Adding upstream version 1.22.1.upstream/1.22.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 448 insertions, 0 deletions

diff --git a/src/embed/embed.go b/src/embed/embed.go
new file mode 100644
index 0000000..b7bb160
--- /dev/null
+++ b/src/embed/embed.go
@@ -0,0 +1,448 @@
+// Copyright 2020 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 embed provides access to files embedded in the running Go program.
+//
+// Go source files that import "embed" can use the //go:embed directive
+// to initialize a variable of type string, []byte, or [FS] with the contents of
+// files read from the package directory or subdirectories at compile time.
+//
+// For example, here are three ways to embed a file named hello.txt
+// and then print its contents at run time.
+//
+// Embedding one file into a string:
+//
+//	import _ "embed"
+//
+//	//go:embed hello.txt
+//	var s string
+//	print(s)
+//
+// Embedding one file into a slice of bytes:
+//
+//	import _ "embed"
+//
+//	//go:embed hello.txt
+//	var b []byte
+//	print(string(b))
+//
+// Embedded one or more files into a file system:
+//
+//	import "embed"
+//
+//	//go:embed hello.txt
+//	var f embed.FS
+//	data, _ := f.ReadFile("hello.txt")
+//	print(string(data))
+//
+// # Directives
+//
+// A //go:embed directive above a variable declaration specifies which files to embed,
+// using one or more path.Match patterns.
+//
+// The directive must immediately precede a line containing the declaration of a single variable.
+// Only blank lines and ‘//’ line comments are permitted between the directive and the declaration.
+//
+// The type of the variable must be a string type, or a slice of a byte type,
+// or [FS] (or an alias of [FS]).
+//
+// For example:
+//
+//	package server
+//
+//	import "embed"
+//
+//	// content holds our static web server content.
+//	//go:embed image/* template/*
+//	//go:embed html/index.html
+//	var content embed.FS
+//
+// The Go build system will recognize the directives and arrange for the declared variable
+// (in the example above, content) to be populated with the matching files from the file system.
+//
+// The //go:embed directive accepts multiple space-separated patterns for
+// brevity, but it can also be repeated, to avoid very long lines when there are
+// many patterns. The patterns are interpreted relative to the package directory
+// containing the source file. The path separator is a forward slash, even on
+// Windows systems. Patterns may not contain ‘.’ or ‘..’ or empty path elements,
+// nor may they begin or end with a slash. To match everything in the current
+// directory, use ‘*’ instead of ‘.’. To allow for naming files with spaces in
+// their names, patterns can be written as Go double-quoted or back-quoted
+// string literals.
+//
+// If a pattern names a directory, all files in the subtree rooted at that directory are
+// embedded (recursively), except that files with names beginning with ‘.’ or ‘_’
+// are excluded. So the variable in the above example is almost equivalent to:
+//
+//	// content is our static web server content.
+//	//go:embed image template html/index.html
+//	var content embed.FS
+//
+// The difference is that ‘image/*’ embeds ‘image/.tempfile’ while ‘image’ does not.
+// Neither embeds ‘image/dir/.tempfile’.
+//
+// If a pattern begins with the prefix ‘all:’, then the rule for walking directories is changed
+// to include those files beginning with ‘.’ or ‘_’. For example, ‘all:image’ embeds
+// both ‘image/.tempfile’ and ‘image/dir/.tempfile’.
+//
+// The //go:embed directive can be used with both exported and unexported variables,
+// depending on whether the package wants to make the data available to other packages.
+// It can only be used with variables at package scope, not with local variables.
+//
+// Patterns must not match files outside the package's module, such as ‘.git/*’ or symbolic links.
+// Patterns must not match files whose names include the special punctuation characters  " * < > ? ` ' | / \ and :.
+// Matches for empty directories are ignored. After that, each pattern in a //go:embed line
+// must match at least one file or non-empty directory.
