| 1 | // Copyright 2016 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Package gccgoexportdata provides functions for reading export data |
| 6 | // files containing type information produced by the gccgo compiler. |
| 7 | // |
| 8 | // This package is a stop-gap until such time as gccgo uses the same |
| 9 | // export data format as gc; see Go issue 17573. Once that occurs, this |
| 10 | // package will be deprecated and eventually deleted. |
| 11 | package gccgoexportdata |
| 12 | |
| 13 | // TODO(adonovan): add Find, Write, Importer to the API, |
| 14 | // for symmetry with gcexportdata. |
| 15 | |
| 16 | import ( |
| 17 | "bytes" |
| 18 | "debug/elf" |
| 19 | "fmt" |
| 20 | "go/token" |
| 21 | "go/types" |
| 22 | "io" |
| 23 | "io/ioutil" |
| 24 | "strconv" |
| 25 | "strings" |
| 26 | |
| 27 | "golang.org/x/tools/go/internal/gccgoimporter" |
| 28 | ) |
| 29 | |
| 30 | // CompilerInfo executes the specified gccgo compiler and returns |
| 31 | // information about it: its version (e.g. "4.8.0"), its target triple |
| 32 | // (e.g. "x86_64-unknown-linux-gnu"), and the list of directories it |
| 33 | // searches to find standard packages. The given arguments are passed |
| 34 | // directly to calls to the specified gccgo compiler. |
| 35 | func CompilerInfo(gccgo string, args ...string) (version, triple string, dirs []string, err error) { |
| 36 | var inst gccgoimporter.GccgoInstallation |
| 37 | err = inst.InitFromDriver(gccgo, args...) |
| 38 | if err == nil { |
| 39 | version = inst.GccVersion |
| 40 | triple = inst.TargetTriple |
| 41 | dirs = inst.SearchPaths() |
| 42 | } |
| 43 | return |
| 44 | } |
| 45 | |
| 46 | // NewReader returns a reader for the export data section of an object |
| 47 | // (.o) or archive (.a) file read from r. |
| 48 | func NewReader(r io.Reader) (io.Reader, error) { |
| 49 | data, err := ioutil.ReadAll(r) |
| 50 | if err != nil { |
| 51 | return nil, err |
| 52 | } |
| 53 | |
| 54 | // If the file is an archive, extract the first section. |
| 55 | const archiveMagic = "!<arch>\n" |
| 56 | if bytes.HasPrefix(data, []byte(archiveMagic)) { |
| 57 | section, err := firstSection(data[len(archiveMagic):]) |
| 58 | if err != nil { |
| 59 | return nil, err |
| 60 | } |
| 61 | data = section |
| 62 | } |
| 63 | |
| 64 | // Data contains an ELF file with a .go_export section. |
| 65 | // ELF magic number is "\x7fELF". |
| 66 | ef, err := elf.NewFile(bytes.NewReader(data)) |
| 67 | if err != nil { |
| 68 | return nil, err |
| 69 | } |
| 70 | sec := ef.Section(".go_export") |
| 71 | if sec == nil { |
| 72 | return nil, fmt.Errorf("no .go_export section") |
| 73 | } |
| 74 | return sec.Open(), nil |
| 75 | } |
| 76 | |
| 77 | // firstSection returns the contents of the first regular file in an ELF |
| 78 | // archive (http://www.sco.com/developers/devspecs/gabi41.pdf, ยง7.2). |
| 79 | func firstSection(a []byte) ([]byte, error) { |
| 80 | for len(a) >= 60 { |
| 81 | var hdr []byte |
| 82 | hdr, a = a[:60], a[60:] |
| 83 | |
| 84 | name := strings.TrimSpace(string(hdr[:16])) |
| 85 | |
| 86 | sizeStr := string(hdr[48:58]) |
| 87 | size, err := strconv.Atoi(strings.TrimSpace(sizeStr)) |
| 88 | if err != nil { |
| 89 | return nil, fmt.Errorf("invalid size: %q", sizeStr) |
| 90 | } |
| 91 | |
| 92 | if len(a) < size { |
| 93 | return nil, fmt.Errorf("invalid section size: %d", size) |
| 94 | } |
| 95 | |
| 96 | // The payload is padded to an even number of bytes. |
| 97 | var payload []byte |
| 98 | payload, a = a[:size], a[size+size&1:] |
| 99 | |
| 100 | // Skip special files: |
| 101 | // "/" archive symbol table |
| 102 | // "/SYM64/" archive symbol table on e.g. s390x |
| 103 | // "//" archive string table (if any filename is >15 bytes) |
| 104 | if name == "/" || name == "/SYM64/" || name == "//" { |
| 105 | continue |
| 106 | } |
| 107 | |
| 108 | return payload, nil |
| 109 | } |
| 110 | return nil, fmt.Errorf("archive has no regular sections") |
| 111 | } |
| 112 | |
| 113 | // Read reads export data from in, decodes it, and returns type |
| 114 | // information for the package. |
| 115 | // The package name is specified by path. |
| 116 | // |
| 117 | // The FileSet parameter is currently unused but exists for symmetry |
| 118 | // with gcexportdata. |
| 119 | // |
| 120 | // Read may inspect and add to the imports map to ensure that references |
| 121 | // within the export data to other packages are consistent. The caller |
| 122 | // must ensure that imports[path] does not exist, or exists but is |
| 123 | // incomplete (see types.Package.Complete), and Read inserts the |
| 124 | // resulting package into this map entry. |
| 125 | // |
| 126 | // On return, the state of the reader is undefined. |
| 127 | func Read(in io.Reader, _ *token.FileSet, imports map[string]*types.Package, path string) (*types.Package, error) { |
| 128 | return gccgoimporter.Parse(in, imports, path) |
| 129 | } |
| 130 |
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