99c

Overview ¶

Command 99c is a c99 compiler targeting a virtual machine.

Usage ¶

Output of 99c -h

99c: Flags:
  -99lib
        Library link mode.
  -Dname
        Equivalent to inserting '#define name 1' at the start of the
        translation unit.
  -Dname=definition
        Equivalent to inserting '#define name definition' at the start of the
        translation unit.
  -E    Copy C-language source files to standard output, executing all
        preprocessor directives; no compilation shall be performed. If any
        operand is not a text file, the effects are unspecified.
  -Ipath
        Add path to the include files search paths.
  -Lpath
        Add path to search paths for -l.
  -Olevel
        Optimization setting, ignored.
  -Wwarn
        Warning level, ignored.
  -ansi
        Ignored.
  -c    Suppress the link-edit phase of the compilation, and do not
        remove any object files that are produced.
  -g    Produce debugging information.
  -l<name>
        Link with lib<name>.
  -o pathname
        Use the specified pathname, instead of the default a.out, for
        the executable file produced. If the -o option is present with
        -c or -E, the result is unspecified.
  -pedantic
        Ignored.
  -pthread
        Ignored. (TODO)
  -rdynamic
        Ignored. (TODO)
  -rpath pathname
        Ignored. (TODO)
  -shared
        Link mode shared library.
  -soname arg
        Ignored. (TODO)
  -99extra flag
     Extra cc flags:
        AlignOf
        AlternateKeywords
        AnonymousStructFields
        Asm
        BuiltinClassifyType
        BuiltinConstantP
        ComputedGotos
        DlrInIdentifiers
        EmptyDeclarations
        EmptyDefine
        EmptyStructs
        ImaginarySuffix
        ImplicitFuncDef
        ImplicitIntType
        IncludeNext
        LegacyDesignators
        NonConstStaticInitExpressions
        Noreturn
        OmitConditionalOperand
        OmitFuncArgTypes
        OmitFuncRetType
        ParenthesizedCompoundStatemen
        StaticAssert
        TypeOf
        UndefExtraTokens
        UnsignedEnums
        WideBitFieldTypes
        WideEnumValues

Rest of the input is a list of file names, either C (.c) files or object (.o, .a) files.

Installation ¶

To install or update the compiler and the virtual machine

$ go get [-u] github.com/cznic/99c github.com/cznic/99c/99run

To update the toolchain and rebuild all commands

$ go generate

Use the -x flag to view the commands executed.

Online documentation: http://godoc.org/github.com/cznic/99c

Changelog ¶

2017-10-19: Handle ar files (.a).

2017-10-18: Executables should be from now on no more tied to a single compatibility number but to a minimal compatibility number. No more permanent recompiling of everything.

2017-10-18: Initial support for using C packages.

2017-10-18: The -g flag is no more ignored. Add the -g flag to have the symbol and line information included in the executable. Without using -g some tools may not work and stack traces will not be really useful. The advantage of not including the additional info by default are substantially smaller executables.

2017-10-07: Initial public release.

Supported platforms and operating systems ¶

See: https://godoc.org/github.com/cznic/ccir#hdr-Supported_platforms_and_architectures

At the time of this writing, in GOOS_GOARCH form

linux_386
linux_amd64
windows_386
windows_amd64

Porting to other platforms/architectures is considered not difficult.

Options ¶

Project status ¶

Both the compiler and the C runtime library implementation are known to be incomplete. Missing pieces are added as needed. Please fill an issue when you run into problems and be patient. Only limited resources can be allocated to this project and to the related parts of the tool chain.

Also, contributions are welcome.

Executing compiled programs ¶

Running a binary on Linux

$ ./a.out
hello world
$

Running a binary on Windows

C:\> 99run a.out
hello world
C:\>

A simple program ¶

All in just a single C file.

