433 lines
7.1 KiB
C
433 lines
7.1 KiB
C
//
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// File-system system calls.
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// Mostly argument checking, since we don't trust
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// user code, and calls into file.c and fs.c.
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//
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#include "types.h"
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#include "riscv.h"
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#include "defs.h"
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#include "param.h"
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#include "stat.h"
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#include "spinlock.h"
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#include "proc.h"
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#include "fs.h"
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#include "sleeplock.h"
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#include "file.h"
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#include "fcntl.h"
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// Fetch the nth word-sized system call argument as a file descriptor
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// and return both the descriptor and the corresponding struct file.
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int argfd(int n, int *pfd, struct file **pf);
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// Allocate a file descriptor for the given file.
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// Takes over file reference from caller on success.
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static int
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fdalloc(struct file *f)
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{
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int fd;
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struct proc *p = myproc();
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for (fd = 0; fd < NOFILE; fd++)
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{
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if (p->ofile[fd] == 0)
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{
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p->ofile[fd] = f;
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return fd;
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}
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}
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return -1;
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}
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// Create the path new as a link to the same inode as old.
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uint64
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sys_link(void)
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{
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char name[DIRSIZ], new[MAXPATH], old[MAXPATH];
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struct inode *dp, *ip;
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if (argstr(0, old, MAXPATH) < 0 || argstr(1, new, MAXPATH) < 0)
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return -1;
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begin_op();
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if ((ip = namei(old)) == 0)
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{
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end_op();
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return -1;
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}
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ilock(ip);
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if (ip->type == T_DIR)
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{
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iunlockput(ip);
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end_op();
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return -1;
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}
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ip->nlink++;
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iupdate(ip);
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iunlock(ip);
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if ((dp = nameiparent(new, name)) == 0)
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goto bad;
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ilock(dp);
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if (dp->dev != ip->dev || dirlink(dp, name, ip->inum) < 0)
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{
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iunlockput(dp);
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goto bad;
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}
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iunlockput(dp);
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iput(ip);
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end_op();
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return 0;
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bad:
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ilock(ip);
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ip->nlink--;
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iupdate(ip);
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iunlockput(ip);
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end_op();
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return -1;
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}
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// Is the directory dp empty except for "." and ".." ?
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static int
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isdirempty(struct inode *dp)
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{
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int off;
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struct dirent de;
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for (off = 2 * sizeof(de); off < dp->size; off += sizeof(de))
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{
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if (readi(dp, 0, (uint64)&de, off, sizeof(de)) != sizeof(de))
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panic("isdirempty: readi");
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if (de.inum != 0)
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return 0;
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}
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return 1;
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}
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uint64
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sys_unlink(void)
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{
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struct inode *ip, *dp;
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struct dirent de;
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char name[DIRSIZ], path[MAXPATH];
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uint off;
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if (argstr(0, path, MAXPATH) < 0)
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return -1;
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begin_op();
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if ((dp = nameiparent(path, name)) == 0)
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{
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end_op();
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return -1;
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}
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ilock(dp);
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// Cannot unlink "." or "..".
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if (namecmp(name, ".") == 0 || namecmp(name, "..") == 0)
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goto bad;
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if ((ip = dirlookup(dp, name, &off)) == 0)
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goto bad;
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ilock(ip);
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if (ip->nlink < 1)
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panic("unlink: nlink < 1");
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if (ip->type == T_DIR && !isdirempty(ip))
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{
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iunlockput(ip);
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goto bad;
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}
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memset(&de, 0, sizeof(de));
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if (writei(dp, 0, (uint64)&de, off, sizeof(de)) != sizeof(de))
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panic("unlink: writei");
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if (ip->type == T_DIR)
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{
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dp->nlink--;
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iupdate(dp);
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}
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iunlockput(dp);
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ip->nlink--;
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iupdate(ip);
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iunlockput(ip);
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end_op();
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return 0;
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bad:
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iunlockput(dp);
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end_op();
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return -1;
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}
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static struct inode *
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create(char *path, short type, short major, short minor)
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{
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struct inode *ip, *dp;
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char name[DIRSIZ];
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if ((dp = nameiparent(path, name)) == 0)
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return 0;
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ilock(dp);
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if ((ip = dirlookup(dp, name, 0)) != 0)
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{
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iunlockput(dp);
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ilock(ip);
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if (type == T_FILE && (ip->type == T_FILE || ip->type == T_DEVICE))
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return ip;
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iunlockput(ip);
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return 0;
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}
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if ((ip = ialloc(dp->dev, type)) == 0)
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{
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iunlockput(dp);
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return 0;
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}
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ilock(ip);
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ip->major = major;
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ip->minor = minor;
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ip->nlink = 1;
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iupdate(ip);
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if (type == T_DIR)
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{ // Create . and .. entries.
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// No ip->nlink++ for ".": avoid cyclic ref count.
