contrib/statvsfstat: add statvsfstat tool

Cli tool to compare the result of Stat() and Fstat().

contrib/statvsfstat/.gitignore

@@ -0,0 +1 @@
+/statvsfstat

contrib/statvsfstat/statvsfstat.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	myName = "statvsfstat"
+)
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "Usage: %s PATH\n", myName)
+		fmt.Fprintf(os.Stderr, "Dump the stat and fstat information for PATH to the console, JSON format.\n")
+		os.Exit(1)
+	}
+	flag.Parse()
+	if flag.NArg() != 1 {
+		flag.Usage()
+	}
+	path := flag.Arg(0)
+
+	var st unix.Stat_t
+	err := unix.Stat(path, &st)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "stat syscall returned error: %v\n", err)
+		os.Exit(4)
+	}
+
+	fd, err := unix.Open(path, unix.O_RDONLY, 0)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "open syscall returned error: %v\n", err)
+		os.Exit(3)
+	}
+	var fst unix.Stat_t
+	err = unix.Fstat(fd, &fst)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "fstat syscall returned error: %v\n", err)
+		os.Exit(2)
+	}
+
+	fmt.Printf("stat  result: %#v\n", st)
+	fmt.Printf("fstat result: %#v\n", fst)
+	if st == fst {
+		fmt.Println("results are identical")
+	} else {
+		fmt.Println("results differ")
+	}
+}