$ cd examples/hello/
$ cat hello.c
#include <stdio.h>

int main() {
	printf("hello world\n");
}
$ 99c hello.c && ./a.out
hello world
$

Setting the output file name ¶

If the output is a single file, use -o to set its name. (POSIX option)

$ cd examples/hello/
$ cat hello.c
#include <stdio.h>

int main() {
	printf("hello world\n");
}
$ 99c -o hello hello.c && ./hello
hello world
$

Obtaining the preprocessor output ¶

Use -E to produce the cpp results. (POSIX option)

$ cd examples/hello/
/home/jnml/src/github.com/cznic/99c/examples/hello
$ 99c -E hello.c
# 24 "/home/jnml/src/github.com/cznic/ccir/libc/predefined.h"
typedef char * __builtin_va_list ;
# 41 "/home/jnml/src/github.com/cznic/ccir/libc/builtin.h"
typedef __builtin_va_list __gnuc_va_list ;
typedef void * __FILE_TYPE__ ;
typedef void * __jmp_buf [ 7 ] ;
__FILE_TYPE__ __builtin_fopen ( char * __filename , char * __modes ) ;
long unsigned int __builtin_strlen ( char * __s ) ;
long unsigned int __builtin_bswap64 ( long unsigned int x ) ;
char * __builtin_strchr ( char * __s , int __c ) ;
char * __builtin_strcpy ( char * __dest , char * __src ) ;
double __builtin_copysign ( double x , double y ) ;
int __builtin_abs ( int j ) ;
...
extern void flockfile ( FILE * __stream ) ;
extern int ftrylockfile ( FILE * __stream ) ;
extern void funlockfile ( FILE * __stream ) ;
# 3 "hello.c"
int main ( ) {
printf ( "hello world\n" ) ;
}
$

Multiple C files projects ¶

A translation unit may consist of multiple source files.

$ cd examples/multifile/
/home/jnml/src/github.com/cznic/99c/examples/multifile
$ cat main.c
char *hello();

#include <stdio.h>
int main() {
	printf("%s\n", hello());
}
$ cat hello.c
char *hello() {
	return "hello world";
}
$ 99c main.c hello.c && ./a.out
hello world
$

Using object files ¶

Use -c to output object files. (POSIX otion)

$ cd examples/multifile/
/home/jnml/src/github.com/cznic/99c/examples/multifile
$ 99c -c hello.c main.c
$ 99c hello.o main.o && ./a.out
hello world
$ 99c hello.o main.c && ./a.out
hello world
$ 99c hello.c main.o && ./a.out
hello world
$

Stack traces ¶

If the program source(s) are available at the same location(s) as when the program was compiled, then any stack trace produced is annotated using the source code lines.

$ cd examples/stack/
/home/jnml/src/github.com/cznic/99c/examples/stack
$ cat stack.c
void f(int n) {
	if (n) {
		f(n-1);
		return;
	}

	*(char *)n;
}

int main() {
	f(4);
}
$ 99c stack.c && ./a.out
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
stack.c.f(0x0)
	stack.c:7:1	0x0002c		load8          0x0	; -	// *(char *)n;
stack.c.f(0x1)
	stack.c:3:1	0x00028		call           0x21	; -	// f(n-1);
stack.c.f(0x2)
	stack.c:3:1	0x00028		call           0x21	; -	// f(n-1);
stack.c.f(0x3)
	stack.c:3:1	0x00028		call           0x21	; -	// f(n-1);
stack.c.f(0x7f3400000004)
	stack.c:3:1	0x00028		call           0x21	; -	// f(n-1);
stack.c.main(0x7f3400000001, 0x7f34c9400030)
	stack.c:11:1	0x0001d		call           0x21	; -	// f(4);
/home/jnml/src/github.com/cznic/ccir/libc/crt0.c._start(0x1, 0x7f34c9400030)
	/home/jnml/src/github.com/cznic/ccir/libc/crt0.c:15:1	0x0000d		call           0x16	; -	// __builtin_exit(((int (*)())main) (argc, argv));

