1 files changed, 97 insertions, 0 deletions
diff --git a/js/src/zydis/ZydisAPI.cpp b/js/src/zydis/ZydisAPI.cpp
new file mode 100644
index 0000000000..de8e8229fb
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+++ b/js/src/zydis/ZydisAPI.cpp
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ *
+ * Zyan Disassembler Library (Zydis)
+ *
+ * Original Author : Code taken from examples on zydis github README.md.
+ *
+ * Modified by Mozilla.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "zydis/ZydisAPI.h"
+
+void zydisDisassemble(const uint8_t* code, size_t codeLen,
+                      void(*println)(const char*)) {
+  ZydisDecoder decoder;
+  ZydisDecoderInit(&decoder, ZYDIS_MACHINE_MODE_LONG_64, ZYDIS_ADDRESS_WIDTH_64);
+
+  ZydisFormatter formatter;
+  ZydisFormatterInit(&formatter, ZYDIS_FORMATTER_STYLE_ATT);
+  ZydisFormatterSetProperty(&formatter, ZYDIS_FORMATTER_PROP_FORCE_SIZE, ZYAN_TRUE);
+
+  ZyanU64 runtime_address = 0;
+  ZyanUSize offset = 0;
+  const ZyanUSize length = (ZyanUSize)codeLen;
+  ZydisDecodedInstruction instruction;
+  char buffer[1024];
+  while (ZYAN_SUCCESS(ZydisDecoderDecodeBuffer(&decoder, code + offset, length - offset,
+                                               &instruction)))
+  {
+#  define LIMIT 36
+#  define LIMSTR "36"
+
+    // We format the tag and the address and the bytes in a field of LIMIT
+    // characters and start the menmonic at position LIMIT.  If the
+    // tag+address+bytes would be too long we put the mnemonic + operands on the
+    // next line.
+
+    // Emit address
+    sprintf(buffer, "%08" PRIX64 "  ", runtime_address);
+
+    // Emit bytes
+    for (size_t i = 0; i < instruction.length; i++) {
+      sprintf(buffer+strlen(buffer), "%s%02x", i == 0 ? "" : " ", *(code + offset + i));
+    }
+
+    // Pad with at least one space
+    sprintf(buffer+strlen(buffer), " ");
+
+    // Pad out to the limit if necessary
+    if (strlen(buffer) < LIMIT) {
+      char* cur_end = buffer + strlen(buffer);
+      size_t spaces = LIMIT - strlen(buffer);
+      memset(cur_end, ' ', spaces);
+      cur_end[spaces] = '\0';
+    }
+
+    // If too long then flush and provide an appropriate indent
+    if (strlen(buffer) > LIMIT) {
+      println(buffer);
+      sprintf(buffer, "%-" LIMSTR "s", "");
+    }
+
+    // Emit instruction mnemonic + operands
+    size_t used = strlen(buffer);
+    ZydisFormatterFormatInstruction(&formatter, &instruction, buffer + used,
+                                    sizeof(buffer) - used, runtime_address);
+    println(buffer);
+
+    offset += instruction.length;
+    runtime_address += instruction.length;
+
+#  undef LIMIT
+#  undef LIMSTR
+  }
+}