mod.go

     1  // Copyright 2018 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 debug
     6  
     7  import (
     8  	"fmt"
     9  	"runtime"
    10  	"strconv"
    11  	"strings"
    12  )
    13  
    14  // exported from runtime.
    15  func modinfo() string
    16  
    17  // ReadBuildInfo returns the build information embedded
    18  // in the running binary. The information is available only
    19  // in binaries built with module support.
    20  func ReadBuildInfo() (info *BuildInfo, ok bool) {
    21  	data := modinfo()
    22  	if len(data) < 32 {
    23  		return nil, false
    24  	}
    25  	data = data[16 : len(data)-16]
    26  	bi, err := ParseBuildInfo(data)
    27  	if err != nil {
    28  		return nil, false
    29  	}
    30  
    31  	// The go version is stored separately from other build info, mostly for
    32  	// historical reasons. It is not part of the modinfo() string, and
    33  	// ParseBuildInfo does not recognize it. We inject it here to hide this
    34  	// awkwardness from the user.
    35  	bi.GoVersion = runtime.Version()
    36  
    37  	return bi, true
    38  }
    39  
    40  // BuildInfo represents the build information read from a Go binary.
    41  type BuildInfo struct {
    42  	// GoVersion is the version of the Go toolchain that built the binary
    43  	// (for example, "go1.19.2").
    44  	GoVersion string
    45  
    46  	// Path is the package path of the main package for the binary
    47  	// (for example, "golang.org/x/tools/cmd/stringer").
    48  	Path string
    49  
    50  	// Main describes the module that contains the main package for the binary.
    51  	Main Module
    52  
    53  	// Deps describes all the dependency modules, both direct and indirect,
    54  	// that contributed packages to the build of this binary.
    55  	Deps []*Module
    56  
    57  	// Settings describes the build settings used to build the binary.
    58  	Settings []BuildSetting
    59  }
    60  
    61  // A Module describes a single module included in a build.
    62  type Module struct {
    63  	Path    string  // module path
    64  	Version string  // module version
    65  	Sum     string  // checksum
    66  	Replace *Module // replaced by this module
    67  }
    68  
    69  // A BuildSetting is a key-value pair describing one setting that influenced a build.
    70  //
    71  // Defined keys include:
    72  //
    73  //   - -buildmode: the buildmode flag used (typically "exe")
    74  //   - -compiler: the compiler toolchain flag used (typically "gc")
    75  //   - CGO_ENABLED: the effective CGO_ENABLED environment variable
    76  //   - CGO_CFLAGS: the effective CGO_CFLAGS environment variable
    77  //   - CGO_CPPFLAGS: the effective CGO_CPPFLAGS environment variable
    78  //   - CGO_CXXFLAGS:  the effective CGO_CXXFLAGS environment variable
    79  //   - CGO_LDFLAGS: the effective CGO_LDFLAGS environment variable
    80  //   - GOARCH: the architecture target
    81  //   - GOAMD64/GOARM/GO386/etc: the architecture feature level for GOARCH
    82  //   - GOOS: the operating system target
    83  //   - vcs: the version control system for the source tree where the build ran
    84  //   - vcs.revision: the revision identifier for the current commit or checkout
    85  //   - vcs.time: the modification time associated with vcs.revision, in RFC3339 format
    86  //   - vcs.modified: true or false indicating whether the source tree had local modifications
    87  type BuildSetting struct {
    88  	// Key and Value describe the build setting.
    89  	// Key must not contain an equals sign, space, tab, or newline.
    90  	// Value must not contain newlines ('\n').
    91  	Key, Value string
    92  }
    93  
    94  // quoteKey reports whether key is required to be quoted.
    95  func quoteKey(key string) bool {
    96  	return len(key) == 0 || strings.ContainsAny(key, "= \t\r\n\"`")
    97  }
    98  
    99  // quoteValue reports whether value is required to be quoted.
