Frédéric G. MARAND
be1f9236e0
tl;dr: - Linux debugging works - macOS running works, debugging doesn't.
83 lines
2.1 KiB
Go
83 lines
2.1 KiB
Go
// Command dwarfcu lists the DWARF compile units of Mach-O and ELF files.
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//
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// It reads the compressed DWARF sections the Go linker produces,
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// which some platform tools, like macOS dwarfdump, do not decode.
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// Use it to check that a host program and its plugins carry debug information:
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//
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// go run ./tools/dwarfcu cmd/demo plugins/foo/foo.so
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package main
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import (
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"debug/dwarf"
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"debug/elf"
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"debug/macho"
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"fmt"
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"os"
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"strings"
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)
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// modulePath is this repository's module, whose plugins the tool reports.
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const modulePath = "code.osinet.fr/fgm/go_plugin_demo"
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func compileUnits(d *dwarf.Data) ([]string, error) {
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var cus []string
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r := d.Reader()
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for {
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e, err := r.Next()
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if err != nil {
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return cus, err
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}
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if e == nil {
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return cus, nil
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}
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if e.Tag == dwarf.TagCompileUnit {
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if name, ok := e.Val(dwarf.AttrName).(string); ok {
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cus = append(cus, name)
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}
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r.SkipChildren()
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}
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}
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}
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func main() {
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status := 0
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for _, path := range os.Args[1:] {
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d, err := openDWARF(path)
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if err != nil {
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fmt.Fprintf(os.Stderr, "%s: %v\n", path, err)
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status = 1
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continue
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}
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cus, err := compileUnits(d)
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if err != nil {
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fmt.Fprintf(os.Stderr, "%s: reading DWARF: %v\n", path, err)
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status = 1
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}
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// The shared package only declares a type, so it has no unit of its own:
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// the demo's code is in main and in each plugin.
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// A plugin built by package keeps its import path,
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// while one built from a file list is named plugin/unnamed-<hash>.
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var own []string
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for _, cu := range cus {
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if cu == "main" || strings.HasPrefix(cu, modulePath+"/") || strings.HasPrefix(cu, "plugin/unnamed-") {
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own = append(own, cu)
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}
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}
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fmt.Printf("%s: %d compile units, own: %v\n", path, len(cus), own)
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}
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os.Exit(status)
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}
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// openDWARF tries Mach-O first, then ELF, so the tool reads macOS and Linux builds alike.
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func openDWARF(path string) (*dwarf.Data, error) {
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if f, err := macho.Open(path); err == nil {
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defer f.Close()
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return f.DWARF()
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}
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f, err := elf.Open(path)
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if err != nil {
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return nil, fmt.Errorf("neither Mach-O nor ELF: %w", err)
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}
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defer f.Close()
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return f.DWARF()
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}
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