scripts/cmd: Replace shell script with implementation in c

[2096779623]

CC @5ec1cff .

[twaik]

Is it supposed to do something like echo $(pm path com.termux 2>&1 </dev/null)? I mean using anonymous pipe to avoid selinux related problems?

[2096779623]

Is it supposed to do something like echo $(pm path com.termux 2>&1 </dev/null)? I mean using anonymous pipe to avoid selinux related problems?

Yes.

[agnostic-apollo]

• pump_stderr definition should be above set_fd() definition.
• Separate blocks of actions done on each fd with a newline in both child and parent, like close/set_fd/dup2/pthread_create.
• It's good practice to close fds explicitly after using them (in child after pumps).
• The code will block on read() in pump_stdout() instead of waitpid() and after parent process exits, read() should return with a 0/EOF after all data parent wrote before exiting has been read, and then code will move to waitpid(). The issue here is that stderr may not have pumped completely before child exists after waitpid(). So after pump_stdout(), it should wait for stderr thread, like with pthread_join() (instead of using pthread_detach()). You can test by running some command that prints an error. This should not be necessary for stdin thread as if waitpid() returns, parent should have already read it completely if it needed to.

[2096779623]

• pump_stderr definition should be above set_fd() definition.
• Separate blocks of actions done on each fd with a newline in both child and parent, like close/set_fd/dup2/pthread_create.
• It's good practice to close fds explicitly after using them (in child after pumps).
• The code will block on read() in pump_stdout() instead of waitpid() and after parent process exits, read() should return with a 0/EOF after all data parent wrote before exiting has been read, and then code will move to waitpid(). The issue here is that stderr may not have pumped completely before child exists after waitpid(). So after pump_stdout(), it should wait for stderr thread, like with pthread_join() (instead of using pthread_detach()). You can test by running some command that prints an error. This should not be necessary for stdin thread as if waitpid() returns, parent should have already read it completely if it needed to.

Done.

[agnostic-apollo]

Looks good, thanks. Maybe replace p2 with t_stdout and p_in with p_stdout, etc as currently p_in and p_out looks like some kind of input and output, instead of stdin/stdout.

Did you to test to see if stderr is fully printing? It should though.

[agnostic-apollo]

You didn't rename p_* variables, otherwise looks fine.

[2096779623]

Did you to test to see if stderr is fully printing? It should though.

Yes,I did.

[2096779623]

You didn't rename p_* variables, otherwise looks fine.

Done.

[agnostic-apollo]

Now you have added a _ after std, like p_std_out, so it's now different from t_stdout and pump_stdout. But you can merge anyways.