+//
+// If any patterns are invalid or have invalid matches, the build will fail.
+//
+// # Strings and Bytes
+//
+// The //go:embed line for a variable of type string or []byte can have only a single pattern,
+// and that pattern can match only a single file. The string or []byte is initialized with
+// the contents of that file.
+//
+// The //go:embed directive requires importing "embed", even when using a string or []byte.
+// In source files that don't refer to [embed.FS], use a blank import (import _ "embed").
+//
+// # File Systems
+//
+// For embedding a single file, a variable of type string or []byte is often best.
+// The [FS] type enables embedding a tree of files, such as a directory of static
+// web server content, as in the example above.
+//
+// FS implements the [io/fs] package's [FS] interface, so it can be used with any package that
+// understands file systems, including [net/http], [text/template], and [html/template].
+//
+// For example, given the content variable in the example above, we can write:
+//
+//	http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.FS(content))))
+//
+//	template.ParseFS(content, "*.tmpl")
+//
+// # Tools
+//
+// To support tools that analyze Go packages, the patterns found in //go:embed lines
+// are available in “go list” output. See the EmbedPatterns, TestEmbedPatterns,
+// and XTestEmbedPatterns fields in the “go help list” output.
+package embed
+
+import (
+	"errors"
+	"io"
+	"io/fs"
+	"time"
+)
+
+// An FS is a read-only collection of files, usually initialized with a //go:embed directive.
+// When declared without a //go:embed directive, an FS is an empty file system.
+//
+// An FS is a read-only value, so it is safe to use from multiple goroutines
+// simultaneously and also safe to assign values of type FS to each other.
+//
+// FS implements fs.FS, so it can be used with any package that understands
+// file system interfaces, including net/http, text/template, and html/template.
+//
+// See the package documentation for more details about initializing an FS.
+type FS struct {
+	// The compiler knows the layout of this struct.
+	// See cmd/compile/internal/staticdata's WriteEmbed.
+	//
+	// The files list is sorted by name but not by simple string comparison.
+	// Instead, each file's name takes the form "dir/elem" or "dir/elem/".
+	// The optional trailing slash indicates that the file is itself a directory.
+	// The files list is sorted first by dir (if dir is missing, it is taken to be ".")
+	// and then by base, so this list of files:
+	//
+	//	p
+	//	q/
+	//	q/r
+	//	q/s/
+	//	q/s/t
+	//	q/s/u
+	//	q/v
+	//	w
+	//
+	// is actually sorted as:
+	//
+	//	p       # dir=.    elem=p
+	//	q/      # dir=.    elem=q
+	//	w/      # dir=.    elem=w
+	//	q/r     # dir=q    elem=r
+	//	q/s/    # dir=q    elem=s
+	//	q/v     # dir=q    elem=v
+	//	q/s/t   # dir=q/s  elem=t
+	//	q/s/u   # dir=q/s  elem=u
+	//
+	// This order brings directory contents together in contiguous sections
+	// of the list, allowing a directory read to use binary search to find
+	// the relevant sequence of entries.
+	files *[]file
+}
+
+// split splits the name into dir and elem as described in the
+// comment in the FS struct above. isDir reports whether the
+// final trailing slash was present, indicating that name is a directory.
+func split(name string) (dir, elem string, isDir bool) {
+	if name[len(name)-1] == '/' {
+		isDir = true
+		name = name[:len(name)-1]
+	}
+	i := len(name) - 1
+	for i >= 0 && name[i] != '/' {
+		i--
+	}
+	if i < 0 {
+		return ".", name, isDir
+	}
+	return name[:i], name[i+1:], isDir
+}
+
+// trimSlash trims a trailing slash from name, if present,
+// returning the possibly shortened name.
+func trimSlash(name string) string {
+	if len(name) > 0 && name[len(name)-1] == '/' {
+		return name[:len(name)-1]
+	}
+	return name
+}
+
+var (
+	_ fs.ReadDirFS  = FS{}
+	_ fs.ReadFileFS = FS{}
+)
+
+// A file is a single file in the FS.
