Address GitHub feedback

- Defer registry close calls
- Ensure size parameter in GetComputerName is properly specified
- Clean up some comments to ensure correctness

Signed-off-by: Ben Ridley <benridley29@gmail.com>

collector/os.go

@@ -173,6 +173,8 @@ func (c *OSCollector) collect(ctx *ScrapeContext, ch chan<- prometheus.Metric) (
 
 	// Get total allocation of paging files across all disks.
 	memManKey, err := registry.OpenKey(registry.LOCAL_MACHINE, `SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management`, registry.QUERY_VALUE)
+	defer memManKey.Close()
+
 	if err != nil {
 		return nil, err
 	}
@@ -181,15 +183,14 @@ func (c *OSCollector) collect(ctx *ScrapeContext, ch chan<- prometheus.Metric) (
 		return nil, err
 	}
 
-	if err := memManKey.Close(); err != nil {
-		return nil, err
-	}
-
 	// Get build number and product name from registry
 	ntKey, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
+	defer ntKey.Close()
+
 	if err != nil {
 		return nil, err
 	}
+
 	pn, _, err := ntKey.GetStringValue("ProductName")
 	if err != nil {
 		return nil, err
@@ -200,10 +201,6 @@ func (c *OSCollector) collect(ctx *ScrapeContext, ch chan<- prometheus.Metric) (
 		return nil, err
 	}
 
-	if err := ntKey.Close(); err != nil {
-		return nil, err
-	}
-
 	var fsipf float64 = 0
 	for _, pagingFile := range pagingFiles {
 		fileString := strings.ReplaceAll(pagingFile, `\??\`, "")

headers/netapi32/netapi32.go

@@ -73,7 +73,6 @@ func netApiBufferFree(buffer *wKSTAInfo102) {
 }
 
 // NetWkstaGetInfo returns information about the configuration of a workstation.
-// WARNING: The caller must call netApiBufferFree to free the memory allocated by this function.
 // https://docs.microsoft.com/en-us/windows/win32/api/lmwksta/nf-lmwksta-netwkstagetinfo
 func netWkstaGetInfo() (*wKSTAInfo102, uint32, error) {
 	var lpwi *wKSTAInfo102

headers/sysinfoapi/sysinfoapi.go

@@ -148,12 +148,12 @@ func GetSystemInfo() SystemInfo {
 }
 
 // GetComputerName wraps the GetComputerNameW function in a more Go-like way
-// https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-getcomputernamew
+// https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getcomputernameexw
 func GetComputerName(f WinComputerNameFormat) (string, error) {
 	// 1kb buffer to accept computer name. This should be more than enough as the maximum size
 	// returned is the max length of a DNS name, which this author believes is 253 characters.
 	size := 1024
-	var buffer [4096]uint16
+	var buffer [1024]uint16
 	r1, _, err := procGetComputerNameExW.Call(uintptr(f), uintptr(unsafe.Pointer(&buffer)), uintptr(unsafe.Pointer(&size)))
 	if r1 == 0 {
 		return "", err