From: Austin Clements Date: Wed, 2 Dec 2015 17:20:29 +0000 (-0500) Subject: debug/elf: transparently decompress compressed sections X-Git-Tag: go1.6beta1~213 X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=76483877052eaa9b2242deee2239e82d3953fd16;p=gostls13.git debug/elf: transparently decompress compressed sections This adds support for compressed ELF sections. This compression is treated as a framing issue and hence the package APIs all transparently decompress compressed sections. This requires some subtlety for (*Section).Open, which returns an io.ReadSeeker: since the decompressed data comes from an io.Reader, this commit introduces a Reader-to-ReadSeeker adapter that is efficient for common uses of Seek and does what it can otherwise. Fixes #11773. Change-Id: Ic0cb7255a85cadf4c1d15fb563d5a2e89dbd3c36 Reviewed-on: https://go-review.googlesource.com/17341 Reviewed-by: Russ Cox Run-TryBot: Austin Clements --- diff --git a/src/debug/elf/elf.go b/src/debug/elf/elf.go index 1c9dd7bc4a..0c79b7a02f 100644 --- a/src/debug/elf/elf.go +++ b/src/debug/elf/elf.go @@ -411,6 +411,7 @@ const ( SHF_OS_NONCONFORMING SectionFlag = 0x100 /* OS-specific processing required. */ SHF_GROUP SectionFlag = 0x200 /* Member of section group. */ SHF_TLS SectionFlag = 0x400 /* Section contains TLS data. */ + SHF_COMPRESSED SectionFlag = 0x800 /* Section is compressed. */ SHF_MASKOS SectionFlag = 0x0ff00000 /* OS-specific semantics. */ SHF_MASKPROC SectionFlag = 0xf0000000 /* Processor-specific semantics. */ ) @@ -426,11 +427,34 @@ var shfStrings = []intName{ {0x100, "SHF_OS_NONCONFORMING"}, {0x200, "SHF_GROUP"}, {0x400, "SHF_TLS"}, + {0x800, "SHF_COMPRESSED"}, } func (i SectionFlag) String() string { return flagName(uint32(i), shfStrings, false) } func (i SectionFlag) GoString() string { return flagName(uint32(i), shfStrings, true) } +// Section compression type. +type CompressionType int + +const ( + COMPRESS_ZLIB CompressionType = 1 /* ZLIB compression. */ + COMPRESS_LOOS CompressionType = 0x60000000 /* First OS-specific. */ + COMPRESS_HIOS CompressionType = 0x6fffffff /* Last OS-specific. */ + COMPRESS_LOPROC CompressionType = 0x70000000 /* First processor-specific type. */ + COMPRESS_HIPROC CompressionType = 0x7fffffff /* Last processor-specific type. */ +) + +var compressionStrings = []intName{ + {0, "COMPRESS_ZLIB"}, + {0x60000000, "COMPRESS_LOOS"}, + {0x6fffffff, "COMPRESS_HIOS"}, + {0x70000000, "COMPRESS_LOPROC"}, + {0x7fffffff, "COMPRESS_HIPROC"}, +} + +func (i CompressionType) String() string { return stringName(uint32(i), compressionStrings, false) } +func (i CompressionType) GoString() string { return stringName(uint32(i), compressionStrings, true) } + // Prog.Type type ProgType int @@ -1878,6 +1902,13 @@ type Dyn32 struct { Val uint32 /* Integer/Address value. */ } +// ELF32 Compression header. +type Chdr32 struct { + Type uint32 + Size uint32 + Addralign uint32 +} + /* * Relocation entries. */ @@ -1972,6 +2003,14 @@ type Dyn64 struct { Val uint64 /* Integer/address value */ } +// ELF64 Compression header. +type Chdr64 struct { + Type uint32 + Reserved uint32 + Size uint64 + Addralign uint64 +} + /* * Relocation entries. */ diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go index a42bde94f8..199aa4ec57 100644 --- a/src/debug/elf/file.go +++ b/src/debug/elf/file.go @@ -58,6 +58,12 @@ type SectionHeader struct { Info uint32 Addralign uint64 Entsize uint64 + + // FileSize is the size of this section in the file in bytes. + // If a section is compressed, FileSize is the size of the + // compressed data, while Size (above) is the size of the + // uncompressed data. + FileSize uint64 } // A Section represents a single section in an ELF