diff options
author | Alex Brainman <alex.brainman@gmail.com> | 2011-04-26 18:09:46 +1000 |
---|---|---|
committer | Alex Brainman <alex.brainman@gmail.com> | 2011-04-26 18:09:46 +1000 |
commit | b1deb3be7f7ff9ec43b65b1adc25fdaf7dce56bb (patch) | |
tree | f25ddfe216a6009519d461d379ac8993ba35b69d | |
parent | 2d99974ec580423241a67d43aacab93a8cda2978 (diff) | |
download | go-b1deb3be7f7ff9ec43b65b1adc25fdaf7dce56bb.tar.gz go-b1deb3be7f7ff9ec43b65b1adc25fdaf7dce56bb.zip |
os: fix race in ReadAt/WriteAt on Windows
R=bradfitzgo, rsc, peterGo
CC=golang-dev
https://golang.org/cl/4441051
-rw-r--r-- | src/pkg/os/file.go | 18 | ||||
-rw-r--r-- | src/pkg/os/file_plan9.go | 33 | ||||
-rw-r--r-- | src/pkg/os/file_unix.go | 33 | ||||
-rw-r--r-- | src/pkg/os/file_windows.go | 71 | ||||
-rw-r--r-- | src/pkg/syscall/syscall_windows.go | 38 |
5 files changed, 147 insertions, 46 deletions
diff --git a/src/pkg/os/file.go b/src/pkg/os/file.go index 643b225ce7..dff8fa862c 100644 --- a/src/pkg/os/file.go +++ b/src/pkg/os/file.go @@ -8,6 +8,7 @@ package os import ( "runtime" + "sync" "syscall" ) @@ -15,8 +16,9 @@ import ( type File struct { fd int name string - dirinfo *dirInfo // nil unless directory being read - nepipe int // number of consecutive EPIPE in Write + dirinfo *dirInfo // nil unless directory being read + nepipe int // number of consecutive EPIPE in Write + l sync.Mutex // used to implement windows pread/pwrite } // Fd returns the integer Unix file descriptor referencing the open file. @@ -30,7 +32,7 @@ func NewFile(fd int, name string) *File { if fd < 0 { return nil } - f := &File{fd, name, nil, 0} + f := &File{fd: fd, name: name} runtime.SetFinalizer(f, (*File).Close) return f } @@ -85,7 +87,7 @@ func (file *File) Read(b []byte) (n int, err Error) { if file == nil { return 0, EINVAL } - n, e := syscall.Read(file.fd, b) + n, e := file.read(b) if n < 0 { n = 0 } @@ -107,7 +109,7 @@ func (file *File) ReadAt(b []byte, off int64) (n int, err Error) { return 0, EINVAL } for len(b) > 0 { - m, e := syscall.Pread(file.fd, b, off) + m, e := file.pread(b, off) if m == 0 && !iserror(e) { return n, EOF } @@ -129,7 +131,7 @@ func (file *File) Write(b []byte) (n int, err Error) { if file == nil { return 0, EINVAL } - n, e := syscall.Write(file.fd, b) + n, e := file.write(b) if n < 0 { n = 0 } @@ -150,7 +152,7 @@ func (file *File) WriteAt(b []byte, off int64) (n int, err Error) { return 0, EINVAL } for len(b) > 0 { - m, e := syscall.Pwrite(file.fd, b, off) + m, e := file.pwrite(b, off) if iserror(e) { err = &PathError{"write", file.name, Errno(e)} break @@ -167,7 +169,7 @@ func (file *File) WriteAt(b []byte, off int64) (n int, err Error) { // relative to the current offset, and 2 means relative to the end. // It returns the new offset and an Error, if any. func (file *File) Seek(offset int64, whence int) (ret int64, err Error) { - r, e := syscall.Seek(file.fd, offset, whence) + r, e := file.seek(offset, whence) if !iserror(e) && file.dirinfo != nil && r != 0 { e = syscall.EISDIR } diff --git a/src/pkg/os/file_plan9.go b/src/pkg/os/file_plan9.go index c8d0efba40..7b473f8022 100644 --- a/src/pkg/os/file_plan9.go +++ b/src/pkg/os/file_plan9.go @@ -117,6 +117,39 @@ func (f *File) Sync() (err Error) { return nil } +// read reads up to len(b) bytes from the File. +// It returns the number of bytes read and an error, if any. +func (f *File) read(b []byte) (n int, err syscall.Error) { + return syscall.Read(f.fd, b) +} + +// pread reads len(b) bytes from the File starting at byte offset