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package system
import (
"bytes"
"errors"
"fmt"
"io"
"os"
"syscall"
"git.gensokyo.uk/security/fortify/internal/fmsg"
)
// CopyFile registers an Op that copies from src.
// A buffer is initialised with size cap and the Op faults if bytes read exceed n.
func (sys *I) CopyFile(payload *[]byte, src string, cap int, n int64) *I {
buf := new(bytes.Buffer)
buf.Grow(cap)
sys.lock.Lock()
sys.ops = append(sys.ops, &Tmpfile{payload, src, n, buf})
sys.lock.Unlock()
return sys
}
type Tmpfile struct {
payload *[]byte
src string
n int64
buf *bytes.Buffer
}
func (t *Tmpfile) Type() Enablement { return Process }
func (t *Tmpfile) apply(_ *I) error {
fmsg.Verbose("copying", t)
if t.payload == nil {
// this is a misuse of the API; do not return an error message
return errors.New("invalid payload")
}
if b, err := os.Stat(t.src); err != nil {
return fmsg.WrapErrorSuffix(err,
fmt.Sprintf("cannot stat %q:", t.src))
} else {
if b.IsDir() {
return fmsg.WrapErrorSuffix(syscall.EISDIR,
fmt.Sprintf("%q is a directory", t.src))
}
if s := b.Size(); s > t.n {
return fmsg.WrapErrorSuffix(syscall.ENOMEM,
fmt.Sprintf("file %q is too long: %d > %d",
t.src, s, t.n))
}
}
if f, err := os.Open(t.src); err != nil {
return fmsg.WrapErrorSuffix(err,
fmt.Sprintf("cannot open %q:", t.src))
} else if _, err = io.CopyN(t.buf, f, t.n); err != nil {
return fmsg.WrapErrorSuffix(err,
fmt.Sprintf("cannot read from %q:", t.src))
}
*t.payload = t.buf.Bytes()
return nil
}
func (t *Tmpfile) revert(*I, *Criteria) error { t.buf.Reset(); return nil }
func (t *Tmpfile) Is(o Op) bool {
t0, ok := o.(*Tmpfile)
return ok && t0 != nil &&
t.src == t0.src && t.n == t0.n
}
func (t *Tmpfile) Path() string { return t.src }
func (t *Tmpfile) String() string { return fmt.Sprintf("up to %d bytes from %q", t.n, t.src) }
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