src

exec_windows.go (7513B)

---

 // 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.
 
 // Fork, exec, wait, etc.
 
 package windows
 
 import (
 	errorspkg "errors"
 	"unsafe"
 )
 
 // EscapeArg rewrites command line argument s as prescribed
 // in http://msdn.microsoft.com/en-us/library/ms880421.
 // This function returns "" (2 double quotes) if s is empty.
 // Alternatively, these transformations are done:
 //   - every back slash (\) is doubled, but only if immediately
 //     followed by double quote (");
 //   - every double quote (") is escaped by back slash (\);
 //   - finally, s is wrapped with double quotes (arg -> "arg"),
 //     but only if there is space or tab inside s.
 func EscapeArg(s string) string {
 	if len(s) == 0 {
 		return `""`
 	}
 	n := len(s)
 	hasSpace := false
 	for i := 0; i < len(s); i++ {
 		switch s[i] {
 		case '"', '\\':
 			n++
 		case ' ', '\t':
 			hasSpace = true
 		}
 	}
 	if hasSpace {
 		n += 2 // Reserve space for quotes.
 	}
 	if n == len(s) {
 		return s
 	}
 
 	qs := make([]byte, n)
 	j := 0
 	if hasSpace {
 		qs[j] = '"'
 		j++
 	}
 	slashes := 0
 	for i := 0; i < len(s); i++ {
 		switch s[i] {
 		default:
 			slashes = 0
 			qs[j] = s[i]
 		case '\\':
 			slashes++
 			qs[j] = s[i]
 		case '"':
 			for ; slashes > 0; slashes-- {
 				qs[j] = '\\'
 				j++
 			}
 			qs[j] = '\\'
 			j++
 			qs[j] = s[i]
 		}
 		j++
 	}
 	if hasSpace {
 		for ; slashes > 0; slashes-- {
 			qs[j] = '\\'
 			j++
 		}
 		qs[j] = '"'
 		j++
 	}
 	return string(qs[:j])
 }
 
 // ComposeCommandLine escapes and joins the given arguments suitable for use as a Windows command line,
 // in CreateProcess's CommandLine argument, CreateService/ChangeServiceConfig's BinaryPathName argument,
 // or any program that uses CommandLineToArgv.
 func ComposeCommandLine(args []string) string {
 	if len(args) == 0 {
 		return ""
 	}
 
 	// Per https://learn.microsoft.com/en-us/windows/win32/api/shellapi/nf-shellapi-commandlinetoargvw:
 	// “This function accepts command lines that contain a program name; the
 	// program name can be enclosed in quotation marks or not.”
 	//
 	// Unfortunately, it provides no means of escaping interior quotation marks
 	// within that program name, and we have no way to report them here.
 	prog := args[0]
 	mustQuote := len(prog) == 0
 	for i := 0; i < len(prog); i++ {
 		c := prog[i]
 		if c <= ' ' || (c == '"' && i == 0) {
 			// Force quotes for not only the ASCII space and tab as described in the
 			// MSDN article, but also ASCII control characters.
 			// The documentation for CommandLineToArgvW doesn't say what happens when
 			// the first argument is not a valid program name, but it empirically
 			// seems to drop unquoted control characters.
 			mustQuote = true
 			break
 		}
 	}
 	var commandLine []byte
 	if mustQuote {
 		commandLine = make([]byte, 0, len(prog)+2)
 		commandLine = append(commandLine, '"')
 		for i := 0; i < len(prog); i++ {
 			c := prog[i]
 			if c == '"' {
 				// This quote would interfere with our surrounding quotes.
 				// We have no way to report an error, so just strip out
 				// the offending character instead.
 				continue
 			}
 			commandLine = append(commandLine, c)
 		}
 		commandLine = append(commandLine, '"')
 	} else {
 		if len(args) == 1 {
 			// args[0] is a valid command line representing itself.
 			// No need to allocate a new slice or string for it.
 			return prog
 		}
 		commandLine = []byte(prog)
 	}
 
 	for _, arg := range args[1:] {
 		commandLine = append(commandLine, ' ')
 		// TODO(bcmills): since we're already appending to a slice, it would be nice
 		// to avoid the intermediate allocations of EscapeArg.
 		// Perhaps we can factor out an appendEscapedArg function.
 		commandLine = append(commandLine, EscapeArg(arg)...)
 	}
 	return string(commandLine)
 }
 