+// It implements fs.FileInfo and fs.DirEntry.
+type file struct {
+	// The compiler knows the layout of this struct.
+	// See cmd/compile/internal/staticdata's WriteEmbed.
+	name string
+	data string
+	hash [16]byte // truncated SHA256 hash
+}
+
+var (
+	_ fs.FileInfo = (*file)(nil)
+	_ fs.DirEntry = (*file)(nil)
+)
+
+func (f *file) Name() string               { _, elem, _ := split(f.name); return elem }
+func (f *file) Size() int64                { return int64(len(f.data)) }
+func (f *file) ModTime() time.Time         { return time.Time{} }
+func (f *file) IsDir() bool                { _, _, isDir := split(f.name); return isDir }
+func (f *file) Sys() any                   { return nil }
+func (f *file) Type() fs.FileMode          { return f.Mode().Type() }
+func (f *file) Info() (fs.FileInfo, error) { return f, nil }
+
+func (f *file) Mode() fs.FileMode {
+	if f.IsDir() {
+		return fs.ModeDir | 0555
+	}
+	return 0444
+}
+
+func (f *file) String() string {
+	return fs.FormatFileInfo(f)
+}
+
+// dotFile is a file for the root directory,
+// which is omitted from the files list in a FS.
+var dotFile = &file{name: "./"}
+
+// lookup returns the named file, or nil if it is not present.
+func (f FS) lookup(name string) *file {
+	if !fs.ValidPath(name) {
+		// The compiler should never emit a file with an invalid name,
+		// so this check is not strictly necessary (if name is invalid,
+		// we shouldn't find a match below), but it's a good backstop anyway.
+		return nil
+	}
+	if name == "." {
+		return dotFile
+	}
+	if f.files == nil {
+		return nil
+	}
+
+	// Binary search to find where name would be in the list,
+	// and then check if name is at that position.
+	dir, elem, _ := split(name)
+	files := *f.files
+	i := sortSearch(len(files), func(i int) bool {
+		idir, ielem, _ := split(files[i].name)
+		return idir > dir || idir == dir && ielem >= elem
+	})
+	if i < len(files) && trimSlash(files[i].name) == name {
+		return &files[i]
+	}
+	return nil
+}
+
+// readDir returns the list of files corresponding to the directory dir.
+func (f FS) readDir(dir string) []file {
+	if f.files == nil {
+		return nil
+	}
+	// Binary search to find where dir starts and ends in the list
+	// and then return that slice of the list.
+	files := *f.files
+	i := sortSearch(len(files), func(i int) bool {
+		idir, _, _ := split(files[i].name)
+		return idir >= dir
+	})
+	j := sortSearch(len(files), func(j int) bool {
+		jdir, _, _ := split(files[j].name)
+		return jdir > dir
+	})
+	return files[i:j]
+}
+
+// Open opens the named file for reading and returns it as an [fs.File].
+//
+// The returned file implements [io.Seeker] and [io.ReaderAt] when the file is not a directory.
+func (f FS) Open(name string) (fs.File, error) {
+	file := f.lookup(name)
+	if file == nil {
+		return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
+	}
+	if file.IsDir() {
+		return &openDir{file, f.readDir(name), 0}, nil
+	}
+	return &openFile{file, 0}, nil
+}
+
+// ReadDir reads and returns the entire named directory.
+func (f FS) ReadDir(name string) ([]fs.DirEntry, error) {
+	file, err := f.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	dir, ok := file.(*openDir)
+	if !ok {
+		return nil, &fs.PathError{Op: "read", Path: name, Err: errors.New("not a directory")}
+	}
+	list := make([]fs.DirEntry, len(dir.files))
+	for i := range list {
+		list[i] = &dir.files[i]
+	}
+	return list, nil
+}
+
+// ReadFile reads and returns the content of the named file.