file. @@ -70,17 +76,23 @@ type Section struct { // If a client wants Read and Seek it must use // Open() to avoid fighting over the seek offset // with other clients. + // + // ReaderAt may be nil if the section is not easily available + // in a random-access form. For example, a compressed section + // may have a nil ReaderAt. io.ReaderAt sr *io.SectionReader + + compressionType CompressionType + compressionOffset int64 } // Data reads and returns the contents of the ELF section. +// Even if the section is stored compressed in the ELF file, +// Data returns uncompressed data. func (s *Section) Data() ([]byte, error) { - dat := make([]byte, s.sr.Size()) - n, err := s.sr.ReadAt(dat, 0) - if n == len(dat) { - err = nil - } + dat := make([]byte, s.Size) + n, err := io.ReadFull(s.Open(), dat) return dat[0:n], err } @@ -94,7 +106,24 @@ func (f *File) stringTable(link uint32) ([]byte, error) { } // Open returns a new ReadSeeker reading the ELF section. -func (s *Section) Open() io.ReadSeeker { return io.NewSectionReader(s.sr, 0, 1<<63-1) } +// Even if the section is stored compressed in the ELF file, +// the ReadSeeker reads uncompressed data. +func (s *Section) Open() io.ReadSeeker { + if s.Flags&SHF_COMPRESSED == 0 { + return io.NewSectionReader(s.sr, 0, 1<<63-1) + } + if s.compressionType == COMPRESS_ZLIB { + return &readSeekerFromReader{ + reset: func() (io.Reader, error) { + fr := io.NewSectionReader(s.sr, s.compressionOffset, int64(s.FileSize)-s.compressionOffset) + return zlib.NewReader(fr) + }, + size: int64(s.Size), + } + } + err := &FormatError{int64(s.Offset), "unknown compression type", s.compressionType} + return errorReader{err} +} // A ProgHeader represents a single ELF program header. type ProgHeader struct { @@ -344,7 +373,7 @@ func NewFile(r io.ReaderAt) (*File, error) { Flags: SectionFlag(sh.Flags), Addr: uint64(sh.Addr), Offset: uint64(sh.Off), - Size: uint64(sh.Size), + FileSize: uint64(sh.Size), Link: uint32(sh.Link), Info: uint32(sh.Info), Addralign: uint64(sh.Addralign), @@ -360,7 +389,7 @@ func NewFile(r io.ReaderAt) (*File, error) { Type: SectionType(sh.Type), Flags: SectionFlag(sh.Flags), Offset: uint64(sh.Off), - Size: uint64(sh.Size), + FileSize: uint64(sh.Size), Addr: uint64(sh.Addr), Link: uint32(sh.Link), Info: uint32(sh.Info), @@ -368,8 +397,35 @@ func NewFile(r io.ReaderAt) (*File, error) { Entsize: uint64(sh.Entsize), } } - s.sr = io.NewSectionReader(r, int64(s.Offset), int64(s.Size)) - s.ReaderAt = s.sr + s.sr = io.NewSectionReader(r, int64(s.Offset), int64(s.FileSize)) + + if s.Flags&SHF_COMPRESSED == 0 { + s.ReaderAt = s.sr + s.Size = s.FileSize + } else { + // Read the compression header. + switch f.Class { + case ELFCLASS32: + ch := new(Chdr32) + if err := binary.Read(s.sr, f.ByteOrder, ch); err != nil { + return nil, err + } + s.compressionType = CompressionType(ch.Type) + s.Size = uint64(ch.Size) + s.Addralign = uint64(ch.Addralign) + s.compressionOffset = int64(binary.Size(ch)) + case ELFCLASS64: + ch := new(Chdr64) + if err := binary.Read(s.sr, f.ByteOrder, ch); err != nil { + return nil, err + } + s.compressionType = CompressionType(ch.Type) + s.Size = ch.Size + s.Addralign = ch.Addralign + s.compressionOffset = int64(binary.Size(ch)) + } + } + f.Sections[i] = s } diff --git a/src/debug/elf/file_test.go b/src/debug/elf/file_test.go index 6864b6df79..5c0df0f1e9 100644 --- a/src/debug/elf/file_test.go +++ b/src/debug/elf/file_test.go @@ -10,6 +10,7 @@ import ( "debug/dwarf" "encoding/binary" "io" + "math/rand" "net" "os" "path" @@ -31,36 +32,36 @@ var fileTests = []fileTest{ "testdata/gcc-386-freebsd-exec", FileHeader{ELFCLASS32, ELFDATA2LSB, EV_CURRENT, ELFOSABI_FREEBSD, 0, binary.LittleEndian, ET_EXEC, EM_386, 