off. +// It returns the number of bytes read and the error, if any. +// EOF is signaled by a zero count with err set to nil. +func (f *File) pread(b []byte, off int64) (n int, err syscall.Error) { + return syscall.Pread(f.fd, b, off) +} + +// write writes len(b) bytes to the File. +// It returns the number of bytes written and an error, if any. +func (f *File) write(b []byte) (n int, err syscall.Error) { + return syscall.Write(f.fd, b) +} + +// pwrite writes len(b) bytes to the File starting at byte offset off. +// It returns the number of bytes written and an error, if any. +func (f *File) pwrite(b []byte, off int64) (n int, err syscall.Error) { + return syscall.Pwrite(f.fd, b, off) +} + +// seek sets the offset for the next Read or Write on file to offset, interpreted +// according to whence: 0 means relative to the origin of the file, 1 means +// relative to the current offset, and 2 means relative to the end. +// It returns the new offset and an error, if any. +func (f *File) seek(offset int64, whence int) (ret int64, err syscall.Error) { + return syscall.Seek(f.fd, offset, whence) +} + // Truncate changes the size of the named file. // If the file is a symbolic link, it changes the size of the link's target. func Truncate(name string, size int64) Error { diff --git a/src/pkg/os/file_unix.go b/src/pkg/os/file_unix.go index f2b94f4c2d..2fb28df655 100644 --- a/src/pkg/os/file_unix.go +++ b/src/pkg/os/file_unix.go @@ -96,6 +96,39 @@ func (file *File) Readdir(count int) (fi []FileInfo, err Error) { return } +// read reads up to len(b) bytes from the File. +// It returns the number of bytes read and an error, if any. +func (f *File) read(b []byte) (n int, err int) { + return syscall.Read(f.fd, b) +} + +// pread reads len(b) bytes from the File starting at byte offset off. +// It returns the number of bytes read and the error, if any. +// EOF is signaled by a zero count with err set to 0. +func (f *File) pread(b []byte, off int64) (n int, err int) { + return syscall.Pread(f.fd, b, off) +} + +// write writes len(b) bytes to the File. +// It returns the number of bytes written and an error, if any. +func (f *File) write(b []byte) (n int, err int) { + return syscall.Write(f.fd, b) +} + +// pwrite writes len(b) bytes to the File starting at byte offset off. +// It returns the number of bytes written and an error, if any. +func (f *File) pwrite(b []byte, off int64) (n int, err int) { + return syscall.Pwrite(f.fd, b, off) +} + +// seek sets the offset for the next Read or Write on file to offset, interpreted +// according to whence: 0 means relative to the origin of the file, 1 means +// relative to the current offset, and 2 means relative to the end. +// It returns the new offset and an error, if any. +func (f *File) seek(offset int64, whence int) (ret int64, err int) { + return syscall.Seek(f.fd, offset, whence) +} + // Truncate changes the size of the named file. // If the file is a symbolic link, it changes the size of the link's target. func Truncate(name string, size int64) Error { diff --git a/src/pkg/os/file_windows.go b/src/pkg/os/file_windows.go index 862baf6b91..95f60b7351 100644 --- a/src/pkg/os/file_windows.go +++ b/src/pkg/os/file_windows.go @@ -165,6 +165,77 @@ func (file *File) Readdir(count int) (fi []FileInfo, err Error) { return fi, nil } +// read reads up to len(b) bytes from the File. +// It returns the number of bytes read and an error, if any. +func (f *File) read(b []byte) (n int, err int) { + f.l.Lock() + defer f.l.Unlock() + return