Add MinidumpContextWriter::CreateFromSnapshot(), everything downstream, and its test

minidump/minidump_context_writer.cc

Index: minidump/minidump_context_writer.cc
diff --git a/minidump/minidump_context_writer.cc b/minidump/minidump_context_writer.cc
index 6b46eeb33df9758c4e236764bd2a306443bbb8d8..9b30997d4e89ad5986ccf704bd690d8a74ff2dda 100644
--- a/minidump/minidump_context_writer.cc
+++ b/minidump/minidump_context_writer.cc
@@ -14,7 +14,10 @@
 
 #include "minidump/minidump_context_writer.h"
 
+#include <string.h>
+
 #include "base/logging.h"
+#include "snapshot/cpu_context.h"
 #include "util/file/file_writer.h"
 
 namespace crashpad {
@@ -22,6 +25,37 @@ namespace crashpad {
 MinidumpContextWriter::~MinidumpContextWriter() {
 }
 
+// static
+scoped_ptr<MinidumpContextWriter> MinidumpContextWriter::CreateFromSnapshot(
+    const CPUContext* context_snapshot) {
+  scoped_ptr<MinidumpContextWriter> context;
+
+  switch (context_snapshot->architecture) {
+    case kCPUArchitectureX86: {
+      MinidumpContextX86Writer* context_x86 = new MinidumpContextX86Writer();
+      context.reset(context_x86);
+      context_x86->InitializeFromSnapshot(context_snapshot->x86);
+      break;
+    }
+
+    case kCPUArchitectureX86_64: {
+      MinidumpContextAMD64Writer* context_amd64 =
+          new MinidumpContextAMD64Writer();
+      context.reset(context_amd64);
+      context_amd64->InitializeFromSnapshot(context_snapshot->x86_64);
+      break;
+    }
+
+    default: {
+      LOG(ERROR) << "unknown context architecture "
+                 << context_snapshot->architecture;
+      break;
+    }
+  }
+
+  return context;
+}
+
 size_t MinidumpContextWriter::SizeOfObject() {
   DCHECK_GE(state(), kStateFrozen);
 
@@ -36,6 +70,65 @@ MinidumpContextX86Writer::MinidumpContextX86Writer()
 MinidumpContextX86Writer::~MinidumpContextX86Writer() {
 }
 
+
+void MinidumpContextX86Writer::InitializeFromSnapshot(
+    const CPUContextX86* context_snapshot) {
+  DCHECK_EQ(state(), kStateMutable);
+  DCHECK_EQ(context_.context_flags, kMinidumpContextX86);
+
+  context_.context_flags = kMinidumpContextX86All;
+
+  context_.dr0 = context_snapshot->dr0;
+  context_.dr1 = context_snapshot->dr1;
+  context_.dr2 = context_snapshot->dr2;
+  context_.dr3 = context_snapshot->dr3;
+  context_.dr6 = context_snapshot->dr6;
+  context_.dr7 = context_snapshot->dr7;
+
+  // The contents of context_.float_save effectively alias everything in
+  // context_.fxsave that’s related to x87 FPU state. context_.float_save
+  // doesn’t carry state specific to SSE (or later), such as mxcsr and the xmm
+  // registers.
+  context_.float_save.control_word = context_snapshot->fxsave.fcw;
+  context_.float_save.status_word = context_snapshot->fxsave.fsw;
+  context_.float_save.tag_word =
+      CPUContextX86::FxsaveToFsaveTagWord(context_snapshot->fxsave.fsw,
+                                          context_snapshot->fxsave.ftw,
+                                          context_snapshot->fxsave.st_mm);
+  context_.float_save.error_offset = context_snapshot->fxsave.fpu_ip;
+  context_.float_save.error_selector = context_snapshot->fxsave.fpu_cs;
+  context_.float_save.data_offset = context_snapshot->fxsave.fpu_dp;
+  context_.float_save.data_selector = context_snapshot->fxsave.fpu_ds;
+
+  for (size_t index = 0, offset = 0;
+       index < arraysize(context_snapshot->fxsave.st_mm);
+       offset += sizeof(context_snapshot->fxsave.st_mm[index].st), ++index) {
+    memcpy(&context_.float_save.register_area[offset],
+           &context_snapshot->fxsave.st_mm[index].st,
+           sizeof(context_snapshot->fxsave.st_mm[index].st));
+  }
+
+  context_.gs = context_snapshot->gs;
+  context_.fs = context_snapshot->fs;
+  context_.es = context_snapshot->es;
+  context_.ds = context_snapshot->ds;
+  context_.edi = context_snapshot->edi;
+  context_.esi = context_snapshot->esi;
+  context_.ebx = context_snapshot->ebx;
+  context_.edx = context_snapshot->edx;
+  context_.ecx = context_snapshot->ecx;
+  context_.eax = context_snapshot->eax;
+  context_.ebp = context_snapshot->ebp;
+  context_.eip = context_snapshot->eip;
+  context_.cs = context_snapshot->cs;
+  context_.eflags = context_snapshot->eflags;
+  context_.esp = context_snapshot->esp;
+  context_.ss = context_snapshot->ss;
+
+  // This is effectively a memcpy() of a big structure.
+  context_.fxsave = context_snapshot->fxsave;
+}
+
 bool MinidumpContextX86Writer::WriteObject(FileWriterInterface* file_writer) {
   DCHECK_EQ(state(), kStateWritable);
 
@@ -56,6 +149,46 @@ MinidumpContextAMD64Writer::MinidumpContextAMD64Writer()
 MinidumpContextAMD64Writer::~MinidumpContextAMD64Writer() {
 }
 
+void MinidumpContextAMD64Writer::InitializeFromSnapshot(
+    const CPUContextX86_64* context_snapshot) {
+  DCHECK_EQ(state(), kStateMutable);
+  DCHECK_EQ(context_.context_flags, kMinidumpContextAMD64);
+
+  context_.context_flags = kMinidumpContextAMD64All;
+
+  context_.mx_csr = context_snapshot->fxsave.mxcsr;
+  context_.cs = context_snapshot->cs;
+  context_.fs = context_snapshot->fs;
+  context_.gs = context_snapshot->gs;
+  context_.eflags = context_snapshot->rflags;
+  context_.dr0 = context_snapshot->dr0;
+  context_.dr1 = context_snapshot->dr1;
+  context_.dr2 = context_snapshot->dr2;
+  context_.dr3 = context_snapshot->dr3;
+  context_.dr6 = context_snapshot->dr6;
+  context_.dr7 = context_snapshot->dr7;
+  context_.rax = context_snapshot->rax;
+  context_.rcx = context_snapshot->rcx;
+  context_.rdx = context_snapshot->rdx;
+  context_.rbx = context_snapshot->rbx;
+  context_.rsp = context_snapshot->rsp;
+  context_.rbp = context_snapshot->rbp;
+  context_.rsi = context_snapshot->rsi;
+  context_.rdi = context_snapshot->rdi;
+  context_.r8 = context_snapshot->r8;
+  context_.r9 = context_snapshot->r9;
+  context_.r10 = context_snapshot->r10;
+  context_.r11 = context_snapshot->r11;
+  context_.r12 = context_snapshot->r12;
+  context_.r13 = context_snapshot->r13;
+  context_.r14 = context_snapshot->r14;
+  context_.r15 = context_snapshot->r15;
+  context_.rip = context_snapshot->rip;
+
+  // This is effectively a memcpy() of a big structure.
+  context_.fxsave = context_snapshot->fxsave;
+}
+
 size_t MinidumpContextAMD64Writer::Alignment() {
   DCHECK_GE(state(), kStateFrozen);