xv6-cs450/syscall.c

176 lines
3.2 KiB
C
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#include "types.h"
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#include "stat.h"
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#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"
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#include "elf.h"
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#include "file.h"
#include "fcntl.h"
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// 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.
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// Fetch 32 bits from a user-supplied pointer.
// Returns 0 if addr was OK, -1 if illegal.
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int
fetchint(struct proc *p, uint addr, int *ip)
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{
*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
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fetchbyte(struct proc *p, uint addr, char *c)
{
if(addr >= p->sz)
return -1;
*c = *(p->mem + addr);
return 0;
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}
int
fetcharg(int argno, void *ip)
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{
uint esp;
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esp = (uint) curproc[cpu()]->tf->esp;
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return fetchint(curproc[cpu()], esp + 4 + 4*argno, ip);
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}
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// Check that an entire string is valid in user space.
// Returns the length, not including null, or -1.
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int
checkstring(uint s)
{
char c;
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int len = 0;
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for(;;){
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if(fetchbyte(curproc[cpu()], s, &c) < 0)
return -1;
if(c == '\0')
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return len;
len++;
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s++;
}
}
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int
putint(struct proc *p, uint addr, int x)
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{
if(addr > p->sz - 4)
return -1;
memmove(p->mem + addr, &x, 4);
return 0;
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}
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);
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void
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syscall(void)
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{
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struct proc *cp = curproc[cpu()];
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int num = cp->tf->eax;
int ret = -1;
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switch(num){
case SYS_fork:
ret = sys_fork();
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break;
case SYS_exit:
ret = sys_exit();
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break;
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case SYS_wait:
ret = sys_wait();
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break;
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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;
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case SYS_exec:
ret = sys_exec();
break;
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case SYS_open:
ret = sys_open();
break;
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case SYS_mknod:
ret = sys_mknod();
break;
case SYS_unlink:
ret = sys_unlink();
break;
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case SYS_fstat:
ret = sys_fstat();
break;
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case SYS_link:
ret = sys_link();
break;
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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;
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default:
cprintf("unknown sys call %d\n", num);
// XXX fault
break;
}
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cp->tf->eax = ret;
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}