symbolizer.go

     1  // Copyright 2014 Google Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package symbolizer provides a routine to populate a profile with
    16  // symbol, file and line number information. It relies on the
    17  // addr2liner and demangle packages to do the actual work.
    18  package symbolizer
    19  
    20  import (
    21  	"fmt"
    22  	"io"
    23  	"net/http"
    24  	"net/url"
    25  	"path/filepath"
    26  	"strings"
    27  
    28  	"github.com/google/pprof/internal/binutils"
    29  	"github.com/google/pprof/internal/plugin"
    30  	"github.com/google/pprof/internal/symbolz"
    31  	"github.com/google/pprof/profile"
    32  	"github.com/ianlancetaylor/demangle"
    33  )
    34  
    35  // Symbolizer implements the plugin.Symbolize interface.
    36  type Symbolizer struct {
    37  	Obj       plugin.ObjTool
    38  	UI        plugin.UI
    39  	Transport http.RoundTripper
    40  }
    41  
    42  // test taps for dependency injection
    43  var symbolzSymbolize = symbolz.Symbolize
    44  var localSymbolize = doLocalSymbolize
    45  var demangleFunction = Demangle
    46  
    47  // Symbolize attempts to symbolize profile p. First uses binutils on
    48  // local binaries; if the source is a URL it attempts to get any
    49  // missed entries using symbolz.
    50  func (s *Symbolizer) Symbolize(mode string, sources plugin.MappingSources, p *profile.Profile) error {
    51  	remote, local, fast, force, demanglerMode := true, true, false, false, ""
    52  	for _, o := range strings.Split(strings.ToLower(mode), ":") {
    53  		switch o {
    54  		case "":
    55  			continue
    56  		case "none", "no":
    57  			return nil
    58  		case "local":
    59  			remote, local = false, true
    60  		case "fastlocal":
    61  			remote, local, fast = false, true, true
    62  		case "remote":
    63  			remote, local = true, false
    64  		case "force":
    65  			force = true
    66  		default:
    67  			switch d := strings.TrimPrefix(o, "demangle="); d {
    68  			case "full", "none", "templates":
    69  				demanglerMode = d
    70  				force = true
    71  				continue
    72  			case "default":
    73  				continue
    74  			}
    75  			s.UI.PrintErr("ignoring unrecognized symbolization option: " + mode)
    76  			s.UI.PrintErr("expecting -symbolize=[local|fastlocal|remote|none][:force][:demangle=[none|full|templates|default]")
    77  		}
    78  	}
    79  
    80  	var err error
    81  	if local {
    82  		// Symbolize locally using binutils.
    83  		if err = localSymbolize(p, fast, force, s.Obj, s.UI); err != nil {
    84  			s.UI.PrintErr("local symbolization: " + err.Error())
    85  		}
    86  	}
    87  	if remote {
    88  		post := func(source, post string) ([]byte, error) {
    89  			return postURL(source, post, s.Transport)
    90  		}
    91  		if err = symbolzSymbolize(p, force, sources, post, s.UI); err != nil {
    92  			return err // Ran out of options.
    93  		}
    94  	}
    95  
    96  	demangleFunction(p, force, demanglerMode)
    97  	return nil
    98  }
    99  
   100  // postURL issues a POST to a URL over HTTP.
   101  func postURL(source, post string, tr http.RoundTripper) ([]byte, error) {
   102  	client := &http.Client{
   103  		Transport: tr,
   104  	}
   105  	resp, err := client.Post(source, "application/octet-stream", strings.NewReader(post))
   106  	if err != nil {
   107  		return nil, fmt.Errorf("http post %s: %v", source, err)
   108  	}
   109  	defer resp.Body.Close()
   110  	if resp.StatusCode != http.StatusOK {
   111  		return nil, fmt.Errorf("http post %s: %v", source, statusCodeError(resp))
   112  	}
   113  	return io.ReadAll(resp.Body)
   114  }
   115  
   116  func statusCodeError(resp *http.Response) error {
   117  	if resp.Header.Get("X-Go-Pprof") != "" && strings.Contains(resp.Header.Get("Content-Type"), "text/plain") {
   118  		// error is from pprof endpoint
   119  		if body, err := io.ReadAll(resp.Body); err == nil {
   120  			return fmt.Errorf("server response: %s - %s", resp.Status, body)
   121  		}
   122  	}
   123  	return fmt.Errorf("server response: %s", resp.Status)
   124  }
   125  
   126  // doLocalSymbolize adds symbol and line number information to all locations
   127  // in a profile. mode enables some options to control
   128  // symbolization.