syscall.Read(f.fd, b) +} + +// pread reads len(b) bytes from the File starting at byte offset off. +// It returns the number of bytes read and the error, if any. +// EOF is signaled by a zero count with err set to 0. +func (f *File) pread(b []byte, off int64) (n int, err int) { + f.l.Lock() + defer f.l.Unlock() + curoffset, e := syscall.Seek(f.fd, 0, 1) + if e != 0 { + return 0, e + } + defer syscall.Seek(f.fd, curoffset, 0) + o := syscall.Overlapped{ + OffsetHigh: uint32(off >> 32), + Offset: uint32(off), + } + var done uint32 + e = syscall.ReadFile(int32(f.fd), b, &done, &o) + if e != 0 { + return 0, e + } + return int(done), 0 +} + +// write writes len(b) bytes to the File. +// It returns the number of bytes written and an error, if any. +func (f *File) write(b []byte) (n int, err int) { + f.l.Lock() + defer f.l.Unlock() + return syscall.Write(f.fd, b) +} + +// pwrite writes len(b) bytes to the File starting at byte offset off. +// It returns the number of bytes written and an error, if any. +func (f *File) pwrite(b []byte, off int64) (n int, err int) { + f.l.Lock() + defer f.l.Unlock() + curoffset, e := syscall.Seek(f.fd, 0, 1) + if e != 0 { + return 0, e + } + defer syscall.Seek(f.fd, curoffset, 0) + o := syscall.Overlapped{ + OffsetHigh: uint32(off >> 32), + Offset: uint32(off), + } + var done uint32 + e = syscall.WriteFile(int32(f.fd), b, &done, &o) + if e != 0 { + return 0, e + } + return int(done), 0 +} + +// seek sets the offset for the next Read or Write on file to offset, interpreted +// according to whence: 0 means relative to the origin of the file, 1 means +// relative to the current offset, and 2 means relative to the end. +// It returns the new offset and an error, if any. +func (f *File) seek(offset int64, whence int) (ret int64, err int) { + f.l.Lock() + defer f.l.Unlock() + return syscall.Seek(f.fd, offset, whence) +} + // Truncate changes the size of the named file. // If the file is a symbolic link, it changes the size of the link's target. func Truncate(name string, size int64) Error { diff --git a/src/pkg/syscall/syscall_windows.go b/src/pkg/syscall/syscall_windows.go index e01310deff..1fbb3ccbf4 100644 --- a/src/pkg/syscall/syscall_windows.go +++ b/src/pkg/syscall/syscall_windows.go @@ -250,27 +250,6 @@ func Read(fd int, p []byte) (n int, errno int) { return int(done), 0 } -// TODO(brainman): ReadFile/WriteFile change file offset, therefore -// i use Seek here to preserve semantics of unix pread/pwrite, -// not sure if I should do that - -func Pread(fd int, p []byte, offset int64) (n int, errno int) { - curoffset, e := Seek(fd, 0, 1) - if e != 0 { - return 0, e - } - defer Seek(fd, curoffset, 0) - var o Overlapped - o.OffsetHigh = uint32(offset >> 32) - o.Offset = uint32(offset) - var done uint32 - e = ReadFile(int32(fd), p, &done, &o) - if e != 0 { - return 0, e - } - return int(done), 0 -} - func Write(fd int, p []byte) (n int, errno int) { var done uint32 e := WriteFile(int32(fd), p, &done, nil) @@ -280,23 +259,6 @@ func Write(fd int, p []byte) (n int, errno int) { return int(done), 0 } -func Pwrite(fd int, p []byte, offset int64) (n int, errno int) { - curoffset, e := Seek(fd, 0, 1) - if e != 0 { - return 0, e - } - defer Seek(fd, curoffset, 0) - var o Overlapped - o.OffsetHigh = uint32(offset >> 32) - o.Offset = uint32(offset) - var done uint32 - e = WriteFile(int32(fd), p, &done, &o) - if e != 0 { - return 0, e - } - return int(done), 0 -} - func Seek(fd int, offset int64, whence int) (newoffset int64, errno int) { var w uint32 switch whence { |