sys_file.c

// System calls for fs

#include "defs.h"
#include "param.h"
#include "file.h"

extern struct proc *cp;

int argfd(uint32_t n, uint32_t *pfd, struct file **pf)
{
	int fd;
	struct file *f;

	if (argint(n, &fd) < 0) {
		kprintf("argfd: cannot get argument",0);
		bbrk();
	}
	if (fd < 0 || fd > NFILE) {
		kprintf("argfd: got invalid fd",0);
		bbrk();
	}
	if (pfd)
		pfd = fd;
	if (pf)
		pf = f;
	return 0;
}

// sys_write(fd, pointer to char buffer, number of chars)
int sys_write(void)
{
	int n;
	struct file *f;
	char *p;

	n = argptr(1, &p, 1);
	fb_put_char(*p);
	//fb_write(p);
	/*
	if ( argfd(0,0,f) < 0 || argint(2, &n) || argptr(1, &p, n) )
		PANIC("sys_write: BAD arguments!");
	return filewrite(f, p , n);
	*/
	return 0;
}

// number read(fd, buffer, count)
int sys_read(void)
{
	struct file *f;
	char *buf;
	int n;


	if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &buf, n) < 0)
		PANIC("sys_read: error reading arguments.");

	return consoleread(0, buf, 100);//fileread(f, buf, n);*/
}

// Allocate a fd to a caller process in the ptable entry
// to indicate it has an open file
fd_t fdalloc(struct file *f)
{
	int fd;
	for(fd = 0; fd < NOFILE; fd++){
		if(cp->ofile[fd]==0){
			cp->ofile[fd] = f;
			return fd;
		}
	}
}

/*
The open system call is the first step a process must take to access the data in a
file. The syntax for the open system call is fd = open(pathname, flags, modes);
where pathname is a file name, flags indicate the type of open (such as for reading or writing),
and modes give the file permissions if the file is being created. The open system cal] returns an
integer' called the user file descripto
*/

//fd = open(pathname, omode);
fd_t sys_open(void)
{

	char *path;
	int omode, fd;
	struct file *f;
	struct inode *ip;

	if (argstr(0, &path) == 0 || argint(1, &omode) == 0)
		return -1;

	if ((ip = namei(path)) == 0)
		PANIC("sys_open: file not found");
	if ((f = filealloc()) == 0)
		PANIC("sys_open: can't allocate file table entry");
	if ((fd = fdalloc(f)) < 0)
		PANIC("sys_open: can't allocate file descriptor");
	f->type = FD_INODE;
  f->ip = ip;
  f->off = 0;
  f->readable = !(omode & O_WRONLY);
  f->writable = (omode & O_WRONLY) || (omode & O_RDWR);
	return fd;
}

int sys_exec(void)
{
	char *argv[MAXARG], *path, *buf;
	int i;
	uint32_t uargv, uarg;

	if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0 )
	 	PANIC("sys_exec: not finding arguments");
	memset(argv, 0, sizeof(argv));
	for(i = 0;;i++){
		if(i >= NELEM(argv))
			PANIC("sys_exec: too many arguments");
		if(fetchint(uargv+4*i, (int*)&uarg) < 0 )
			PANIC("sys_exec: fetchint");
		if(uarg == 0 ) {
			argv[i] = 0;
			break;
		}
		if(fetchstr(uarg, &argv[i]) < 0)
			PANIC("sys_exec: fetchstr");
		//kprintf("sys_exec: argv[i] %d >", i);
		fb_write(argv[i]);
	}
	//fb_write(">>>>>>>>");
	//fb_write(path);
	//fb_write("<<<<<<<<");
	return exec(path, argv);
}