html/template: CL 274450 (in go1.16beta1) causes panic #43295
Comments
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Can you tell us how we can recreate the problem ourselves? Thanks. It looks like somehow |
ianlancetaylor
changed the title
ianlancetaylor
added
NeedsInvestigation
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Try to write a reproducer according to your description, but fail to reproduce. |
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I’ll try to extract a reproduction case today |
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Got a standalone reproduction case: package main
import (
"bytes"
"fmt"
"html/template"
)
type eepromVersion struct {
PieepromSHA256 string // pieeprom.sig
VL805SHA256 string // vl805.sig
}
type A struct {
EEPROM *eepromVersion
}
func main() {
s := `
{{ if .EEPROM }}
<tr>
<th>EEPROM<br>(SHA256)</th>
<td>{{ shortenSHA256 .EEPROM.PieepromSHA256 }}<br>{{ shortenSHA256 .EEPROM.VL805SHA256 }}</td>
</tr>
{{ end }}
`
e := eepromVersion{
"pieeprom.sig",
"vl805.sig",
}
a := A{
EEPROM: &e,
}
commonTmpls := template.New("root").Funcs(map[string]interface{}{
"shortenSHA256": func(hash string) string {
return hash
},
})
commonTmpls = template.Must(commonTmpls.New("header").Parse("head"))
overviewTmpl := template.Must(template.Must(commonTmpls.Clone()).New("overview").Parse(s))
out := &bytes.Buffer{}
if err := overviewTmpl.Execute(out, a); err != nil {
panic(err)
}
fmt.Println(out.String())
}Note that parsing the header template, and calling the shortenSHA256 function are both required to reproduce the bug. This also reproduces on linux/amd64. |
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Change https://golang.org/cl/279432 mentions this issue: |
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Change https://golang.org/cl/279492 mentions this issue: |
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@stapelberg Thanks for the reproduction case. I think that https://golang.org/cl/279492 fixes the problem. It does fix your test case, at least. When you have time, give it a try on your original code. Thanks. |
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Thanks for the quick fix! I just got a chance to test it in my original environment, and I hereby confirm that your https://golang.org/cl/279492 indeed does fix the problem for me. |
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Closing, this appears to be fixed. Please let me know if I am mistaken. |
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No, https://go-review.googlesource.com/c/go/+/279492/ has not yet been submitted. This isn’t fixed yet. |
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Thanks, I was mistaken! |
and others
What version of Go are you using (
go version)?Does this issue reproduce with the latest release?
Reproduces with Go tip
What operating system and processor architecture are you using (
go env)?go envOutputWhat did you do?
As soon as I try to evaluate this template:
where
shortenSHA256is defined as such:and EEPROM is of type
I get a panic at runtime:
The full panic is at https://gist.github.com/stapelberg/b804f2e0582b34b31ae069bfc36304ab in case it’s relevant.
I tracked this problem down to commit 5a4db10. Once I revert that commit, I no longer get the panic.
cc @ianlancetaylor
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