0x80483cc}, []SectionHeader{ - {"", SHT_NULL, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, - {".interp", SHT_PROGBITS, SHF_ALLOC, 0x80480d4, 0xd4, 0x15, 0x0, 0x0, 0x1, 0x0}, - {".hash", SHT_HASH, SHF_ALLOC, 0x80480ec, 0xec, 0x90, 0x3, 0x0, 0x4, 0x4}, - {".dynsym", SHT_DYNSYM, SHF_ALLOC, 0x804817c, 0x17c, 0x110, 0x4, 0x1, 0x4, 0x10}, - {".dynstr", SHT_STRTAB, SHF_ALLOC, 0x804828c, 0x28c, 0xbb, 0x0, 0x0, 0x1, 0x0}, - {".rel.plt", SHT_REL, SHF_ALLOC, 0x8048348, 0x348, 0x20, 0x3, 0x7, 0x4, 0x8}, - {".init", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x8048368, 0x368, 0x11, 0x0, 0x0, 0x4, 0x0}, - {".plt", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x804837c, 0x37c, 0x50, 0x0, 0x0, 0x4, 0x4}, - {".text", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x80483cc, 0x3cc, 0x180, 0x0, 0x0, 0x4, 0x0}, - {".fini", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x804854c, 0x54c, 0xc, 0x0, 0x0, 0x4, 0x0}, - {".rodata", SHT_PROGBITS, SHF_ALLOC, 0x8048558, 0x558, 0xa3, 0x0, 0x0, 0x1, 0x0}, - {".data", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80495fc, 0x5fc, 0xc, 0x0, 0x0, 0x4, 0x0}, - {".eh_frame", SHT_PROGBITS, SHF_ALLOC, 0x8049608, 0x608, 0x4, 0x0, 0x0, 0x4, 0x0}, - {".dynamic", SHT_DYNAMIC, SHF_WRITE + SHF_ALLOC, 0x804960c, 0x60c, 0x98, 0x4, 0x0, 0x4, 0x8}, - {".ctors", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80496a4, 0x6a4, 0x8, 0x0, 0x0, 0x4, 0x0}, - {".dtors", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80496ac, 0x6ac, 0x8, 0x0, 0x0, 0x4, 0x0}, - {".jcr", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80496b4, 0x6b4, 0x4, 0x0, 0x0, 0x4, 0x0}, - {".got", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80496b8, 0x6b8, 0x1c, 0x0, 0x0, 0x4, 0x4}, - {".bss", SHT_NOBITS, SHF_WRITE + SHF_ALLOC, 0x80496d4, 0x6d4, 0x20, 0x0, 0x0, 0x4, 0x0}, - {".comment", SHT_PROGBITS, 0x0, 0x0, 0x6d4, 0x12d, 0x0, 0x0, 0x1, 0x0}, - {".debug_aranges", SHT_PROGBITS, 0x0, 0x0, 0x801, 0x20, 0x0, 0x0, 0x1, 0x0}, - {".debug_pubnames", SHT_PROGBITS, 0x0, 0x0, 0x821, 0x1b, 0x0, 0x0, 0x1, 0x0}, - {".debug_info", SHT_PROGBITS, 0x0, 0x0, 0x83c, 0x11d, 0x0, 0x0, 0x1, 0x0}, - {".debug_abbrev", SHT_PROGBITS, 0x0, 0x0, 0x959, 0x41, 0x0, 0x0, 0x1, 0x0}, - {".debug_line", SHT_PROGBITS, 0x0, 0x0, 0x99a, 0x35, 0x0, 0x0, 0x1, 0x0}, - {".debug_frame", SHT_PROGBITS, 0x0, 0x0, 0x9d0, 0x30, 0x0, 0x0, 0x4, 0x0}, - {".debug_str", SHT_PROGBITS, 0x0, 0x0, 0xa00, 0xd, 0x0, 0x0, 0x1, 0x0}, - {".shstrtab", SHT_STRTAB, 0x0, 0x0, 0xa0d, 0xf8, 0x0, 0x0, 0x1, 0x0}, - {".symtab", SHT_SYMTAB, 0x0, 0x0, 0xfb8, 0x4b0, 0x1d, 0x38, 0x4, 0x10}, - {".strtab", SHT_STRTAB, 0x0, 0x0, 0x1468, 0x206, 0x0, 0x0, 0x1, 0x0}, + {"", SHT_NULL, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, + {".interp", SHT_PROGBITS, SHF_ALLOC, 0x80480d4, 0xd4, 0x15, 0x0, 0x0, 0x1, 0x0, 0x15}, + {".hash", SHT_HASH, SHF_ALLOC, 0x80480ec, 0xec, 0x90, 0x3, 0x0, 0x4, 0x4, 0x90}, + {".dynsym", SHT_DYNSYM, SHF_ALLOC, 0x804817c, 0x17c, 0x110, 0x4, 0x1, 0x4, 0x10, 0x110}, + {".dynstr", SHT_STRTAB, SHF_ALLOC, 0x804828c, 0x28c, 0xbb, 0x0, 0x0, 0x1, 0x0, 0xbb}, + {".rel.plt", SHT_REL, SHF_ALLOC, 0x8048348, 0x348, 0x20, 0x3, 0x7, 0x4, 0x8, 0x20}, + {".init", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x8048368, 0x368, 0x11, 0x0, 0x0, 0x4, 0x0, 0x11}, + {".plt", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x804837c, 0x37c, 0x50, 0x0, 0x0, 0x4, 0x4, 0x50}, + {".text", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x80483cc, 0x3cc, 0x180, 0x0, 0x0, 0x4, 0x0, 0x180}, + {".fini", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x804854c, 0x54c, 0xc, 0x0, 0x0, 0x4, 0x0, 0xc}, + {".rodata", SHT_PROGBITS, SHF_ALLOC, 0x8048558, 0x558, 0xa3, 0x0, 0x0, 0x1, 