158 lines
6.5 KiB
Go
158 lines
6.5 KiB
Go
package getproviders
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import (
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"fmt"
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"path/filepath"
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"strings"
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"golang.org/x/mod/sumdb/dirhash"
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)
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// PackageHash computes a hash of the contents of the package at the given
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// location, using whichever hash algorithm is the current default.
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//
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// Currently, this method returns version 1 hashes as produced by the
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// function PackageHashV1, but this function may switch to other versions in
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// later releases. Call PackageHashV1 directly if you specifically need a V1
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// hash.
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//
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// PackageHash can be used only with the two local package location types
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// PackageLocalDir and PackageLocalArchive, because it needs to access the
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// contents of the indicated package in order to compute the hash. If given
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// a non-local location this function will always return an error.
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func PackageHash(loc PackageLocation) (string, error) {
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return PackageHashV1(loc)
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}
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// PackageMatchesHash returns true if the package at the given location matches
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// the given hash, or false otherwise.
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//
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// If it cannot read from the given location, or if the given hash is in an
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// unsupported format, PackageMatchesHash returns an error.
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//
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// There is currently only one hash format, as implemented by HashV1. However,
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// if others are introduced in future PackageMatchesHash may accept multiple
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// formats, and may generate errors for any formats that become obsolete.
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//
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// PackageMatchesHash can be used only with the two local package location types
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// PackageLocalDir and PackageLocalArchive, because it needs to access the
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// contents of the indicated package in order to compute the hash. If given
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// a non-local location this function will always return an error.
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func PackageMatchesHash(loc PackageLocation, want string) (bool, error) {
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switch {
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case strings.HasPrefix(want, "h1"):
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got, err := PackageHashV1(loc)
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if err != nil {
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return false, err
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}
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return got == want, nil
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default:
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return false, fmt.Errorf("unsupported hash format (this may require a newer version of Terraform)")
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}
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}
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// PackageHashV1 computes a hash of the contents of the package at the given
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// location using hash algorithm 1.
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//
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// The hash covers the paths to files in the directory and the contents of
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// those files. It does not cover other metadata about the files, such as
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// permissions.
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//
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// This function is named "PackageHashV1" in anticipation of other hashing
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// algorithms being added in a backward-compatible way in future. The result
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// from PackageHashV1 always begins with the prefix "h1:" so that callers can
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// distinguish the results of potentially multiple different hash algorithms in
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// future.
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//
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// PackageHashV1 can be used only with the two local package location types
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// PackageLocalDir and PackageLocalArchive, because it needs to access the
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// contents of the indicated package in order to compute the hash. If given
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// a non-local location this function will always return an error.
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func PackageHashV1(loc PackageLocation) (string, error) {
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// Our HashV1 is really just the Go Modules hash version 1, which is
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// sufficient for our needs and already well-used for identity of
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// Go Modules distribution packages. It is also blocked from incompatible
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// changes by being used in a wide array of go.sum files already.
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//
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// In particular, it also supports computing an equivalent hash from
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// an unpacked zip file, which is not important for Terraform workflow
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// today but is likely to become so in future if we adopt a top-level
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// lockfile mechanism that is intended to be checked in to version control,
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// rather than just a transient lock for a particular local cache directory.
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// (In that case we'd need to check hashes of _packed_ packages, too.)
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//
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// Internally, dirhash.Hash1 produces a string containing a sequence of
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// newline-separated path+filehash pairs for all of the files in the
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// directory, and then finally produces a hash of that string to return.
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// In both cases, the hash algorithm is SHA256.
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switch loc := loc.(type) {
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case PackageLocalDir:
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// We'll first dereference a possible symlink at our PackageDir location,
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// as would be created if this package were linked in from another cache.
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packageDir, err := filepath.EvalSymlinks(string(loc))
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if err != nil {
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return "", err
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}
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return dirhash.HashDir(packageDir, "", dirhash.Hash1)
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case PackageLocalArchive:
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archivePath, err := filepath.EvalSymlinks(string(loc))
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if err != nil {
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return "", err
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}
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return dirhash.HashZip(archivePath, dirhash.Hash1)
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default:
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return "", fmt.Errorf("cannot hash package at %s", loc.String())
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}
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}
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// Hash computes a hash of the contents of the package at the location
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// associated with the reciever, using whichever hash algorithm is the current
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// default.
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//
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// This method will change to use new hash versions as they are introduced
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// in future. If you need a specific hash version, call the method for that
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// version directly instead, such as HashV1.
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//
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// Hash can be used only with the two local package location types
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// PackageLocalDir and PackageLocalArchive, because it needs to access the
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// contents of the indicated package in order to compute the hash. If given
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// a non-local location this function will always return an error.
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func (m PackageMeta) Hash() (string, error) {
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return PackageHash(m.Location)
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}
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// MatchesHash returns true if the package at the location associated with
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// the receiver matches the given hash, or false otherwise.
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//
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// If it cannot read from the given location, or if the given hash is in an
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// unsupported format, MatchesHash returns an error.
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//
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// MatchesHash can be used only with the two local package location types
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// PackageLocalDir and PackageLocalArchive, because it needs to access the
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// contents of the indicated package in order to compute the hash. If given
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// a non-local location this function will always return an error.
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func (m PackageMeta) MatchesHash(want string) (bool, error) {
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return PackageMatchesHash(m.Location, want)
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}
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// HashV1 computes a hash of the contents of the package at the location
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// associated with the receiver using hash algorithm 1.
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//
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// The hash covers the paths to files in the directory and the contents of
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// those files. It does not cover other metadata about the files, such as
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// permissions.
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//
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// HashV1 can be used only with the two local package location types
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// PackageLocalDir and PackageLocalArchive, because it needs to access the
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// contents of the indicated package in order to compute the hash. If given
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// a non-local location this function will always return an error.
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func (m PackageMeta) HashV1() (string, error) {
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return PackageHashV1(m.Location)
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}
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