query.go

     1  // Copyright 2020 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 modget
     6  
     7  import (
     8  	"fmt"
     9  	"path/filepath"
    10  	"regexp"
    11  	"strings"
    12  	"sync"
    13  
    14  	"cmd/go/internal/base"
    15  	"cmd/go/internal/gover"
    16  	"cmd/go/internal/modload"
    17  	"cmd/go/internal/search"
    18  	"cmd/go/internal/str"
    19  	"cmd/internal/pkgpattern"
    20  
    21  	"golang.org/x/mod/module"
    22  )
    23  
    24  // A query describes a command-line argument and the modules and/or packages
    25  // to which that argument may resolve..
    26  type query struct {
    27  	// raw is the original argument, to be printed in error messages.
    28  	raw string
    29  
    30  	// rawVersion is the portion of raw corresponding to version, if any
    31  	rawVersion string
    32  
    33  	// pattern is the part of the argument before "@" (or the whole argument
    34  	// if there is no "@"), which may match either packages (preferred) or
    35  	// modules (if no matching packages).
    36  	//
    37  	// The pattern may also be "-u", for the synthetic query representing the -u
    38  	// (“upgrade”)flag.
    39  	pattern string
    40  
    41  	// patternIsLocal indicates whether pattern is restricted to match only paths
    42  	// local to the main module, such as absolute filesystem paths or paths
    43  	// beginning with './'.
    44  	//
    45  	// A local pattern must resolve to one or more packages in the main module.
    46  	patternIsLocal bool
    47  
    48  	// version is the part of the argument after "@", or an implied
    49  	// "upgrade" or "patch" if there is no "@". version specifies the
    50  	// module version to get.
    51  	version string
    52  
    53  	// matchWildcard, if non-nil, reports whether pattern, which must be a
    54  	// wildcard (with the substring "..."), matches the given package or module
    55  	// path.
    56  	matchWildcard func(path string) bool
    57  
    58  	// canMatchWildcardInModule, if non-nil, reports whether the module with the given
    59  	// path could lexically contain a package matching pattern, which must be a
    60  	// wildcard.
    61  	canMatchWildcardInModule func(mPath string) bool
    62  
    63  	// conflict is the first query identified as incompatible with this one.
    64  	// conflict forces one or more of the modules matching this query to a
    65  	// version that does not match version.
    66  	conflict *query
    67  
    68  	// candidates is a list of sets of alternatives for a path that matches (or
    69  	// contains packages that match) the pattern. The query can be resolved by
    70  	// choosing exactly one alternative from each set in the list.
    71  	//
    72  	// A path-literal query results in only one set: the path itself, which
    73  	// may resolve to either a package path or a module path.
    74  	//
    75  	// A wildcard query results in one set for each matching module path, each
    76  	// module for which the matching version contains at least one matching
    77  	// package, and (if no other modules match) one candidate set for the pattern
    78  	// overall if no existing match is identified in the build list.
    79  	//
    80  	// A query for pattern "all" results in one set for each package transitively
    81  	// imported by the main module.
    82  	//
    83  	// The special query for the "-u" flag results in one set for each
    84  	// otherwise-unconstrained package that has available upgrades.
    85  	candidates   []pathSet
    86  	candidatesMu sync.Mutex
    87  
    88  	// pathSeen ensures that only one pathSet is added to the query per
    89  	// unique path.
    90  	pathSeen sync.Map
    91  
    92  	// resolved contains the set of modules whose versions have been determined by
    93  	// this query, in the order in which they were determined.
    94  	//
    95  	// The resolver examines the candidate sets for each query, resolving one
    96  	// module per candidate set in a way that attempts to avoid obvious conflicts
    97  	// between the versions resolved by different queries.
    98  	resolved []module.Version
    99  
   100  	// matchesPackages is true if the resolved modules provide at least one
   101  	// package matching q.pattern.
   102  	matchesPackages bool
   103  }
   104  
   105  // A pathSet describes the possible options for resolving a specific path
   106  // to a package and/or module.
   107  type pathSet struct {
   108  	// path is a package (if "all" or "-u" or a non-wildcard) or module (if
   109  	// wildcard) path that could be resolved by adding any of the modules in this
   110  	// set. For a wildcard pattern that so far matches no packages, the path is
   111  	// the wildcard pattern itself.
   112  	//
   113  	// Each path must occur only once in a query's candidate sets, and the path is
   114  	// added implicitly to each pathSet returned to pathOnce.
   115  	path string
   116  
   117  	// pkgMods is a set of zero or more modules, each of which contains the
   118  	// package with the indicated path. Due to the requirement that imports be
   119  	// unambiguous, only one such module can be in the build list, and all others
   120  	// must be excluded.