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if (dirlink(ip, ".", ip->inum) < 0 || dirlink(ip, "..", dp->inum) < 0)
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goto fail;
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}
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if (dirlink(dp, name, ip->inum) < 0)
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goto fail;
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if (type == T_DIR)
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{
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// now that success is guaranteed:
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dp->nlink++; // for ".."
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iupdate(dp);
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}
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iunlockput(dp);
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return ip;
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fail:
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// something went wrong. de-allocate ip.
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ip->nlink = 0;
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iupdate(ip);
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iunlockput(ip);
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iunlockput(dp);
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return 0;
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}
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uint64
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sys_open(void)
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{
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char path[MAXPATH];
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int fd, omode;
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struct file *f;
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struct inode *ip;
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int n;
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argint(1, &omode);
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if ((n = argstr(0, path, MAXPATH)) < 0)
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return -1;
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begin_op();
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if (omode & O_CREATE)
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{
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ip = create(path, T_FILE, 0, 0);
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if (ip == 0)
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{
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end_op();
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return -1;
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}
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}
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else
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{
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if ((ip = namei(path)) == 0)
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{
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end_op();
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return -1;
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}
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ilock(ip);
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if (ip->type == T_DIR && omode != O_RDONLY)
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{
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iunlockput(ip);
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end_op();
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return -1;
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}
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}
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if (ip->type == T_DEVICE && (ip->major < 0 || ip->major >= NDEV))
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{
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iunlockput(ip);
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end_op();
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return -1;
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}
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if ((f = filealloc()) == 0 || (fd = fdalloc(f)) < 0)
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{
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if (f)
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fileclose(f);
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iunlockput(ip);
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end_op();
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return -1;
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}
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if (ip->type == T_DEVICE)
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{
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f->type = FD_DEVICE;
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f->major = ip->major;
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}
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else
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{
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f->type = FD_INODE;
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f->off = 0;
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}
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f->ip = ip;
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f->readable = !(omode & O_WRONLY);
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f->writable = (omode & O_WRONLY) || (omode & O_RDWR);
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if ((omode & O_TRUNC) && ip->type == T_FILE)
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{
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itrunc(ip);
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}
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iunlock(ip);
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end_op();
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return fd;
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}
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uint64
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sys_mkdir(void)
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{
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char path[MAXPATH];
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struct inode *ip;
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begin_op();
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if (argstr(0, path, MAXPATH) < 0 || (ip = create(path, T_DIR, 0, 0)) == 0)
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{
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end_op();
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return -1;
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}
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iunlockput(ip);
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end_op();
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return 0;
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}
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uint64
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sys_mknod(void)
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{
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struct inode *ip;
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char path[MAXPATH];
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int major, minor;
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begin_op();
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argint(1, &major);
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argint(2, &minor);
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if ((argstr(0, path, MAXPATH)) < 0 ||
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(ip = create(path, T_DEVICE, major, minor)) == 0)
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{
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end_op();
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return -1;
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}
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iunlockput(ip);
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end_op();
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return 0;
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}
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uint64
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sys_exec(void)
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{
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char path[MAXPATH], *argv[MAXARG];
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int i;
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uint64 uargv, uarg;
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argaddr(1, &uargv);
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if (argstr(0, path, MAXPATH) < 0)
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{
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return -1;
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}
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memset(argv, 0, sizeof(argv));
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for (i = 0;; i++)
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{
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if (i >= NELEM(argv))
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{
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goto bad;
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}
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if (fetchaddr(uargv + sizeof(uint64) * i, (uint64 *)&uarg) < 0)
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{
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goto bad;
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}
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if (uarg == 0)
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{
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argv[i] = 0;
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break;
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}
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argv[i] = kalloc();
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if (argv[i] == 0)
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goto bad;
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if (fetchstr(uarg, argv[i], PGSIZE) < 0)
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goto bad;
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}
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int ret = exec(path, argv);
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for (i = 0; i < NELEM(argv) && argv[i] != 0; i++)
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kfree(argv[i]);
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return ret;
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bad:
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for (i = 0; i < NELEM(argv) && argv[i] != 0; i++)
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kfree(argv[i]);
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return -1;
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}
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uint64
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sys_pipe(void)
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{
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uint64 fdarray; // user pointer to array of two integers
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struct file *rf, *wf;
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int fd0, fd1;
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struct proc *p = myproc();
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argaddr(0, &fdarray);
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if (pipealloc(&rf, &wf) < 0)
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return -1;
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fd0 = -1;
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if ((fd0 = fdalloc(rf)) < 0 || (fd1 = fdalloc(wf)) < 0)
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{
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if (fd0 >= 0)
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p->ofile[fd0] = 0;
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fileclose(rf);
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fileclose(wf);
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return -1;
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}
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if (copyout(p->pagetable, fdarray, (char *)&fd0, sizeof(fd0)) < 0 ||
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copyout(p->pagetable, fdarray + sizeof(fd0), (char *)&fd1, sizeof(fd1)) < 0)
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{
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p->ofile[fd0] = 0;
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p->ofile[fd1] = 0;
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fileclose(rf);
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fileclose(wf);
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return -1;
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}
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return 0;
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}
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