Add new constant called SYSTEM_PROCESS_NAME_BUFFER_LENGTH

Previously we were using the value of C.PR_SET_NAME to limit the size of
the buffer used to write the process name into when calling
'nvmlSystemGetProcessName()'. While this technically wouldn't cause a
buffer overrun, it limited the length of the process name by a
(somewhat) arbitrary amount since C.PR_SET_NAME is not meant to indicate
a maximum length for a process name, but rather an arbitrary code for
telling 'prctl()' to set the name for a process (which has nothing to do
with its length).

It was a clear oversight to use this random value as the buffer length.
In the new implementation we simply hard code a new variable called
SYSTEM_PROCESS_NAME_BUFFER_LENGTH to 256 (which is well more than the
actual maximum process name length on linux). Having a larger value
won't hurt anything, and will make it more portable if / when we decide
to start supporting windows.

Signed-off-by: Kevin Klues <[email protected]>

gen/nvml/const_gen.go

@@ -0,0 +1,19 @@
+// Copyright (c) 2021, NVIDIA CORPORATION.  All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package nvml
+
+const (
+	SYSTEM_PROCESS_NAME_BUFFER_SIZE = 256
+)

gen/nvml/system.go

@@ -14,9 +14,6 @@
 
 package nvml
 
-// #include <sys/prctl.h>
-import "C"
-
 // nvml.SystemGetDriverVersion()
 func SystemGetDriverVersion() (string, Return) {
 	Version := make([]byte, SYSTEM_DRIVER_VERSION_BUFFER_SIZE)
@@ -47,8 +44,8 @@ func SystemGetCudaDriverVersion_v2() (int, Return) {
 
 // nvml.SystemGetProcessName()
 func SystemGetProcessName(Pid int) (string, Return) {
-	Name := make([]byte, C.PR_SET_NAME)
-	ret := nvmlSystemGetProcessName(uint32(Pid), &Name[0], C.PR_SET_NAME)
+	Name := make([]byte, SYSTEM_PROCESS_NAME_BUFFER_SIZE)
+	ret := nvmlSystemGetProcessName(uint32(Pid), &Name[0], SYSTEM_PROCESS_NAME_BUFFER_SIZE)
 	return string(Name[:clen(Name)]), ret
 }