grim/convey

Fix infinite expanion with self-reference (not mutual reference).
env-loop-nice-try
2017-10-11, Eric Fritz
4477a08d8a0b
Parents 59abcebc6c37
Children 64afa024b3bfc9d01e05fae49f1221fc112f
Fix infinite expanion with self-reference (not mutual reference).
2 files changed, 19 insertions(+), 5 deletions(-)
  • +12 -3
    environment/mapper.go
  • +7 -2
    environment/mapper_test.go
    • --- a/environment/mapper.go Mon Oct 09 11:05:46 2017 -0500
    +++ b/environment/mapper.go Wed Oct 11 20:57:52 2017 -0500
    @@ -27,6 +27,10 @@
    env []string
    }
    +const (
    + MaxExpandWidth = 100
    +)
    +
    func (e *envMapper) Map(name string) string {
    for _, item := range e.env {
    if parts := strings.SplitN(item, "=", 2); parts[0] == name {
    @@ -53,13 +57,18 @@
    func Mapper(str string, env []string) (string, error) {
    mapper := envMapper{env}
    + orig := str
    last := str
    next := os.Expand(last, mapper.Map)
    prev := map[string]struct{}{}
    - for last != next {
    + for i := 0; i < MaxExpandWidth; i++ {
    + if last == next {
    + return next, nil
    + }
    +
    if _, ok := prev[next]; ok {
    - return "", fmt.Errorf("infinite environment mapping loop while expanding '%s'", next)
    + break
    }
    last = next
    @@ -67,7 +76,7 @@
    prev[last] = struct{}{}
    }
    - return next, nil
    + return "", fmt.Errorf("infinite environment mapping loop while expanding '%s'", orig)
    }
    // SliceMapper calls Mapper for each item in a slice and returns a new slice.
    --- a/environment/mapper_test.go Mon Oct 09 11:05:46 2017 -0500
    +++ b/environment/mapper_test.go Wed Oct 11 20:57:52 2017 -0500
    @@ -75,7 +75,12 @@
    Expect(result).To(Equal("123-ohhai!-cba"))
    }
    -func (e *environmentSuite) TestInfiniteExpansion(t sweet.T) {
    +func (e *environmentSuite) TestInfiniteDepthExpansion(t sweet.T) {
    _, err := Mapper("${FOO}", []string{"FOO=$BAR", "BAR=$FOO"})
    - Expect(err).To(MatchError("infinite environment mapping loop while expanding '$BAR'"))
    + Expect(err).To(MatchError("infinite environment mapping loop while expanding '${FOO}'"))
    }
    +
    +func (e *environmentSuite) TestInfiniteWidthExpansion(t sweet.T) {
    + _, err := Mapper("${FOO}", []string{"FOO=FOO${FOO}"})
    + Expect(err).To(MatchError("infinite environment mapping loop while expanding '${FOO}'"))
    +}