   129  func doLocalSymbolize(prof *profile.Profile, fast, force bool, obj plugin.ObjTool, ui plugin.UI) error {
   130  	if fast {
   131  		if bu, ok := obj.(*binutils.Binutils); ok {
   132  			bu.SetFastSymbolization(true)
   133  		}
   134  	}
   135  
   136  	functions := map[profile.Function]*profile.Function{}
   137  	addFunction := func(f *profile.Function) *profile.Function {
   138  		if fp := functions[*f]; fp != nil {
   139  			return fp
   140  		}
   141  		functions[*f] = f
   142  		f.ID = uint64(len(prof.Function)) + 1
   143  		prof.Function = append(prof.Function, f)
   144  		return f
   145  	}
   146  
   147  	missingBinaries := false
   148  	mappingLocs := map[*profile.Mapping][]*profile.Location{}
   149  	for _, l := range prof.Location {
   150  		mappingLocs[l.Mapping] = append(mappingLocs[l.Mapping], l)
   151  	}
   152  	for midx, m := range prof.Mapping {
   153  		locs := mappingLocs[m]
   154  		if len(locs) == 0 {
   155  			// The mapping is dangling and has no locations pointing to it.
   156  			continue
   157  		}
   158  		// Do not attempt to re-symbolize a mapping that has already been symbolized.
   159  		if !force && (m.HasFunctions || m.HasFilenames || m.HasLineNumbers) {
   160  			continue
   161  		}
   162  		if m.File == "" {
   163  			if midx == 0 {
   164  				ui.PrintErr("Main binary filename not available.")
   165  				continue
   166  			}
   167  			missingBinaries = true
   168  			continue
   169  		}
   170  		if m.Unsymbolizable() {
   171  			// Skip well-known system mappings
   172  			continue
   173  		}
   174  		if m.BuildID == "" {
   175  			if u, err := url.Parse(m.File); err == nil && u.IsAbs() && strings.Contains(strings.ToLower(u.Scheme), "http") {
   176  				// Skip mappings pointing to a source URL
   177  				continue
   178  			}
   179  		}
   180  
   181  		name := filepath.Base(m.File)
   182  		if m.BuildID != "" {
   183  			name += fmt.Sprintf(" (build ID %s)", m.BuildID)
   184  		}
   185  		f, err := obj.Open(m.File, m.Start, m.Limit, m.Offset, m.KernelRelocationSymbol)
   186  		if err != nil {
   187  			ui.PrintErr("Local symbolization failed for ", name, ": ", err)
   188  			missingBinaries = true
   189  			continue
   190  		}
   191  		if fid := f.BuildID(); m.BuildID != "" && fid != "" && fid != m.BuildID {
   192  			ui.PrintErr("Local symbolization failed for ", name, ": build ID mismatch")
   193  			f.Close()
   194  			continue
   195  		}
   196  		symbolizeOneMapping(m, locs, f, addFunction)
   197  		f.Close()
   198  	}
   199  
   200  	if missingBinaries {
   201  		ui.PrintErr("Some binary filenames not available. Symbolization may be incomplete.\n" +
   202  			"Try setting PPROF_BINARY_PATH to the search path for local binaries.")
   203  	}
   204  	return nil
   205  }
   206  
   207  func symbolizeOneMapping(m *profile.Mapping, locs []*profile.Location, obj plugin.ObjFile, addFunction func(*profile.Function) *profile.Function) {
   208  	for _, l := range locs {
   209  		stack, err := obj.SourceLine(l.Address)
   210  		if err != nil || len(stack) == 0 {
   211  			// No answers from addr2line.
   212  			continue
   213  		}
   214  
   215  		l.Line = make([]profile.Line, len(stack))
   216  		l.IsFolded = false
   217  		for i, frame := range stack {
   218  			if frame.Func != "" {
   219  				m.HasFunctions = true
   220  			}
   221  			if frame.File != "" {
   222  				m.HasFilenames = true
   223  			}
   224  			if frame.Line != 0 {
   225  				m.HasLineNumbers = true
   226  			}
   227  			f := addFunction(&profile.Function{
   228  				Name:       frame.Func,
   229  				SystemName: frame.Func,
   230  				Filename:   frame.File,
   231  				StartLine:  int64(frame.StartLine),
   232  			})
   233  			l.Line[i] = profile.Line{
   234  				Function: f,
   235  				Line:     int64(frame.Line),
   236  				Column:   int64(frame.Column),
   237  			}
   238  		}
   239  
   240  		if len(stack) > 0 {
   241  			m.HasInlineFrames = true
   242  		}
   243  	}
   244  }
   245  
   246  // Demangle updates the function names in a profile with demangled C++
   247  // names, simplified according to demanglerMode. If force is set,
   248  // overwrite any names that appear already demangled.
