init.go

     1  // Copyright 2017 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  // Build initialization (after flag parsing).
     6  
     7  package work
     8  
     9  import (
    10  	"bytes"
    11  	"cmd/go/internal/base"
    12  	"cmd/go/internal/cfg"
    13  	"cmd/go/internal/fsys"
    14  	"cmd/go/internal/modload"
    15  	"cmd/internal/quoted"
    16  	"fmt"
    17  	"internal/platform"
    18  	"os"
    19  	"os/exec"
    20  	"path/filepath"
    21  	"regexp"
    22  	"runtime"
    23  	"slices"
    24  	"strconv"
    25  	"sync"
    26  )
    27  
    28  var buildInitStarted = false
    29  
    30  // makeCfgChangedEnv is the environment to set to
    31  // override the current environment for GOOS, GOARCH, and the GOARCH-specific
    32  // architecture environment variable to the configuration used by
    33  // the go command. They may be different because go tool <tool> for builtin
    34  // tools need to be built using the host configuration, so the configuration
    35  // used will be changed from that set in the environment. It is clipped
    36  // so its can append to it without changing it.
    37  var cfgChangedEnv []string
    38  
    39  func makeCfgChangedEnv() []string {
    40  	var env []string
    41  	if cfg.Getenv("GOOS") != cfg.Goos {
    42  		env = append(env, "GOOS="+cfg.Goos)
    43  	}
    44  	if cfg.Getenv("GOARCH") != cfg.Goarch {
    45  		env = append(env, "GOARCH="+cfg.Goarch)
    46  	}
    47  	if archenv, val, changed := cfg.GetArchEnv(); changed {
    48  		env = append(env, archenv+"="+val)
    49  	}
    50  	return slices.Clip(env)
    51  }
    52  
    53  func BuildInit() {
    54  	if buildInitStarted {
    55  		base.Fatalf("go: internal error: work.BuildInit called more than once")
    56  	}
    57  	buildInitStarted = true
    58  	base.AtExit(closeBuilders)
    59  
    60  	modload.Init()
    61  	instrumentInit()
    62  	buildModeInit()
    63  	cfgChangedEnv = makeCfgChangedEnv()
    64  
    65  	if err := fsys.Init(); err != nil {
    66  		base.Fatal(err)
    67  	}
    68  	if from, replaced := fsys.DirContainsReplacement(cfg.GOMODCACHE); replaced {
    69  		base.Fatalf("go: overlay contains a replacement for %s. Files beneath GOMODCACHE (%s) must not be replaced.", from, cfg.GOMODCACHE)
    70  	}
    71  
    72  	// Make sure -pkgdir is absolute, because we run commands
    73  	// in different directories.
    74  	if cfg.BuildPkgdir != "" && !filepath.IsAbs(cfg.BuildPkgdir) {
    75  		p, err := filepath.Abs(cfg.BuildPkgdir)
    76  		if err != nil {
    77  			fmt.Fprintf(os.Stderr, "go: evaluating -pkgdir: %v\n", err)
    78  			base.SetExitStatus(2)
    79  			base.Exit()
    80  		}
    81  		cfg.BuildPkgdir = p
    82  	}
    83  
    84  	if cfg.BuildP <= 0 {
    85  		base.Fatalf("go: -p must be a positive integer: %v\n", cfg.BuildP)
    86  	}
    87  
    88  	// Make sure CC, CXX, and FC are absolute paths.
    89  	for _, key := range []string{"CC", "CXX", "FC"} {
    90  		value := cfg.Getenv(key)
    91  		args, err := quoted.Split(value)
    92  		if err != nil {
    93  			base.Fatalf("go: %s environment variable could not be parsed: %v", key, err)
    94  		}
    95  		if len(args) == 0 {
    96  			continue
    97  		}
    98  		path := args[0]
    99  		if !filepath.IsAbs(path) && path != filepath.Base(path) {
   100  			base.Fatalf("go: %s environment variable is relative; must be absolute path: %s\n", key, path)
   101  		}
   102  	}
   103  
   104  	// Set covermode if not already set.
   105  	// Ensure that -race and -covermode are compatible.
