Good call! Tested with this code:

package main

import "os"

func main() {
	// foo.txt contains "foobar"
	f, err := os.Open("foo.txt")

	if err != nil {
		panic(err)
	}

	b := make([]byte, 10)
	_, err = f.ReadAt(b, 3)
	panic(err)
}

Needed to make some tweaks - this change returned nil, not io.EOF, and we want the behavior of io.ReadFull where it calls Read in a loop.

@colinmarc awesome thanks, bit confused why the Read didn't work? Should this not behave like Read() with a seek method?

https://golang.org/pkg/os/#File.Read I think Read() should return io.EOF.

@afking File.ReadAt actually calls Read in a loop, just like ReadFull:

for len(b) > 0 {
  		m, e := f.pread(b, off)
  		if e != nil {
  			err = f.wrapErr("read", e)
  			break
  		}
  		n += m
  		b = b[m:]
  		off += int64(m)
  	}

And Read doesn't have to return io.EOF on a partial read - it can just return n < len(b) and nil.

https://golang.org/pkg/os/#File.Read I think Read() should return io.EOF.

It doesn't until the second call to Read. Try running this code:

package main

import "os"
import "log"

func main() {
	// foo.txt contains "foobar"
	f, err := os.Open("foo.txt")

	if err != nil {
		panic(err)
	}

	b := make([]byte, 10)
	n, err := f.Read(b)
	log.Fatal(n, err)
}

I get 7 <nil>.

@colinmarc yep it does 👍 thanks for taking the time to clarify.