   100  func quoteValue(value string) bool {
   101  	return strings.ContainsAny(value, " \t\r\n\"`")
   102  }
   103  
   104  func (bi *BuildInfo) String() string {
   105  	buf := new(strings.Builder)
   106  	if bi.GoVersion != "" {
   107  		fmt.Fprintf(buf, "go\t%s\n", bi.GoVersion)
   108  	}
   109  	if bi.Path != "" {
   110  		fmt.Fprintf(buf, "path\t%s\n", bi.Path)
   111  	}
   112  	var formatMod func(string, Module)
   113  	formatMod = func(word string, m Module) {
   114  		buf.WriteString(word)
   115  		buf.WriteByte('\t')
   116  		buf.WriteString(m.Path)
   117  		buf.WriteByte('\t')
   118  		buf.WriteString(m.Version)
   119  		if m.Replace == nil {
   120  			buf.WriteByte('\t')
   121  			buf.WriteString(m.Sum)
   122  		} else {
   123  			buf.WriteByte('\n')
   124  			formatMod("=>", *m.Replace)
   125  		}
   126  		buf.WriteByte('\n')
   127  	}
   128  	if bi.Main != (Module{}) {
   129  		formatMod("mod", bi.Main)
   130  	}
   131  	for _, dep := range bi.Deps {
   132  		formatMod("dep", *dep)
   133  	}
   134  	for _, s := range bi.Settings {
   135  		key := s.Key
   136  		if quoteKey(key) {
   137  			key = strconv.Quote(key)
   138  		}
   139  		value := s.Value
   140  		if quoteValue(value) {
   141  			value = strconv.Quote(value)
   142  		}
   143  		fmt.Fprintf(buf, "build\t%s=%s\n", key, value)
   144  	}
   145  
   146  	return buf.String()
   147  }
   148  
   149  func ParseBuildInfo(data string) (bi *BuildInfo, err error) {
   150  	lineNum := 1
   151  	defer func() {
   152  		if err != nil {
   153  			err = fmt.Errorf("could not parse Go build info: line %d: %w", lineNum, err)
   154  		}
   155  	}()
   156  
   157  	var (
   158  		pathLine  = "path\t"
   159  		modLine   = "mod\t"
   160  		depLine   = "dep\t"
   161  		repLine   = "=>\t"
   162  		buildLine = "build\t"
   163  		newline   = "\n"
   164  		tab       = "\t"
   165  	)
   166  
   167  	readModuleLine := func(elem []string) (Module, error) {
   168  		if len(elem) != 2 && len(elem) != 3 {
   169  			return Module{}, fmt.Errorf("expected 2 or 3 columns; got %d", len(elem))
   170  		}
   171  		version := elem[1]
   172  		sum := ""
   173  		if len(elem) == 3 {
   174  			sum = elem[2]
   175  		}
   176  		return Module{
   177  			Path:    elem[0],
   178  			Version: version,
   179  			Sum:     sum,
   180  		}, nil
   181  	}
   182  
   183  	bi = new(BuildInfo)
   184  	var (
   185  		last *Module
   186  		line string
   187  		ok   bool
   188  	)
   189  	// Reverse of BuildInfo.String(), except for go version.
   190  	for len(data) > 0 {
   191  		line, data, ok = strings.Cut(data, newline)
   192  		if !ok {
   193  			break
   194  		}
   195  		switch {
   196  		case strings.HasPrefix(line, pathLine):
   197  			elem := line[len(pathLine):]
   198  			bi.Path = string(elem)
   199  		case strings.HasPrefix(line, modLine):
   200  			elem := strings.Split(line[len(modLine):], tab)
   201  			last = &bi.Main
   202  			*last, err = readModuleLine(elem)
   203  			if err != nil {
   204  				return nil, err
   205  			}
   206  		case strings.HasPrefix(line, depLine):
   207  			elem := strings.Split(line[len(depLine):], tab)
   208  			last = new(Module)
   209  			bi.Deps = append(bi.Deps, last)
   210  			*last, err = readModuleLine(elem)
   211  			if err != nil {
   212  				return nil, err
   213  			}
   214  		case strings.HasPrefix(line, repLine):
   215  			elem := strings.Split(line[len(repLine):], tab)
   216  			if len(elem) != 3 {
   217  				return nil, fmt.Errorf("expected 3 columns for replacement; got %d", len(elem))
   218  			}
   219  			if last == nil {
   220  				return nil, fmt.Errorf("replacement with no module on previous line")
   221  			}
   222  			last.Replace = &Module{
   223  				Path:    string(elem[0]),
   224  				Version: string(elem[1]),
   225  				Sum:     string(elem[2]),
   226  			}
   227  			last = nil
   228  		case strings.HasPrefix(line, buildLine):
   229  			kv := line[len(buildLine):]
   230  			if len(kv) < 1 {
   231  				return nil, fmt.Errorf("build line missing '='")
   232  			}
   233  
   234  			var key, rawValue string
   235  			switch kv[0] {
   236  			case '=':
   237  				return nil, fmt.Errorf("build line with missing key")
   238  
   239  			case '`', '"':
   240  				rawKey, err := strconv.QuotedPrefix(kv)
   241  				if err != nil {
   242  					return nil, fmt.Errorf("invalid quoted key in build line")
   243  				}
   244  				if len(kv) == len(rawKey) {
   245  					return nil, fmt.Errorf("build line missing '=' after quoted key")
   246  				}
   247  				if c := kv[len(rawKey)]; c != '=' {
   248  					return nil, fmt.Errorf("unexpected character after quoted key: %q", c)
   249  				}
   250  				key, _ = strconv.Unquote(rawKey)
   251  				rawValue = kv[len(rawKey)+1:]
   252  
   253  			default:
   254  				var ok bool
   255  				key, rawValue, ok = strings.Cut(kv, "=")
   256  				if !ok {
   257  					return nil, fmt.Errorf("build line missing '=' after key")
   258  				}
   259  				if quoteKey(key) {
   260  					return nil, fmt.Errorf("unquoted key %q must be quoted", key)
   261  				}
   262  			}
   263  
   264  			var value string
   265  			if len(rawValue) > 0 {
   266  				switch rawValue[0] {
   267  				case '`', '"':
   268  					var err error
   269  					value, err = strconv.Unquote(rawValue)
   270  					if err != nil {
   271  						return nil, fmt.Errorf("invalid quoted value in build line")
   272  					}
   273  
   274  				default:
   275  					value = rawValue
   276  					if quoteValue(value) {
   277  						return nil, fmt.Errorf("unquoted value %q must be quoted", value)
   278  					}
   279  				}
   280  			}
   281  
   282  			bi.Settings = append(bi.Settings, BuildSetting{Key: key, Value: value})
   283  		}
   284  		lineNum++
   285  	}
   286  	return bi, nil
   287  }
   288
View as plain text