+func (f FS) ReadFile(name string) ([]byte, error) {
+	file, err := f.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	ofile, ok := file.(*openFile)
+	if !ok {
+		return nil, &fs.PathError{Op: "read", Path: name, Err: errors.New("is a directory")}
+	}
+	return []byte(ofile.f.data), nil
+}
+
+// An openFile is a regular file open for reading.
+type openFile struct {
+	f      *file // the file itself
+	offset int64 // current read offset
+}
+
+var (
+	_ io.Seeker   = (*openFile)(nil)
+	_ io.ReaderAt = (*openFile)(nil)
+)
+
+func (f *openFile) Close() error               { return nil }
+func (f *openFile) Stat() (fs.FileInfo, error) { return f.f, nil }
+
+func (f *openFile) Read(b []byte) (int, error) {
+	if f.offset >= int64(len(f.f.data)) {
+		return 0, io.EOF
+	}
+	if f.offset < 0 {
+		return 0, &fs.PathError{Op: "read", Path: f.f.name, Err: fs.ErrInvalid}
+	}
+	n := copy(b, f.f.data[f.offset:])
+	f.offset += int64(n)
+	return n, nil
+}
+
+func (f *openFile) Seek(offset int64, whence int) (int64, error) {
+	switch whence {
+	case 0:
+		// offset += 0
+	case 1:
+		offset += f.offset
+	case 2:
+		offset += int64(len(f.f.data))
+	}
+	if offset < 0 || offset > int64(len(f.f.data)) {
+		return 0, &fs.PathError{Op: "seek", Path: f.f.name, Err: fs.ErrInvalid}
+	}
+	f.offset = offset
+	return offset, nil
+}
+
+func (f *openFile) ReadAt(b []byte, offset int64) (int, error) {
+	if offset < 0 || offset > int64(len(f.f.data)) {
+		return 0, &fs.PathError{Op: "read", Path: f.f.name, Err: fs.ErrInvalid}
+	}
+	n := copy(b, f.f.data[offset:])
+	if n < len(b) {
+		return n, io.EOF
+	}
+	return n, nil
+}
+
+// An openDir is a directory open for reading.
+type openDir struct {
+	f      *file  // the directory file itself
+	files  []file // the directory contents
+	offset int    // the read offset, an index into the files slice
+}
+
+func (d *openDir) Close() error               { return nil }
+func (d *openDir) Stat() (fs.FileInfo, error) { return d.f, nil }
+
+func (d *openDir) Read([]byte) (int, error) {
+	return 0, &fs.PathError{Op: "read", Path: d.f.name, Err: errors.New("is a directory")}
+}
+
+func (d *openDir) ReadDir(count int) ([]fs.DirEntry, error) {
+	n := len(d.files) - d.offset
+	if n == 0 {
+		if count <= 0 {
+			return nil, nil
+		}
+		return nil, io.EOF
+	}
+	if count > 0 && n > count {
+		n = count
+	}
+	list := make([]fs.DirEntry, n)
+	for i := range list {
+		list[i] = &d.files[d.offset+i]
+	}
+	d.offset += n
+	return list, nil
+}
+
+// sortSearch is like sort.Search, avoiding an import.
+func sortSearch(n int, f func(int) bool) int {
+	// Define f(-1) == false and f(n) == true.
+	// Invariant: f(i-1) == false, f(j) == true.
+	i, j := 0, n
+	for i < j {
+		h := int(uint(i+j) >> 1) // avoid overflow when computing h
+		// i ≤ h < j
+		if !f(h) {
+			i = h + 1 // preserves f(i-1) == false
+		} else {
+			j = h // preserves f(j) == true
+		}
+	}
+	// i == j, f(i-1) == false, and f(j) (= f(i)) == true  =>  answer is i.
+	return i
+}