xv6/sysfile.c

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8.4 KiB
C
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#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"
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#include "file.h"
#include "fcntl.h"
int
sys_pipe(void)
{
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struct file *rfd = 0, *wfd = 0;
int f1 = -1, f2 = -1;
struct proc *p = curproc[cpu()];
uint fdp;
if(pipe_alloc(&rfd, &wfd) < 0)
goto oops;
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if((f1 = fdalloc()) < 0)
goto oops;
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p->ofile[f1] = rfd;
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if((f2 = fdalloc()) < 0)
goto oops;
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p->ofile[f2] = wfd;
if(fetcharg(0, &fdp) < 0)
goto oops;
if(putint(p, fdp, f1) < 0)
goto oops;
if(putint(p, fdp+4, f2) < 0)
goto oops;
return 0;
oops:
if(rfd)
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fileclose(rfd);
if(wfd)
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fileclose(wfd);
if(f1 >= 0)
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p->ofile[f1] = 0;
if(f2 >= 0)
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p->ofile[f2] = 0;
return -1;
}
int
sys_write(void)
{
int fd, n, ret;
uint addr;
struct proc *p = curproc[cpu()];
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if(fetcharg(0, &fd) < 0 ||
fetcharg(1, &addr) < 0 ||
fetcharg(2, &n) < 0)
return -1;
if(fd < 0 || fd >= NOFILE)
return -1;
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if(p->ofile[fd] == 0)
return -1;
if(addr + n > p->sz)
return -1;
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ret = filewrite(p->ofile[fd], p->mem + addr, n);
return ret;
}
int
sys_read(void)
{
int fd, n, ret;
uint addr;
struct proc *p = curproc[cpu()];
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if(fetcharg(0, &fd) < 0 ||
fetcharg(1, &addr) < 0 ||
fetcharg(2, &n) < 0)
return -1;
if(fd < 0 || fd >= NOFILE)
return -1;
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if(p->ofile[fd] == 0)
return -1;
if(addr + n > p->sz)
return -1;
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ret = fileread(p->ofile[fd], p->mem + addr, n);
return ret;
}
int
sys_close(void)
{
int fd;
struct proc *p = curproc[cpu()];
if(fetcharg(0, &fd) < 0)
return -1;
if(fd < 0 || fd >= NOFILE)
return -1;
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if(p->ofile[fd] == 0)
return -1;
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fileclose(p->ofile[fd]);
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p->ofile[fd] = 0;
return 0;
}
int
sys_open(void)
{
struct proc *cp = curproc[cpu()];
struct inode *ip, *dp;
uint arg0, arg1;
int ufd;
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struct file *fd;
int l;
char *last;
if(fetcharg(0, &arg0) < 0 || fetcharg(1, &arg1) < 0)
return -1;
if((l = checkstring(arg0)) < 0)
return -1;
if(arg1 & O_CREATE){
dp = namei(cp->mem + arg0, NAMEI_CREATE, 0, &last, &ip);
if(dp){
ip = mknod1(dp, last, T_FILE, 0, 0);
iput(dp);
if(ip == 0)
return -1;
} else if(ip == 0){
return -1;
} else if(ip->type == T_DIR){
iput(ip);
return -1;
}
} else {
ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0, 0, 0);
if(ip == 0)
return -1;
}
if(ip->type == T_DIR && ((arg1 & O_RDWR) || (arg1 & O_WRONLY))){
iput(ip);
return -1;
}
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if((fd = filealloc()) == 0){
iput(ip);
return -1;
}
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if((ufd = fdalloc()) < 0){
iput(ip);
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fileclose(fd);
return -1;
}
iunlock(ip);
fd->type = FD_FILE;
if(arg1 & O_RDWR) {
fd->readable = 1;
fd->writable = 1;
} else if(arg1 & O_WRONLY) {
fd->readable = 0;
fd->writable = 1;
} else {
fd->readable = 1;
fd->writable = 0;
}
fd->ip = ip;
fd->off = 0;
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cp->ofile[ufd] = fd;
return ufd;
}
int
sys_mknod(void)
{
struct proc *cp = curproc[cpu()];
struct inode *nip;
uint arg0, arg1, arg2, arg3;
int l;
if(fetcharg(0, &arg0) < 0 || fetcharg(1, &arg1) < 0 ||
fetcharg(2, &arg2) < 0 || fetcharg(3, &arg3) < 0)
return -1;
if((l = checkstring(arg0)) < 0)
return -1;
if(l >= DIRSIZ)
return -1;
nip = mknod(cp->mem + arg0, (short) arg1, (short) arg2, (short) arg3);
if(nip)
iput(nip);
return (nip == 0) ? -1 : 0;
}
int
sys_mkdir(void)
{
struct proc *cp = curproc[cpu()];
struct inode *nip;
struct inode *dp;
uint arg0;
int l;
struct dirent de;
char *last;