   121  	pkgMods []module.Version
   122  
   123  	// mod is either the zero Version, or a module that does not contain any
   124  	// packages matching the query but for which the module path itself
   125  	// matches the query pattern.
   126  	//
   127  	// We track this module separately from pkgMods because, all else equal, we
   128  	// prefer to match a query to a package rather than just a module. Also,
   129  	// unlike the modules in pkgMods, this module does not inherently exclude
   130  	// any other module in pkgMods.
   131  	mod module.Version
   132  
   133  	err error
   134  }
   135  
   136  // errSet returns a pathSet containing the given error.
   137  func errSet(err error) pathSet { return pathSet{err: err} }
   138  
   139  // newQuery returns a new query parsed from the raw argument,
   140  // which must be either path or path@version.
   141  func newQuery(raw string) (*query, error) {
   142  	pattern, rawVers, found, err := modload.ParsePathVersion(raw)
   143  	if err != nil {
   144  		return nil, err
   145  	}
   146  	if found && (strings.Contains(rawVers, "@") || rawVers == "") {
   147  		return nil, fmt.Errorf("invalid module version syntax %q", raw)
   148  	}
   149  
   150  	// If no version suffix is specified, assume @upgrade.
   151  	// If -u=patch was specified, assume @patch instead.
   152  	version := rawVers
   153  	if version == "" {
   154  		if getU.version == "" {
   155  			version = "upgrade"
   156  		} else {
   157  			version = getU.version
   158  		}
   159  	}
   160  
   161  	q := &query{
   162  		raw:            raw,
   163  		rawVersion:     rawVers,
   164  		pattern:        pattern,
   165  		patternIsLocal: filepath.IsAbs(pattern) || search.IsRelativePath(pattern),
   166  		version:        version,
   167  	}
   168  	if strings.Contains(q.pattern, "...") {
   169  		q.matchWildcard = pkgpattern.MatchPattern(q.pattern)
   170  		q.canMatchWildcardInModule = pkgpattern.TreeCanMatchPattern(q.pattern)
   171  	}
   172  	if err := q.validate(); err != nil {
   173  		return q, err
   174  	}
   175  	return q, nil
   176  }
   177  
   178  // validate reports a non-nil error if q is not sensible and well-formed.
   179  func (q *query) validate() error {
   180  	if q.patternIsLocal {
   181  		if q.rawVersion != "" {
   182  			return fmt.Errorf("can't request explicit version %q of path %q in main module", q.rawVersion, q.pattern)
   183  		}
   184  		return nil
   185  	}
   186  
   187  	if q.pattern == "all" {
   188  		// If there is no main module, "all" is not meaningful.
   189  		if !modload.HasModRoot() {
   190  			return fmt.Errorf(`cannot match "all": %v`, modload.ErrNoModRoot)
   191  		}
   192  		if !versionOkForMainModule(q.version) {
   193  			// TODO(bcmills): "all@none" seems like a totally reasonable way to
   194  			// request that we remove all module requirements, leaving only the main
   195  			// module and standard library. Perhaps we should implement that someday.
   196  			return &modload.QueryUpgradesAllError{
   197  				MainModules: modload.MainModules.Versions(),
   198  				Query:       q.version,
   199  			}
   200  		}
   201  	}
   202  
   203  	if search.IsMetaPackage(q.pattern) && q.pattern != "all" {
   204  		if q.pattern != q.raw {
   205  			if q.pattern == "tool" {
   206  				return fmt.Errorf("can't request explicit version of \"tool\" pattern")
   207  			}
   208  			return fmt.Errorf("can't request explicit version of standard-library pattern %q", q.pattern)
   209  		}
   210  	}
   211  
   212  	return nil
   213  }
   214  
   215  // String returns the original argument from which q was parsed.
   216  func (q *query) String() string { return q.raw }
   217  
   218  // ResolvedString returns a string describing m as a resolved match for q.
   219  func (q *query) ResolvedString(m module.Version) string {
   220  	if m.Path != q.pattern {
   221  		if m.Version != q.version {
   222  			return fmt.Sprintf("%v (matching %s@%s)", m, q.pattern, q.version)
   223  		}
   224  		return fmt.Sprintf("%v (matching %v)", m, q)
   225  	}
   226  	if m.Version != q.version {
   227  		return fmt.Sprintf("%s@%s (%s)", q.pattern, q.version, m.Version)
   228  	}
   229  	return q.String()
   230  }
   231  
   232  // isWildcard reports whether q is a pattern that can match multiple paths.
   233  func (q *query) isWildcard() bool {
   234  	return q.matchWildcard != nil || (q.patternIsLocal && strings.Contains(q.pattern, "..."))
   235  }
   236  
   237  // matchesPath reports whether the given path matches q.pattern.
