672 lines
12 KiB
C
672 lines
12 KiB
C
#include "types.h"
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#include "stat.h"
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#include "param.h"
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#include "mmu.h"
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#include "proc.h"
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#include "defs.h"
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#include "x86.h"
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#include "traps.h"
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#include "syscall.h"
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#include "spinlock.h"
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#include "buf.h"
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#include "fs.h"
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#include "fsvar.h"
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#include "elf.h"
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#include "fd.h"
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#include "fcntl.h"
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/*
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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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*
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* Return value? Error indication? Errno?
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*/
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/*
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* fetch 32 bits from a user-supplied pointer.
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* returns 0 if addr was OK, -1 if illegal.
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*/
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int
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fetchint(struct proc *p, uint addr, int *ip)
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{
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*ip = 0;
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if(addr > p->sz - 4)
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return -1;
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*ip = *(int*)(p->mem + addr);
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return 0;
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}
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// Fetch byte from a user-supplied pointer.
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// Returns 0 on success, -1 if pointer is illegal.
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int
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fetchbyte(struct proc *p, uint addr, char* c)
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{
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if(addr >= p->sz)
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return -1;
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*c = *(p->mem + addr);
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return 0;
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}
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// This arg is void* so that both int* and uint* can be passed.
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int
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fetcharg(int argno, void *ip)
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{
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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.
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// returns the length, not including null, or -1.
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int
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checkstring(uint s)
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{
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char c;
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int len = 0;
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while(1){
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if(fetchbyte(curproc[cpu()], s, &c) < 0)
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return -1;
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if(c == '\0')
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return len;
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len++;
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s++;
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}
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}
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int
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putint(struct proc *p, uint addr, int x)
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{
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if(addr > p->sz - 4)
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return -1;
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memmove(p->mem + addr, &x, 4);
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return 0;
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}
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int
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sys_pipe(void)
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{
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struct fd *rfd = 0, *wfd = 0;
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int f1 = -1, f2 = -1;
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struct proc *p = curproc[cpu()];
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uint fdp;
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if(pipe_alloc(&rfd, &wfd) < 0)
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goto oops;
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if((f1 = fd_ualloc()) < 0)
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goto oops;
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p->fds[f1] = rfd;
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if((f2 = fd_ualloc()) < 0)
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goto oops;
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p->fds[f2] = wfd;
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if(fetcharg(0, &fdp) < 0)
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goto oops;
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if(putint(p, fdp, f1) < 0)
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goto oops;
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if(putint(p, fdp+4, f2) < 0)
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goto oops;
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return 0;
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oops:
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cprintf("sys_pipe failed\n");
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if(rfd)
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fd_close(rfd);
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if(wfd)
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fd_close(wfd);
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if(f1 >= 0)
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p->fds[f1] = 0;
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if(f2 >= 0)
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p->fds[f2] = 0;
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return -1;
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}
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int
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sys_write(void)
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{
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int fd, n, ret;
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uint addr;
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struct proc *p = curproc[cpu()];
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if(fetcharg(0, &fd) < 0 || fetcharg(1, &addr) < 0 || fetcharg(2, &n) < 0)
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return -1;
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if(fd < 0 || fd >= NOFILE)
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return -1;
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if(p->fds[fd] == 0)
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return -1;
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if(addr + n > p->sz)
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return -1;
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ret = fd_write(p->fds[fd], p->mem + addr, n);
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return ret;
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}
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int
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sys_read(void)
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{
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int fd, n, ret;
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uint addr;
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struct proc *p = curproc[cpu()];
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if(fetcharg(0, &fd) < 0 || fetcharg(1, &addr) < 0 || fetcharg(2, &n) < 0)
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return -1;
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if(fd < 0 || fd >= NOFILE)
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return -1;
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if(p->fds[fd] == 0)
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return -1;
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if(addr + n > p->sz)
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return -1;
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ret = fd_read(p->fds[fd], p->mem + addr, n);
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return ret;
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}
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int
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sys_close(void)
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{
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int fd;
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struct proc *p = curproc[cpu()];
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if(fetcharg(0, &fd) < 0)
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return -1;
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if(fd < 0 || fd >= NOFILE)
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return -1;
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if(p->fds[fd] == 0)
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return -1;
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fd_close(p->fds[fd]);
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p->fds[fd] = 0;
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return 0;
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}
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int
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sys_fork(void)
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{
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struct proc *np;
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if((np = copyproc(curproc[cpu()])) == 0)
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return -1;
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np->state = RUNNABLE;
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return np->pid;
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}
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int
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sys_exit(void)
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{
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proc_exit();
