github.com/m10x/go/src@v0.0.0-20220112094212-ba61592315da/os/file_posix.go (about) 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 aix || darwin || dragonfly || freebsd || (js && wasm) || linux || netbsd || openbsd || solaris || windows 6 7 package os 8 9 import ( 10 "runtime" 11 "syscall" 12 "time" 13 ) 14 15 func sigpipe() // implemented in package runtime 16 17 // Close closes the File, rendering it unusable for I/O. 18 // On files that support SetDeadline, any pending I/O operations will 19 // be canceled and return immediately with an ErrClosed error. 20 // Close will return an error if it has already been called. 21 func (f *File) Close() error { 22 if f == nil { 23 return ErrInvalid 24 } 25 return f.file.close() 26 } 27 28 // read reads up to len(b) bytes from the File. 29 // It returns the number of bytes read and an error, if any. 30 func (f *File) read(b []byte) (n int, err error) { 31 n, err = f.pfd.Read(b) 32 runtime.KeepAlive(f) 33 return n, err 34 } 35 36 // pread reads len(b) bytes from the File starting at byte offset off. 37 // It returns the number of bytes read and the error, if any. 38 // EOF is signaled by a zero count with err set to nil. 39 func (f *File) pread(b []byte, off int64) (n int, err error) { 40 n, err = f.pfd.Pread(b, off) 41 runtime.KeepAlive(f) 42 return n, err 43 } 44 45 // write writes len(b) bytes to the File. 46 // It returns the number of bytes written and an error, if any. 47 func (f *File) write(b []byte) (n int, err error) { 48 n, err = f.pfd.Write(b) 49 runtime.KeepAlive(f) 50 return n, err 51 } 52 53 // pwrite writes len(b) bytes to the File starting at byte offset off. 54 // It returns the number of bytes written and an error, if any. 55 func (f *File) pwrite(b []byte, off int64) (n int, err error) { 56 n, err = f.pfd.Pwrite(b, off) 57 runtime.KeepAlive(f) 58 return n, err 59 } 60 61 // syscallMode returns the syscall-specific mode bits from Go's portable mode bits. 62 func syscallMode(i FileMode) (o uint32) { 63 o |= uint32(i.Perm()) 64 if i&ModeSetuid != 0 { 65 o |= syscall.S_ISUID 66 } 67 if i&ModeSetgid != 0 { 68 o |= syscall.S_ISGID 69 } 70 if i&ModeSticky != 0 { 71 o |= syscall.S_ISVTX 72 } 73 // No mapping for Go's ModeTemporary (plan9 only). 74 return 75 } 76 77 // See docs in file.go:Chmod. 78 func chmod(name string, mode FileMode) error { 79 longName := fixLongPath(name) 80 e := ignoringEINTR(func() error { 81 return syscall.Chmod(longName, syscallMode(mode)) 82 }) 83 if e != nil { 84 return &PathError{Op: "chmod", Path: name, Err: e} 85 } 86 return nil 87 } 88 89 // See docs in file.go:(*File).Chmod. 90 func (f *File) chmod(mode FileMode) error { 91 if err := f.checkValid("chmod"); err != nil { 92 return err 93 } 94 if e := f.pfd.Fchmod(syscallMode(mode)); e != nil { 95 return f.wrapErr("chmod", e) 96 } 97 return nil 98 } 99 100 // Chown changes the numeric uid and gid of the named file. 101 // If the file is a symbolic link, it changes the uid and gid of the link's target. 102 // A uid or gid of -1 means to not change that value. 103 // If there is an error, it will be of type *PathError. 104 // 105 // On Windows or Plan 9, Chown always returns the syscall.EWINDOWS or 106 // EPLAN9 error, wrapped in *PathError. 107 func Chown(name string, uid, gid int) error { 108 e := ignoringEINTR(func() error { 109 return syscall.Chown(name, uid, gid) 110 }) 111 if e != nil { 112 return &PathError{Op: "chown", Path: name, Err: e} 113 } 114 return nil 115 } 116 117 // Lchown changes the numeric uid and gid of the named file. 118 // If the file is a symbolic link, it changes the uid and gid of the link itself. 119 // If there is an error, it will be of type *PathError. 120 // 121 // On Windows, it always returns the syscall.EWINDOWS error, wrapped 122 // in *PathError. 