[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x511e46]

goroutine 1 [running]:
github.com/cznic/virtual.(*cpu).run.func1(0xc42009e2a0)
	/home/jnml/src/github.com/cznic/virtual/cpu.go:222 +0x26e
panic(0x555340, 0x66a270)
	/home/jnml/go/src/runtime/panic.go:491 +0x283
github.com/cznic/virtual.readI8(...)
	/home/jnml/src/github.com/cznic/virtual/cpu.go:74
github.com/cznic/virtual.(*cpu).run(0xc42009e2a0, 0x2, 0x0, 0x0, 0x0)
	/home/jnml/src/github.com/cznic/virtual/cpu.go:993 +0x2116
github.com/cznic/virtual.New(0xc4201d2000, 0xc42000a090, 0x1, 0x1, 0x656540, 0xc42000c010, 0x656580, 0xc42000c018, 0x656580, 0xc42000c020, ...)
	/home/jnml/src/github.com/cznic/virtual/virtual.go:73 +0x2be
github.com/cznic/virtual.Exec(0xc4201d2000, 0xc42000a090, 0x1, 0x1, 0x656540, 0xc42000c010, 0x656580, 0xc42000c018, 0x656580, 0xc42000c020, ...)
	/home/jnml/src/github.com/cznic/virtual/virtual.go:84 +0xe9
main.main()
	/home/jnml/src/github.com/cznic/99c/99run/main.go:37 +0x382
$

Argument passing ¶

Command line arguments are passed the standard way.

$ cd examples/args/
/home/jnml/src/github.com/cznic/99c/examples/args
$ cat args.c
#include <stdio.h>

int main(int argc, char **argv) {
	for (int i = 0; i < argc; i++) {
		printf("%i: %s\n", i, argv[i]);
	}
}
$ 99c args.c && ./a.out foo bar -x -y - qux
0: ./a.out
1: foo
2: bar
3: -x
4: -y
5: -
6: qux
$

Executing a C program embedded in a Go program ¶

This example requires installation of additional tools

$ go get -u github.com/cznic/assets github.com/cznic/httpfs
$ cd examples/embedding/
/home/jnml/src/github.com/cznic/99c/examples/embedding
$ ls *
main.c  main.go

assets:
keepdir
$ cat main.c
// +build ignore

#include <stdio.h>

int main() {
	int c;
	while ((c = getc(stdin)) != EOF) {
		printf("%c", c >= 'a' && c <= 'z' ? c^' ' : c);
	}
}
$ cat main.go
//go:generate 99c -o assets/a.out main.c
//go:generate assets

package main

import (
	"bytes"
	"fmt"
	"strings"
	"time"

	"github.com/cznic/httpfs"
	"github.com/cznic/virtual"
)

func main() {
	fs := httpfs.NewFileSystem(assets, time.Now())
	f, err := fs.Open("/a.out")
	if err != nil {
		panic(err)
	}

	var bin virtual.Binary
	if _, err := bin.ReadFrom(f); err != nil {
		panic(err)
	}

	var out bytes.Buffer
	exitCode, err := virtual.Exec(&bin, nil, strings.NewReader("Foo Bar"), &out, &out, 0, 1<<20, "")
	if err != nil {
		panic(err)
	}

	fmt.Printf("%s\n%v\n", out.Bytes(), exitCode)
}
$ go generate && go build && ./embedding
FOO BAR
0
$

Calling into an embedded C library from Go ¶

It's possible to call individual C functions from Go.

This example requires installation of additional tools

$ go get -u github.com/cznic/assets github.com/cznic/httpfs
$ cd examples/ffi/
/home/jnml/src/github.com/cznic/99c/examples/ffi
$ ls *
lib42.c  main.go

assets:
keepdir
$ cat lib42.c
// +build ignore

static int answer;

int main() {
	// Any library initialization comes here.
	answer = 42;
}

// Use the -99lib option to prevent the linker from eliminating this function.
int f42(int arg) {
	return arg*answer;
}
$ cat main.go
//go:generate 99c -99lib -o assets/a.out lib42.c
//go:generate assets

package main

import (
	"fmt"
	"time"

