| Commit message (Collapse) | Author | Age | Files | Lines |
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This adds some preliminary support for pipes (|), forks (&), and
consecutive command calls (&&) to the shell.
Notes:
This branch is a huge WIP, and am only pushing it, cause it's late, and
want to have my changes saved. A lot of cleanup and comments will be
necessary moving forward.
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Only print out the command name in error messages, rather than printing
out the full path to the command.
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The 'eval' function was renamed to 'repl'.
The code to refresh the $PATH was moved into it's own function:
'prefresh', and is now being called in three locations:
- At the beginning of 'repl', before the main loop
- Inside the main loop, possibly during a path search if the command
is not initially found
- Inside the main loop, if the call to Command::spawn() throws an
error, and the error is ErrorKind::NotFound
Doc comments were added for each function, as well as a few more
comments throughout that detail the program's control flow.
The error messages in the main repl loop were cleaned up to have a more
consistent style, and to provide more/better detail.
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Adds two additional error checks when the shell forks:
1. Checks for permission (+r, +x)
2. Checks if the file exists
The first error may occur if the user does not have read access to the
file, or if the file is not executable. The second error may occur if a
file was removed from the $PATH, and the $PATH hasn't been refreshed
yet.
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This is a modified implementation of the 'refresh path on every
iteration of the loop' idea. It instead, only refreshes the path if the
command is not found. After the first refresh, if the command still is
not found, it throws and error.
Notes:
This is probably the most sane solution, however, it has an issue. It
can detect new files in the path just fine, but it cannot detect if a
file was removed from the path. It may be prudent to expand the error
handling when we fork, to see what kind of error the process is
returning, and handle it more apropriately.
Another solution may be to check the always check the existence of a
file in the path before returning it from the match closure. This will
overall slow down the REPL, however, since we'd now be making that check
twice.
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Implements the path refresh at the start of each REPL loop. On this
commit, it is printing out how long it needed to refresh all the paths
in milliseconds.
Notes:
This may be an easier solution than using inotify. There is the obvious
downside of a small delay each time we need to print the loop, but the
highest I've seen so far is around 12 milliseconds, which seems
acceptable. Using inotify as an alternative, it adds quite a few more
dependencies, and some overhead in way of a watcher.
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Allow user to input a fullpath or relative path to a file that should be
forked to.
Notes:
Currently, this does not check whether or not that file at the path
specified is executable or not, but, if it isn't we will throw an
'Unable to fork' error, before printing the next prompt.
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Make the control flow in our cd implementation a bit easier to
read/follow.
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Print a newline before quitting when we receive an EOF.
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Instead of printing an error if the path is not specified, simply 'cd'
into the user's home directory instead.
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Added logic to change directories with 'cd'.
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Added logic to capture the interrupt signal. Using a rust crate called
'ctrlc' to do the heavy lifting. Program will simply reprint the prompt
on a new line if the interrup signal is detected.
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Added logic to detect for an EOF (i.e. <C-d>).
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An extremely miniamal shell. It is capable of forking processes, and
passing arguments to them, but that's pretty much it.
Notes:
This is pretty much a prototype, to see how easily something like a
shell could be implemented in Rust.
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