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svartalf / rust-battery

Rust crate providing cross-platform information about the notebook batteries.
https://crates.io/crates/battery
Apache License 2.0
358 stars 40 forks source link

About how to build and battery info scraping #25

Closed Dentrax closed 5 years ago

Dentrax commented 5 years ago

Hey,

I want to use this awesome project in polybar via shell script. But i can't figure it out how to compile cli or ffi. I installed battop via yay battop. It works perfectly.

Actually, i couldn't see a installation guide or it could be a not-well documented. Simply,

  1. When i run this: cargo install battery-ffi

Returns:

Updating crates.io index
  Installing battery-ffi v0.7.0
error: specified package has no binaries
  1. battop is not supporting output args like this:

battop --time-to-empty

It may be really really life saver.

  1. cargo build --release

Returns:

error: failed to resolve patches for `https://github.com/rust-lang/crates.io-index`

Caused by:
  patch for `battery` in `https://github.com/rust-lang/crates.io-index` did not resolve to any crates. If this is unexpected, you may wish to consult: https://github.com/rust-lang/cargo/issues/4678

The bare-minimum thing I want is looks like:

$ battery-cli --time-to-empty

Consequently, I want to write the battery's battery_get_time_to_empty output to the polybar. I am trying to figure it out how to write a script that scrapes about battery informations.

svartalf commented 5 years ago

Hey, @Dentrax!

Here is a deal:

battery-ffi is a thin interface for communication with programs written in other languages; for example, you can write a Python script, which will load the compiled battery_ffi.so library, call the battery_get_time_to_empty function and get back the Python int type. There are examples for C and Python exists, you may want to check them out: https://github.com/svartalf/rust-battery/tree/master/battery-ffi/examples

Also, please note that battery-ffi is a library and not a binary application, so you can't cargo install it.

battop is the TUI interface, like vim or midnight commander. It sounds like a good idea to implement one-time output into JSON or plain text, but at the moment it just does not have that ¯_(ツ)_/¯

What I can suggest right now: take the example and write your own application which will output data in the required format. Since it would be the shell script, you just need to create the Manager struct, iterate over available batteries and write the data into stdout. You can also find multiple example here at the docs.rs

P.S. I'm also glad to hear that AUR package is working correctly :)

Dentrax commented 5 years ago

@svartalf Thank you so much! So in this case, i should write my own wrapper using the battery-ffi lib. Previously repo had the battery-cli but i guess it no longer exists.

My second question is: can i use compiled battery_ffi.so in my .sh scripts?

svartalf commented 5 years ago

@Dentrax, there are two options here: either you can write wrapper in Rust or in any other language.

In the former case you will need the battery crate only: add it into Cargo.toml dependencies block and call as any other crate library.

In the latter case you will need to:

  1. Compile battery-ffi crate
  2. Get the compiled .so file (and .h file if you want to)
  3. Link or load them into your wrapper
  4. Call any function available.

I doubt that there is any good way exists to call FFI functions directly from the shell scripts, so you'll probably need to call your wrapper binary instead.

Dentrax commented 5 years ago

Thank you i will try that. And finally, how can i compile the battery-ffi crate? I am asking this simply question because cargo build --release not works. When i run rustc build.rs, it creates build file.

build: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=522085c26c0bbc8efc450c3c2e2a9fa3f83b645b, not stripped

Is that correct? Am i missing something? (Yet another newbie question :)) Ty.

svartalf commented 5 years ago

@Dentrax what is an error for cargo build --release? Any chance it fails with the following message?

error: failed to resolve patches for `https://github.com/rust-lang/crates.io-index`

Caused by:
  patch for `battery` in `https://github.com/rust-lang/crates.io-index` did not resolve to any crates. If this is unexpected, you may wish to consult: https://github.com/rust-lang/cargo/issues/4678
Dentrax commented 5 years ago

@svartalf Exactly same error with mine. How can i build that with correct way?

svartalf commented 5 years ago

@Dentrax there is a "0.7.1" branch with a fix for this bug.

I'm planning to merge it into the master tomorrow and publish properly. Before that, you can use either this git branch or the pre-compiled .so file from the previous release.

svartalf commented 5 years ago

Hey, @Dentrax, fyi, I've published 0.7.1 version to the crates.io. Sorry it took so long.

Do you still need this issue to be opened?

Dentrax commented 5 years ago

@svartalf

Thank you, now it's compiling without any error. :)