fd_posix.go

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build unix || (js && wasm) || wasip1 || windows
     6  
     7  package poll
     8  
     9  import (
    10  	"io"
    11  	"syscall"
    12  )
    13  
    14  // eofError returns io.EOF when fd is available for reading end of
    15  // file.
    16  func (fd *FD) eofError(n int, err error) error {
    17  	if n == 0 && err == nil && fd.ZeroReadIsEOF {
    18  		return io.EOF
    19  	}
    20  	return err
    21  }
    22  
    23  // Shutdown wraps syscall.Shutdown.
    24  func (fd *FD) Shutdown(how int) error {
    25  	if err := fd.incref(); err != nil {
    26  		return err
    27  	}
    28  	defer fd.decref()
    29  	return syscall.Shutdown(fd.Sysfd, how)
    30  }
    31  
    32  // Fchown wraps syscall.Fchown.
    33  func (fd *FD) Fchown(uid, gid int) error {
    34  	if err := fd.incref(); err != nil {
    35  		return err
    36  	}
    37  	defer fd.decref()
    38  	return ignoringEINTR(func() error {
    39  		return syscall.Fchown(fd.Sysfd, uid, gid)
    40  	})
    41  }
    42  
    43  // Ftruncate wraps syscall.Ftruncate.
    44  func (fd *FD) Ftruncate(size int64) error {
    45  	if err := fd.incref(); err != nil {
    46  		return err
    47  	}
    48  	defer fd.decref()
    49  	return ignoringEINTR(func() error {
    50  		return syscall.Ftruncate(fd.Sysfd, size)
    51  	})
    52  }
    53  
    54  // RawControl invokes the user-defined function f for a non-IO
    55  // operation.
    56  func (fd *FD) RawControl(f func(uintptr)) error {
    57  	if err := fd.incref(); err != nil {
    58  		return err
    59  	}
    60  	defer fd.decref()
    61  	f(uintptr(fd.Sysfd))
    62  	return nil
    63  }
    64  
    65  // ignoringEINTR makes a function call and repeats it if it returns
    66  // an EINTR error. This appears to be required even though we install all
    67  // signal handlers with SA_RESTART: see #22838, #38033, #38836, #40846.
    68  // Also #20400 and #36644 are issues in which a signal handler is
    69  // installed without setting SA_RESTART. None of these are the common case,
    70  // but there are enough of them that it seems that we can't avoid
    71  // an EINTR loop.
    72  func ignoringEINTR(fn func() error) error {
    73  	for {
    74  		err := fn()
    75  		if err != syscall.EINTR {
    76  			return err
    77  		}
    78  	}
    79  }
    80
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