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return 0; // not reached
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}
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int
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sys_wait(void)
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{
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return proc_wait();
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}
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int
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sys_kill(void)
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{
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int pid;
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if(fetcharg(0, &pid) < 0)
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return -1;
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return proc_kill(pid);
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}
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int
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sys_open(void)
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{
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struct proc *cp = curproc[cpu()];
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struct inode *ip, *dp;
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uint arg0, arg1;
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int ufd;
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struct fd *fd;
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int l;
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char *last;
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if(fetcharg(0, &arg0) < 0 || fetcharg(1, &arg1) < 0)
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return -1;
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if((l = checkstring(arg0)) < 0)
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return -1;
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if(arg1 & O_CREATE){
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dp = namei(cp->mem + arg0, NAMEI_CREATE, 0, &last, &ip);
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if(dp){
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ip = mknod1(dp, last, T_FILE, 0, 0);
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iput(dp);
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if(ip == 0)
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return -1;
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} else if(ip == 0){
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return -1;
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}
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} else {
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ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0, 0, 0);
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if(ip == 0)
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return -1;
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}
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if((fd = fd_alloc()) == 0){
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iput(ip);
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return -1;
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}
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if((ufd = fd_ualloc()) < 0){
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iput(ip);
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fd_close(fd);
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return -1;
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}
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iunlock(ip);
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fd->type = FD_FILE;
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if (arg1 & O_RDWR) {
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fd->readable = 1;
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fd->writeable = 1;
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} else if (arg1 & O_WRONLY) {
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fd->readable = 0;
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fd->writeable = 1;
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} else {
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fd->readable = 1;
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fd->writeable = 0;
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}
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fd->ip = ip;
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fd->off = 0;
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cp->fds[ufd] = fd;
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return ufd;
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}
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int
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sys_mknod(void)
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{
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struct proc *cp = curproc[cpu()];
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struct inode *nip;
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uint arg0, arg1, arg2, arg3;
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int l;
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if(fetcharg(0, &arg0) < 0 || fetcharg(1, &arg1) < 0 ||
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fetcharg(2, &arg2) < 0 || fetcharg(3, &arg3) < 0)
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return -1;
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if((l = checkstring(arg0)) < 0)
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return -1;
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if(l >= DIRSIZ)
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return -1;
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nip = mknod (cp->mem + arg0, (short) arg1, (short) arg2, (short) arg3);
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if(nip)
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iput(nip);
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return (nip == 0) ? -1 : 0;
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}
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int
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sys_mkdir(void)
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{
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struct proc *cp = curproc[cpu()];
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struct inode *nip;
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struct inode *pip;
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uint arg0;
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int l;
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struct dirent de;
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if(fetcharg(0, &arg0) < 0)
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return -1;
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if((l = checkstring(arg0)) < 0)
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return -1;
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if(l >= DIRSIZ)
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return -1;
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nip = mknod (cp->mem + arg0, T_DIR, 0, 0);
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memset (de.name, '\0', DIRSIZ);
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de.name[0] = '.';
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de.inum = nip->inum;
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writei (nip, (char *) &de, 0, sizeof(de));
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pip = namei(".", NAMEI_LOOKUP, 0, 0, 0);
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de.inum = pip->inum;
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de.name[1] = '.';
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iput(pip);
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writei (nip, (char *) &de, sizeof(de), sizeof(de));
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iput(nip);
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return (nip == 0) ? -1 : 0;
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}
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int
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sys_chdir(void)
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{
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struct proc *cp = curproc[cpu()];
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struct inode *ip;
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uint arg0;
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int l;
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if(fetcharg(0, &arg0) < 0)
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return -1;
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if((l = checkstring(arg0)) < 0)
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return -1;
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if(l >= DIRSIZ)
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return -1;
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if ((ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0, 0, 0)) == 0)
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return -1;
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if (ip == cp->cwd) {
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iput (ip);
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return 0;
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}
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if (ip->type != T_DIR) {
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iput(ip);
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return 0;
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}
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idecref(cp->cwd);
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cp->cwd = ip;
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iunlock(cp->cwd);
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return 0;
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}
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int
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sys_unlink(void)
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{
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struct proc *cp = curproc[cpu()];
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uint arg0;
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int r;
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if(fetcharg(0, &arg0) < 0)
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return -1;
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if(checkstring(arg0) < 0)
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return -1;
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r = unlink(cp->mem + arg0);
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return r;
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}
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int
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sys_fstat(void)
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{
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struct proc *cp = curproc[cpu()];
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uint fd, addr;
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int r;
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if(fetcharg(0, &fd) < 0)
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return -1;
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if(fetcharg(1, &addr) < 0)
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return -1;