   238  func (q *query) matchesPath(path string) bool {
   239  	if q.matchWildcard != nil && !gover.IsToolchain(path) {
   240  		return q.matchWildcard(path)
   241  	}
   242  	return path == q.pattern
   243  }
   244  
   245  // canMatchInModule reports whether the given module path can potentially
   246  // contain q.pattern.
   247  func (q *query) canMatchInModule(mPath string) bool {
   248  	if gover.IsToolchain(mPath) {
   249  		return false
   250  	}
   251  	if q.canMatchWildcardInModule != nil {
   252  		return q.canMatchWildcardInModule(mPath)
   253  	}
   254  	return str.HasPathPrefix(q.pattern, mPath)
   255  }
   256  
   257  // pathOnce invokes f to generate the pathSet for the given path,
   258  // if one is still needed.
   259  //
   260  // Note that, unlike sync.Once, pathOnce does not guarantee that a concurrent
   261  // call to f for the given path has completed on return.
   262  //
   263  // pathOnce is safe for concurrent use by multiple goroutines, but note that
   264  // multiple concurrent calls will result in the sets being added in
   265  // nondeterministic order.
   266  func (q *query) pathOnce(path string, f func() pathSet) {
   267  	if _, dup := q.pathSeen.LoadOrStore(path, nil); dup {
   268  		return
   269  	}
   270  
   271  	cs := f()
   272  
   273  	if len(cs.pkgMods) > 0 || cs.mod != (module.Version{}) || cs.err != nil {
   274  		cs.path = path
   275  		q.candidatesMu.Lock()
   276  		q.candidates = append(q.candidates, cs)
   277  		q.candidatesMu.Unlock()
   278  	}
   279  }
   280  
   281  // reportError logs err concisely using base.Errorf.
   282  func reportError(q *query, err error) {
   283  	errStr := err.Error()
   284  
   285  	// If err already mentions all of the relevant parts of q, just log err to
   286  	// reduce stutter. Otherwise, log both q and err.
   287  	//
   288  	// TODO(bcmills): Use errors.As to unpack these errors instead of parsing
   289  	// strings with regular expressions.
   290  
   291  	patternRE := regexp.MustCompile("(?m)(?:[ \t(\"`]|^)" + regexp.QuoteMeta(q.pattern) + "(?:[ @:;)\"`]|$)")
   292  	if patternRE.MatchString(errStr) {
   293  		if q.rawVersion == "" {
   294  			base.Errorf("go: %s", errStr)
   295  			return
   296  		}
   297  
   298  		versionRE := regexp.MustCompile("(?m)(?:[ @(\"`]|^)" + regexp.QuoteMeta(q.version) + "(?:[ :;)\"`]|$)")
   299  		if versionRE.MatchString(errStr) {
   300  			base.Errorf("go: %s", errStr)
   301  			return
   302  		}
   303  	}
   304  
   305  	if qs := q.String(); qs != "" {
   306  		base.Errorf("go: %s: %s", qs, errStr)
   307  	} else {
   308  		base.Errorf("go: %s", errStr)
   309  	}
   310  }
   311  
   312  func reportConflict(pq *query, m module.Version, conflict versionReason) {
   313  	if pq.conflict != nil {
   314  		// We've already reported a conflict for the proposed query.
   315  		// Don't report it again, even if it has other conflicts.
   316  		return
   317  	}
   318  	pq.conflict = conflict.reason
   319  
   320  	proposed := versionReason{
   321  		version: m.Version,
   322  		reason:  pq,
   323  	}
   324  	if pq.isWildcard() && !conflict.reason.isWildcard() {
   325  		// Prefer to report the specific path first and the wildcard second.
   326  		proposed, conflict = conflict, proposed
   327  	}
   328  	reportError(pq, &conflictError{
   329  		mPath:    m.Path,
   330  		proposed: proposed,
   331  		conflict: conflict,
   332  	})
   333  }
   334  
   335  type conflictError struct {
   336  	mPath    string
   337  	proposed versionReason
   338  	conflict versionReason
   339  }
   340  
   341  func (e *conflictError) Error() string {
   342  	argStr := func(q *query, v string) string {
   343  		if v != q.version {
   344  			return fmt.Sprintf("%s@%s (%s)", q.pattern, q.version, v)
   345  		}
   346  		return q.String()
   347  	}
   348  
   349  	pq := e.proposed.reason
   350  	rq := e.conflict.reason
   351  	modDetail := ""
   352  	if e.mPath != pq.pattern {
   353  		modDetail = fmt.Sprintf("for module %s, ", e.mPath)
   354  	}
   355  
   356  	return fmt.Sprintf("%s%s conflicts with %s",
   357  		modDetail,
   358  		argStr(pq, e.proposed.version),
   359  		argStr(rq, e.conflict.version))
   360  }
   361  
   362  func versionOkForMainModule(version string) bool {
   363  	return version == "upgrade" || version == "patch"
   364  }
   365
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