Add contrib/getdents

Small tool to try to debug unix.Getdents problems on CIFS mounts
https://github.com/rfjakob/gocryptfs/issues/483

1 files changed, 75 insertions, 0 deletions

diff --git a/contrib/getdents/getdents.go b/contrib/getdents/getdents.go
new file mode 100644
index 0000000..a70692a
--- /dev/null
+++ b/contrib/getdents/getdents.go
@@ -0,0 +1,75 @@
+/*
+Small tool to try to debug unix.Getdents problems on CIFS mounts
+( https://github.com/rfjakob/gocryptfs/issues/483 )
+
+Example output:
+
+$ while sleep 1 ; do ./getdents /mnt/synology/public/tmp/g1 ; done
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=3192, err=<nil>
+unix.Getdents fd3: n=0, err=<nil>
+total 24072 bytes
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=-1, err=no such file or directory
+total 16704 bytes
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=4176, err=<nil>
+unix.Getdents fd3: n=3192, err=<nil>
+unix.Getdents fd3: n=0, err=<nil>
+total 24072 bytes
+*/
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	myName = "getdents"
+)
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "Usage: %s PATH\n", myName)
+		fmt.Fprintf(os.Stderr, "Run getdents(2) on PATH\n")
+		os.Exit(1)
+	}
+	flag.Parse()
+	if flag.NArg() != 1 {
+		flag.Usage()
+	}
+	path := flag.Arg(0)
+
+	fd, err := unix.Open(path, unix.O_RDONLY, 0)
+	if err != nil {
+		log.Fatalf("unix.Open returned err=%v", err)
+	}
+
+	tmp := make([]byte, 10000)
+	sum := 0
+	for {
+		n, err := unix.Getdents(fd, tmp)
+		fmt.Printf("unix.Getdents fd%d: n=%d, err=%v\n", fd, n, err)
+		if n <= 0 {
+			fmt.Printf("total %d bytes\n", sum)
+			break
+		}
+		sum += n
+	}
+}