if(fetcharg(0, &arg0) < 0)
return -1;
if((l = checkstring(arg0)) < 0)
return -1;
dp = namei(cp->mem + arg0, NAMEI_CREATE, 0, &last, 0);
if(dp == 0)
return -1;
nip = mknod1(dp, last, T_DIR, 0, 0);
if(nip == 0){
iput(dp);
return -1;
}
dp->nlink += 1;
iupdate(dp);
memset(de.name, '\0', DIRSIZ);
de.name[0] = '.';
de.inum = nip->inum;
writei(nip, (char*) &de, 0, sizeof(de));
de.inum = dp->inum;
de.name[1] = '.';
writei(nip, (char*) &de, sizeof(de), sizeof(de));
iput(dp);
iput(nip);
return 0;
}
int
sys_chdir(void)
{
struct proc *cp = curproc[cpu()];
struct inode *ip;
uint arg0;
int l;
if(fetcharg(0, &arg0) < 0)
return -1;
if((l = checkstring(arg0)) < 0)
return -1;
if((ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0, 0, 0)) == 0)
return -1;
if(ip == cp->cwd) {
iput(ip);
return 0;
}
if(ip->type != T_DIR) {
iput(ip);
return -1;
}
idecref(cp->cwd);
cp->cwd = ip;
iunlock(cp->cwd);
return 0;
}
int
sys_unlink(void)
{
struct proc *cp = curproc[cpu()];
uint arg0;
int r;
if(fetcharg(0, &arg0) < 0)
return -1;
if(checkstring(arg0) < 0)
return -1;
r = unlink(cp->mem + arg0);
return r;
}
int
sys_fstat(void)
{
struct proc *cp = curproc[cpu()];
uint fd, addr;
int r;
if(fetcharg(0, &fd) < 0)
return -1;
if(fetcharg(1, &addr) < 0)
return -1;
if(fd < 0 || fd >= NOFILE)
return -1;
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if(cp->ofile[fd] == 0)
return -1;
if(addr + sizeof(struct stat) > cp->sz)
return -1;
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r = filestat(cp->ofile[fd], (struct stat*)(cp->mem + addr));
return r;
}
int
sys_dup(void)
{
struct proc *cp = curproc[cpu()];
uint fd, ufd1;
if(fetcharg(0, &fd) < 0)
return -1;
if(fd < 0 || fd >= NOFILE)
return -1;
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if(cp->ofile[fd] == 0)
return -1;
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if((ufd1 = fdalloc()) < 0)
return -1;
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cp->ofile[ufd1] = cp->ofile[fd];
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fileincref(cp->ofile[ufd1]);
return ufd1;
}
int
sys_link(void)
{
struct proc *cp = curproc[cpu()];
uint name1, name2;
int r;
if(fetcharg(0, &name1) < 0 || checkstring(name1) < 0)
return -1;
if(fetcharg(1, &name2) < 0 || checkstring(name2) < 0)
return -1;
r = link(cp->mem + name1, cp->mem + name2);
return r;
}
int
sys_exec(void)
{
struct proc *cp = curproc[cpu()];
uint arg0, arg1, sz=0, ap, sp, p1, p2;
int i, nargs, argbytes, len;
struct inode *ip;
struct elfhdr elf;
struct proghdr ph;
char *mem = 0;
if(fetcharg(0, &arg0) < 0)
return -1;
if(fetcharg(1, &arg1) < 0)
return -1;
if(checkstring(arg0) < 0)
return -1;
ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0, 0, 0);
if(ip == 0)
return -1;
if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
goto bad;
if(elf.magic != ELF_MAGIC)
goto bad;
sz = 0;
for(i = 0; i < elf.phnum; i++){
if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph),
sizeof(ph)) != sizeof(ph))
goto bad;
if(ph.type != ELF_PROG_LOAD)
continue;
if(ph.memsz < ph.filesz)
goto bad;
sz += ph.memsz;
}
sz += 4096 - (sz % 4096);
sz += 4096;
mem = kalloc(sz);
if(mem == 0)
goto bad;
memset(mem, 0, sz);
// arg1 is a pointer to an array of pointers to string.
nargs = 0;
argbytes = 0;
for(i = 0; ; i++){
if(fetchint(cp, arg1 + 4*i, &ap) < 0)
goto bad;
if(ap == 0)
break;
len = checkstring(ap);
if(len < 0)
goto bad;
nargs++;
argbytes += len + 1;
}
// argn\0
// ...
// arg0\0
// 0
// ptr to argn
// ...
// 12: ptr to arg0
// 8: argv (points to ptr to arg0)
// 4: argc
// 0: fake return pc
sp = sz - argbytes - (nargs+1)*4 - 4 - 4 - 4;
*(uint*)(mem + sp) = 0xffffffff;
*(uint*)(mem + sp + 4) = nargs;
*(uint*)(mem + sp + 8) = (uint)(sp + 12);
p1 = sp + 12;
p2 = sp + 12 + (nargs + 1) * 4;
for(i = 0; i < nargs; i++){
fetchint(cp, arg1 + 4*i, &ap);
len = checkstring(ap);
memmove(mem + p2, cp->mem + ap, len + 1);
*(uint*)(mem + p1) = p2;
p1 += 4;
p2 += len + 1;
}
*(uint*)(mem + p1) = 0;
// commit to the new image.
kfree(cp->mem, cp->sz);
cp->sz = sz;
cp->mem = mem;
mem = 0;
for(i = 0; i < elf.phnum; i++){
if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph),
sizeof(ph)) != sizeof(ph))
goto bad2;
if(ph.type != ELF_PROG_LOAD)
continue;
if(ph.va + ph.memsz > sz)
goto bad2;
if(readi(ip, cp->mem + ph.va, ph.offset, ph.filesz) != ph.filesz)
goto bad2;
memset(cp->mem + ph.va + ph.filesz, 0, ph.memsz - ph.filesz);
}
iput(ip);
cp->tf->eip = elf.entry;
cp->tf->esp = sp;
setupsegs(cp);
return 0;
bad:
if(mem)
kfree(mem, sz);
iput(ip);
return -1;
bad2:
iput(ip);
proc_exit();
return 0;
}