flag.go

     1  // Copyright 2015 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 objabi
     6  
     7  import (
     8  	"flag"
     9  	"fmt"
    10  	"internal/bisect"
    11  	"internal/buildcfg"
    12  	"io"
    13  	"log"
    14  	"os"
    15  	"reflect"
    16  	"sort"
    17  	"strconv"
    18  	"strings"
    19  )
    20  
    21  func Flagcount(name, usage string, val *int) {
    22  	flag.Var((*count)(val), name, usage)
    23  }
    24  
    25  func Flagfn1(name, usage string, f func(string)) {
    26  	flag.Var(fn1(f), name, usage)
    27  }
    28  
    29  func Flagprint(w io.Writer) {
    30  	flag.CommandLine.SetOutput(w)
    31  	flag.PrintDefaults()
    32  }
    33  
    34  func Flagparse(usage func()) {
    35  	flag.Usage = usage
    36  	os.Args = expandArgs(os.Args)
    37  	flag.Parse()
    38  }
    39  
    40  // expandArgs expands "response files" arguments in the provided slice.
    41  //
    42  // A "response file" argument starts with '@' and the rest of that
    43  // argument is a filename with CR-or-CRLF-separated arguments. Each
    44  // argument in the named files can also contain response file
    45  // arguments. See Issue 18468.
    46  //
    47  // The returned slice 'out' aliases 'in' iff the input did not contain
    48  // any response file arguments.
    49  //
    50  // TODO: handle relative paths of recursive expansions in different directories?
    51  // Is there a spec for this? Are relative paths allowed?
    52  func expandArgs(in []string) (out []string) {
    53  	// out is nil until we see a "@" argument.
    54  	for i, s := range in {
    55  		if strings.HasPrefix(s, "@") {
    56  			if out == nil {
    57  				out = make([]string, 0, len(in)*2)
    58  				out = append(out, in[:i]...)
    59  			}
    60  			slurp, err := os.ReadFile(s[1:])
    61  			if err != nil {
    62  				log.Fatal(err)
    63  			}
    64  			args := strings.Split(strings.TrimSpace(strings.Replace(string(slurp), "\r", "", -1)), "\n")
    65  			for i, arg := range args {
    66  				args[i] = DecodeArg(arg)
    67  			}
    68  			out = append(out, expandArgs(args)...)
    69  		} else if out != nil {
    70  			out = append(out, s)
    71  		}
    72  	}
    73  	if out == nil {
    74  		return in
    75  	}
    76  	return
    77  }
    78  
    79  func AddVersionFlag() {
    80  	flag.Var(versionFlag{}, "V", "print version and exit")
    81  }
    82  
    83  var buildID string // filled in by linker
    84  
    85  type versionFlag struct{}
    86  
    87  func (versionFlag) IsBoolFlag() bool { return true }
    88  func (versionFlag) Get() interface{} { return nil }
    89  func (versionFlag) String() string   { return "" }
    90  func (versionFlag) Set(s string) error {
    91  	name := os.Args[0]
    92  	name = name[strings.LastIndex(name, `/`)+1:]
    93  	name = name[strings.LastIndex(name, `\`)+1:]
    94  	name = strings.TrimSuffix(name, ".exe")
    95  
    96  	p := ""
    97  
    98  	if s == "goexperiment" {
    99  		// test/run.go uses this to discover the full set of
   100  		// experiment tags. Report everything.
   101  		p = " X:" + strings.Join(buildcfg.Experiment.All(), ",")
   102  	} else {
   103  		// If the enabled experiments differ from the baseline,
   104  		// include that difference.
   105  		if goexperiment := buildcfg.Experiment.String(); goexperiment != "" {
   106  			p = " X:" + goexperiment
   107  		}
   108  	}
   109  
   110  	// The go command invokes -V=full to get a unique identifier
   111  	// for this tool. It is assumed that the release version is sufficient
   112  	// for releases, but during development we include the full
   113  	// build ID of the binary, so that if the compiler is changed and
   114  	// rebuilt, we notice and rebuild all packages.
   115  	if s == "full" {
   116  		if strings.HasPrefix(buildcfg.Version, "devel") {
   117  			p += " buildID=" + buildID
   118  		}
   119  	}
   120  
   121  	fmt.Printf("%s version %s%s\n", name, buildcfg.Version, p)
   122  	os.Exit(0)
   123  	return nil
   124  }
   125  
   126  // count is a flag.Value that is like a flag.Bool and a flag.Int.
   127  // If used as -name, it increments the count, but -name=x sets the count.
