scanner: Update prevPos even when returning utf8.RuneError. #240
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```
panic: regexp: Compile("[[:space:]]*<\xc8\\z"): error parsing regexp: invalid UTF-8: `�\z`
goroutine 32 [running]:
testing.tRunner.func1(0xc4200cae10)
/usr/lib/google-golang/src/testing/testing.go:742 +0x29d
panic(0x507a00, 0xc420290690)
/usr/lib/google-golang/src/runtime/panic.go:505 +0x229
regexp.MustCompile(0xc420289e10, 0x10, 0xc420087680)
/usr/lib/google-golang/src/regexp/regexp.go:240 +0x171
github.com/hashicorp/hcl/hcl/scanner.(*Scanner).scanHeredoc(0xc4200878c0)
gopath/src/github.com/hashicorp/hcl/hcl/scanner/scanner.go:444 +0x3a9
github.com/hashicorp/hcl/hcl/scanner.(*Scanner).Scan(0xc4200878c0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
gopath/src/github.com/hashicorp/hcl/hcl/scanner/scanner.go:186 +0x3e5
```
The calling code will still call unread(), causing panics. This fixes the TestScanHeredocRegexpCompile() unit test.
|
Great find, thank you! |
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This fixes an off-by-one error that's triggered by a combination of
next()returningutf8.RuneErrorandunread()being called.Without this fix, the provided unit test crashes, the the following stack trace. This is because the off-by-one error triggers the here-doc marker, which is a multi-byte unicode codepoint, to only be partially included in the regular expression, causing a regexp compile error.
Notice the off-by-one error in the regexp: the regular expression is not supposed to contain the
<character.Kudos to dvyukov/go-fuzz for finding this!