Commit 26119179 authored by Russ Cox's avatar Russ Cox

cmd/go: fix loading of buildid on OS X executables

This is a bit of a belt-and-suspenders fix.
On OS X, we now parse the Mach-O file to find the __text section,
which is arguably the more proper fix. But it's a bit worrisome to
depend on a name like __text not changing, so we also read more
of the initial file (now 32 kB, up from 8 kB) and scan that too.

Fixes #12327.

Change-Id: I3a201a3dc278d24707109bb3961c3bdd8b8a0b7b
Reviewed-on: https://go-review.googlesource.com/17038Reviewed-by: 's avatarIan Lance Taylor <iant@golang.org>
parent 3ea668a0
...@@ -10,6 +10,7 @@ var builddeps = map[string][]string{ ...@@ -10,6 +10,7 @@ var builddeps = map[string][]string{
"crypto/sha1": {"crypto", "errors", "hash", "io", "math", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strconv", "sync", "sync/atomic", "unicode/utf8"}, "crypto/sha1": {"crypto", "errors", "hash", "io", "math", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strconv", "sync", "sync/atomic", "unicode/utf8"},
"debug/dwarf": {"encoding/binary", "errors", "fmt", "internal/syscall/windows", "internal/syscall/windows/registry", "io", "math", "os", "path", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"}, "debug/dwarf": {"encoding/binary", "errors", "fmt", "internal/syscall/windows", "internal/syscall/windows/registry", "io", "math", "os", "path", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
"debug/elf": {"bytes", "debug/dwarf", "encoding/binary", "errors", "fmt", "internal/syscall/windows", "internal/syscall/windows/registry", "io", "math", "os", "path", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"}, "debug/elf": {"bytes", "debug/dwarf", "encoding/binary", "errors", "fmt", "internal/syscall/windows", "internal/syscall/windows/registry", "io", "math", "os", "path", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
"debug/macho": {"bytes", "debug/dwarf", "encoding/binary", "errors", "fmt", "internal/syscall/windows", "internal/syscall/windows/registry", "io", "math", "os", "path", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
"encoding": {"runtime", "runtime/internal/atomic", "runtime/internal/sys"}, "encoding": {"runtime", "runtime/internal/atomic", "runtime/internal/sys"},
"encoding/base64": {"errors", "io", "math", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strconv", "sync", "sync/atomic", "unicode/utf8"}, "encoding/base64": {"errors", "io", "math", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strconv", "sync", "sync/atomic", "unicode/utf8"},
"encoding/binary": {"errors", "io", "math", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strconv", "sync", "sync/atomic", "unicode/utf8"}, "encoding/binary": {"errors", "io", "math", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strconv", "sync", "sync/atomic", "unicode/utf8"},
...@@ -55,5 +56,5 @@ var builddeps = map[string][]string{ ...@@ -55,5 +56,5 @@ var builddeps = map[string][]string{
"unicode": {"runtime", "runtime/internal/atomic", "runtime/internal/sys"}, "unicode": {"runtime", "runtime/internal/atomic", "runtime/internal/sys"},
"unicode/utf16": {"runtime", "runtime/internal/atomic", "runtime/internal/sys"}, "unicode/utf16": {"runtime", "runtime/internal/atomic", "runtime/internal/sys"},
"unicode/utf8": {"runtime", "runtime/internal/atomic", "runtime/internal/sys"}, "unicode/utf8": {"runtime", "runtime/internal/atomic", "runtime/internal/sys"},