	"github.com/cznic/httpfs"
	"github.com/cznic/ir"
	"github.com/cznic/virtual"
	"github.com/cznic/xc"
)

func main() {
	fs := httpfs.NewFileSystem(assets, time.Now())
	f, err := fs.Open("/a.out")
	if err != nil {
		panic(err)
	}

	var bin virtual.Binary
	if _, err := bin.ReadFrom(f); err != nil {
		panic(err)
	}

	m, _, err := virtual.New(&bin, nil, nil, nil, nil, 0, 1<<10, "")
	if err != nil {
		panic(err)
	}

	defer m.Close()

	pc, ok := bin.Sym[ir.NameID(xc.Dict.SID("f42"))]
	if !ok {
		panic("symbol not found")
	}

	t, err := m.NewThread(1 << 10)
	if err != nil {
		panic(err)
	}

	for _, v := range []int{-1, 0, 1} {
		var y int32
		_, err := t.FFI1(pc, virtual.Int32Result{&y}, virtual.Int32(int32(v)))
		if err != nil {
			panic(err)
		}

		fmt.Println(y)
	}
}
$ go generate && go build && ./ffi
-42
0
42
$

Loading C plugins at run-time ¶

It's possible to load C plugins at run-time.

$ cd examples/plugin/
/home/jnml/src/github.com/cznic/99c/examples/plugin
$ ls *
lib42.c  main.go
$ cat lib42.c
// +build ignore

static int answer;

int main() {
	// Any library initialization comes here.
	answer = 42;
}

// Use the -99lib option to prevent the linker from eliminating this function.
int f42(int arg) {
	return arg*answer;
}
$ cat main.go
//go:generate 99c -99lib lib42.c

package main

import (
	"fmt"
	"os"

	"github.com/cznic/ir"
	"github.com/cznic/virtual"
	"github.com/cznic/xc"
)

func main() {
	f, err := os.Open("a.out")
	if err != nil {
		panic(err)
	}

	var bin virtual.Binary
	if _, err := bin.ReadFrom(f); err != nil {
		panic(err)
	}

	m, _, err := virtual.New(&bin, nil, nil, nil, nil, 0, 1<<10, "")
	if err != nil {
		panic(err)
	}

	defer m.Close()

	pc, ok := bin.Sym[ir.NameID(xc.Dict.SID("f42"))]
	if !ok {
		panic("symbol not found")
	}

	t, err := m.NewThread(1 << 10)
	if err != nil {
		panic(err)
	}

	for _, v := range []int{1, 2, 3} {
		var y int32
		_, err := t.FFI1(pc, virtual.Int32Result{&y}, virtual.Int32(int32(v)))
		if err != nil {
			panic(err)
		}

		fmt.Println(y)
	}
}
$ go generate && go run main.go
42
84
126
$

Inserting defines ¶

Use the -D flag to define additional macros on the command line.

$ cd examples/define/
/home/jnml/src/github.com/cznic/99c/examples/define
$ ls *
main.c
$ cat main.c
#include <stdio.h>

int main() {
#ifdef VERBOSE
	printf(GREETING);
#endif
}
$ 99c -DVERBOSE -DGREETING=\"hello\\n\" main.c && ./a.out
hello
$ 99c -DGREETING=\"hello\\n\" main.c && ./a.out
$

Specifying include paths ¶

The -I flag defines additional include files search path(s).

$ cd examples/include/
/home/jnml/src/github.com/cznic/99c/examples/include
$ ls *
main.c

foo:
main.h
$ cat main.c
#include <stdio.h>
#include "main.h"

int main() {
	printf(HELLO);
}
$ cat foo/main.h
#ifndef _MAIN_H_
#define _MAIN_H_

#define HELLO "hello\n"

#endif
$ 99c main.c && ./a.out
99c: main.c:2:10: include file not found: main.h (and 2 more errors)
$ 99c -Ifoo main.c && ./a.out
hello
$

Installing C packages ¶

To use a C package with programs compiled by 99c it's necessary to install a 99c version of the package. The lib directory contains some such installers. For example

$ cd lib/xcb
$ go generate

or equivalently

$ go generate github.com/cznic/99c/lib/xcb

will install the 99c version of libxcb on your system in '$HOME/.99c'. Currently supported only on Linux.

