SNOW-1825790 Implement safer file based token cache

os_specific_posix.go

@@ -0,0 +1,25 @@
+//go:build darwin || linux
+
+package gosnowflake
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+)
+
+func provideFileOwner(file *os.File) (uint32, error) {
+	info, err := file.Stat()
+	if err != nil {
+		return 0, err
+	}
+	return provideOwnerFromStat(info, file.Name())
+}
+
+func provideOwnerFromStat(info os.FileInfo, filepath string) (uint32, error) {
+	nativeStat, ok := info.Sys().(*syscall.Stat_t)
+	if !ok {
+		return 0, fmt.Errorf("cannot cast file info for %v to *syscall.Stat_t", filepath)
+	}
+	return nativeStat.Uid, nil
+}

os_specific_windows.go

@@ -0,0 +1,12 @@
+// go:build windows
+
+package gosnowflake
+
+import (
+	"errors"
+	"os"
+)
+
+func provideFileOwner(file *os.File) (uint32, error) {
+	return 0, errors.New("provideFileOwner is unsupported on windows")
+}