Merge pull request #702 from aofei/os.CreateTemp

lib/os: patch `TempDir`, `MkdirTemp`, `CreateTemp`

internal/lib/internal/bytealg/bytealg.go

@@ -105,3 +105,21 @@ type sliceHead struct {
 	len  int
 	cap  int
 }
+
+func LastIndexByte(s []byte, c byte) int {
+	for i := len(s) - 1; i >= 0; i-- {
+		if s[i] == c {
+			return i
+		}
+	}
+	return -1
+}
+
+func LastIndexByteString(s string, c byte) int {
+	for i := len(s) - 1; i >= 0; i-- {
+		if s[i] == c {
+			return i
+		}
+	}
+	return -1
+}

internal/lib/os/file.go

@@ -286,7 +286,6 @@ func (f *File) wrapErr(op string, err error) error {
 	return &PathError{Op: op, Path: f.name, Err: err}
 }
 
-/*
 // TempDir returns the default directory to use for temporary files.
 //
 // On Unix systems, it returns $TMPDIR if non-empty, else /tmp.
@@ -299,7 +298,6 @@ func (f *File) wrapErr(op string, err error) error {
 func TempDir() string {
 	return tempDir()
 }
-*/
 
 // Chmod changes the mode of the file to mode.
 // If there is an error, it will be of type *PathError.

internal/lib/os/os.go

@@ -272,7 +272,6 @@ func Mkdir(name string, perm FileMode) error {
 
 // TODO(xsw):
 // func MkdirAll(path string, perm FileMode) error
-// func MkdirTemp(dir, pattern string) (string, error)
 // func NewSyscallError(syscall string, err error) error
 
 // func ReadFile(name string) ([]byte, error)
@@ -327,9 +326,6 @@ func Symlink(oldname, newname string) error {
 	return &LinkError{"symlink", oldname, newname, syscall.Errno(ret)}
 }
 
-// TODO(xsw):
-// func TempDir() string
-
 func Truncate(name string, size int64) error {
 	ret := os.Truncate(c.AllocaCStr(name), os.OffT(size))
 	if ret == 0 {

internal/lib/os/tempfile.go

@@ -0,0 +1,115 @@
+// 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 (
+	"errors"
+
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/internal/lib/internal/bytealg"
+	"github.com/goplus/llgo/internal/lib/internal/itoa"
+)
+
+func nextRandom() string {
+	return itoa.Uitoa(uint(uint32(c.Rand())))
+}
+
+// CreateTemp creates a new temporary file in the directory dir,
+// opens the file for reading and writing, and returns the resulting file.
+// The filename is generated by taking pattern and adding a random string to the end.
+// If pattern includes a "*", the random string replaces the last "*".
+// If dir is the empty string, CreateTemp uses the default directory for temporary files, as returned by TempDir.
+// Multiple programs or goroutines calling CreateTemp simultaneously will not choose the same file.
+// The caller can use the file's Name method to find the pathname of the file.
+// It is the caller's responsibility to remove the file when it is no longer needed.
+func CreateTemp(dir, pattern string) (*File, error) {
+	if dir == "" {
+		dir = TempDir()
+	}
+
+	prefix, suffix, err := prefixAndSuffix(pattern)
+	if err != nil {
+		return nil, &PathError{Op: "createtemp", Path: pattern, Err: err}
+	}
+	prefix = joinPath(dir, prefix)
+
+	try := 0
+	for {
+		name := prefix + nextRandom() + suffix
+		f, err := OpenFile(name, O_RDWR|O_CREATE|O_EXCL, 0600)
+		if IsExist(err) {
+			if try++; try < 10000 {
+				continue
+			}
+			return nil, &PathError{Op: "createtemp", Path: prefix + "*" + suffix, Err: ErrExist}
+		}
+		return f, err
+	}
+}
+
+var errPatternHasSeparator = errors.New("pattern contains path separator")
+
+// prefixAndSuffix splits pattern by the last wildcard "*", if applicable,
+// returning prefix as the part before "*" and suffix as the part after "*".
+func prefixAndSuffix(pattern string) (prefix, suffix string, err error) {
+	for i := 0; i < len(pattern); i++ {
+		if IsPathSeparator(pattern[i]) {
+			return "", "", errPatternHasSeparator
+		}
+	}
+	if pos := bytealg.LastIndexByteString(pattern, '*'); pos != -1 {
+		prefix, suffix = pattern[:pos], pattern[pos+1:]
+	} else {
+		prefix = pattern
+	}
+	return prefix, suffix, nil
+}
+
+// MkdirTemp creates a new temporary directory in the directory dir
+// and returns the pathname of the new directory.
+// The new directory's name is generated by adding a random string to the end of pattern.
+// If pattern includes a "*", the random string replaces the last "*" instead.
+// If dir is the empty string, MkdirTemp uses the default directory for temporary files, as returned by TempDir.
+// Multiple programs or goroutines calling MkdirTemp simultaneously will not choose the same directory.
+// It is the caller's responsibility to remove the directory when it is no longer needed.
+func MkdirTemp(dir, pattern string) (string, error) {
+	if dir == "" {
+		dir = TempDir()
+	}
+
+	prefix, suffix, err := prefixAndSuffix(pattern)
+	if err != nil {
+		return "", &PathError{Op: "mkdirtemp", Path: pattern, Err: err}
+	}
+	prefix = joinPath(dir, prefix)
+
+	try := 0
+	for {
+		name := prefix + nextRandom() + suffix
+		err := Mkdir(name, 0700)
+		if err == nil {
+			return name, nil
+		}
+		if IsExist(err) {
+			if try++; try < 10000 {
+				continue
+			}
+			return "", &PathError{Op: "mkdirtemp", Path: dir + string(PathSeparator) + prefix + "*" + suffix, Err: ErrExist}
+		}
+		if IsNotExist(err) {
+			if _, err := Stat(dir); IsNotExist(err) {
+				return "", err
+			}
+		}
+		return "", err
+	}
+}
+
+func joinPath(dir, name string) string {
+	if len(dir) > 0 && IsPathSeparator(dir[len(dir)-1]) {
+		return dir + name
+	}
+	return dir + string(PathSeparator) + name
+}