   106  	if cfg.BuildCoverMode == "" {
   107  		cfg.BuildCoverMode = "set"
   108  		if cfg.BuildRace {
   109  			// Default coverage mode is atomic when -race is set.
   110  			cfg.BuildCoverMode = "atomic"
   111  		}
   112  	}
   113  	if cfg.BuildRace && cfg.BuildCoverMode != "atomic" {
   114  		base.Fatalf(`-covermode must be "atomic", not %q, when -race is enabled`, cfg.BuildCoverMode)
   115  	}
   116  }
   117  
   118  // fuzzInstrumentFlags returns compiler flags that enable fuzzing instrumentation
   119  // on supported platforms.
   120  //
   121  // On unsupported platforms, fuzzInstrumentFlags returns nil, meaning no
   122  // instrumentation is added. 'go test -fuzz' still works without coverage,
   123  // but it generates random inputs without guidance, so it's much less effective.
   124  func fuzzInstrumentFlags() []string {
   125  	if !platform.FuzzInstrumented(cfg.Goos, cfg.Goarch) {
   126  		return nil
   127  	}
   128  	return []string{"-d=libfuzzer"}
   129  }
   130  
   131  func instrumentInit() {
   132  	if !cfg.BuildRace && !cfg.BuildMSan && !cfg.BuildASan {
   133  		return
   134  	}
   135  	if cfg.BuildRace && cfg.BuildMSan {
   136  		fmt.Fprintf(os.Stderr, "go: may not use -race and -msan simultaneously\n")
   137  		base.SetExitStatus(2)
   138  		base.Exit()
   139  	}
   140  	if cfg.BuildRace && cfg.BuildASan {
   141  		fmt.Fprintf(os.Stderr, "go: may not use -race and -asan simultaneously\n")
   142  		base.SetExitStatus(2)
   143  		base.Exit()
   144  	}
   145  	if cfg.BuildMSan && cfg.BuildASan {
   146  		fmt.Fprintf(os.Stderr, "go: may not use -msan and -asan simultaneously\n")
   147  		base.SetExitStatus(2)
   148  		base.Exit()
   149  	}
   150  	if cfg.BuildMSan && !platform.MSanSupported(cfg.Goos, cfg.Goarch) {
   151  		fmt.Fprintf(os.Stderr, "-msan is not supported on %s/%s\n", cfg.Goos, cfg.Goarch)
   152  		base.SetExitStatus(2)
   153  		base.Exit()
   154  	}
   155  	if cfg.BuildRace && !platform.RaceDetectorSupported(cfg.Goos, cfg.Goarch) {
   156  		fmt.Fprintf(os.Stderr, "-race is not supported on %s/%s\n", cfg.Goos, cfg.Goarch)
   157  		base.SetExitStatus(2)
   158  		base.Exit()
   159  	}
   160  	if cfg.BuildASan && !platform.ASanSupported(cfg.Goos, cfg.Goarch) {
   161  		fmt.Fprintf(os.Stderr, "-asan is not supported on %s/%s\n", cfg.Goos, cfg.Goarch)
   162  		base.SetExitStatus(2)
   163  		base.Exit()
   164  	}
   165  	// The current implementation is only compatible with the ASan library from version
   166  	// v7 to v9 (See the description in src/runtime/asan/asan.go). Therefore, using the
   167  	// -asan option must use a compatible version of ASan library, which requires that
   168  	// the gcc version is not less than 7 and the clang version is not less than 9,
   169  	// otherwise a segmentation fault will occur.
   170  	if cfg.BuildASan {
   171  		if err := compilerRequiredAsanVersion(); err != nil {
   172  			fmt.Fprintf(os.Stderr, "%v\n", err)
   173  			base.SetExitStatus(2)
   174  			base.Exit()
   175  		}
   176  	}
   177  
   178  	mode := "race"
   179  	if cfg.BuildMSan {
   180  		mode = "msan"
   181  		// MSAN needs PIE on all platforms except linux/amd64.