   128  // Used for verbose flag -v.
   129  type count int
   130  
   131  func (c *count) String() string {
   132  	return fmt.Sprint(int(*c))
   133  }
   134  
   135  func (c *count) Set(s string) error {
   136  	switch s {
   137  	case "true":
   138  		*c++
   139  	case "false":
   140  		*c = 0
   141  	default:
   142  		n, err := strconv.Atoi(s)
   143  		if err != nil {
   144  			return fmt.Errorf("invalid count %q", s)
   145  		}
   146  		*c = count(n)
   147  	}
   148  	return nil
   149  }
   150  
   151  func (c *count) Get() interface{} {
   152  	return int(*c)
   153  }
   154  
   155  func (c *count) IsBoolFlag() bool {
   156  	return true
   157  }
   158  
   159  func (c *count) IsCountFlag() bool {
   160  	return true
   161  }
   162  
   163  type fn1 func(string)
   164  
   165  func (f fn1) Set(s string) error {
   166  	f(s)
   167  	return nil
   168  }
   169  
   170  func (f fn1) String() string { return "" }
   171  
   172  // DecodeArg decodes an argument.
   173  //
   174  // This function is public for testing with the parallel encoder.
   175  func DecodeArg(arg string) string {
   176  	// If no encoding, fastpath out.
   177  	if !strings.ContainsAny(arg, "\\\n") {
   178  		return arg
   179  	}
   180  
   181  	var b strings.Builder
   182  	var wasBS bool
   183  	for _, r := range arg {
   184  		if wasBS {
   185  			switch r {
   186  			case '\\':
   187  				b.WriteByte('\\')
   188  			case 'n':
   189  				b.WriteByte('\n')
   190  			default:
   191  				// This shouldn't happen. The only backslashes that reach here
   192  				// should encode '\n' and '\\' exclusively.
   193  				panic("badly formatted input")
   194  			}
   195  		} else if r == '\\' {
   196  			wasBS = true
   197  			continue
   198  		} else {
   199  			b.WriteRune(r)
   200  		}
   201  		wasBS = false
   202  	}
   203  	return b.String()
   204  }
   205  
   206  type debugField struct {
   207  	name         string
   208  	help         string
   209  	concurrentOk bool        // true if this field/flag is compatible with concurrent compilation
   210  	val          interface{} // *int or *string
   211  }
   212  
   213  type DebugFlag struct {
   214  	tab          map[string]debugField
   215  	concurrentOk *bool    // this is non-nil only for compiler's DebugFlags, but only compiler has concurrent:ok fields
   216  	debugSSA     DebugSSA // this is non-nil only for compiler's DebugFlags.
   217  }
   218  
   219  // A DebugSSA function is called to set a -d ssa/... option.
   220  // If nil, those options are reported as invalid options.
   221  // If DebugSSA returns a non-empty string, that text is reported as a compiler error.
   222  // If phase is "help", it should print usage information and terminate the process.
   223  type DebugSSA func(phase, flag string, val int, valString string) string
   224  
   225  // NewDebugFlag constructs a DebugFlag for the fields of debug, which
   226  // must be a pointer to a struct.
   227  //
   228  // Each field of *debug is a different value, named for the lower-case of the field name.
   229  // Each field must be an int or string and must have a `help` struct tag.
   230  // There may be an "Any bool" field, which will be set if any debug flags are set.
   231  //
   232  // The returned flag takes a comma-separated list of settings.
   233  // Each setting is name=value; for ints, name is short for name=1.
   234  //
   235  // If debugSSA is non-nil, any debug flags of the form ssa/... will be
   236  // passed to debugSSA for processing.
