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