[OpenWrt-Devel] [PATCH 0/4] Add multi-line option value support to UCI config file parser.

Felix Fietkau nbd at openwrt.org
Tue Nov 25 05:57:45 EST 2014

On 2014-11-06 21:21, Yousong Zhou wrote:
> I am not quite familiar with the early history of how UCI file was parsed, but
> thought that UCI config files were parsed in a quite clever way all by shell
> scripts which made it possible to have multi-line value for options.  AFAIK, at
> least package openvpn [1] depends on this feature.
> This series tries to fix an issue with current C implementation of parser for
> UCI config file.  The current code uses pointers into line buffer
> `ctx->pctx->buf` which may need to grow in size when a backslash was found at
> the end of line.  The grow is implemented by function uci_realloc() which may
> return an address different from the original.  Then the parser will be in a
> state where ctx->pctx->buf changed, but various char **str and char **target
> are not updated along.
> The realloc() can be triggered by something like below (in function
> parse_double_quote()).
> 	config sockd 'instance0'
> 	    option internal_network 'vpn'
> 	    option external_network 'wan'
> 	    option extra_config "a \
> 		 bbbbbbbbbbbbb \
> 		 ccccccccccccc \
> 	"
> A few test cases, including importing/exporting config, getting/setting option
> values were also included trying to verify the patch.
> I do not expect this to be accepted in the neare future because at later stage
> of preparing this series I saw that LF and NL characters are explicitly deemed
> illegal for option value in uci_validate_text().  But if you are interested in
> this feature, you can give it a try.
> I found multi-line option value useful in cases where I want parts of the
> program's configuration values to be connected with OpenWrt system state, e.g.
> stop/start services when the status of the dependent network go down/up, while
> still keep the related bits all in one place, not just many remedy scripts
> scattered here and there.
> [1] see `append_params()` in package/network/services/openvpn/files/openvpn.init
Applied to uci git. I will commit the update to trunk soon.


- Felix
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