mime: ParseMediaType parses invalid media types

[dvyukov]

The following program fails with the panic:

package main

import (
    "mime"
    "fmt"
)

func main() {
    sdata := "0"
    mt, params, err := mime.ParseMediaType(sdata)
    if err != nil {
        return
    }
    sdata1 := mime.FormatMediaType(mt, params)
    _, _, err = mime.ParseMediaType(sdata1)
    if err != nil {
        fmt.Printf("%q(%q, %+v) -> %q\n", sdata, mt, params, sdata1)
        panic(err)
    }
}

"0"("0", map[]) -> ""
panic: mime: no media type

If "0" is not a valid mediatype, then the first ParseMediaType should produce an error.

go version devel +514014c Thu Jun 18 15:54:35 2015 +0200 linux/amd64

[rsc]

@bradfitz, can you look at this and #11290 and #11291? I assume they're all kind of the same.

[bradfitz]

Will do.

[gopherbot]

CL https://golang.org/cl/17135 mentions this issue.