Allow passing TPM device path in the environment.

firmware/stub/tpm_lite_stub.c

 /* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  * Stub implementations of utility functions which call their linux-specific
  * equivalents.
  */
 
 #define _STUB_IMPLEMENTATION_
 #include "tlcl.h"
 #include "tlcl_internal.h"
 #include "utility.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
 #include <tss/tcs.h>
 #include "tpmextras.h"
 #define TPM_DEVICE_PATH "/dev/tpm0"
 
 /* TODO: these functions should pass errors back rather than returning void */
@@ skipping 76 matching lines @@
 }
 
 
 void TlclCloseDevice(void) {
   close(tpm_fd);
   tpm_fd = -1;
 }
 
 
 void TlclOpenDevice(void) {
+  char* device_path;
+
   if (tpm_fd >= 0)
     return;  /* Already open */
 
-  tpm_fd = open(TPM_DEVICE_PATH, O_RDWR);
+  device_path = getenv("TPM_DEVICE_PATH");
+  if (device_path == NULL) {
+    device_path = TPM_DEVICE_PATH;
+  }
+
+  tpm_fd = open(device_path, O_RDWR);
   if (tpm_fd < 0) {
-    error("cannot open TPM device %s: %s\n", TPM_DEVICE_PATH, strerror(errno));
+    error("cannot open TPM device %s: %s\n", device_path, strerror(errno));
   }
 }
 
 
 void TlclStubSendReceive(uint8_t* request, int request_length,
                          uint8_t* response, int max_length) {
   /*
    * In a real firmware implementation, this function should contain
    * the equivalent API call for the firmware TPM driver which takes a
    * raw sequence of bytes as input command and a pointer to the
@@ skipping 39 matching lines @@
   response_tag = TpmTag(response);
   assert(
     (tag == TPM_TAG_RQU_COMMAND &&
      response_tag == TPM_TAG_RSP_COMMAND) ||
     (tag == TPM_TAG_RQU_AUTH1_COMMAND &&
      response_tag == TPM_TAG_RSP_AUTH1_COMMAND) ||
     (tag == TPM_TAG_RQU_AUTH2_COMMAND &&
      response_tag == TPM_TAG_RSP_AUTH2_COMMAND));
   assert(response_length == TpmResponseSize(response));
 }