"cmd/go": {"bufio", "bytes", "container/heap", "crypto", "crypto/sha1", "debug/dwarf", "debug/elf", "encoding", "encoding/base64", "encoding/binary", "encoding/json", "errors", "flag", "fmt", "go/ast", "go/build", "go/doc", "go/parser", "go/scanner", "go/token", "hash", "internal/singleflight", "internal/syscall/windows", "internal/syscall/windows/registry", "io", "io/ioutil", "log", "math", "net/url", "os", "os/exec", "os/signal", "path", "path/filepath", "reflect", "regexp", "regexp/syntax", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "text/template", "text/template/parse", "time", "unicode", "unicode/utf16", "unicode/utf8"}, "cmd/go": {"bufio", "bytes", "container/heap", "crypto", "crypto/sha1", "debug/dwarf", "debug/elf", "debug/macho", "encoding", "encoding/base64", "encoding/binary", "encoding/json", "errors", "flag", "fmt", "go/ast", "go/build", "go/doc", "go/parser", "go/scanner", "go/token", "hash", "internal/singleflight", "internal/syscall/windows", "internal/syscall/windows/registry", "io", "io/ioutil", "log", "math", "net/url", "os", "os/exec", "os/signal", "path", "path/filepath", "reflect", "regexp", "regexp/syntax", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "text/template", "text/template/parse", "time", "unicode", "unicode/utf16", "unicode/utf8"},
} }
...@@ -7,6 +7,7 @@ package main ...@@ -7,6 +7,7 @@ package main
import ( import (
"bytes" "bytes"
"debug/elf" "debug/elf"
"debug/macho"
"encoding/binary" "encoding/binary"
"fmt" "fmt"
"io" "io"
...@@ -134,3 +135,42 @@ func readELFGoBuildID(filename string, f *os.File, data []byte) (buildid string, ...@@ -134,3 +135,42 @@ func readELFGoBuildID(filename string, f *os.File, data []byte) (buildid string,
// No note. Treat as successful but build ID empty. // No note. Treat as successful but build ID empty.
return "", nil return "", nil
} }
// The Go build ID is stored at the beginning of the Mach-O __text segment.
// The caller has already opened filename, to get f, and read a few kB out, in data.
// Sadly, that's not guaranteed to hold the note, because there is an arbitrary amount
// of other junk placed in the file ahead of the main text.
func readMachoGoBuildID(filename string, f *os.File, data []byte) (buildid string, err error) {
// If the data we want has already been read, don't worry about Mach-O parsing.
// This is both an optimization and a hedge against the Mach-O parsing failing
// in the future due to, for example, the name of the __text section changing.
if b, err := readRawGoBuildID(filename, data); b != "" && err == nil {
return b, err
}
mf, err := macho.NewFile(f)
if err != nil {
return "", &os.PathError{Path: filename, Op: "parse", Err: err}
}
sect := mf.Section("__text")
if sect == nil {
// Every binary has a __text section. Something is wrong.
return "", &os.PathError{Path: filename, Op: "parse", Err: fmt.Errorf("cannot find __text section")}
}
// It should be in the first few bytes, but read a lot just in case,
// especially given our past problems on OS X with the build ID moving.
// There shouldn't be much difference between reading 4kB and 32kB:
// the hard part is getting to the data, not transferring it.
n := sect.Size
if n > uint64(BuildIDReadSize) {
n = uint64(BuildIDReadSize)
}
buf := make([]byte, n)
if _, err := f.ReadAt(buf, int64(sect.Offset)); err != nil {
return "", err
}
return readRawGoBuildID(filename, buf)
}
...@@ -11,6 +11,20 @@ import ( ...@@ -11,6 +11,20 @@ import (
) )
func TestNoteReading(t *testing.T) { func TestNoteReading(t *testing.T) {
testNoteReading(t)
}
func TestNoteReading2K(t *testing.T) {
// Set BuildIDReadSize to 2kB to exercise Mach-O parsing more strictly.
defer func(old int) {
main.BuildIDReadSize = old
}(main.BuildIDReadSize)
main.BuildIDReadSize = 2 * 1024
testNoteReading(t)
}
func testNoteReading(t *testing.T) {
tg := testgo(t) tg := testgo(t)
defer tg.cleanup() defer tg.cleanup()
tg.tempFile("hello.go", `package main; func main() { print("hello, world\n") }`) tg.tempFile("hello.go", `package main; func main() { print("hello, world\n") }`)
......
