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Diffstat (limited to '')
| -rw-r--r-- | src/internal/xcoff/ar.go | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/src/internal/xcoff/ar.go b/src/internal/xcoff/ar.go new file mode 100644 index 0000000..2b432d5 --- /dev/null +++ b/src/internal/xcoff/ar.go @@ -0,0 +1,228 @@ +// Copyright 2018 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 xcoff + +import ( + "encoding/binary" + "fmt" + "io" + "os" + "strconv" + "strings" +) + +const ( + SAIAMAG = 0x8 + AIAFMAG = "`\n" + AIAMAG = "<aiaff>\n" + AIAMAGBIG = "<bigaf>\n" + + // Sizeof + FL_HSZ_BIG = 0x80 + AR_HSZ_BIG = 0x70 +) + +type bigarFileHeader struct { + Flmagic [SAIAMAG]byte // Archive magic string + Flmemoff [20]byte // Member table offset + Flgstoff [20]byte // 32-bits global symtab offset + Flgst64off [20]byte // 64-bits global symtab offset + Flfstmoff [20]byte // First member offset + Fllstmoff [20]byte // Last member offset + Flfreeoff [20]byte // First member on free list offset +} + +type bigarMemberHeader struct { + Arsize [20]byte // File member size + Arnxtmem [20]byte // Next member pointer + Arprvmem [20]byte // Previous member pointer + Ardate [12]byte // File member date + Aruid [12]byte // File member uid + Argid [12]byte // File member gid + Armode [12]byte // File member mode (octal) + Arnamlen [4]byte // File member name length + // _ar_nam is removed because it's easier to get name without it. +} + +// Archive represents an open AIX big archive. +type Archive struct { + ArchiveHeader + Members []*Member + + closer io.Closer +} + +// MemberHeader holds information about a big archive file header +type ArchiveHeader struct { + magic string +} + +// Member represents a member of an AIX big archive. +type Member struct { + MemberHeader + sr *io.SectionReader +} + +// MemberHeader holds information about a big archive member +type MemberHeader struct { + Name string + Size uint64 +} + +// OpenArchive opens the named archive using os.Open and prepares it for use +// as an AIX big archive. +func OpenArchive(name string) (*Archive, error) { + f, err := os.Open(name) + if err != nil { + return nil, err + } + arch, err := NewArchive(f) + if err != nil { + f.Close() + return nil, err + } + arch.closer = f + return arch, nil +} + +// Close closes the Archive. +// If the Archive was created using NewArchive directly instead of OpenArchive, +// Close has no effect. +func (a *Archive) Close() error { + var err error + if a.closer != nil { + err = a.closer.Close() + a.closer = nil + } + return err +} + +// NewArchive creates a new Archive for accessing an AIX big archive in an underlying reader. +func NewArchive(r io.ReaderAt) (*Archive, error) { + parseDecimalBytes := func(b []byte) (int64, error) { + return strconv.ParseInt(strings.TrimSpace(string(b)), 10, 64) + } + sr := io.NewSectionReader(r, 0, 1<<63-1) + + // Read File Header + var magic [SAIAMAG]byte + if _, err := sr.ReadAt(magic[:], 0); err != nil { + return nil, err + } + + arch := new(Archive) + switch string(magic[:]) { + case AIAMAGBIG: + arch.magic = string(magic[:]) + case AIAMAG: + return nil, fmt.Errorf("small AIX archive not supported") + default: + return nil, fmt.Errorf("unrecognised archive magic: 0x%x", magic) + } + + var fhdr bigarFileHeader + if _, err := sr.Seek(0, io.SeekStart); err != nil { + return nil, err + } + if err := binary.Read(sr, binary.BigEndian, &fhdr); err != nil { + return nil, err + } + + off, err := parseDecimalBytes(fhdr.Flfstmoff[:]) + if err != nil { + return nil, fmt.Errorf("error parsing offset of first member in archive header(%q); %v", fhdr, err) + } + + if off == 0 { + // Occurs if the archive is empty. + return arch, nil + } + + lastoff, err := parseDecimalBytes(fhdr.Fllstmoff[:]) + if err != nil { + return nil, fmt.Errorf("error parsing offset of first member in archive header(%q); %v", fhdr, err) + } + + // Read members + for { + // Read Member Header + // The member header is normally 2 bytes larger. But it's easier + // to read the name if the header is read without _ar_nam. + // However, AIAFMAG must be read afterward. + if _, err := sr.Seek(off, io.SeekStart); err != nil { + return nil, err + } + + var mhdr bigarMemberHeader + if err := binary.Read(sr, binary.BigEndian, &mhdr); err != nil { + return nil, err + } + + member := new(Member) + arch.Members = append(arch.Members, member) + + size, err := parseDecimalBytes(mhdr.Arsize[:]) + if err != nil { + return nil, fmt.Errorf("error parsing size in member header(%q); %v", mhdr, err) + } + member.Size = uint64(size) + + // Read name + namlen, err := parseDecimalBytes(mhdr.Arnamlen[:]) + if err != nil { + return nil, fmt.Errorf("error parsing name length in member header(%q); %v", mhdr, err) + } + name := make([]byte, namlen) + if err := binary.Read(sr, binary.BigEndian, name); err != nil { + return nil, err + } + member.Name = string(name) + + fileoff := off + AR_HSZ_BIG + namlen + if fileoff&1 != 0 { + fileoff++ + if _, err := sr.Seek(1, io.SeekCurrent); err != nil { + return nil, err + } + } + + // Read AIAFMAG string + var fmag [2]byte + if err := binary.Read(sr, binary.BigEndian, &fmag); err != nil { + return nil, err + } + if string(fmag[:]) != AIAFMAG { + return nil, fmt.Errorf("AIAFMAG not found after member header") + } + + fileoff += 2 // Add the two bytes of AIAFMAG + member.sr = io.NewSectionReader(sr, fileoff, size) + + if off == lastoff { + break + } + off, err = parseDecimalBytes(mhdr.Arnxtmem[:]) + if err != nil { + return nil, fmt.Errorf("error parsing offset of first member in archive header(%q); %v", fhdr, err) + } + + } + + return arch, nil + +} + +// GetFile returns the XCOFF file defined by member name. +// FIXME: This doesn't work if an archive has two members with the same +// name which can occur if a archive has both 32-bits and 64-bits files. +func (arch *Archive) GetFile(name string) (*File, error) { + for _, mem := range arch.Members { + if mem.Name == name { + return NewFile(mem.sr) + } + } + return nil, fmt.Errorf("unknown member %s in archive", name) + +} |