Talking to X server ¶

A bare bones example, currently supported only on Linux.

$ go generate ./lib/xcb ./lib/xau
... lot of output
$ cd examples/xcb/
/home/jnml/src/github.com/cznic/99c/examples/xcb
$ ls
screen.c
$ cat screen.c
// +build ignore

// src: https://xcb.freedesktop.org/tutorial/

#include <stdio.h>
#include <xcb/xcb.h>
#include <inttypes.h>

int main()
{
	/* Open the connection to the X server. Use the DISPLAY environment variable */

	int i, screenNum;
	xcb_connection_t *connection = xcb_connect(NULL, &screenNum);

	/* Get the screen whose number is screenNum */

	const xcb_setup_t *setup = xcb_get_setup(connection);
	xcb_screen_iterator_t iter = xcb_setup_roots_iterator(setup);

	// we want the screen at index screenNum of the iterator
	for (i = 0; i < screenNum; ++i) {
		xcb_screen_next(&iter);
	}

	xcb_screen_t *screen = iter.data;

	/* report */

	printf("\n");
	printf("Informations of screen %" PRIu32 ":\n", screen->root);
	printf("  width.........: %" PRIu16 "\n", screen->width_in_pixels);
	printf("  height........: %" PRIu16 "\n", screen->height_in_pixels);
	printf("  white pixel...: %" PRIu32 "\n", screen->white_pixel);
	printf("  black pixel...: %" PRIu32 "\n", screen->black_pixel);
	printf("\n");

	return 0;
}
$ 99c screen.c -lxcb && ./a.out

Informations of screen 927:
  width.........: 1920
  height........: 1200
  white pixel...: 16777215
  black pixel...: 0

$

Creating a X window ¶

This example will show a small 150x150 pixel window in the top left corner of the screen. The window content is not handled by this example, but it can be moved, resized and closed.

$ go generate ./lib/xcb ./lib/xau
... lot of output
$ cd examples/xcb/
$ cat helloworld.c
// +build ignore

// src: https://www.x.org/releases/current/doc/libxcb/tutorial/index.html#helloworld

#include <stdio.h>
#include <unistd.h>		/* pause() */

#include <xcb/xcb.h>

int main()
{
	xcb_connection_t *c;
	xcb_screen_t *screen;
	xcb_window_t win;

	/* Open the connection to the X server */
	c = xcb_connect(NULL, NULL);

	/* Get the first screen */
	screen = xcb_setup_roots_iterator(xcb_get_setup(c)).data;
	screen = iter.data;

	/* Ask for our window's Id */
	win = xcb_generate_id(c);

	/* Create the window */
	xcb_create_window(c,	/* Connection          */
			  XCB_COPY_FROM_PARENT,	/* depth (same as root) */
			  win,	/* window Id           */
			  screen->root,	/* parent window       */
			  0, 0,	/* x, y                */
			  150, 150,	/* width, height       */
			  10,	/* border_width        */
			  XCB_WINDOW_CLASS_INPUT_OUTPUT,	/* class               */
			  screen->root_visual,	/* visual              */
			  0, NULL);	/* masks, not used yet */

	/* Map the window on the screen */
	xcb_map_window(c, win);

	/* Make sure commands are sent before we pause, so window is shown */
	xcb_flush(c);

	printf("Close the demo window and/or press ctrl-c while the terminal is focused to exit.\n");
	int i = pause();		/* hold client until Ctrl-C */
	printf("pause() returned %i\n", i);

	return 0;
}
$ 99c helloworld.c -lxcb && ./a.out
Close the demo window and/or press ctrl-c while the terminal is focused to exit.
... close the demo window (optional)
... focus the terminal and press ctrl-c
^Cpause() returned -1
$