0x0, 0xa3}, + {".data", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80495fc, 0x5fc, 0xc, 0x0, 0x0, 0x4, 0x0, 0xc}, + {".eh_frame", SHT_PROGBITS, SHF_ALLOC, 0x8049608, 0x608, 0x4, 0x0, 0x0, 0x4, 0x0, 0x4}, + {".dynamic", SHT_DYNAMIC, SHF_WRITE + SHF_ALLOC, 0x804960c, 0x60c, 0x98, 0x4, 0x0, 0x4, 0x8, 0x98}, + {".ctors", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80496a4, 0x6a4, 0x8, 0x0, 0x0, 0x4, 0x0, 0x8}, + {".dtors", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80496ac, 0x6ac, 0x8, 0x0, 0x0, 0x4, 0x0, 0x8}, + {".jcr", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80496b4, 0x6b4, 0x4, 0x0, 0x0, 0x4, 0x0, 0x4}, + {".got", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x80496b8, 0x6b8, 0x1c, 0x0, 0x0, 0x4, 0x4, 0x1c}, + {".bss", SHT_NOBITS, SHF_WRITE + SHF_ALLOC, 0x80496d4, 0x6d4, 0x20, 0x0, 0x0, 0x4, 0x0, 0x20}, + {".comment", SHT_PROGBITS, 0x0, 0x0, 0x6d4, 0x12d, 0x0, 0x0, 0x1, 0x0, 0x12d}, + {".debug_aranges", SHT_PROGBITS, 0x0, 0x0, 0x801, 0x20, 0x0, 0x0, 0x1, 0x0, 0x20}, + {".debug_pubnames", SHT_PROGBITS, 0x0, 0x0, 0x821, 0x1b, 0x0, 0x0, 0x1, 0x0, 0x1b}, + {".debug_info", SHT_PROGBITS, 0x0, 0x0, 0x83c, 0x11d, 0x0, 0x0, 0x1, 0x0, 0x11d}, + {".debug_abbrev", SHT_PROGBITS, 0x0, 0x0, 0x959, 0x41, 0x0, 0x0, 0x1, 0x0, 0x41}, + {".debug_line", SHT_PROGBITS, 0x0, 0x0, 0x99a, 0x35, 0x0, 0x0, 0x1, 0x0, 0x35}, + {".debug_frame", SHT_PROGBITS, 0x0, 0x0, 0x9d0, 0x30, 0x0, 0x0, 0x4, 0x0, 0x30}, + {".debug_str", SHT_PROGBITS, 0x0, 0x0, 0xa00, 0xd, 0x0, 0x0, 0x1, 0x0, 0xd}, + {".shstrtab", SHT_STRTAB, 0x0, 0x0, 0xa0d, 0xf8, 0x0, 0x0, 0x1, 0x0, 0xf8}, + {".symtab", SHT_SYMTAB, 0x0, 0x0, 0xfb8, 0x4b0, 0x1d, 0x38, 0x4, 0x10, 0x4b0}, + {".strtab", SHT_STRTAB, 0x0, 0x0, 0x1468, 0x206, 0x0, 0x0, 0x1, 0x0, 0x206}, }, []ProgHeader{ {PT_PHDR, PF_R + PF_X, 0x34, 0x8048034, 0x8048034, 0xa0, 0xa0, 0x4}, @@ -75,43 +76,43 @@ var fileTests = []fileTest{ "testdata/gcc-amd64-linux-exec", FileHeader{ELFCLASS64, ELFDATA2LSB, EV_CURRENT, ELFOSABI_NONE, 0, binary.LittleEndian, ET_EXEC, EM_X86_64, 0x4003e0}, []SectionHeader{ - {"", SHT_NULL, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, - {".interp", SHT_PROGBITS, SHF_ALLOC, 0x400200, 0x200, 0x1c, 0x0, 0x0, 0x1, 0x0}, - {".note.ABI-tag", SHT_NOTE, SHF_ALLOC, 0x40021c, 0x21c, 0x20, 0x0, 0x0, 0x4, 0x0}, - {".hash", SHT_HASH, SHF_ALLOC, 0x400240, 0x240, 0x24, 0x5, 0x0, 0x8, 0x4}, - {".gnu.hash", SHT_LOOS + 268435446, SHF_ALLOC, 0x400268, 0x268, 0x1c, 0x5, 0x0, 0x8, 0x0}, - {".dynsym", SHT_DYNSYM, SHF_ALLOC, 0x400288, 0x288, 0x60, 0x6, 0x1, 0x8, 0x18}, - {".dynstr", SHT_STRTAB, SHF_ALLOC, 0x4002e8, 0x2e8, 0x3d, 0x0, 0x0, 0x1, 0x0}, - {".gnu.version", SHT_HIOS, SHF_ALLOC, 0x400326, 0x326, 0x8, 0x5, 0x0, 0x2, 0x2}, - {".gnu.version_r", SHT_LOOS + 268435454, SHF_ALLOC, 0x400330, 0x330, 0x20, 0x6, 0x1, 0x8, 0x0}, - {".rela.dyn", SHT_RELA, SHF_ALLOC, 0x400350, 0x350, 0x18, 0x5, 0x0, 0x8, 0x18}, - {".rela.plt", SHT_RELA, SHF_ALLOC, 0x400368, 0x368, 0x30, 0x5, 0xc, 0x8, 0x18}, - {".init", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x400398, 0x398, 0x18, 0x0, 0x0, 0x4, 0x0}, - {".plt", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x4003b0, 0x3b0, 0x30, 0x0, 0x0, 0x4, 0x10}, - {".text", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x4003e0, 0x3e0, 0x1b4, 0x0, 0x0, 0x10, 0x0}, - {".fini", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x400594, 0x594, 0xe, 0x0, 0x0, 0x4, 0x0}, - {".rodata", SHT_PROGBITS, SHF_ALLOC, 0x4005a4, 0x5a4, 0x11, 0x0, 0x0, 0x4, 0x0}, - {".eh_frame_hdr", SHT_PROGBITS, SHF_ALLOC, 0x4005b8, 0x5b8, 0x24, 0x0, 0x0, 0x4, 0x0}, - {".eh_frame", SHT_PROGBITS, SHF_ALLOC, 0x4005e0, 0x5e0, 0xa4, 0x0, 0x0, 0x8, 0x0}, - {".ctors", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600688, 