From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Rini Date: Tue, 2 Mar 2021 08:20:39 -0500 Subject: [PATCH] hush: Fix assignments being misinterpreted as commands In-Reply-To: <4e476358-e511-90de-fd47-ad24ddeecd2e@gmail.com> References: <20210228212951.1175231-1-seanga2@gmail.com> <914D3972-B8A7-45A8-AC3E-95519C56EEB7@gmx.de> <20210301141705.GZ10169@bill-the-cat> <4e476358-e511-90de-fd47-ad24ddeecd2e@gmail.com> Message-ID: <20210302132039.GT10169@bill-the-cat> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Mon, Mar 01, 2021 at 06:07:36PM -0500, Sean Anderson wrote: > On 3/1/21 1:26 PM, Heinrich Schuchardt wrote: > > On 3/1/21 3:17 PM, Tom Rini wrote: > > > On Sun, Feb 28, 2021 at 06:51:53PM -0500, Sean Anderson wrote: > > > > On 2/28/21 6:40 PM, Heinrich Schuchardt wrote: > > > > > Am 28. Februar 2021 22:29:51 MEZ schrieb Sean Anderson : > > > > > > If there were no variable substitutions in a command, then initial > > > > > > assignments would be misinterpreted as commands, instead of being > > > > > > skipped > > > > > > over. This is demonstrated by the following example: > > > > > > > > > > > > => foo=bar echo baz > > > > > > > > > > The commit message does not explain why this patch is needed. > > > > > > > > This is a bug I noticed while writing some tests of hush. > > > > > > > > > What shall be the value off foo after this line? > > > > > > > > It should be bar. This is an existing difference when compared with > > > > bash. For example, without this patch, we have > > > > > > > > => foo=bar echo $foo > > > > bar > > > > => echo $foo > > > > bar > > > > This seems really awkward. In bash I get: > > > > $ foo=bar ./test.sh > > bar > > $ echo $foo > > > > $ > > > > Where test.sh > > > > #!/bin/sh > > echo $foo > > > > I did not expect an assignment made before a command to stick. > > Yeah, this is because hush does not have the concept of per-command > assignments (scope). So everything happens in the global scope. > > > > > > > > > > > > > > > What will be the output of > > > > > > > > > > foo=bar echo ${foo} > > > > > > > > > > with and without your patch? > > > > > > > > It is the same. > > > > Please, provide an example where the patch makes a difference. > > > > Best regards > > > > Heinrich > > > > > > > > bash works as you describe. dash and busybox-sh both function like > > > this: > > > $ foo=bar echo $foo > > > > > > $ echo $foo > > > > > > $ > > > > > > That we error out entirely is different from everyone. Is that a good > > > thing? Maybe. I know I've caught myself making thinkos due to that > > > logic. It does also violate the principal of least surprise, that we > > > don't act like anything else. But I would suggest the behavior of > > > busybox-sh (what we forked long long ago) is what we should model here > > > rather than be more bash-like. I'm not all that firm on this opinion > > > frankly, especially given the one-line nature of the change to bring us > > > that behavior and I assume dash/busybox are acting like pure sh would in > > > this case, which we aren't anyhow. > > Ok, I'd like to clear things up. Here is the current behavior of U-Boot: > > > => foo=bar echo $foo > bar > => echo $foo > bar > => baz=bar echo qux > Unknown command 'baz=bar' - try 'help' I see this as well (which isn't what I said in another part of this thread, so I re-checked just now). > with this patch, this changes to > > => foo=bar echo $foo > bar > => echo $foo > bar > => baz=bar echo qux > qux > > This patch *only* affects cases where there is an assignment at the > beginning of the line, but there is *no* variable reference in the > command. I know this is an edge case, but the current logic is clearly > wrong here. OK. But I don't see that behavior in bash 4.4.20 (Ubuntu 18.04). Where does one get a shell that works like you're changing our hush to? -- Tom -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 659 bytes Desc: not available URL: