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package mmap
import (
"io/fs"
"path"
"syscall"
"time"
)
type fileStat struct {
syscall.Stat_t
name string
mode fs.FileMode
}
func (s *fileStat) Name() string { return s.name }
func (s *fileStat) IsDir() bool { return s.mode.IsDir() }
func (s *fileStat) Mode() fs.FileMode { return s.mode }
func (s *fileStat) Size() int64 { return s.Stat_t.Size }
func (s *fileStat) ModTime() time.Time { return time.Unix(s.Stat_t.Mtim.Unix()) }
func (s *fileStat) Sys() any { return &s.Stat_t }
// open is a simple wrapper around syscall.Open().
func open(filepath string, mode int, perm uint32) (fd int, err error) {
err = retryOnEINTR(func() (err error) {
fd, err = syscall.Open(filepath, mode, perm)
return
})
return
}
// stat is a simple wrapper around syscall.Stat().
func stat(filepath string) (*fileStat, error) {
var stat fileStat
err := retryOnEINTR(func() error {
return syscall.Stat(filepath, &stat.Stat_t)
})
if err != nil {
return nil, err
}
stat.name = path.Base(filepath)
stat.mode = fs.FileMode(stat.Stat_t.Mode & 0777)
switch stat.Stat_t.Mode & syscall.S_IFMT {
case syscall.S_IFBLK:
stat.mode |= fs.ModeDevice
case syscall.S_IFCHR:
stat.mode |= fs.ModeDevice | fs.ModeCharDevice
case syscall.S_IFDIR:
stat.mode |= fs.ModeDir
case syscall.S_IFIFO:
stat.mode |= fs.ModeNamedPipe
case syscall.S_IFLNK:
stat.mode |= fs.ModeSymlink
case syscall.S_IFREG:
// nothing to do
case syscall.S_IFSOCK:
stat.mode |= fs.ModeSocket
}
if stat.Stat_t.Mode&syscall.S_ISGID != 0 {
stat.mode |= fs.ModeSetgid
}
if stat.Stat_t.Mode&syscall.S_ISUID != 0 {
stat.mode |= fs.ModeSetuid
}
if stat.Stat_t.Mode&syscall.S_ISVTX != 0 {
stat.mode |= fs.ModeSticky
}
return &stat, nil
}
// mmap is a simple wrapper around syscall.Mmap().
func mmap(fd int, offset int64, length int, prot int, flags int) (b []byte, err error) {
err = retryOnEINTR(func() error {
b, err = syscall.Mmap(fd, offset, length, prot, flags)
return err
})
return
}
// munmap is a simple wrapper around syscall.Munmap().
func munmap(b []byte) error {
return retryOnEINTR(func() error {
return syscall.Munmap(b)
})
}
// close_ is a simple wrapper around syscall.Close().
func close_(fd int) error {
return retryOnEINTR(func() error {
return syscall.Close(fd)
})
}
// retryOnEINTR is a low-level filesystem function
// for retrying syscalls on O_EINTR received.
func retryOnEINTR(do func() error) error {
for {
err := do()
if err == syscall.EINTR {
continue
}
return err
}
}
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