0x688, 0x10, 0x0, 0x0, 0x8, 0x0}, - {".dtors", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600698, 0x698, 0x10, 0x0, 0x0, 0x8, 0x0}, - {".jcr", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x6006a8, 0x6a8, 0x8, 0x0, 0x0, 0x8, 0x0}, - {".dynamic", SHT_DYNAMIC, SHF_WRITE + SHF_ALLOC, 0x6006b0, 0x6b0, 0x1a0, 0x6, 0x0, 0x8, 0x10}, - {".got", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600850, 0x850, 0x8, 0x0, 0x0, 0x8, 0x8}, - {".got.plt", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600858, 0x858, 0x28, 0x0, 0x0, 0x8, 0x8}, - {".data", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600880, 0x880, 0x18, 0x0, 0x0, 0x8, 0x0}, - {".bss", SHT_NOBITS, SHF_WRITE + SHF_ALLOC, 0x600898, 0x898, 0x8, 0x0, 0x0, 0x4, 0x0}, - {".comment", SHT_PROGBITS, 0x0, 0x0, 0x898, 0x126, 0x0, 0x0, 0x1, 0x0}, - {".debug_aranges", SHT_PROGBITS, 0x0, 0x0, 0x9c0, 0x90, 0x0, 0x0, 0x10, 0x0}, - {".debug_pubnames", SHT_PROGBITS, 0x0, 0x0, 0xa50, 0x25, 0x0, 0x0, 0x1, 0x0}, - {".debug_info", SHT_PROGBITS, 0x0, 0x0, 0xa75, 0x1a7, 0x0, 0x0, 0x1, 0x0}, - {".debug_abbrev", SHT_PROGBITS, 0x0, 0x0, 0xc1c, 0x6f, 0x0, 0x0, 0x1, 0x0}, - {".debug_line", SHT_PROGBITS, 0x0, 0x0, 0xc8b, 0x13f, 0x0, 0x0, 0x1, 0x0}, - {".debug_str", SHT_PROGBITS, SHF_MERGE + SHF_STRINGS, 0x0, 0xdca, 0xb1, 0x0, 0x0, 0x1, 0x1}, - {".debug_ranges", SHT_PROGBITS, 0x0, 0x0, 0xe80, 0x90, 0x0, 0x0, 0x10, 0x0}, - {".shstrtab", SHT_STRTAB, 0x0, 0x0, 0xf10, 0x149, 0x0, 0x0, 0x1, 0x0}, - {".symtab", SHT_SYMTAB, 0x0, 0x0, 0x19a0, 0x6f0, 0x24, 0x39, 0x8, 0x18}, - {".strtab", SHT_STRTAB, 0x0, 0x0, 0x2090, 0x1fc, 0x0, 0x0, 0x1, 0x0}, + {"", SHT_NULL, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, + {".interp", SHT_PROGBITS, SHF_ALLOC, 0x400200, 0x200, 0x1c, 0x0, 0x0, 0x1, 0x0, 0x1c}, + {".note.ABI-tag", SHT_NOTE, SHF_ALLOC, 0x40021c, 0x21c, 0x20, 0x0, 0x0, 0x4, 0x0, 0x20}, + {".hash", SHT_HASH, SHF_ALLOC, 0x400240, 0x240, 0x24, 0x5, 0x0, 0x8, 0x4, 0x24}, + {".gnu.hash", SHT_LOOS + 268435446, SHF_ALLOC, 0x400268, 0x268, 0x1c, 0x5, 0x0, 0x8, 0x0, 0x1c}, + {".dynsym", SHT_DYNSYM, SHF_ALLOC, 0x400288, 0x288, 0x60, 0x6, 0x1, 0x8, 0x18, 0x60}, + {".dynstr", SHT_STRTAB, SHF_ALLOC, 0x4002e8, 0x2e8, 0x3d, 0x0, 0x0, 0x1, 0x0, 0x3d}, + {".gnu.version", SHT_HIOS, SHF_ALLOC, 0x400326, 0x326, 0x8, 0x5, 0x0, 0x2, 0x2, 0x8}, + {".gnu.version_r", SHT_LOOS + 268435454, SHF_ALLOC, 0x400330, 0x330, 0x20, 0x6, 0x1, 0x8, 0x0, 0x20}, + {".rela.dyn", SHT_RELA, SHF_ALLOC, 0x400350, 0x350, 0x18, 0x5, 0x0, 0x8, 0x18, 0x18}, + {".rela.plt", SHT_RELA, SHF_ALLOC, 0x400368, 0x368, 0x30, 0x5, 0xc, 0x8, 0x18, 0x30}, + {".init", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x400398, 0x398, 0x18, 0x0, 0x0, 0x4, 0x0, 0x18}, + {".plt", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x4003b0, 0x3b0, 0x30, 0x0, 0x0, 0x4, 0x10, 0x30}, + {".text", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x4003e0, 0x3e0, 0x1b4, 0x0, 0x0, 0x10, 0x0, 0x1b4}, + {".fini", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR, 0x400594, 0x594, 0xe, 0x0, 0x0, 0x4, 0x0, 0xe}, + {".rodata", SHT_PROGBITS, SHF_ALLOC, 0x4005a4, 0x5a4, 0x11, 0x0, 0x0, 0x4, 0x0, 0x11}, + {".eh_frame_hdr", SHT_PROGBITS, SHF_ALLOC, 0x4005b8, 0x5b8, 0x24, 0x0, 0x0, 0x4, 0x0, 0x24}, + {".eh_frame", SHT_PROGBITS, SHF_ALLOC, 0x4005e0, 0x5e0, 0xa4, 0x0, 0x0, 0x8, 0x0, 0xa4}, + {".ctors", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600688, 0x688, 0x10, 0x0, 0x0, 0x8, 0x0, 0x10}, + {".dtors", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600698, 0x698, 0x10, 0x0, 0x0, 0x8, 0x0, 0x10}, + {".jcr", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x6006a8, 0x6a8, 0x8, 0x0, 0x0, 0x8, 0x0, 