src

pseudo.go (8630B)

---

 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // Pseudo-versions
 //
 // Code authors are expected to tag the revisions they want users to use,
 // including prereleases. However, not all authors tag versions at all,
 // and not all commits a user might want to try will have tags.
 // A pseudo-version is a version with a special form that allows us to
 // address an untagged commit and order that version with respect to
 // other versions we might encounter.
 //
 // A pseudo-version takes one of the general forms:
 //
 //	(1) vX.0.0-yyyymmddhhmmss-abcdef123456
 //	(2) vX.Y.(Z+1)-0.yyyymmddhhmmss-abcdef123456
 //	(3) vX.Y.(Z+1)-0.yyyymmddhhmmss-abcdef123456+incompatible
 //	(4) vX.Y.Z-pre.0.yyyymmddhhmmss-abcdef123456
 //	(5) vX.Y.Z-pre.0.yyyymmddhhmmss-abcdef123456+incompatible
 //
 // If there is no recently tagged version with the right major version vX,
 // then form (1) is used, creating a space of pseudo-versions at the bottom
 // of the vX version range, less than any tagged version, including the unlikely v0.0.0.
 //
 // If the most recent tagged version before the target commit is vX.Y.Z or vX.Y.Z+incompatible,
 // then the pseudo-version uses form (2) or (3), making it a prerelease for the next
 // possible semantic version after vX.Y.Z. The leading 0 segment in the prerelease string
 // ensures that the pseudo-version compares less than possible future explicit prereleases
 // like vX.Y.(Z+1)-rc1 or vX.Y.(Z+1)-1.
 //
 // If the most recent tagged version before the target commit is vX.Y.Z-pre or vX.Y.Z-pre+incompatible,
 // then the pseudo-version uses form (4) or (5), making it a slightly later prerelease.
 
 package module
 
 import (
 	"errors"
 	"fmt"
 	"strings"
 	"time"
 
 	"golang.org/x/mod/internal/lazyregexp"
 	"golang.org/x/mod/semver"
 )
 
 var pseudoVersionRE = lazyregexp.New(`^v[0-9]+\.(0\.0-|\d+\.\d+-([^+]*\.)?0\.)\d{14}-[A-Za-z0-9]+(\+[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$`)
 
 const PseudoVersionTimestampFormat = "20060102150405"
 
 // PseudoVersion returns a pseudo-version for the given major version ("v1")
 // preexisting older tagged version ("" or "v1.2.3" or "v1.2.3-pre"), revision time,
 // and revision identifier (usually a 12-byte commit hash prefix).
 func PseudoVersion(major, older string, t time.Time, rev string) string {
 	if major == "" {
 		major = "v0"
 	}
 	segment := fmt.Sprintf("%s-%s", t.UTC().Format(PseudoVersionTimestampFormat), rev)
 	build := semver.Build(older)
 	older = semver.Canonical(older)
 	if older == "" {
 		return major + ".0.0-" + segment // form (1)
 	}
 	if semver.Prerelease(older) != "" {
 		return older + ".0." + segment + build // form (4), (5)
 	}
 
 	// Form (2), (3).
 	// Extract patch from vMAJOR.MINOR.PATCH
 	i := strings.LastIndex(older, ".") + 1
 	v, patch := older[:i], older[i:]
 
 	// Reassemble.
 	return v + incDecimal(patch) + "-0." + segment + build
 }
 
 // ZeroPseudoVersion returns a pseudo-version with a zero timestamp and
 // revision, which may be used as a placeholder.
 func ZeroPseudoVersion(major string) string {
 	return PseudoVersion(major, "", time.Time{}, "000000000000")
 }
 
 // incDecimal returns the decimal string incremented by 1.
 func incDecimal(decimal string) string {
 	// Scan right to left turning 9s to 0s until you find a digit to increment.
 	digits := []byte(decimal)
 	i := len(digits) - 1
 	for ; i >= 0 && digits[i] == '9'; i-- {
 		digits[i] = '0'
 	}
 	if i >= 0 {
 		digits[i]++
 	} else {
 		// digits is all zeros
 		digits[0] = '1'
 		digits = append(digits, '0')
 	}
 	return string(digits)
 }
 
 // decDecimal returns the decimal string decremented by 1, or the empty string
 // if the decimal is all zeroes.
 func decDecimal(decimal string) string {
 	// Scan right to left turning 0s to 9s until you find a digit to decrement.
 	digits := []byte(decimal)
 	i := len(digits) - 1
 	for ; i >= 0 && digits[i] == '0'; i-- {
 		digits[i] = '9'
 	}
 	if i < 0 {
 		// decimal is all zeros
 		return ""
 	}
 	if i == 0 && digits[i] == '1' && len(digits) > 1 {
 		digits = digits[1:]
 	} else {
 		digits[i]--
 	}
 	return string(digits)
 }
 
 // IsPseudoVersion reports whether v is a pseudo-version.
 func IsPseudoVersion(v string) bool {
 	return strings.Count(v, "-") >= 2 && semver.IsValid(v) && pseudoVersionRE.MatchString(v)
 }
 