   182  		// https://github.com/llvm/llvm-project/blob/llvmorg-13.0.1/clang/lib/Driver/SanitizerArgs.cpp#L621
   183  		if cfg.BuildBuildmode == "default" && (cfg.Goos != "linux" || cfg.Goarch != "amd64") {
   184  			cfg.BuildBuildmode = "pie"
   185  		}
   186  	}
   187  	if cfg.BuildASan {
   188  		mode = "asan"
   189  	}
   190  	modeFlag := "-" + mode
   191  
   192  	// Check that cgo is enabled.
   193  	// Note: On macOS, -race does not require cgo. -asan and -msan still do.
   194  	if !cfg.BuildContext.CgoEnabled && (cfg.Goos != "darwin" || cfg.BuildASan || cfg.BuildMSan) {
   195  		if runtime.GOOS != cfg.Goos || runtime.GOARCH != cfg.Goarch {
   196  			fmt.Fprintf(os.Stderr, "go: %s requires cgo\n", modeFlag)
   197  		} else {
   198  			fmt.Fprintf(os.Stderr, "go: %s requires cgo; enable cgo by setting CGO_ENABLED=1\n", modeFlag)
   199  		}
   200  
   201  		base.SetExitStatus(2)
   202  		base.Exit()
   203  	}
   204  	forcedGcflags = append(forcedGcflags, modeFlag)
   205  	forcedLdflags = append(forcedLdflags, modeFlag)
   206  
   207  	if cfg.BuildContext.InstallSuffix != "" {
   208  		cfg.BuildContext.InstallSuffix += "_"
   209  	}
   210  	cfg.BuildContext.InstallSuffix += mode
   211  	cfg.BuildContext.ToolTags = append(cfg.BuildContext.ToolTags, mode)
   212  }
   213  
   214  func buildModeInit() {
   215  	gccgo := cfg.BuildToolchainName == "gccgo"
   216  	var codegenArg string
   217  
   218  	// Configure the build mode first, then verify that it is supported.
   219  	// That way, if the flag is completely bogus we will prefer to error out with
   220  	// "-buildmode=%s not supported" instead of naming the specific platform.
   221  
   222  	switch cfg.BuildBuildmode {
   223  	case "archive":
   224  		pkgsFilter = pkgsNotMain
   225  	case "c-archive":
   226  		pkgsFilter = oneMainPkg
   227  		if gccgo {
   228  			codegenArg = "-fPIC"
   229  		} else {
   230  			switch cfg.Goos {
   231  			case "darwin", "ios":
   232  				switch cfg.Goarch {
   233  				case "arm64":
   234  					codegenArg = "-shared"
   235  				}
   236  
   237  			case "dragonfly", "freebsd", "illumos", "linux", "netbsd", "openbsd", "solaris":
   238  				// Use -shared so that the result is
   239  				// suitable for inclusion in a PIE or
   240  				// shared library.
   241  				codegenArg = "-shared"
   242  			}
   243  		}
   244  		cfg.ExeSuffix = ".a"
   245  		ldBuildmode = "c-archive"
   246  	case "c-shared":
   247  		pkgsFilter = oneMainPkg
   248  		if gccgo {
   249  			codegenArg = "-fPIC"
   250  		} else {
   251  			switch cfg.Goos {
   252  			case "linux", "android", "freebsd":
   253  				codegenArg = "-shared"
   254  			case "windows":
   255  				// Do not add usual .exe suffix to the .dll file.
   256  				cfg.ExeSuffix = ""
   257  			}
   258  		}
   259  		ldBuildmode = "c-shared"
   260  	case "default":
   261  		ldBuildmode = "exe"
   262  		if platform.DefaultPIE(cfg.Goos, cfg.Goarch, cfg.BuildRace) {
   263  			ldBuildmode = "pie"
   264  			if cfg.Goos != "windows" && !gccgo {
   265  				codegenArg = "-shared"
   266  			}
   267  		}
   268  	case "exe":
   269  		pkgsFilter = pkgsMain
   270  		ldBuildmode = "exe"
   271  		// Set the pkgsFilter to oneMainPkg if the user passed a specific binary output
   272  		// and is using buildmode=exe for a better error message.
   273  		// See issue #20017.
