no-cli

Cheesy command line interpreter designed for tiny memory-constrained systems. Minimal dependencies: just string.h.

Features

• low footprint; the library is ~600 bytes .text (~335 bytes under minimal configuration), and uses a (configurable) 128 byte buffer (.bss) and 24 byte (.data) context structure.

  ❯ arm-none-eabi-gcc -DNOCLI_RUNTIME_ECHO_CONTROL=0 -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mfloat-abi=hard -Os -Itest -c nocli.c -o nocli.o
  ❯ arm-none-eabi-size nocli.o
      text    data     bss     dec     hex filename
      562       0       0     562     232 nocli.o

• incremental parsing of input stream

• static memory usage

• supports doubly- and singly- quoted args (can be disabled to save ~100 bytes)

• 100% test coverage

• fuzz tested via LibFuzzer

Possible future features, if I need them:

• UNIMPLEMENTED optional tab completion or history?

Usage

Example

See test/example.c for an example that runs on host.

You can try the example by building it and running it:

# build
❯ make -f test/Makefile
Compiling nocli.c
Compiling test/example.c
Linking build/example/example

# run
❯ ./build/example/example

nocli$ help

?
help
count-args      print number of args passed
change-prompt   set prompt to new string
nocli$ count-args 1 2 3
Arg count: 3

nocli$

Integration

API is documented in nocli.h. There's only two functions used:

1. initialize the library: void Nocli_Init(struct Nocli *nocli);

   this includes a callback for outputting data and the table of commands.

2. pass any amount of data: void Nocli_Feed(struct Nocli *nocli, const char *input, size_t length);

   commands are executed within this function, so be sure to call it in a safe context

libfuzzer crashes

Run libfuzzer with make -f test/Makefile fuzz; it will run continuously until a crash occurs (AddressSanitizer and UndefinedBehaviorSanitizer are enabled on the fuzz build)

Crashes that libfuzzer finds are saved in test/corpus, which are run through the library in ci to catch regressions.

License

WTFPL (http://www.wtfpl.net/) or public domain, whichever you prefer.

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Alternatives!

This library conflates two operations:

• line editing
• command line argument parsing

There are a LOT of alternatives. Here's some commonly used ones:

Line editing

• readline
• linenoise

Argument parsing

• getopt
• argp
• argparse3