xv6-cs450/syscall.c
2006-09-07 13:07:52 +00:00

175 lines
3.2 KiB
C

#include "types.h"
#include "stat.h"
#include "param.h"
#include "mmu.h"
#include "proc.h"
#include "defs.h"
#include "x86.h"
#include "traps.h"
#include "syscall.h"
#include "spinlock.h"
#include "buf.h"
#include "fs.h"
#include "fsvar.h"
#include "elf.h"
#include "file.h"
#include "fcntl.h"
// User code makes a system call with INT T_SYSCALL.
// System call number in %eax.
// Arguments on the stack, from the user call to the C
// library system call function. The saved user %esp points
// to a saved program counter, and then the first argument.
// Fetch 32 bits from a user-supplied pointer.
// Returns 0 if addr was OK, -1 if illegal.
int
fetchint(struct proc *p, uint addr, int *ip)
{
*ip = 0;
if(addr > p->sz - 4)
return -1;
*ip = *(int*)(p->mem + addr);
return 0;
}
// Fetch byte from a user-supplied pointer.
// Returns 0 on success, -1 if pointer is illegal.
int
fetchbyte(struct proc *p, uint addr, char *c)
{
if(addr >= p->sz)
return -1;
*c = *(p->mem + addr);
return 0;
}
int
fetcharg(int argno, void *ip)
{
uint esp;
esp = (uint) curproc[cpu()]->tf->esp;
return fetchint(curproc[cpu()], esp + 4 + 4*argno, ip);
}
// Check that an entire string is valid in user space.
// Returns the length, not including null, or -1.
int
checkstring(uint s)
{
char c;
int len = 0;
for(;;){
if(fetchbyte(curproc[cpu()], s, &c) < 0)
return -1;
if(c == '\0')
return len;
len++;
s++;
}
}
int
putint(struct proc *p, uint addr, int x)
{
if(addr > p->sz - 4)
return -1;
memmove(p->mem + addr, &x, 4);
return 0;
}
extern int sys_chdir(void);
extern int sys_close(void);
extern int sys_dup(void);
extern int sys_exec(void);
extern int sys_exit(void);
extern int sys_fork(void);
extern int sys_fstat(void);
extern int sys_getpid(void);
extern int sys_kill(void);
extern int sys_link(void);
extern int sys_mkdir(void);
extern int sys_mknod(void);
extern int sys_open(void);
extern int sys_pipe(void);
extern int sys_read(void);
extern int sys_sbrk(void);
extern int sys_unlink(void);
extern int sys_wait(void);
extern int sys_write(void);
void
syscall(void)
{
struct proc *cp = curproc[cpu()];
int num = cp->tf->eax;
int ret = -1;
switch(num){
case SYS_fork:
ret = sys_fork();
break;
case SYS_exit:
ret = sys_exit();
break;
case SYS_wait:
ret = sys_wait();
break;
case SYS_pipe:
ret = sys_pipe();
break;
case SYS_write:
ret = sys_write();
break;
case SYS_read:
ret = sys_read();
break;
case SYS_close:
ret = sys_close();
break;
case SYS_kill:
ret = sys_kill();
break;
case SYS_exec:
ret = sys_exec();
break;
case SYS_open:
ret = sys_open();
break;
case SYS_mknod:
ret = sys_mknod();
break;
case SYS_unlink:
ret = sys_unlink();
break;
case SYS_fstat:
ret = sys_fstat();
break;
case SYS_link:
ret = sys_link();
break;
case SYS_mkdir:
ret = sys_mkdir();
break;
case SYS_chdir:
ret = sys_chdir();
break;
case SYS_dup:
ret = sys_dup();
break;
case SYS_getpid:
ret = sys_getpid();
break;
case SYS_sbrk:
ret = sys_sbrk();
break;
default:
cprintf("unknown sys call %d\n", num);
// Maybe kill the process?
break;
}
cp->tf->eax = ret;
}