   274  		if cfg.BuildO != "" {
   275  			pkgsFilter = oneMainPkg
   276  		}
   277  	case "pie":
   278  		if cfg.BuildRace && !platform.DefaultPIE(cfg.Goos, cfg.Goarch, cfg.BuildRace) {
   279  			base.Fatalf("-buildmode=pie not supported when -race is enabled on %s/%s", cfg.Goos, cfg.Goarch)
   280  		}
   281  		if gccgo {
   282  			codegenArg = "-fPIE"
   283  		} else {
   284  			switch cfg.Goos {
   285  			case "aix", "windows":
   286  			default:
   287  				codegenArg = "-shared"
   288  			}
   289  		}
   290  		ldBuildmode = "pie"
   291  	case "shared":
   292  		pkgsFilter = pkgsNotMain
   293  		if gccgo {
   294  			codegenArg = "-fPIC"
   295  		} else {
   296  			codegenArg = "-dynlink"
   297  		}
   298  		if cfg.BuildO != "" {
   299  			base.Fatalf("-buildmode=shared and -o not supported together")
   300  		}
   301  		ldBuildmode = "shared"
   302  	case "plugin":
   303  		pkgsFilter = oneMainPkg
   304  		if gccgo {
   305  			codegenArg = "-fPIC"
   306  		} else {
   307  			codegenArg = "-dynlink"
   308  		}
   309  		cfg.ExeSuffix = ".so"
   310  		ldBuildmode = "plugin"
   311  	default:
   312  		base.Fatalf("buildmode=%s not supported", cfg.BuildBuildmode)
   313  	}
   314  
   315  	if cfg.BuildBuildmode != "default" && !platform.BuildModeSupported(cfg.BuildToolchainName, cfg.BuildBuildmode, cfg.Goos, cfg.Goarch) {
   316  		base.Fatalf("-buildmode=%s not supported on %s/%s\n", cfg.BuildBuildmode, cfg.Goos, cfg.Goarch)
   317  	}
   318  
   319  	if cfg.BuildLinkshared {
   320  		if !platform.BuildModeSupported(cfg.BuildToolchainName, "shared", cfg.Goos, cfg.Goarch) {
   321  			base.Fatalf("-linkshared not supported on %s/%s\n", cfg.Goos, cfg.Goarch)
   322  		}
   323  		if gccgo {
   324  			codegenArg = "-fPIC"
   325  		} else {
   326  			forcedAsmflags = append(forcedAsmflags, "-D=GOBUILDMODE_shared=1",
   327  				"-linkshared")
   328  			codegenArg = "-dynlink"
   329  			forcedGcflags = append(forcedGcflags, "-linkshared")
   330  			// TODO(mwhudson): remove -w when that gets fixed in linker.
   331  			forcedLdflags = append(forcedLdflags, "-linkshared", "-w")
   332  		}
   333  	}
   334  	if codegenArg != "" {
   335  		if gccgo {
   336  			forcedGccgoflags = append([]string{codegenArg}, forcedGccgoflags...)
   337  		} else {
   338  			forcedAsmflags = append([]string{codegenArg}, forcedAsmflags...)
   339  			forcedGcflags = append([]string{codegenArg}, forcedGcflags...)
   340  		}
   341  		// Don't alter InstallSuffix when modifying default codegen args.
   342  		if cfg.BuildBuildmode != "default" || cfg.BuildLinkshared {
   343  			if cfg.BuildContext.InstallSuffix != "" {
   344  				cfg.BuildContext.InstallSuffix += "_"
   345  			}
   346  			cfg.BuildContext.InstallSuffix += codegenArg[1:]
   347  		}
   348  	}
   349  
   350  	switch cfg.BuildMod {
   351  	case "":
   352  		// Behavior will be determined automatically, as if no flag were passed.
