));
+  if (AddrIsInShadowGap(addr)) {
+    *shadow_kind = kShadowKindGap;
+  } else if (AddrIsInHighShadow(addr)) {
+    *shadow_kind = kShadowKindHigh;
+  } else if (AddrIsInLowShadow(addr)) {
+    *shadow_kind = kShadowKindLow;
+  } else {
+    CHECK(0 && "Address is not in memory and not in shadow?");
+    return false;
+  }
+  return true;
+}
+
+bool DescribeAddressIfShadow(uptr addr) {
+  ShadowAddressDescription descr;
+  if (!GetShadowAddressInformation(addr, &descr)) return false;
+  Printf("Address %p is located in the %s area.\n", addr,
+         ShadowNames[descr.kind]);
+  return true;
+}
+
+bool GetShadowAddressInformation(uptr addr, ShadowAddressDescription *descr) {
+  if (AddrIsInMem(addr)) return false;
+  ShadowKind shadow_kind;
+  if (!GetShadowKind(addr, &shadow_kind)) return false;
+  if (shadow_kind != kShadowKindGap) descr->byte = *(u8 *)addr;
+  descr->addr = addr;
+  descr->kind = shadow_kind;
+  return true;
+}
+
+}  // namespace __asan

lib/asan/asan_report.h

 // Returns the number of globals close to the provided address and copies
 // them to "globals" array.
 int GetGlobalsForAddress(uptr addr, __asan_global *globals, u32 *reg_sites,
                          int max_globals);
 bool GetInfoForAddressIfGlobal(uptr addr, AddressDescription *descr);
 // The following functions prints address description depending
 // on the memory type (shadow/heap/stack/global).
 void DescribeHeapAddress(uptr addr, uptr access_size);
-bool DescribeAddressIfShadow(uptr addr, AddressDescription *descr = nullptr,
-                             bool print = true);
 bool ParseFrameDescription(const char *frame_descr,
                            InternalMmapVector<StackVarDescr> *vars);
 bool DescribeAddressIfStack(uptr addr, uptr access_size);
 void DescribeThread(AsanThreadContext *context);
 
 // Different kinds of error reports.
 void ReportGenericError(uptr pc, uptr bp, uptr sp, uptr addr, bool is_write,
                         uptr access_size, u32 exp, bool fatal);

lib/asan/asan_report.cc

 //===-- asan_report.cc ----------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file is a part of AddressSanitizer, an address sanity checker.
 //
 // This file contains error reporting code.
 //===----------------------------------------------------------------------===//
 
 #include "asan_flags.h"
+#include "asan_descriptions.h"
 #include "asan_internal.h"
 #include "asan_mapping.h"
 #include "asan_report.h"
 #include "asan_scariness_score.h"
 #include "asan_stack.h"
 #include "asan_thread.h"
 #include "sanitizer_common/sanitizer_common.h"
 #include "sanitizer_common/sanitizer_flags.h"
if (0 == internal_strcmp(bug_type, "initialization-order-fiasco") &&
         reg_sites[i]) {
       Printf("  registered at:\n");
       StackDepotGet(reg_sites[i]).Print();
     }
   }
   return true;
 }
 
-bool DescribeAddressIfShadow(uptr addr, AddressDescription *descr, bool print) {
-  if (AddrIsInMem(addr))
-    return false;
-  const char *area_type = nullptr;
-  if (AddrIsInShadowGap(addr)) area_type = "shadow gap";
-  else if (AddrIsInHighShadow(addr)) area_type = "high shadow";
-  else if (AddrIsInLowShadow(addr)) area_type = "low shadow";
-  if (area_type != nullptr) {
-    if (print) {
-      Printf("Address %p is located in the %s area.\n", addr, area_type);
-    } else {
-      CHECK(descr);
-      descr->region_kind = area_type;
-    }
-    return true;
-  }
-  CHECK(0 && "Address is not in memory and not in shadow?");
-  return false;
-}
-
 // Return " (thread_name) " or an empty string if the name is empty.
 const char *ThreadNameWithParenthesis(AsanThreadContext *t, char buff[],
                                       uptr buff_len) {
   const char *name = t->name;
   if (name[0] == '\0') return "";
   buff[0] = 0;
   internal_strncat(buff, " (", 3);
   internal_strncat(buff, name, buff_len - 4);