123 func Lchown(name string, uid, gid int) error { 124 e := ignoringEINTR(func() error { 125 return syscall.Lchown(name, uid, gid) 126 }) 127 if e != nil { 128 return &PathError{Op: "lchown", Path: name, Err: e} 129 } 130 return nil 131 } 132 133 // Chown changes the numeric uid and gid of the named file. 134 // If there is an error, it will be of type *PathError. 135 // 136 // On Windows, it always returns the syscall.EWINDOWS error, wrapped 137 // in *PathError. 138 func (f *File) Chown(uid, gid int) error { 139 if err := f.checkValid("chown"); err != nil { 140 return err 141 } 142 if e := f.pfd.Fchown(uid, gid); e != nil { 143 return f.wrapErr("chown", e) 144 } 145 return nil 146 } 147 148 // Truncate changes the size of the file. 149 // It does not change the I/O offset. 150 // If there is an error, it will be of type *PathError. 151 func (f *File) Truncate(size int64) error { 152 if err := f.checkValid("truncate"); err != nil { 153 return err 154 } 155 if e := f.pfd.Ftruncate(size); e != nil { 156 return f.wrapErr("truncate", e) 157 } 158 return nil 159 } 160 161 // Sync commits the current contents of the file to stable storage. 162 // Typically, this means flushing the file system's in-memory copy 163 // of recently written data to disk. 164 func (f *File) Sync() error { 165 if err := f.checkValid("sync"); err != nil { 166 return err 167 } 168 if e := f.pfd.Fsync(); e != nil { 169 return f.wrapErr("sync", e) 170 } 171 return nil 172 } 173 174 // Chtimes changes the access and modification times of the named 175 // file, similar to the Unix utime() or utimes() functions. 176 // 177 // The underlying filesystem may truncate or round the values to a 178 // less precise time unit. 179 // If there is an error, it will be of type *PathError. 180 func Chtimes(name string, atime time.Time, mtime time.Time) error { 181 var utimes [2]syscall.Timespec 182 utimes[0] = syscall.NsecToTimespec(atime.UnixNano()) 183 utimes[1] = syscall.NsecToTimespec(mtime.UnixNano()) 184 if e := syscall.UtimesNano(fixLongPath(name), utimes[0:]); e != nil { 185 return &PathError{Op: "chtimes", Path: name, Err: e} 186 } 187 return nil 188 } 189 190 // Chdir changes the current working directory to the file, 191 // which must be a directory. 192 // If there is an error, it will be of type *PathError. 193 func (f *File) Chdir() error { 194 if err := f.checkValid("chdir"); err != nil { 195 return err 196 } 197 if e := f.pfd.Fchdir(); e != nil { 198 return f.wrapErr("chdir", e) 199 } 200 return nil 201 } 202 203 // setDeadline sets the read and write deadline. 204 func (f *File) setDeadline(t time.Time) error { 205 if err := f.checkValid("SetDeadline"); err != nil { 206 return err 207 } 208 return f.pfd.SetDeadline(t) 209 } 210 211 // setReadDeadline sets the read deadline. 212 func (f *File) setReadDeadline(t time.Time) error { 213 if err := f.checkValid("SetReadDeadline"); err != nil { 214 return err 215 } 216 return f.pfd.SetReadDeadline(t) 217 } 218 219 // setWriteDeadline sets the write deadline. 220 func (f *File) setWriteDeadline(t time.Time) error { 221 if err := f.checkValid("SetWriteDeadline"); err != nil { 222 return err 223 } 224 return f.pfd.SetWriteDeadline(t) 225 } 226 227 // checkValid checks whether f is valid for use. 228 // If not, it returns an appropriate error, perhaps incorporating the operation name op. 229 func (f *File) checkValid(op string) error { 230 if f == nil { 231 return ErrInvalid 232 } 233 return nil 234 } 235 236 // ignoringEINTR makes a function call and repeats it if it returns an 237 // EINTR error. This appears to be required even though we install all 238 // signal handlers with SA_RESTART: see #22838, #38033, #38836, #40846. 239 // Also #20400 and #36644 are issues in which a signal handler is 240 // installed without setting SA_RESTART. None of these are the common case, 241 // but there are enough of them that it seems that we can't avoid 242 // an EINTR loop. 243 func ignoringEINTR(fn func() error) error { 244 for { 245 err := fn() 246 if err != syscall.EINTR { 247 return err 248 } 249 } 250 }