   353  	case "readonly", "vendor", "mod":
   354  		if !cfg.ModulesEnabled && !base.InGOFLAGS("-mod") {
   355  			base.Fatalf("build flag -mod=%s only valid when using modules", cfg.BuildMod)
   356  		}
   357  	default:
   358  		base.Fatalf("-mod=%s not supported (can be '', 'mod', 'readonly', or 'vendor')", cfg.BuildMod)
   359  	}
   360  	if !cfg.ModulesEnabled {
   361  		if cfg.ModCacheRW && !base.InGOFLAGS("-modcacherw") {
   362  			base.Fatalf("build flag -modcacherw only valid when using modules")
   363  		}
   364  		if cfg.ModFile != "" && !base.InGOFLAGS("-mod") {
   365  			base.Fatalf("build flag -modfile only valid when using modules")
   366  		}
   367  	}
   368  }
   369  
   370  type version struct {
   371  	name         string
   372  	major, minor int
   373  }
   374  
   375  var compiler struct {
   376  	sync.Once
   377  	version
   378  	err error
   379  }
   380  
   381  // compilerVersion detects the version of $(go env CC).
   382  // It returns a non-nil error if the compiler matches a known version schema but
   383  // the version could not be parsed, or if $(go env CC) could not be determined.
   384  func compilerVersion() (version, error) {
   385  	compiler.Once.Do(func() {
   386  		compiler.err = func() error {
   387  			compiler.name = "unknown"
   388  			cc := os.Getenv("CC")
   389  			cmd := exec.Command(cc, "--version")
   390  			cmd.Env = append(cmd.Environ(), "LANG=C")
   391  			out, err := cmd.Output()
   392  			if err != nil {
   393  				// Compiler does not support "--version" flag: not Clang or GCC.
   394  				return err
   395  			}
   396  
   397  			var match [][]byte
   398  			if bytes.HasPrefix(out, []byte("gcc")) {
   399  				compiler.name = "gcc"
   400  				cmd := exec.Command(cc, "-v")
   401  				cmd.Env = append(cmd.Environ(), "LANG=C")
   402  				out, err := cmd.CombinedOutput()
   403  				if err != nil {
   404  					// gcc, but does not support gcc's "-v" flag?!
   405  					return err
   406  				}
   407  				gccRE := regexp.MustCompile(`gcc version (\d+)\.(\d+)`)
   408  				match = gccRE.FindSubmatch(out)
   409  			} else {
   410  				clangRE := regexp.MustCompile(`clang version (\d+)\.(\d+)`)
   411  				if match = clangRE.FindSubmatch(out); len(match) > 0 {
   412  					compiler.name = "clang"
   413  				}
   414  			}
   415  
   416  			if len(match) < 3 {
   417  				return nil // "unknown"
   418  			}
   419  			if compiler.major, err = strconv.Atoi(string(match[1])); err != nil {
   420  				return err
   421  			}
   422  			if compiler.minor, err = strconv.Atoi(string(match[2])); err != nil {
   423  				return err
   424  			}
   425  			return nil
   426  		}()
   427  	})
   428  	return compiler.version, compiler.err
   429  }
   430  
   431  // compilerRequiredAsanVersion is a copy of the function defined in
   432  // cmd/cgo/internal/testsanitizers/cc_test.go
   433  // compilerRequiredAsanVersion reports whether the compiler is the version
   434  // required by Asan.
   435  func compilerRequiredAsanVersion() error {
   436  	compiler, err := compilerVersion()
   437  	if err != nil {
   438  		return fmt.Errorf("-asan: the version of $(go env CC) could not be parsed")
   439  	}
   440  
   441  	switch compiler.name {
   442  	case "gcc":
   443  		if runtime.GOARCH == "ppc64le" && compiler.major < 9 {
   444  			return fmt.Errorf("-asan is not supported with %s compiler %d.%d\n", compiler.name, compiler.major, compiler.minor)
   445  		}
   446  		if compiler.major < 7 {
   447  			return fmt.Errorf("-asan is not supported with %s compiler %d.%d\n", compiler.name, compiler.major, compiler.minor)
   448  		}
   449  	case "clang":
   450  		if compiler.major < 9 {
   451  			return fmt.Errorf("-asan is not supported with %s compiler %d.%d\n", compiler.name, compiler.major, compiler.minor)
   452  		}
   453  	default:
   454  		return fmt.Errorf("-asan: C compiler is not gcc or clang")
   455  	}
   456  	return nil
   457  }
   458
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