 // IsZeroPseudoVersion returns whether v is a pseudo-version with a zero base,
 // timestamp, and revision, as returned by [ZeroPseudoVersion].
 func IsZeroPseudoVersion(v string) bool {
 	return v == ZeroPseudoVersion(semver.Major(v))
 }
 
 // PseudoVersionTime returns the time stamp of the pseudo-version v.
 // It returns an error if v is not a pseudo-version or if the time stamp
 // embedded in the pseudo-version is not a valid time.
 func PseudoVersionTime(v string) (time.Time, error) {
 	_, timestamp, _, _, err := parsePseudoVersion(v)
 	if err != nil {
 		return time.Time{}, err
 	}
 	t, err := time.Parse("20060102150405", timestamp)
 	if err != nil {
 		return time.Time{}, &InvalidVersionError{
 			Version: v,
 			Pseudo:  true,
 			Err:     fmt.Errorf("malformed time %q", timestamp),
 		}
 	}
 	return t, nil
 }
 
 // PseudoVersionRev returns the revision identifier of the pseudo-version v.
 // It returns an error if v is not a pseudo-version.
 func PseudoVersionRev(v string) (rev string, err error) {
 	_, _, rev, _, err = parsePseudoVersion(v)
 	return
 }
 
 // PseudoVersionBase returns the canonical parent version, if any, upon which
 // the pseudo-version v is based.
 //
 // If v has no parent version (that is, if it is "vX.0.0-[…]"),
 // PseudoVersionBase returns the empty string and a nil error.
 func PseudoVersionBase(v string) (string, error) {
 	base, _, _, build, err := parsePseudoVersion(v)
 	if err != nil {
 		return "", err
 	}
 
 	switch pre := semver.Prerelease(base); pre {
 	case "":
 		// vX.0.0-yyyymmddhhmmss-abcdef123456 → ""
 		if build != "" {
 			// Pseudo-versions of the form vX.0.0-yyyymmddhhmmss-abcdef123456+incompatible
 			// are nonsensical: the "vX.0.0-" prefix implies that there is no parent tag,
 			// but the "+incompatible" suffix implies that the major version of
 			// the parent tag is not compatible with the module's import path.
 			//
 			// There are a few such entries in the index generated by proxy.golang.org,
 			// but we believe those entries were generated by the proxy itself.
 			return "", &InvalidVersionError{
 				Version: v,
 				Pseudo:  true,
 				Err:     fmt.Errorf("lacks base version, but has build metadata %q", build),
 			}
 		}
 		return "", nil
 
 	case "-0":
 		// vX.Y.(Z+1)-0.yyyymmddhhmmss-abcdef123456 → vX.Y.Z
 		// vX.Y.(Z+1)-0.yyyymmddhhmmss-abcdef123456+incompatible → vX.Y.Z+incompatible
 		base = strings.TrimSuffix(base, pre)
 		i := strings.LastIndexByte(base, '.')
 		if i < 0 {
 			panic("base from parsePseudoVersion missing patch number: " + base)
 		}
 		patch := decDecimal(base[i+1:])
 		if patch == "" {
 			// vX.0.0-0 is invalid, but has been observed in the wild in the index
 			// generated by requests to proxy.golang.org.
 			//
 			// NOTE(bcmills): I cannot find a historical bug that accounts for
 			// pseudo-versions of this form, nor have I seen such versions in any
 			// actual go.mod files. If we find actual examples of this form and a
 			// reasonable theory of how they came into existence, it seems fine to
 			// treat them as equivalent to vX.0.0 (especially since the invalid
 			// pseudo-versions have lower precedence than the real ones). For now, we
 			// reject them.
 			return "", &InvalidVersionError{
 				Version: v,
 				Pseudo:  true,
 				Err:     fmt.Errorf("version before %s would have negative patch number", base),
 			}
 		}
 		return base[:i+1] + patch + build, nil
 
 	default:
 		// vX.Y.Z-pre.0.yyyymmddhhmmss-abcdef123456 → vX.Y.Z-pre
 		// vX.Y.Z-pre.0.yyyymmddhhmmss-abcdef123456+incompatible → vX.Y.Z-pre+incompatible
 		if !strings.HasSuffix(base, ".0") {
 			panic(`base from parsePseudoVersion missing ".0" before date: ` + base)
 		}
 		return strings.TrimSuffix(base, ".0") + build, nil
 	}
 }
 
 var errPseudoSyntax = errors.New("syntax error")
 
 func parsePseudoVersion(v string) (base, timestamp, rev, build string, err error) {
 	if !IsPseudoVersion(v) {
 		return "", "", "", "", &InvalidVersionError{
 			Version: v,
 			Pseudo:  true,
 			Err:     errPseudoSyntax,
 		}
 	}
 	build = semver.Build(v)
 	v = strings.TrimSuffix(v, build)
 	j := strings.LastIndex(v, "-")
 	v, rev = v[:j], v[j+1:]
 	i := strings.LastIndex(v, "-")
 	if j := strings.LastIndex(v, "."); j > i {
 		base = v[:j] // "vX.Y.Z-pre.0" or "vX.Y.(Z+1)-0"
 		timestamp = v[j+1:]
 	} else {
 		base = v[:i] // "vX.0.0"
 		timestamp = v[i+1:]
 	}
 	return base, timestamp, rev, build, nil
 }