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#include "types.h"
#include "defs.h"
#include "param.h"
#include "mmu.h"
#include "proc.h"
#include "x86.h"
#include "syscall.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 the int at addr from process p.
fetchint(struct proc *p, uint addr, int *ip)
if(addr >= p->sz || addr+4 > p->sz)
return -1;
*ip = *(int*)(p->mem + addr);
return 0;
// Fetch the nul-terminated string at addr from process p.
// Doesn't actually copy the string - just sets *pp to point at it.
// Returns length of string, not including nul.
fetchstr(struct proc *p, uint addr, char **pp)
char *s, *ep;
if(addr >= p->sz)
return -1;
*pp = p->mem + addr;
ep = p->mem + p->sz;
for(s = *pp; s < ep; s++)
if(*s == 0)
return s - *pp;
return -1;
// Fetch the nth 32-bit system call argument.
argint(int n, int *ip)
return fetchint(cp, cp->tf->esp + 4 + 4*n, ip);
// Fetch the nth word-sized system call argument as a pointer
// to a block of memory of size n bytes. Check that the pointer
// lies within the process address space.
argptr(int n, char **pp, int size)
int i;
if(argint(n, &i) < 0)
return -1;
if((uint)i >= cp->sz || (uint)i+size >= cp->sz)
return -1;
*pp = cp->mem + i;
return 0;
// Fetch the nth word-sized system call argument as a string pointer.
// Check that the pointer is valid and the string is nul-terminated.
// (There is no shared writable memory, so the string can't change
// between this check and being used by the kernel.)
argstr(int n, char **pp)
int addr;
if(argint(n, &addr) < 0)
return -1;
return fetchstr(cp, addr, pp);
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_sleep(void);
extern int sys_unlink(void);
extern int sys_wait(void);
extern int sys_write(void);
static int (*syscalls[])(void) = {
[SYS_chdir] sys_chdir,
[SYS_close] sys_close,
[SYS_dup] sys_dup,
[SYS_exec] sys_exec,
[SYS_exit] sys_exit,
[SYS_fork] sys_fork,
[SYS_fstat] sys_fstat,
[SYS_getpid] sys_getpid,
[SYS_kill] sys_kill,
[SYS_link] sys_link,
[SYS_mkdir] sys_mkdir,
[SYS_mknod] sys_mknod,
[SYS_open] sys_open,
[SYS_pipe] sys_pipe,
[SYS_read] sys_read,
[SYS_sbrk] sys_sbrk,
[SYS_sleep] sys_sleep,
[SYS_unlink] sys_unlink,
[SYS_wait] sys_wait,
[SYS_write] sys_write,
int num;
num = cp->tf->eax;
if(num >= 0 && num < NELEM(syscalls) && syscalls[num])
cp->tf->eax = syscalls[num]();
else {
cprintf("%d %s: unknown sys call %d\n",
cp->pid, cp->name, num);
cp->tf->eax = -1;