0x8}, + {".dynamic", SHT_DYNAMIC, SHF_WRITE + SHF_ALLOC, 0x6006b0, 0x6b0, 0x1a0, 0x6, 0x0, 0x8, 0x10, 0x1a0}, + {".got", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600850, 0x850, 0x8, 0x0, 0x0, 0x8, 0x8, 0x8}, + {".got.plt", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600858, 0x858, 0x28, 0x0, 0x0, 0x8, 0x8, 0x28}, + {".data", SHT_PROGBITS, SHF_WRITE + SHF_ALLOC, 0x600880, 0x880, 0x18, 0x0, 0x0, 0x8, 0x0, 0x18}, + {".bss", SHT_NOBITS, SHF_WRITE + SHF_ALLOC, 0x600898, 0x898, 0x8, 0x0, 0x0, 0x4, 0x0, 0x8}, + {".comment", SHT_PROGBITS, 0x0, 0x0, 0x898, 0x126, 0x0, 0x0, 0x1, 0x0, 0x126}, + {".debug_aranges", SHT_PROGBITS, 0x0, 0x0, 0x9c0, 0x90, 0x0, 0x0, 0x10, 0x0, 0x90}, + {".debug_pubnames", SHT_PROGBITS, 0x0, 0x0, 0xa50, 0x25, 0x0, 0x0, 0x1, 0x0, 0x25}, + {".debug_info", SHT_PROGBITS, 0x0, 0x0, 0xa75, 0x1a7, 0x0, 0x0, 0x1, 0x0, 0x1a7}, + {".debug_abbrev", SHT_PROGBITS, 0x0, 0x0, 0xc1c, 0x6f, 0x0, 0x0, 0x1, 0x0, 0x6f}, + {".debug_line", SHT_PROGBITS, 0x0, 0x0, 0xc8b, 0x13f, 0x0, 0x0, 0x1, 0x0, 0x13f}, + {".debug_str", SHT_PROGBITS, SHF_MERGE + SHF_STRINGS, 0x0, 0xdca, 0xb1, 0x0, 0x0, 0x1, 0x1, 0xb1}, + {".debug_ranges", SHT_PROGBITS, 0x0, 0x0, 0xe80, 0x90, 0x0, 0x0, 0x10, 0x0, 0x90}, + {".shstrtab", SHT_STRTAB, 0x0, 0x0, 0xf10, 0x149, 0x0, 0x0, 0x1, 0x0, 0x149}, + {".symtab", SHT_SYMTAB, 0x0, 0x0, 0x19a0, 0x6f0, 0x24, 0x39, 0x8, 0x18, 0x6f0}, + {".strtab", SHT_STRTAB, 0x0, 0x0, 0x2090, 0x1fc, 0x0, 0x0, 0x1, 0x0, 0x1fc}, }, []ProgHeader{ {PT_PHDR, PF_R + PF_X, 0x40, 0x400040, 0x400040, 0x1c0, 0x1c0, 0x8}, @@ -150,6 +151,64 @@ var fileTests = []fileTest{ }, nil, }, + { + "testdata/compressed-32.obj", + FileHeader{ELFCLASS32, ELFDATA2LSB, EV_CURRENT, ELFOSABI_NONE, 0x0, binary.LittleEndian, ET_REL, EM_386, 0x0}, + []SectionHeader{ + {"", SHT_NULL, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, + {".text", SHT_PROGBITS, SHF_ALLOC | SHF_EXECINSTR, 0x0, 0x34, 0x17, 0x0, 0x0, 0x1, 0x0, 0x17}, + {".rel.text", SHT_REL, SHF_INFO_LINK, 0x0, 0x3dc, 0x10, 0x13, 0x1, 0x4, 0x8, 0x10}, + {".data", SHT_PROGBITS, SHF_WRITE | SHF_ALLOC, 0x0, 0x4b, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0}, + {".bss", SHT_NOBITS, SHF_WRITE | SHF_ALLOC, 0x0, 0x4b, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0}, + {".rodata", SHT_PROGBITS, SHF_ALLOC, 0x0, 0x4b, 0xd, 0x0, 0x0, 0x1, 0x0, 0xd}, + {".debug_info", SHT_PROGBITS, SHF_COMPRESSED, 0x0, 0x58, 0xb4, 0x0, 0x0, 0x1, 0x0, 0x84}, + {".rel.debug_info", SHT_REL, SHF_INFO_LINK, 0x0, 0x3ec, 0xa0, 0x13, 0x6, 0x4, 0x8, 0xa0}, + {".debug_abbrev", SHT_PROGBITS, 0x0, 0x0, 0xdc, 0x5a, 0x0, 0x0, 0x1, 0x0, 0x5a}, + {".debug_aranges", SHT_PROGBITS, 0x0, 0x0, 0x136, 0x20, 0x0, 0x0, 0x1, 0x0, 0x20}, + {".rel.debug_aranges", SHT_REL, SHF_INFO_LINK, 0x0, 0x48c, 0x10, 0x13, 0x9, 0x4, 0x8, 0x10}, + {".debug_line", SHT_PROGBITS, 0x0, 0x0, 0x156, 0x5c, 0x0, 0x0, 0x1, 0x0, 0x5c}, + {".rel.debug_line", SHT_REL, SHF_INFO_LINK, 0x0, 0x49c, 0x8, 0x13, 0xb, 0x4, 0x8, 0x8}, + {".debug_str", SHT_PROGBITS, SHF_MERGE | SHF_STRINGS | SHF_COMPRESSED, 0x0, 0x1b2, 0x10f, 0x0, 0x0, 0x1, 0x1, 0xb3}, + {".comment", SHT_PROGBITS, SHF_MERGE | SHF_STRINGS, 0x0, 0x265, 0x2a, 0x0, 0x0, 0x1, 0x1, 0x2a}, + {".note.GNU-stack", SHT_PROGBITS, 0x0, 0x0, 0x28f, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0}, + {".eh_frame", SHT_PROGBITS, SHF_ALLOC, 0x0, 0x290, 0x38, 0x0, 0x0, 0x4, 0x0, 0x38}, + {".rel.eh_frame", SHT_REL, SHF_INFO_LINK, 0x0, 0x4a4, 0x8, 0x13, 0x10, 0x4, 0x8, 0x8}, + {".shstrtab", SHT_STRTAB, 0x0, 0x0, 0x4ac, 0xab, 0x0, 0x0, 0x1, 0x0, 0xab}, + {".symtab", SHT_SYMTAB, 0x0, 0x0, 0x2c8, 0x100, 0x14, 0xe, 0x4, 0x10, 0x100}, + {".strtab", SHT_STRTAB, 0x0, 0x0, 0x3c8, 0x13, 0x0, 0x0, 0x1, 0x0, 