   249  func Demangle(prof *profile.Profile, force bool, demanglerMode string) {
   250  	if force {
   251  		// Remove the current demangled names to force demangling
   252  		for _, f := range prof.Function {
   253  			if f.Name != "" && f.SystemName != "" {
   254  				f.Name = f.SystemName
   255  			}
   256  		}
   257  	}
   258  
   259  	options := demanglerModeToOptions(demanglerMode)
   260  	for _, fn := range prof.Function {
   261  		demangleSingleFunction(fn, options)
   262  	}
   263  }
   264  
   265  func demanglerModeToOptions(demanglerMode string) []demangle.Option {
   266  	switch demanglerMode {
   267  	case "": // demangled, simplified: no parameters, no templates, no return type
   268  		return []demangle.Option{demangle.NoParams, demangle.NoEnclosingParams, demangle.NoTemplateParams}
   269  	case "templates": // demangled, simplified: no parameters, no return type
   270  		return []demangle.Option{demangle.NoParams, demangle.NoEnclosingParams}
   271  	case "full":
   272  		return []demangle.Option{demangle.NoClones}
   273  	case "none": // no demangling
   274  		return []demangle.Option{}
   275  	}
   276  
   277  	panic(fmt.Sprintf("unknown demanglerMode %s", demanglerMode))
   278  }
   279  
   280  func demangleSingleFunction(fn *profile.Function, options []demangle.Option) {
   281  	if fn.Name != "" && fn.SystemName != fn.Name {
   282  		return // Already demangled.
   283  	}
   284  	// Copy the options because they may be updated by the call.
   285  	o := make([]demangle.Option, len(options))
   286  	copy(o, options)
   287  	if demangled := demangle.Filter(fn.SystemName, o...); demangled != fn.SystemName {
   288  		fn.Name = demangled
   289  		return
   290  	}
   291  	// Could not demangle. Apply heuristics in case the name is
   292  	// already demangled.
   293  	name := fn.SystemName
   294  	if looksLikeDemangledCPlusPlus(name) {
   295  		for _, o := range options {
   296  			switch o {
   297  			case demangle.NoParams:
   298  				name = removeMatching(name, '(', ')')
   299  			case demangle.NoTemplateParams:
   300  				name = removeMatching(name, '<', '>')
   301  			}
   302  		}
   303  	}
   304  	fn.Name = name
   305  }
   306  
   307  // looksLikeDemangledCPlusPlus is a heuristic to decide if a name is
   308  // the result of demangling C++. If so, further heuristics will be
   309  // applied to simplify the name.
   310  func looksLikeDemangledCPlusPlus(demangled string) bool {
   311  	// Skip java names of the form "class.<init>".
   312  	if strings.Contains(demangled, ".<") {
   313  		return false
   314  	}
   315  	// Skip Go names of the form "foo.(*Bar[...]).Method".
   316  	if strings.Contains(demangled, "]).") {
   317  		return false
   318  	}
   319  	return strings.ContainsAny(demangled, "<>[]") || strings.Contains(demangled, "::")
   320  }
   321  
   322  // removeMatching removes nested instances of start..end from name.
   323  func removeMatching(name string, start, end byte) string {
   324  	s := string(start) + string(end)
   325  	var nesting, first, current int
   326  	for index := strings.IndexAny(name[current:], s); index != -1; index = strings.IndexAny(name[current:], s) {
   327  		switch current += index; name[current] {
   328  		case start:
   329  			nesting++
   330  			if nesting == 1 {
   331  				first = current
   332  			}
   333  		case end:
   334  			nesting--
   335  			switch {
   336  			case nesting < 0:
   337  				return name // Mismatch, abort
   338  			case nesting == 0:
   339  				name = name[:first] + name[current+1:]
   340  				current = first - 1
   341  			}
   342  		}
   343  		current++
   344  	}
   345  	return name
   346  }
   347
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