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if(fd < 0 || fd >= NOFILE)
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return -1;
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if(cp->fds[fd] == 0)
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return -1;
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if(addr + sizeof(struct stat) > cp->sz)
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return -1;
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r = fd_stat (cp->fds[fd], (struct stat *)(cp->mem + addr));
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return r;
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}
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int
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sys_dup(void)
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{
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struct proc *cp = curproc[cpu()];
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uint fd, ufd1;
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if(fetcharg(0, &fd) < 0)
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return -1;
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if(fd < 0 || fd >= NOFILE)
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return -1;
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if(cp->fds[fd] == 0)
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return -1;
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if (cp->fds[fd]->type != FD_PIPE && cp->fds[fd]->type != FD_FILE)
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return -1;
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if ((ufd1 = fd_ualloc()) < 0) {
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return -1;
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}
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cp->fds[ufd1] = cp->fds[fd];
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fd_incref(cp->fds[ufd1]);
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return ufd1;
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}
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int
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sys_link(void)
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{
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struct proc *cp = curproc[cpu()];
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uint name1, name2;
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int r;
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if(fetcharg(0, &name1) < 0 || checkstring(name1) < 0)
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return -1;
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if(fetcharg(1, &name2) < 0 || checkstring(name2) < 0)
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return -1;
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r = link(cp->mem + name1, cp->mem + name2);
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return r;
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}
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int
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sys_getpid(void)
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{
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struct proc *cp = curproc[cpu()];
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return cp->pid;
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}
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int
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sys_sbrk(void)
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{
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char *r;
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int n;
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struct proc *cp = curproc[cpu()];
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if(fetcharg(0, &n) < 0)
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return -1;
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r = growproc(n);
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setupsegs(cp);
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return (int) r;
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}
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int
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sys_exec(void)
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{
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struct proc *cp = curproc[cpu()];
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uint arg0, arg1, sz=0, ap, sp, p1, p2;
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int i, nargs, argbytes, len;
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struct inode *ip;
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struct elfhdr elf;
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struct proghdr ph;
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char *mem = 0;
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if(fetcharg(0, &arg0) < 0)
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return -1;
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if(fetcharg(1, &arg1) < 0)
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return -1;
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if(checkstring(arg0) < 0)
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return -1;
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ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0, 0, 0);
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if(ip == 0)
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return -1;
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if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
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goto bad;
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if(elf.magic != ELF_MAGIC)
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goto bad;
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sz = 0;
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for(i = 0; i < elf.phnum; i++){
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if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph),
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sizeof(ph)) != sizeof(ph))
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goto bad;
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if(ph.type != ELF_PROG_LOAD)
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continue;
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if(ph.memsz < ph.filesz)
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goto bad;
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sz += ph.memsz;
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}
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sz += 4096 - (sz % 4096);
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sz += 4096;
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mem = kalloc(sz);
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if(mem == 0)
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goto bad;
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memset(mem, 0, sz);
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// arg1 is a pointer to an array of pointers to string.
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nargs = 0;
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argbytes = 0;
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for(i = 0; ; i++){
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if(fetchint(cp, arg1 + 4*i, &ap) < 0)
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goto bad;
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if(ap == 0)
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break;
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len = checkstring(ap);
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if(len < 0)
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goto bad;
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nargs++;
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argbytes += len + 1;
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}
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// argn\0
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// ...
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// arg0\0
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// 0
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// ptr to argn
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// ...
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// 12: ptr to arg0
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// 8: argv (points to ptr to arg0)
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// 4: argc
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// 0: fake return pc
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sp = sz - argbytes - (nargs+1)*4 - 4 - 4 - 4;
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*(uint*)(mem + sp) = 0xffffffff;
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*(uint*)(mem + sp + 4) = nargs;
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*(uint*)(mem + sp + 8) = (uint)(sp + 12);
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p1 = sp + 12;
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p2 = sp + 12 + (nargs + 1) * 4;
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for(i = 0; i < nargs; i++){
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fetchint(cp, arg1 + 4*i, &ap);
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len = checkstring(ap);
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memmove(mem + p2, cp->mem + ap, len + 1);
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*(uint*)(mem + p1) = p2;
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p1 += 4;
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p2 += len + 1;
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}
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*(uint*)(mem + p1) = 0;
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// commit to the new image.
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kfree(cp->mem, cp->sz);
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cp->sz = sz;
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cp->mem = mem;
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mem = 0;
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for(i = 0; i < elf.phnum; i++){
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if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph),
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sizeof(ph)) != sizeof(ph))
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goto bad2;
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if(ph.type != ELF_PROG_LOAD)
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continue;
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if(ph.va + ph.memsz > sz)
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goto bad2;
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if(readi(ip, cp->mem + ph.va, ph.offset, ph.filesz) != ph.filesz)
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goto bad2;
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memset(cp->mem + ph.va + ph.filesz, 0, ph.memsz - ph.filesz);
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}
|
|
|
|
iput(ip);
|
|
|
|
cp->tf->eip = elf.entry;
|
|
cp->tf->esp = sp;
|
|
setupsegs(cp);
|
|
|
|
return 0;
|
|
|
|
bad:
|
|
cprintf("exec failed early\n");
|
|
if(mem)
|
|
kfree(mem, sz);
|
|
iput(ip);
|
|
return -1;
|
|
|
|
bad2:
|
|
cprintf("exec failed late\n");
|
|
iput(ip);
|
|
proc_exit();
|
|
return 0;
|
|
}
|
|
|
|
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);
|
|
// XXX fault
|
|
break;
|
|
}
|
|
cp->tf->eax = ret;
|
|
}
|