Got rid of a lot of subshell calls

[ischeinkman]

Replaced a lot of subshell calls with normal, in-process syscalls.

Specifically:

• Calls to echo {} > {} have been replaced with new write_ helper functions for writing either strs, u32s, or bool values. This mirrors the existing helpers in sysfs::reading.
• Calls to readlink {} have been replaced with the std::fs::read_link function.

Implications:

• The only places left where we actually need to use a subshell (as opposed to a shell-independent Command call) are:
  • Refreshing the kernel modules in NetworkSettings::apply_kernel_module_settings, since we currently remove & add 2 modules in a single command (instead of 4 different subprocesses)
  • Pulling out the PCI information in PCIInfo::obtain, where we use a sed block to filter & parse the output of lspci -s.

[TheAlexDev23]

Thanks for your work!

Would you mind moving profile::write_all_cores to the sysfs::writing module that you just created? Feels a bit more suited for that.

Also thanks for highlighting the required uses of subshells too, I will need to research ways of getting rid of those, as creating a shell is technically worse than running an independent Command for commands that do not necessarily require it. The modprobe one shouldn't be hard to do, just multiple synchronous calls to run_command but the lsusb and lspci ones would be harder, either recreating what they do through sysfs or moving the sed code into rust using regex.

[ischeinkman]

Would you mind moving profile::write_all_cores to the sysfs::writing module that you just created? Feels a bit more suited for that.

Yup, done!

Also thanks for highlighting the required uses of subshells too, I will need to research ways of getting rid of those, as creating a shell is technically worse than running an independent Command for commands that do not necessarily require it. The modprobe one shouldn't be hard to do, just multiple synchronous calls to run_command but the lsusb and lspci ones would be harder, either recreating what they do through sysfs or moving the sed code into rust using regex.

Funnily enough the lsusb one will actually be one of the easiest because it seems you've already pulled out the regex parsing code into Rust itself. Really the only difficult one is the lspci call thanks to its sed pipe, but we can use the existing lsusb code as a base to figure that one out.

[TheAlexDev23]

Thanks.