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|
package common
import (
"errors"
"os"
"sync"
"syscall"
)
var bufferPool = sync.Pool{
New: func() any {
b := make([]byte, syscall.PathMax)
return &b
},
}
// The following three functions are copied from stdlib.
// ignoringEINTR2 is ignoringEINTR, but returning an additional value.
func ignoringEINTR2[T any](fn func() (T, error)) (T, error) {
for {
v, err := fn()
if !errors.Is(err, syscall.EINTR) {
return v, err
}
}
}
// Many functions in package syscall return a count of -1 instead of 0.
// Using fixCount(call()) instead of call() corrects the count.
func fixCount(n int, err error) (int, error) {
if n < 0 {
n = 0
}
return n, err
}
// Readlink behaves like os.Readlink but caches the buffer passed to syscall.Readlink.
func Readlink(name string) (string, error) {
b := bufferPool.Get().(*[]byte)
n, err := ignoringEINTR2(func() (int, error) {
return fixCount(syscall.Readlink(name, *b))
})
if err != nil {
bufferPool.Put(b)
return "", &os.PathError{Op: "readlink", Path: name, Err: err}
}
result := string((*b)[:n])
bufferPool.Put(b)
return result, nil
}
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