mirror of https://github.com/docker/cli.git
100 lines
2.8 KiB
Go
100 lines
2.8 KiB
Go
package system
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import (
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"syscall"
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"unsafe"
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)
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var _zero uintptr
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// Returns the size of xattrs and nil error
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// Requires path, takes allocated []byte or nil as last argument
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func Llistxattr(path string, dest []byte) (size int, err error) {
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pathBytes, err := syscall.BytePtrFromString(path)
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if err != nil {
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return -1, err
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}
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var newpathBytes unsafe.Pointer
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if len(dest) > 0 {
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newpathBytes = unsafe.Pointer(&dest[0])
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} else {
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newpathBytes = unsafe.Pointer(&_zero)
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}
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_size, _, errno := syscall.Syscall6(syscall.SYS_LLISTXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(newpathBytes), uintptr(len(dest)), 0, 0, 0)
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size = int(_size)
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if errno != 0 {
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return -1, errno
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}
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return size, nil
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}
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// Returns a []byte slice if the xattr is set and nil otherwise
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// Requires path and its attribute as arguments
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func Lgetxattr(path string, attr string) ([]byte, error) {
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var sz int
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pathBytes, err := syscall.BytePtrFromString(path)
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if err != nil {
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return nil, err
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}
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attrBytes, err := syscall.BytePtrFromString(attr)
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if err != nil {
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return nil, err
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}
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// Start with a 128 length byte array
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sz = 128
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dest := make([]byte, sz)
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destBytes := unsafe.Pointer(&dest[0])
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_sz, _, errno := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
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switch {
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case errno == syscall.ENODATA:
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return nil, errno
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case errno == syscall.ENOTSUP:
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return nil, errno
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case errno == syscall.ERANGE:
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// 128 byte array might just not be good enough,
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// A dummy buffer is used ``uintptr(0)`` to get real size
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// of the xattrs on disk
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_sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(unsafe.Pointer(nil)), uintptr(0), 0, 0)
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sz = int(_sz)
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if sz < 0 {
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return nil, errno
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}
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dest = make([]byte, sz)
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destBytes := unsafe.Pointer(&dest[0])
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_sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
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if errno != 0 {
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return nil, errno
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}
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case errno != 0:
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return nil, errno
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}
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sz = int(_sz)
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return dest[:sz], nil
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}
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func Lsetxattr(path string, attr string, data []byte, flags int) error {
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pathBytes, err := syscall.BytePtrFromString(path)
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if err != nil {
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return err
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}
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attrBytes, err := syscall.BytePtrFromString(attr)
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if err != nil {
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return err
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}
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var dataBytes unsafe.Pointer
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if len(data) > 0 {
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dataBytes = unsafe.Pointer(&data[0])
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} else {
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dataBytes = unsafe.Pointer(&_zero)
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}
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_, _, errno := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(dataBytes), uintptr(len(data)), uintptr(flags), 0)
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if errno != 0 {
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return errno
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}
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return nil
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}
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