Add ReservedAddressRange to sanitizer_common.h.

[flowerhack]

Summary

We'd like to refactor the MmapNoAccess/MmapFixedOrDie APIs to be
a bit more sensible. In particular, these are better represented
as first reserving a specifically-utilized address space, and then
mapping subsections of that space at will.

This will make the Fuchsia implementation of these functions more flexible.

As a first step, this commit creates the class to be used by the
new API, but all functions still call into the old API.

[flowerhack]

discussed some changes offline w/ cryptoad@; going to submit a new approach soon

lib/sanitizer_common/sanitizer_common.h

 tid_t GetTid();
 uptr GetThreadSelf();
 void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
                                 uptr *stack_bottom);
 void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
                           uptr *tls_addr, uptr *tls_size);
 
 // Memory management
+// This class relies on zero-initialization.
+class ReservedAddressRange {
+ public:
+  uptr Init(uptr size, const char *name = nullptr, uptr fixed_addr = (uptr)0);
+  uptr Map(uptr offset, uptr size, bool tolerate_enomem = false);
+  void *base() { return base_; }
+ private:
+  uptr os_cookie_;
+  void* base_;
+  uptr size_;
+};
+
 void *MmapOrDie(uptr size, const char *mem_type, bool raw_report = false);
 INLINE void *MmapOrDieQuietly(uptr size, const char *mem_type) {
   return MmapOrDie(size, mem_type, /*raw_report*/ true);
 }
 void UnmapOrDie(void *addr, uptr size);
 // Behaves just like MmapOrDie, but tolerates out of memory condition, in that
 // case returns nullptr.
 void *MmapOrDieOnFatalError(uptr size, const char *mem_type);

lib/sanitizer_common/sanitizer_fuchsia.cc

 void *MmapNoReserveOrDie(uptr size, const char *mem_type) {
   return MmapOrDie(size, mem_type);
 }
 
 void *MmapOrDieOnFatalError(uptr size, const char *mem_type) {
   return DoAnonymousMmapOrDie(size, mem_type, false, false);
 }
 
+uptr ReservedAddressRange::Init(uptr init_size, const char* name = nullptr,
+                                uptr fixed_addr = uptr(0)) {
+  return reinterpret_cast<uptr>(MmapNoAccess(init_size));
+}
+
+// Uses fixed_addr for now.
+// Will use offset instead once we've implemented this function for real.
+uptr ReservedAddressRange::Map(uptr fixed_addr, uptr map_size,
+                               bool tolerate_enomem = true) {
+  return reinterpret_cast<uptr>(MmapFixedOrDie(fixed_addr, size,
+                                               tolerate_enomem));
+}
+
 // MmapNoAccess and MmapFixedOrDie are used only by sanitizer_allocator.
 // Instead of doing exactly what they say, we make MmapNoAccess actually
 // just allocate a VMAR to reserve the address space.  Then MmapFixedOrDie
 // uses that VMAR instead of the root.
 
 zx_handle_t allocator_vmar = ZX_HANDLE_INVALID;
 uintptr_t allocator_vmar_base;
 size_t allocator_vmar_size;

lib/sanitizer_common/sanitizer_posix.cc

void *MmapFixedImpl(uptr fixed_addr, uptr size, bool tolerate_enomem) {
   IncreaseTotalMmap(size);
   return (void *)p;
 }
 
 void *MmapFixedOrDie(uptr fixed_addr, uptr size) {
   return MmapFixedImpl(fixed_addr, size, false /*tolerate_enomem*/);
 }
 
+// Uses fixed_addr for now.
+// Will use offset instead once we've implemented this function for real.
+uptr ReservedAddressRange::Map(uptr fixed_addr, uptr size,
+                               bool tolerate_enomem) {
+  if (tolerate_enomem) {
+    return reinterpret_cast<uptr>(MmapFixedOrDieOnFatalError(fixed_addr, size));
+  }
+  return reinterpret_cast<uptr>(MmapFixedOrDie(fixed_addr, size));
+}
+
 void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size) {
   return MmapFixedImpl(fixed_addr, size, true /*tolerate_enomem*/);
 }
 
 bool MprotectNoAccess(uptr addr, uptr size) {
   return 0 == internal_mprotect((void*)addr, size, PROT_NONE);
 }
 

lib/sanitizer_common/sanitizer_posix_libcdep.cc

void *MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
   if (internal_iserror(p, &reserrno))
     Report("ERROR: %s failed to "
            "allocate 0x%zx (%zd) bytes at address %zx (errno: %d)\n",
            SanitizerToolName, size, size, fixed_addr, reserrno);
   IncreaseTotalMmap(size);
   return (void *)p;
 }
 
+uptr ReservedAddressRange::Init(uptr size, const char *name, uptr fixed_addr) {
+  if (fixed_addr) {
+    return reinterpret_cast<uptr>(MmapFixedNoAccess(fixed_addr, size, name));
+  }
+  return reinterpret_cast<uptr>(MmapNoAccess(size));
+}
+
 void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name) {
   int fd = name ? GetNamedMappingFd(name, size) : -1;
   unsigned flags = MAP_PRIVATE | MAP_FIXED | MAP_NORESERVE;
   if (fd == -1) flags |= MAP_ANON;
 
   return (void *)internal_mmap((void *)fixed_addr, size, PROT_NONE, flags, fd,
                                0);
 }

lib/sanitizer_common/sanitizer_win.cc

if (p == 0) {
     char mem_type[30];
     internal_snprintf(mem_type, sizeof(mem_type), "memory at address 0x%zx",
                       fixed_addr);
     ReportMmapFailureAndDie(size, mem_type, "allocate", GetLastError());
   }
   return p;
 }
 
+// Uses fixed_addr for now.
+// Will use offset instead once we've implemented this function for real.
+uptr ReservedAddressRange::Map(uptr fixed_addr, uptr size,
+                               bool tolerate_enomem) {
+  if (tolerate_enomem) {
+    return reinterpret_cast<uptr>(MmapFixedOrDieOnFatalError(fixed_addr, size));
+  }
+  return reinterpret_cast<uptr>(MmapFixedOrDie(uptr fixed_addr, uptr size));
+}
+
 void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size) {
   void *p = VirtualAlloc((LPVOID)fixed_addr, size,
       MEM_COMMIT, PAGE_READWRITE);
   if (p == 0) {
     char mem_type[30];
     internal_snprintf(mem_type, sizeof(mem_type), "memory at address 0x%zx",
                       fixed_addr);
     return ReturnNullptrOnOOMOrDie(size, mem_type, "allocate");
   }
   return p;
 }
 
 void *MmapNoReserveOrDie(uptr size, const char *mem_type) {
   // FIXME: make this really NoReserve?
   return MmapOrDie(size, mem_type);
 }
 
+uptr ReservedAddressRange::Init(uptr size, const char *name, uptr fixed_addr) {
+  if (fixed_addr) {
+    return reinterpret_cast<uptr>(MmapFixedNoAccess(fixed_addr, size, name));
+  }
+  return reinterpret_cast<uptr>(MmapNoAccess(size));
+}
+
 void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name) {
   (void)name; // unsupported
   void *res = VirtualAlloc((LPVOID)fixed_addr, size,
                            MEM_RESERVE, PAGE_NOACCESS);
   if (res == 0)
     Report("WARNING: %s failed to "
            "mprotect %p (%zd) bytes at %p (error code: %d)\n",
            SanitizerToolName, size, size, fixed_addr, GetLastError());