1 files changed, 100 insertions, 0 deletions
diff --git a/src/lib/os/error.go b/src/lib/os/error.go
new file mode 100644
index 000000000..63b2dbcca
--- /dev/null
+++ b/src/lib/os/error.go
@@ -0,0 +1,100 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os
+
+import syscall "syscall"
+
+// Errors are singleton structures. Use the String() method to get their contents --
+// it handles the nil (no error) case.
+type Error struct {
+	s string
+}
+
+// Indexed by errno.
+// If we worry about syscall speed (only relevant on failure), we could
+// make it an array, but it's probably not important.
+var errorTab = make(map[int64] *Error);
+
+// Table of all known errors in system.  Use the same error string twice,
+// get the same *os.Error.
+var errorStringTab = make(map[string] *Error);
+
+// These functions contain a race if two goroutines add identical
+// errors simultaneously but the consequences are unimportant.
+
+// Allocate an Error object, but if it's been seen before, share that one.
+func NewError(s string) *Error {
+	if s == "" {
+		return nil
+	}
+	err, ok := errorStringTab[s];
+	if ok {
+		return err
+	}
+	err = &Error{s};
+	errorStringTab[s] = err;
+	return err;
+}
+
+// Allocate an Error objecct, but if it's been seen before, share that one.
+func ErrnoToError(errno int64) *Error {
+	if errno == 0 {
+		return nil
+	}
+	// Quick lookup by errno.
+	err, ok := errorTab[errno];
+	if ok {
+		return err
+	}
+	err = NewError(syscall.Errstr(errno));
+	errorTab[errno] = err;
+	return err;
+}
+
+var (
+	ENONE = ErrnoToError(syscall.ENONE);
+	EPERM = ErrnoToError(syscall.EPERM);
+	ENOENT = ErrnoToError(syscall.ENOENT);
+	ESRCH = ErrnoToError(syscall.ESRCH);
+	EINTR = ErrnoToError(syscall.EINTR);
+	EIO = ErrnoToError(syscall.EIO);
+	ENXIO = ErrnoToError(syscall.ENXIO);
+	E2BIG = ErrnoToError(syscall.E2BIG);
+	ENOEXEC = ErrnoToError(syscall.ENOEXEC);
+	EBADF = ErrnoToError(syscall.EBADF);
+	ECHILD = ErrnoToError(syscall.ECHILD);
+	EDEADLK = ErrnoToError(syscall.EDEADLK);
+	ENOMEM = ErrnoToError(syscall.ENOMEM);
+	EACCES = ErrnoToError(syscall.EACCES);
+	EFAULT = ErrnoToError(syscall.EFAULT);
+	ENOTBLK = ErrnoToError(syscall.ENOTBLK);
+	EBUSY = ErrnoToError(syscall.EBUSY);
+	EEXIST = ErrnoToError(syscall.EEXIST);
+	EXDEV = ErrnoToError(syscall.EXDEV);
+	ENODEV = ErrnoToError(syscall.ENODEV);
+	ENOTDIR = ErrnoToError(syscall.ENOTDIR);
+	EISDIR = ErrnoToError(syscall.EISDIR);
+	EINVAL = ErrnoToError(syscall.EINVAL);
+	ENFILE = ErrnoToError(syscall.ENFILE);
+	EMFILE = ErrnoToError(syscall.EMFILE);
+	ENOTTY = ErrnoToError(syscall.ENOTTY);
+	ETXTBSY = ErrnoToError(syscall.ETXTBSY);
+	EFBIG = ErrnoToError(syscall.EFBIG);
+	ENOSPC = ErrnoToError(syscall.ENOSPC);
+	ESPIPE = ErrnoToError(syscall.ESPIPE);
+	EROFS = ErrnoToError(syscall.EROFS);
+	EMLINK = ErrnoToError(syscall.EMLINK);
+	EPIPE = ErrnoToError(syscall.EPIPE);
+	EDOM = ErrnoToError(syscall.EDOM);
+	ERANGE = ErrnoToError(syscall.ERANGE);
+	EAGAIN = ErrnoToError(syscall.EAGAIN);
+)
+
+func (e *Error) String() string {
+	if e == nil {
+		return "No Error"
+	}
+	return e.s
+}