mixer(8): Make mute and recsrc argument parsing more robust

[christos]

Summary

For the deprecated argument interfaces of the mute (1, 0, ^) and recsrc
(+, -, =, ^) controls, we only check the first character of the
argument, which means that an argument such as "vol.mute=10" would be a
valid. Fix this by checking the whole argument string.

Sponsored by: The FreeBSD Foundation
MFC after: 2 days

[christos]

usr.sbin/mixer/mixer.c

436

I guess strcmp()s would be fine as well.

475

Ditto.

[dev_submerge.ch]

Did some brief tests, looks good to me.

[dev_submerge.ch]

For the deprecated argument interfaces of the mute (1, 0, ^) and recsrc
(+, -, =, ^) controls,

On a side note, how do people know that these are deprecated? The CLI interface of mixer(8) is used as an API by user scripts - there's been some resentment already due to the change from percentage to decimal values (difficult to parse and modify in shell script).

[christos]

In D45973#1049896, @dev_submerge.ch wrote:

For the deprecated argument interfaces of the mute (1, 0, ^) and recsrc
(+, -, =, ^) controls,

On a side note, how do people know that these are deprecated? The CLI interface of mixer(8) is used as an API by user scripts - there's been some resentment already due to the change from percentage to decimal values (difficult to parse and modify in shell script).

I think adding a man page notice would suffice for now. Also regarding percentage values, they are still available. You can do mixer vol.volume=[+|-]<n>%[:[+|-]<n>%] just fine.

[dev_submerge.ch]

In D45973#1050056, @christos wrote:

In D45973#1049896, @dev_submerge.ch wrote:

For the deprecated argument interfaces of the mute (1, 0, ^) and recsrc
(+, -, =, ^) controls,

On a side note, how do people know that these are deprecated? The CLI interface of mixer(8) is used as an API by user scripts - there's been some resentment already due to the change from percentage to decimal values (difficult to parse and modify in shell script).

I think adding a man page notice would suffice for now.

Adding a man page notice about deprecation is fine, but it should be communicated before the actual removal. People on the release train should have a chance to know that one or two releases in advance. Or at least communicate it explicitly via release notes, if possible.

Also regarding percentage values, they are still available. You can do mixer vol.volume=[+|-]<n>%[:[+|-]<n>%] just fine.

Yes, but reading the current value and turning it into a percentage for display / comparison requires some non-trivial awk skills. People have suggested to support libxo(3) output, as an alternative.