Rust port of Apple's shell_cmds

Port Apple's shell commands from C to Rust.

Contributing

• Want to help? Jump right in! If you would rather talk first then contact me by creating an issue

• Code to port: shell_cmds version 198

• Commands need a file in src/bin/ with a fn main(). For example echo has src/bin/echo.rs

• To compile+run your new command (for example) echo arg1 arg2 you would do cargo run --bin echo -- arg1 arg2

• Use std::env::args() directly for the dirt-simple utilities. Use getopts for the fancier ones.

• Put the man pages (files ending in .1) in the man/ directory.

• Put the companion shell scripts in the sh/ directory.

• When there's a license header, copy it over verbatim into the .rs file for the binary. (Lawyer repellent.)

Porting Status

• alias - Just a man page pointer to builtin.1, which is csh's manpage.
• apply - Some serious pointer-loop reverse engineering on this one.
• basename - Ancient utilities are frustrating because their behavior with arguments makes no blasted sense. basename is one of these. If it has exactly two arguments, then it acts completely differently.
• chroot - Many calls to libc. Seems to have matched behavior exactly, except for the buffer overflow vulnerability.
• date
• dirname - Shares a man page with basename.
• echo - Got an education in rust Strings.
• env
• expr
• false - Simple.
• find
• getopt
• hexdump
• hostname
• id
• jot
• kill
• killall
• lastcomm
• locate
• logname
• mktemp
• nice
• nohup
• path_helper
• printenv - Done. Did you know printenv silently ignores any extra arguments?
• pwd
• renice
• script
• seq
• sh
• shlock
• sleep - Instead of treating invalid input as 0 silently, we spit out the usage and die.
• su
• systime
• tee - Done. Good practice with Vec, zip(), stdin/stdout/stderr, and files.
• test
• time
• true - Simple.
• uname
• users
• w
• what
• whereis
• which
• who
• xargs
• yes - Did you know that yes takes an optional argument?

Bugs in Original

Below is a partial list of bugs discovered in C code of Apple's shell_cmds version 198 -- which ships on macOS Sierra.

chroot.c

• Buffer Overflow: If more than 16 valid groups are provided to the -G option, then the gidlist buffer overflows and starts overwriting later data in the stack frame with resolved group ids. That is not difficult to do since macOS ships with over 100 valid groups by default. In Rust, we use a Vec to store the resolved group ids. Vec is dynamically sized, so it won't overflow.