Remove useless command calls

[linkmauve]

Someone on lobste.rs found those out two years ago, but besides complaining nobody fixed them… So here I am, I’ve only fixed the most glaring issues, I plan on replacing the remaining loginctl calls with zbus and then this issue can be closed as fixed.

[Copilot]

Pull request overview

This PR removes unnecessary shell command invocations in the Linux platform code, replacing them with native Rust implementations. The changes eliminate dependencies on external commands like sh, awk, ps, cat, and whoami, improving performance and reducing potential security issues from shell command injection.

• Replaces shell commands with direct file I/O for reading /etc/os-release and /proc/self/sessionid
• Removes unused command path constants (CMD_PS, CMD_SH)
• Replaces whoami/getent commands with std::env::home_dir() for home directory resolution
• Simplifies pgrep invocation by removing unnecessary shell wrapper

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/platform/linux.rs	Refactors Distro::new() to read /etc/os-release directly, simplifies is_kde_session() pgrep call, replaces cat with fs::read_to_string(), removes unused helper functions and their tests
src/config.rs	Replaces whoami/getent command chain with std::env::home_dir() for home directory detection

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[Copilot]

The line.unwrap_or_default() call silently ignores I/O errors when reading lines from the file. If a line read fails, it will be treated as an empty string, potentially skipping valid data. Consider using a pattern that either propagates errors or handles them explicitly, such as:

if let Ok(line_content) = line {
    if let Some((key, value)) = line_content.split_once('=') {
        // process key-value pairs
    }
}

Suggested change

	if let Some((key, value)) = line.unwrap_or_default().split_once('=') {
	if key == "NAME" {
	name = Some(value.trim_matches('"').to_owned());
	} else if key == "VERSION_ID" {
	version_id = Some(value.trim_matches('"').to_owned());
	if let Ok(line_content) = line {
	if let Some((key, value)) = line_content.split_once('=') {
	if key == "NAME" {
	name = Some(value.trim_matches('"').to_owned());
	} else if key == "VERSION_ID" {
	version_id = Some(value.trim_matches('"').to_owned());
	}

[Copilot]

The std::env::home_dir() function has been deprecated since Rust 1.29 (2018) due to incorrect behavior on Windows and platform inconsistencies. The deprecation notice recommends using the dirs or dirs_next crate instead. This codebase already uses dirs_next::home_dir() in other places (lines 628, 667), so you should use the same function here for consistency and to avoid using deprecated APIs.

[Copilot]

The std::fs::read_to_string() call includes any trailing newline characters from the file. The previous cat /proc/self/sessionid command through the shell would have included the newline, but the comparison with INVALID_SESSION on line 155 might now fail if the file content has trailing whitespace. Consider trimming the result: std::fs::read_to_string("/proc/self/sessionid").unwrap_or_default().trim().to_string()

Suggested change

	session = std::fs::read_to_string("/proc/self/sessionid").unwrap_or_default();
	session = std::fs::read_to_string("/proc/self/sessionid").unwrap_or_default().trim().to_string();

[linkmauve]

This file can’t ever contain any newline, it can only be a decimal integer.

[fufesou]

I thinks it's better to always trim() here.

[linkmauve]

I disagree, this is ABI, the kernel will never ever add a newline or any other character here, so trim() will always be a noop.

That said, in a future PR I have already started working on, this whole mess of fetching the session is simplified by always using logind using zbus.

[fufesou]

CMD_PS is required here https://github.com/rustdesk/rustdesk/blob/7bdfa121f39c6f2aeee33da7f248db59fd605953/src/platform/linux.rs#L611

CMD_SH is required here https://github.com/rustdesk/rustdesk/blob/7bdfa121f39c6f2aeee33da7f248db59fd605953/libs/scrap/src/wayland/pipewire.rs#L26

[linkmauve]

Oh, I was working on this repository alone, and didn’t notice it was API for rustdesk, my bad! I’ll put all of the pub symbols back to their former state then, and also do the same kind of fixes in rustdesk, thanks!

[fufesou]

run_cmds() is commonly used in https://github.com/rustdesk/rustdesk

Maybe we need to keep it in this PR.

[fufesou]

Directly removing CMD_SH.as_str() may generate an excessive number of audit logs.

hbb_common/src/platform/linux.rs

Line 26 in 8b0e258

// `ausearch -x /usr/share/rustdesk/rustdesk` will return

ausearch -x /usr/share/rustdesk/rustdesk

This is because the audit log will record ENOENT errors when the system attempts to resolve the absolute path of the command.

[fufesou]

Maybe a better change could be

  pub fn is_kde_session() -> bool {
      let Ok(entries) = fs::read_dir("/proc") else {
          return false;
      };

      for entry in entries.flatten() {
          let name = entry.file_name();
          let name_str = name.to_string_lossy();

          // Skip non-pid directories
          if !name_str.chars().all(|c| c.is_ascii_digit()) {
              continue;
          }

          // Read /proc/[pid]/comm (process name, max 16 chars, no args)
          let comm_path = entry.path().join("comm");
          if let Ok(comm) = fs::read_to_string(&comm_path) {
              let comm = comm.trim();
              // Match kded5, kded6, etc.
              if comm.starts_with("kded") && comm[4..].chars().all(|c| c.is_ascii_digit()) {
                  return true;
              }
          }
      }
      false
  }

[linkmauve]

Indeed that’s much better, I’ll update that PR with your code. Using shell commands for pretty much anything is a red flag anyway, silencing the audit logs was always a bad workaround.