 // DecomposeCommandLine breaks apart its argument command line into unescaped parts using CommandLineToArgv,
 // as gathered from GetCommandLine, QUERY_SERVICE_CONFIG's BinaryPathName argument, or elsewhere that
 // command lines are passed around.
 // DecomposeCommandLine returns an error if commandLine contains NUL.
 func DecomposeCommandLine(commandLine string) ([]string, error) {
 	if len(commandLine) == 0 {
 		return []string{}, nil
 	}
 	utf16CommandLine, err := UTF16FromString(commandLine)
 	if err != nil {
 		return nil, errorspkg.New("string with NUL passed to DecomposeCommandLine")
 	}
 	var argc int32
 	argv, err := commandLineToArgv(&utf16CommandLine[0], &argc)
 	if err != nil {
 		return nil, err
 	}
 	defer LocalFree(Handle(unsafe.Pointer(argv)))
 
 	var args []string
 	for _, p := range unsafe.Slice(argv, argc) {
 		args = append(args, UTF16PtrToString(p))
 	}
 	return args, nil
 }
 
 // CommandLineToArgv parses a Unicode command line string and sets
 // argc to the number of parsed arguments.
 //
 // The returned memory should be freed using a single call to LocalFree.
 //
 // Note that although the return type of CommandLineToArgv indicates 8192
 // entries of up to 8192 characters each, the actual count of parsed arguments
 // may exceed 8192, and the documentation for CommandLineToArgvW does not mention
 // any bound on the lengths of the individual argument strings.
 // (See https://go.dev/issue/63236.)
 func CommandLineToArgv(cmd *uint16, argc *int32) (argv *[8192]*[8192]uint16, err error) {
 	argp, err := commandLineToArgv(cmd, argc)
 	argv = (*[8192]*[8192]uint16)(unsafe.Pointer(argp))
 	return argv, err
 }
 
 func CloseOnExec(fd Handle) {
 	SetHandleInformation(Handle(fd), HANDLE_FLAG_INHERIT, 0)
 }
 
 // FullPath retrieves the full path of the specified file.
 func FullPath(name string) (path string, err error) {
 	p, err := UTF16PtrFromString(name)
 	if err != nil {
 		return "", err
 	}
 	n := uint32(100)
 	for {
 		buf := make([]uint16, n)
 		n, err = GetFullPathName(p, uint32(len(buf)), &buf[0], nil)
 		if err != nil {
 			return "", err
 		}
 		if n <= uint32(len(buf)) {
 			return UTF16ToString(buf[:n]), nil
 		}
 	}
 }
 
 // NewProcThreadAttributeList allocates a new ProcThreadAttributeListContainer, with the requested maximum number of attributes.
 func NewProcThreadAttributeList(maxAttrCount uint32) (*ProcThreadAttributeListContainer, error) {
 	var size uintptr
 	err := initializeProcThreadAttributeList(nil, maxAttrCount, 0, &size)
 	if err != ERROR_INSUFFICIENT_BUFFER {
 		if err == nil {
 			return nil, errorspkg.New("unable to query buffer size from InitializeProcThreadAttributeList")
 		}
 		return nil, err
 	}
 	alloc, err := LocalAlloc(LMEM_FIXED, uint32(size))
 	if err != nil {
 		return nil, err
 	}
 	// size is guaranteed to be ≥1 by InitializeProcThreadAttributeList.
 	al := &ProcThreadAttributeListContainer{data: (*ProcThreadAttributeList)(unsafe.Pointer(alloc))}
 	err = initializeProcThreadAttributeList(al.data, maxAttrCount, 0, &size)
 	if err != nil {
 		return nil, err
 	}
 	return al, err
 }
 
 // Update modifies the ProcThreadAttributeList using UpdateProcThreadAttribute.
 func (al *ProcThreadAttributeListContainer) Update(attribute uintptr, value unsafe.Pointer, size uintptr) error {
 	al.pointers = append(al.pointers, value)
 	return updateProcThreadAttribute(al.data, 0, attribute, value, size, nil, nil)
 }
 
 // Delete frees ProcThreadAttributeList's resources.
 func (al *ProcThreadAttributeListContainer) Delete() {
 	deleteProcThreadAttributeList(al.data)
 	LocalFree(Handle(unsafe.Pointer(al.data)))
 	al.data = nil
 	al.pointers = nil
 }
 
 // List returns the actual ProcThreadAttributeList to be passed to StartupInfoEx.
 func (al *ProcThreadAttributeListContainer) List() *ProcThreadAttributeList {
 	return al.data
 }