0x13}, + }, + []ProgHeader{}, + nil, + }, + { + "testdata/compressed-64.obj", + FileHeader{ELFCLASS64, ELFDATA2LSB, EV_CURRENT, ELFOSABI_NONE, 0x0, binary.LittleEndian, ET_REL, EM_X86_64, 0x0}, + []SectionHeader{ + {"", SHT_NULL, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, + {".text", SHT_PROGBITS, SHF_ALLOC | SHF_EXECINSTR, 0x0, 0x40, 0x1b, 0x0, 0x0, 0x1, 0x0, 0x1b}, + {".rela.text", SHT_RELA, SHF_INFO_LINK, 0x0, 0x488, 0x30, 0x13, 0x1, 0x8, 0x18, 0x30}, + {".data", SHT_PROGBITS, SHF_WRITE | SHF_ALLOC, 0x0, 0x5b, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0}, + {".bss", SHT_NOBITS, SHF_WRITE | SHF_ALLOC, 0x0, 0x5b, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0}, + {".rodata", SHT_PROGBITS, SHF_ALLOC, 0x0, 0x5b, 0xd, 0x0, 0x0, 0x1, 0x0, 0xd}, + {".debug_info", SHT_PROGBITS, SHF_COMPRESSED, 0x0, 0x68, 0xba, 0x0, 0x0, 0x1, 0x0, 0x72}, + {".rela.debug_info", SHT_RELA, SHF_INFO_LINK, 0x0, 0x4b8, 0x1c8, 0x13, 0x6, 0x8, 0x18, 0x1c8}, + {".debug_abbrev", SHT_PROGBITS, 0x0, 0x0, 0xda, 0x5c, 0x0, 0x0, 0x1, 0x0, 0x5c}, + {".debug_aranges", SHT_PROGBITS, SHF_COMPRESSED, 0x0, 0x136, 0x30, 0x0, 0x0, 0x1, 0x0, 0x2f}, + {".rela.debug_aranges", SHT_RELA, SHF_INFO_LINK, 0x0, 0x680, 0x30, 0x13, 0x9, 0x8, 0x18, 0x30}, + {".debug_line", SHT_PROGBITS, 0x0, 0x0, 0x165, 0x60, 0x0, 0x0, 0x1, 0x0, 0x60}, + {".rela.debug_line", SHT_RELA, SHF_INFO_LINK, 0x0, 0x6b0, 0x18, 0x13, 0xb, 0x8, 0x18, 0x18}, + {".debug_str", SHT_PROGBITS, SHF_MERGE | SHF_STRINGS | SHF_COMPRESSED, 0x0, 0x1c5, 0x104, 0x0, 0x0, 0x1, 0x1, 0xc3}, + {".comment", SHT_PROGBITS, SHF_MERGE | SHF_STRINGS, 0x0, 0x288, 0x2a, 0x0, 0x0, 0x1, 0x1, 0x2a}, + {".note.GNU-stack", SHT_PROGBITS, 0x0, 0x0, 0x2b2, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0}, + {".eh_frame", SHT_PROGBITS, SHF_ALLOC, 0x0, 0x2b8, 0x38, 0x0, 0x0, 0x8, 0x0, 0x38}, + {".rela.eh_frame", SHT_RELA, SHF_INFO_LINK, 0x0, 0x6c8, 0x18, 0x13, 0x10, 0x8, 0x18, 0x18}, + {".shstrtab", SHT_STRTAB, 0x0, 0x0, 0x6e0, 0xb0, 0x0, 0x0, 0x1, 0x0, 0xb0}, + {".symtab", SHT_SYMTAB, 0x0, 0x0, 0x2f0, 0x180, 0x14, 0xe, 0x8, 0x18, 0x180}, + {".strtab", SHT_STRTAB, 0x0, 0x0, 0x470, 0x13, 0x0, 0x0, 0x1, 0x0, 0x13}, + }, + []ProgHeader{}, + nil, + }, } func TestOpen(t *testing.T) { @@ -542,6 +601,91 @@ func TestCompressedDWARF(t *testing.T) { } } +func TestCompressedSection(t *testing.T) { + // Test files built with gcc -g -S hello.c and assembled with + // --compress-debug-sections=zlib-gabi. + f, err := Open("testdata/compressed-64.obj") + if err != nil { + t.Fatal(err) + } + sec := f.Section(".debug_info") + wantData := []byte{ + 182, 0, 0, 0, 4, 0, 0, 0, 0, 0, 8, 1, 0, 0, 0, 0, + 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 27, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 8, 7, + 0, 0, 0, 0, 2, 1, 8, 0, 0, 0, 0, 2, 2, 7, 0, 0, + 0, 0, 2, 4, 7, 0, 0, 0, 0, 2, 1, 6, 0, 0, 0, 0, + 2, 2, 5, 0, 0, 0, 0, 3, 4, 5, 105, 110, 116, 0, 2, 8, + 5, 0, 0, 0, 0, 2, 8, 7, 0, 0, 0, 0, 4, 8, 114, 0, + 0, 0, 2, 1, 6, 0, 0, 0, 0, 5, 0, 0, 0, 0, 1, 4, + 0, 0, 0, 0, 0, 0, 0, 0, 27, 0, 0, 0, 0, 0, 0, 0, + 1, 156, 179, 0, 0, 0, 6, 0, 0, 0, 0, 1, 4, 87, 0, 0, + 0, 2, 145, 108, 6, 0, 0, 0, 0, 1, 4, 179, 0, 0, 0, 2, + 145, 96, 0, 4, 8, 108, 0, 0, 0, 0, + } + + // Test Data method. + b, err := sec.Data() + if err != nil { + t.Fatal(err) + } + if !bytes.Equal(wantData, b) { + t.Fatalf("want data %x, got %x", wantData, b) + } + + // Test Open method and seeking. + buf, have, count := make([]byte, len(b)), make([]bool, len(b)), 0 + sf := sec.Open() + if got, err := sf.Seek(0, 2); got != int64(len(b)) || err != nil { + t.Fatalf("want seek end %d, got %d error %v", len(b), got, err) + } + if n, err := sf.Read(buf); n != 0 || err != io.EOF { + t.Fatalf("want EOF with 0 bytes, got %v with %d bytes", err, n) + } + pos := int64(len(buf)) + for count < len(buf) { + // Construct random seek arguments. + whence := rand.Intn(3) + target := rand.Int63n(int64(len(buf))) + var offset int64 + switch whence { + case 0: + offset = target + case 1: + offset = target - pos + case 2: + offset = target - int64(len(buf)) + } + pos, err = sf.Seek(offset, whence) + if err != nil { + t.Fatal(err) + } + if pos != target { + t.Fatalf("want position %d, got %d", target, pos) + } + + // Read data from the new position. + end := pos + 16 + if end > int64(len(buf)) { + end = int64(len(buf)) + } + n, err := sf.Read(buf[pos:end]) + if err != nil { + t.Fatal(err) + } + for i := 0; i < n; i++ { + if !have[pos] { + have[pos] = true + count++ + } + pos++ + } + } + if !bytes.Equal(wantData, buf) { + t.Fatalf("want data %x, got %x", wantData, buf) + } +} + func TestNoSectionOverlaps(t *testing.T) { // Ensure 6l outputs sections without overlaps. if runtime.GOOS != "linux" && runtime.GOOS != "freebsd" { diff --git a/src/debug/elf/reader.go b/src/debug/elf/reader.go new file mode 100644 index 0000000000..17b57165bc --- /dev/null +++ b/src/debug/elf/reader.go @@ -0,0 +1,108 @@ +// Copyright 2015 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 elf + +import ( + "io" + "os" +) + +// errorReader returns error from all operations. +type errorReader struct { + error +} + +func (r errorReader) Read(p []byte) (n int, err error) { + return 0, r.error +} + +func (r errorReader) ReadAt(p []byte, off int64) (n int, err error) { + return 0, r.error +} + +func (r errorReader) Seek(offset int64, whence int) (int64, error) { + return 0, r.error +} + +func (r errorReader) Close() error { + return r.error +} + +// readSeekerFromReader converts an io.Reader into an io.ReadSeeker. +// In general Seek may not be efficient, but it is optimized for +// common cases such as seeking to the end to find the length of the +// data. +type readSeekerFromReader struct { + reset func() (io.Reader, error) + r io.Reader + size int64 + offset int64 +} + +func (r *readSeekerFromReader) start() { + x, err := r.reset() + if err != nil { + r.r = errorReader{err} + } else { + r.r = x + } + r.offset = 0 +} + +func (r *readSeekerFromReader) Read(p []byte) (n int, err error) { + if r.r == nil { + r.start() + } + n, err = r.r.Read(p) + r.offset += int64(n) + return n, err +} + +func (r *readSeekerFromReader) Seek(offset int64, whence int) (int64, error) { + var newOffset int64 + switch whence { + case 0: + newOffset = offset + case 1: + newOffset = r.offset + offset + case 2: + newOffset = r.size + offset + default: + return 0, os.ErrInvalid + } + + switch { + case newOffset == r.offset: + return newOffset, nil + + case newOffset < 0, newOffset > r.size: + return 0, os.ErrInvalid + + case newOffset == 0: + r.r = nil + + case newOffset == r.size: + r.r = errorReader{io.EOF} + + default: + if newOffset < r.offset { + // Restart at the beginning. + r.start() + } + // Read until we reach offset. + var buf [512]byte + for r.offset < newOffset { + b := buf[:] + if newOffset-r.offset < int64(len(buf)) { + b = buf[:newOffset-r.offset] + } + if _, err := r.Read(b); err != nil { + return 0, err + } + } + } + r.offset = newOffset + return r.offset, nil +} diff --git a/src/debug/elf/testdata/compressed-32.obj b/src/debug/elf/testdata/compressed-32.obj new file mode 100644 index 0000000000..2bfdb44240 Binary files /dev/null and b/src/debug/elf/testdata/compressed-32.obj differ diff --git a/src/debug/elf/testdata/compressed-64.obj b/src/debug/elf/testdata/compressed-64.obj new file mode 100644 index 0000000000..ffae56a931 Binary files /dev/null and b/src/debug/elf/testdata/compressed-64.obj differ