   237  func NewDebugFlag(debug interface{}, debugSSA DebugSSA) *DebugFlag {
   238  	flag := &DebugFlag{
   239  		tab:      make(map[string]debugField),
   240  		debugSSA: debugSSA,
   241  	}
   242  
   243  	v := reflect.ValueOf(debug).Elem()
   244  	t := v.Type()
   245  	for i := 0; i < t.NumField(); i++ {
   246  		f := t.Field(i)
   247  		ptr := v.Field(i).Addr().Interface()
   248  		if f.Name == "ConcurrentOk" {
   249  			switch ptr := ptr.(type) {
   250  			default:
   251  				panic("debug.ConcurrentOk must have type bool")
   252  			case *bool:
   253  				flag.concurrentOk = ptr
   254  			}
   255  			continue
   256  		}
   257  		name := strings.ToLower(f.Name)
   258  		help := f.Tag.Get("help")
   259  		if help == "" {
   260  			panic(fmt.Sprintf("debug.%s is missing help text", f.Name))
   261  		}
   262  		concurrent := f.Tag.Get("concurrent")
   263  
   264  		switch ptr.(type) {
   265  		default:
   266  			panic(fmt.Sprintf("debug.%s has invalid type %v (must be int, string, or *bisect.Matcher)", f.Name, f.Type))
   267  		case *int, *string, **bisect.Matcher:
   268  			// ok
   269  		}
   270  		flag.tab[name] = debugField{name, help, concurrent == "ok", ptr}
   271  	}
   272  
   273  	return flag
   274  }
   275  
   276  func (f *DebugFlag) Set(debugstr string) error {
   277  	if debugstr == "" {
   278  		return nil
   279  	}
   280  	for _, name := range strings.Split(debugstr, ",") {
   281  		if name == "" {
   282  			continue
   283  		}
   284  		// display help about the debug option itself and quit
   285  		if name == "help" {
   286  			fmt.Print(debugHelpHeader)
   287  			maxLen, names := 0, []string{}
   288  			if f.debugSSA != nil {
   289  				maxLen = len("ssa/help")
   290  			}
   291  			for name := range f.tab {
   292  				if len(name) > maxLen {
   293  					maxLen = len(name)
   294  				}
   295  				names = append(names, name)
   296  			}
   297  			sort.Strings(names)
   298  			// Indent multi-line help messages.
   299  			nl := fmt.Sprintf("\n\t%-*s\t", maxLen, "")
   300  			for _, name := range names {
   301  				help := f.tab[name].help
   302  				fmt.Printf("\t%-*s\t%s\n", maxLen, name, strings.Replace(help, "\n", nl, -1))
   303  			}
   304  			if f.debugSSA != nil {
   305  				// ssa options have their own help
   306  				fmt.Printf("\t%-*s\t%s\n", maxLen, "ssa/help", "print help about SSA debugging")
   307  			}
   308  			os.Exit(0)
   309  		}
   310  
   311  		val, valstring, haveInt := 1, "", true
   312  		if i := strings.IndexAny(name, "=:"); i >= 0 {
   313  			var err error
   314  			name, valstring = name[:i], name[i+1:]
   315  			val, err = strconv.Atoi(valstring)
   316  			if err != nil {
   317  				val, haveInt = 1, false
   318  			}
   319  		}
   320  
   321  		if t, ok := f.tab[name]; ok {
   322  			switch vp := t.val.(type) {
   323  			case nil:
   324  				// Ignore
   325  			case *string:
   326  				*vp = valstring
   327  			case *int:
   328  				if !haveInt {
   329  					log.Fatalf("invalid debug value %v", name)
   330  				}
   331  				*vp = val
   332  			case **bisect.Matcher:
   333  				var err error
   334  				*vp, err = bisect.New(valstring)
   335  				if err != nil {
   336  					log.Fatalf("debug flag %v: %v", name, err)
   337  				}
   338  			default:
   339  				panic("bad debugtab type")
   340  			}
   341  			// assembler DebugFlags don't have a ConcurrentOk field to reset, so check against that.
   342  			if !t.concurrentOk && f.concurrentOk != nil {
   343  				*f.concurrentOk = false
   344  			}
   345  		} else if f.debugSSA != nil && strings.HasPrefix(name, "ssa/") {
   346  			// expect form ssa/phase/flag
   347  			// e.g. -d=ssa/generic_cse/time
   348  			// _ in phase name also matches space
   349  			phase := name[4:]
   350  			flag := "debug" // default flag is debug
   351  			if i := strings.Index(phase, "/"); i >= 0 {
   352  				flag = phase[i+1:]
   353  				phase = phase[:i]
   354  			}
   355  			err := f.debugSSA(phase, flag, val, valstring)
   356  			if err != "" {
   357  				log.Fatal(err)
   358  			}
   359  			// Setting this false for -d=ssa/... preserves old behavior
   360  			// of turning off concurrency for any debug flags.
   361  			// It's not known for sure if this is necessary, but it is safe.
   362  			*f.concurrentOk = false
   363  
   364  		} else {
   365  			return fmt.Errorf("unknown debug key %s\n", name)
   366  		}
   367  	}
   368  
   369  	return nil
   370  }
   371  
   372  const debugHelpHeader = `usage: -d arg[,arg]* and arg is <key>[=<value>]
   373  
   374  <key> is one of:
   375  
   376  `
   377  
   378  func (f *DebugFlag) String() string {
   379  	return ""
   380  }
   381
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