rocm_smi_lib: Fix rocm-smi --showfan shows 'unable to detect fan'

Code changes related to the following:
  * Reverts earlier fix for the same issue
  * Check for existence of files before reading

Change-Id: I175b20c3343c414b12b79dc3fc404f53fbaabf3a
Signed-off-by: Oliveira, Daniel <daniel.oliveira@amd.com>

python_smi_tools/rocm_smi.py

@@ -785,12 +785,8 @@ def resetFans(deviceList):
     for device in deviceList:
         sensor_ind = c_uint32(0)
         ret = rocmsmi.rsmi_dev_fan_reset(device, sensor_ind)
-        if (ret == rsmi_status_t.RSMI_STATUS_NOT_SUPPORTED) or (ret == rsmi_status_t.RSMI_STATUS_PERMISSION):
-            if not rsmi_ret_ok(rsmi_status_t.RSMI_STATUS_NOT_SUPPORTED, device, 'reset_fan'):
-                continue
-        else:
-            if rsmi_ret_ok(ret, device, 'reset_fan'):
-                printLog(device, 'Successfully reset fan speed to driver control', None)
+        if rsmi_ret_ok(ret, device, 'reset_fan'):
+            printLog(device, 'Successfully reset fan speed to driver control', None)
     printLogSpacer()
 
 

src/rocm_smi_device.cc

@@ -593,7 +593,6 @@ int Device::openSysfsFileStream(DevInfoTypes type, T *fs, const char *str) {
   bool reg_file;
 
   int ret = isRegularFile(sysfs_path, &reg_file);
-
   if (ret != 0) {
     ss << "File did not exist - SYSFS file (" << sysfs_path
        << ") for DevInfoInfoType (" << RocmSMI::devInfoTypesStrings.at(type)
@@ -804,7 +803,8 @@ int Device::readDevInfoBinary(DevInfoTypes type, std::size_t b_size,
   FILE *ptr;
   sysfs_path += "/device/";
   sysfs_path += kDevAttribNameMap.at(type);
-  ptr  = fopen(sysfs_path.c_str(), "rb");
+
+  ptr = fopen(sysfs_path.c_str(), "rb");
   if (!ptr) {
     ss << "Could not read DevInfoBinary for DevInfoType ("
        << RocmSMI::devInfoTypesStrings.at(type) << ")"

src/rocm_smi_utils.cc

@@ -158,13 +158,15 @@ int isRegularFile(std::string fname, bool *is_reg) {
   struct stat file_stat;
   int ret;
 
-  assert(is_reg != nullptr);
-
   ret = stat(fname.c_str(), &file_stat);
   if (ret) {
     return errno;
   }
-  *is_reg = S_ISREG(file_stat.st_mode);
+
+  if (is_reg != nullptr) {
+    *is_reg = S_ISREG(file_stat.st_mode);
+  }
+
   return 0;
 }
 
@@ -192,6 +194,13 @@ int WriteSysfsStr(std::string path, std::string val) {
 }
 
 int ReadSysfsStr(std::string path, std::string *retStr) {
+  //  On success, zero is returned.  On error, -1 is returned, and
+  //  errno is set to indicate the error.
+  auto is_regular_file_result = isRegularFile(path, nullptr);
+  if (is_regular_file_result != 0) {
+    return ENOENT;
+  }
+
   std::stringstream ss;
   int ret = 0;
   std::ostringstream oss;