...@@ -1799,8 +1799,17 @@ var ( ...@@ -1799,8 +1799,17 @@ var (
goBuildEnd = []byte("\"\n \xff") goBuildEnd = []byte("\"\n \xff")
elfPrefix = []byte("\x7fELF") elfPrefix = []byte("\x7fELF")
machoPrefixes = [][]byte{
{0xfe, 0xed, 0xfa, 0xce},
{0xfe, 0xed, 0xfa, 0xcf},
{0xce, 0xfa, 0xed, 0xfe},
{0xcf, 0xfa, 0xed, 0xfe},
}
) )
var BuildIDReadSize = 32 * 1024 // changed for testing
// ReadBuildIDFromBinary reads the build ID from a binary. // ReadBuildIDFromBinary reads the build ID from a binary.
// //
// ELF binaries store the build ID in a proper PT_NOTE section. // ELF binaries store the build ID in a proper PT_NOTE section.
...@@ -1815,10 +1824,11 @@ func ReadBuildIDFromBinary(filename string) (id string, err error) { ...@@ -1815,10 +1824,11 @@ func ReadBuildIDFromBinary(filename string) (id string, err error) {
return "", &os.PathError{Op: "parse", Path: filename, Err: errBuildIDUnknown} return "", &os.PathError{Op: "parse", Path: filename, Err: errBuildIDUnknown}
} }
// Read the first 16 kB of the binary file. // Read the first 32 kB of the binary file.
// That should be enough to find the build ID. // That should be enough to find the build ID.
// In ELF files, the build ID is in the leading headers, // In ELF files, the build ID is in the leading headers,
// which are typically less than 4 kB, not to mention 16 kB. // which are typically less than 4 kB, not to mention 32 kB.
// In Mach-O files, there's no limit, so we have to parse the file.
// On other systems, we're trying to read enough that // On other systems, we're trying to read enough that
// we get the beginning of the text segment in the read. // we get the beginning of the text segment in the read.
// The offset where the text segment begins in a hello // The offset where the text segment begins in a hello
...@@ -1826,7 +1836,6 @@ func ReadBuildIDFromBinary(filename string) (id string, err error) { ...@@ -1826,7 +1836,6 @@ func ReadBuildIDFromBinary(filename string) (id string, err error) {
// //
// Plan 9: 0x20 // Plan 9: 0x20
// Windows: 0x600 // Windows: 0x600
// Mach-O: 0x2000
// //
f, err := os.Open(filename) f, err := os.Open(filename)
if err != nil { if err != nil {
...@@ -1834,7 +1843,7 @@ func ReadBuildIDFromBinary(filename string) (id string, err error) { ...@@ -1834,7 +1843,7 @@ func ReadBuildIDFromBinary(filename string) (id string, err error) {
} }
defer f.Close() defer f.Close()
data := make([]byte, 16*1024) data := make([]byte, BuildIDReadSize)
_, err = io.ReadFull(f, data) _, err = io.ReadFull(f, data)
if err == io.ErrUnexpectedEOF { if err == io.ErrUnexpectedEOF {
err = nil err = nil
...@@ -1846,7 +1855,17 @@ func ReadBuildIDFromBinary(filename string) (id string, err error) { ...@@ -1846,7 +1855,17 @@ func ReadBuildIDFromBinary(filename string) (id string, err error) {
if bytes.HasPrefix(data, elfPrefix) { if bytes.HasPrefix(data, elfPrefix) {
return readELFGoBuildID(filename, f, data) return readELFGoBuildID(filename, f, data)
} }
for _, m := range machoPrefixes {
if bytes.HasPrefix(data, m) {
return readMachoGoBuildID(filename, f, data)
}
}
return readRawGoBuildID(filename, data)
}
// readRawGoBuildID finds the raw build ID stored in text segment data.
func readRawGoBuildID(filename string, data []byte) (id string, err error) {
i := bytes.Index(data, goBuildPrefix) i := bytes.Index(data, goBuildPrefix)
if i < 0 { if i < 0 {
// Missing. Treat as successful but build ID empty. // Missing. Treat as successful but build ID empty.
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment