1*12abb1a5SRobert Morris // 2*12abb1a5SRobert Morris // File-system system calls. 3*12abb1a5SRobert Morris // Mostly argument checking, since we don't trust 4*12abb1a5SRobert Morris // user code, and calls into file.c and fs.c. 5*12abb1a5SRobert Morris // 6*12abb1a5SRobert Morris 72685309fSrsc #include "types.h" 8558ab49fSrsc #include "defs.h" 92685309fSrsc #include "param.h" 10558ab49fSrsc #include "stat.h" 112685309fSrsc #include "mmu.h" 122685309fSrsc #include "proc.h" 132685309fSrsc #include "fs.h" 149936bffaSrsc #include "file.h" 152685309fSrsc #include "fcntl.h" 162685309fSrsc 17224f6598Srsc // Fetch the nth word-sized system call argument as a file descriptor 18224f6598Srsc // and return both the descriptor and the corresponding struct file. 19224f6598Srsc static int 2064c47374Srsc argfd(int n, int *pfd, struct file **pf) 21224f6598Srsc { 22224f6598Srsc int fd; 23224f6598Srsc struct file *f; 24224f6598Srsc 253a2310f7Srsc if(argint(n, &fd) < 0) 26224f6598Srsc return -1; 2748755214SRuss Cox if(fd < 0 || fd >= NOFILE || (f=proc->ofile[fd]) == 0) 28224f6598Srsc return -1; 29224f6598Srsc if(pfd) 30224f6598Srsc *pfd = fd; 31224f6598Srsc if(pf) 32224f6598Srsc *pf = f; 33224f6598Srsc return 0; 34224f6598Srsc } 35224f6598Srsc 36224f6598Srsc // Allocate a file descriptor for the given file. 37224f6598Srsc // Takes over file reference from caller on success. 38224f6598Srsc static int 39224f6598Srsc fdalloc(struct file *f) 40224f6598Srsc { 41224f6598Srsc int fd; 429583b476Srsc 43224f6598Srsc for(fd = 0; fd < NOFILE; fd++){ 4448755214SRuss Cox if(proc->ofile[fd] == 0){ 4548755214SRuss Cox proc->ofile[fd] = f; 46224f6598Srsc return fd; 47224f6598Srsc } 48224f6598Srsc } 49224f6598Srsc return -1; 50224f6598Srsc } 51224f6598Srsc 522685309fSrsc int 53f9a06440SRuss Cox sys_dup(void) 54f9a06440SRuss Cox { 55f9a06440SRuss Cox struct file *f; 56f9a06440SRuss Cox int fd; 57f9a06440SRuss Cox 58f9a06440SRuss Cox if(argfd(0, 0, &f) < 0) 59f9a06440SRuss Cox return -1; 60f9a06440SRuss Cox if((fd=fdalloc(f)) < 0) 61f9a06440SRuss Cox return -1; 62f9a06440SRuss Cox filedup(f); 63f9a06440SRuss Cox return fd; 64f9a06440SRuss Cox } 65f9a06440SRuss Cox 66f9a06440SRuss Cox int 67eaea18cbSrsc sys_read(void) 682685309fSrsc { 69eaea18cbSrsc struct file *f; 70eaea18cbSrsc int n; 71666f58c7Srsc char *p; 722685309fSrsc 73666f58c7Srsc if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &p, n) < 0) 742685309fSrsc return -1; 75666f58c7Srsc return fileread(f, p, n); 762685309fSrsc } 772685309fSrsc 782685309fSrsc int 792685309fSrsc sys_write(void) 802685309fSrsc { 81224f6598Srsc struct file *f; 82224f6598Srsc int n; 83666f58c7Srsc char *p; 842685309fSrsc 85666f58c7Srsc if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &p, n) < 0) 862685309fSrsc return -1; 87666f58c7Srsc return filewrite(f, p, n); 882685309fSrsc } 892685309fSrsc 902685309fSrsc int 912685309fSrsc sys_close(void) 922685309fSrsc { 932685309fSrsc int fd; 94224f6598Srsc struct file *f; 952685309fSrsc 96224f6598Srsc if(argfd(0, &fd, &f) < 0) 972685309fSrsc return -1; 9848755214SRuss Cox proc->ofile[fd] = 0; 99224f6598Srsc fileclose(f); 1002685309fSrsc return 0; 1012685309fSrsc } 1022685309fSrsc 1038d2e9a48Srsc int 1048d2e9a48Srsc sys_fstat(void) 1058d2e9a48Srsc { 1068d2e9a48Srsc struct file *f; 1078d2e9a48Srsc struct stat *st; 1088d2e9a48Srsc 1098d2e9a48Srsc if(argfd(0, 0, &f) < 0 || argptr(1, (void*)&st, sizeof(*st)) < 0) 1108d2e9a48Srsc return -1; 1118d2e9a48Srsc return filestat(f, st); 1128d2e9a48Srsc } 1138d2e9a48Srsc 114eaea18cbSrsc // Create the path new as a link to the same inode as old. 115eaea18cbSrsc int 116eaea18cbSrsc sys_link(void) 117eaea18cbSrsc { 118eaea18cbSrsc char name[DIRSIZ], *new, *old; 119eaea18cbSrsc struct inode *dp, *ip; 120eaea18cbSrsc 121eaea18cbSrsc if(argstr(0, &old) < 0 || argstr(1, &new) < 0) 122eaea18cbSrsc return -1; 12307090dd7Srsc if((ip = namei(old)) == 0) 124eaea18cbSrsc return -1; 1255053dd6aSRobert Morris 1265053dd6aSRobert Morris begin_trans(); 1275053dd6aSRobert Morris 12807090dd7Srsc ilock(ip); 129eaea18cbSrsc if(ip->type == T_DIR){ 13007090dd7Srsc iunlockput(ip); 1315053dd6aSRobert Morris commit_trans(); 132eaea18cbSrsc return -1; 133eaea18cbSrsc } 1342e590463SRobert Morris 135eaea18cbSrsc ip->nlink++; 136eaea18cbSrsc iupdate(ip); 13707090dd7Srsc iunlock(ip); 138eaea18cbSrsc 13907090dd7Srsc if((dp = nameiparent(new, name)) == 0) 14007090dd7Srsc goto bad; 14107090dd7Srsc ilock(dp); 142f3685aa3Srsc if(dp->dev != ip->dev || dirlink(dp, name, ip->inum) < 0){ 143f3685aa3Srsc iunlockput(dp); 14407090dd7Srsc goto bad; 145f3685aa3Srsc } 14607090dd7Srsc iunlockput(dp); 14707090dd7Srsc iput(ip); 1482e590463SRobert Morris 1492e590463SRobert Morris commit_trans(); 1502e590463SRobert Morris 15107090dd7Srsc return 0; 15207090dd7Srsc 15307090dd7Srsc bad: 15407090dd7Srsc ilock(ip); 155eaea18cbSrsc ip->nlink--; 156eaea18cbSrsc iupdate(ip); 15707090dd7Srsc iunlockput(ip); 1582e590463SRobert Morris commit_trans(); 159eaea18cbSrsc return -1; 160eaea18cbSrsc } 161eaea18cbSrsc 162eaea18cbSrsc // Is the directory dp empty except for "." and ".." ? 163eaea18cbSrsc static int 164eaea18cbSrsc isdirempty(struct inode *dp) 165eaea18cbSrsc { 166eaea18cbSrsc int off; 167eaea18cbSrsc struct dirent de; 168eaea18cbSrsc 169eaea18cbSrsc for(off=2*sizeof(de); off<dp->size; off+=sizeof(de)){ 170eaea18cbSrsc if(readi(dp, (char*)&de, off, sizeof(de)) != sizeof(de)) 171eaea18cbSrsc panic("isdirempty: readi"); 172eaea18cbSrsc if(de.inum != 0) 173eaea18cbSrsc return 0; 174eaea18cbSrsc } 175eaea18cbSrsc return 1; 176eaea18cbSrsc } 177eaea18cbSrsc 1788d2e9a48Srsc //PAGEBREAK! 179eaea18cbSrsc int 180eaea18cbSrsc sys_unlink(void) 181eaea18cbSrsc { 182eaea18cbSrsc struct inode *ip, *dp; 183eaea18cbSrsc struct dirent de; 184eaea18cbSrsc char name[DIRSIZ], *path; 185eaea18cbSrsc uint off; 186eaea18cbSrsc 187eaea18cbSrsc if(argstr(0, &path) < 0) 188eaea18cbSrsc return -1; 18907090dd7Srsc if((dp = nameiparent(path, name)) == 0) 190eaea18cbSrsc return -1; 1915053dd6aSRobert Morris 1925053dd6aSRobert Morris begin_trans(); 1935053dd6aSRobert Morris 19407090dd7Srsc ilock(dp); 195eaea18cbSrsc 196eaea18cbSrsc // Cannot unlink "." or "..". 1974e015d81SAustin Clements if(namecmp(name, ".") == 0 || namecmp(name, "..") == 0) 1984e015d81SAustin Clements goto bad; 199eaea18cbSrsc 2004e015d81SAustin Clements if((ip = dirlookup(dp, name, &off)) == 0) 2014e015d81SAustin Clements goto bad; 20207090dd7Srsc ilock(ip); 203eaea18cbSrsc 204eaea18cbSrsc if(ip->nlink < 1) 205eaea18cbSrsc panic("unlink: nlink < 1"); 206eaea18cbSrsc if(ip->type == T_DIR && !isdirempty(ip)){ 20707090dd7Srsc iunlockput(ip); 2084e015d81SAustin Clements goto bad; 209eaea18cbSrsc } 210eaea18cbSrsc 211eaea18cbSrsc memset(&de, 0, sizeof(de)); 212eaea18cbSrsc if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de)) 213eaea18cbSrsc panic("unlink: writei"); 21415a26936Skolya if(ip->type == T_DIR){ 21515a26936Skolya dp->nlink--; 21615a26936Skolya iupdate(dp); 21715a26936Skolya } 21807090dd7Srsc iunlockput(dp); 219eaea18cbSrsc 220eaea18cbSrsc ip->nlink--; 221eaea18cbSrsc iupdate(ip); 22207090dd7Srsc iunlockput(ip); 2232e590463SRobert Morris 2242e590463SRobert Morris commit_trans(); 2252e590463SRobert Morris 226eaea18cbSrsc return 0; 2274e015d81SAustin Clements 2284e015d81SAustin Clements bad: 2294e015d81SAustin Clements iunlockput(dp); 2304e015d81SAustin Clements commit_trans(); 2314e015d81SAustin Clements return -1; 232eaea18cbSrsc } 233eaea18cbSrsc 234eaea18cbSrsc static struct inode* 235f3685aa3Srsc create(char *path, short type, short major, short minor) 236eaea18cbSrsc { 237eaea18cbSrsc uint off; 238eaea18cbSrsc struct inode *ip, *dp; 239eaea18cbSrsc char name[DIRSIZ]; 240eaea18cbSrsc 24107090dd7Srsc if((dp = nameiparent(path, name)) == 0) 242eaea18cbSrsc return 0; 24307090dd7Srsc ilock(dp); 244eaea18cbSrsc 245f3685aa3Srsc if((ip = dirlookup(dp, name, &off)) != 0){ 24607090dd7Srsc iunlockput(dp); 24707090dd7Srsc ilock(ip); 248f9a06440SRuss Cox if(type == T_FILE && ip->type == T_FILE) 249f9a06440SRuss Cox return ip; 25007090dd7Srsc iunlockput(ip); 251eaea18cbSrsc return 0; 252eaea18cbSrsc } 253eaea18cbSrsc 254f9a06440SRuss Cox if((ip = ialloc(dp->dev, type)) == 0) 255f9a06440SRuss Cox panic("create: ialloc"); 256f9a06440SRuss Cox 25707090dd7Srsc ilock(ip); 258eaea18cbSrsc ip->major = major; 259eaea18cbSrsc ip->minor = minor; 260603deefcSrsc ip->nlink = 1; 261eaea18cbSrsc iupdate(ip); 262eaea18cbSrsc 263eaea18cbSrsc if(type == T_DIR){ // Create . and .. entries. 264eaea18cbSrsc dp->nlink++; // for ".." 265eaea18cbSrsc iupdate(dp); 266eaea18cbSrsc // No ip->nlink++ for ".": avoid cyclic ref count. 267eaea18cbSrsc if(dirlink(ip, ".", ip->inum) < 0 || dirlink(ip, "..", dp->inum) < 0) 268e79b1659Srsc panic("create dots"); 269eaea18cbSrsc } 270f3e87bc8Skolya 271f3685aa3Srsc if(dirlink(dp, name, ip->inum) < 0) 272f3685aa3Srsc panic("create: dirlink"); 273f3e87bc8Skolya 27407090dd7Srsc iunlockput(dp); 2752e590463SRobert Morris 276eaea18cbSrsc return ip; 277eaea18cbSrsc } 278eaea18cbSrsc 2792685309fSrsc int 2802685309fSrsc sys_open(void) 2812685309fSrsc { 282f32f3638Srsc char *path; 283f32f3638Srsc int fd, omode; 284224f6598Srsc struct file *f; 285f32f3638Srsc struct inode *ip; 2862685309fSrsc 287224f6598Srsc if(argstr(0, &path) < 0 || argint(1, &omode) < 0) 2882685309fSrsc return -1; 289eaea18cbSrsc if(omode & O_CREATE){ 2902e590463SRobert Morris begin_trans(); 2912e590463SRobert Morris ip = create(path, T_FILE, 0, 0); 2922e590463SRobert Morris commit_trans(); 2932e590463SRobert Morris if(ip == 0) 294e2a620daSrsc return -1; 295eaea18cbSrsc } else { 29607090dd7Srsc if((ip = namei(path)) == 0) 297eaea18cbSrsc return -1; 29807090dd7Srsc ilock(ip); 299f3685aa3Srsc if(ip->type == T_DIR && omode != O_RDONLY){ 30007090dd7Srsc iunlockput(ip); 3012685309fSrsc return -1; 3022685309fSrsc } 303eaea18cbSrsc } 3042685309fSrsc 305eaea18cbSrsc if((f = filealloc()) == 0 || (fd = fdalloc(f)) < 0){ 306eaea18cbSrsc if(f) 307224f6598Srsc fileclose(f); 30807090dd7Srsc iunlockput(ip); 3092685309fSrsc return -1; 3102685309fSrsc } 31107090dd7Srsc iunlock(ip); 3122685309fSrsc 313eaea18cbSrsc f->type = FD_INODE; 31407090dd7Srsc f->ip = ip; 315eaea18cbSrsc f->off = 0; 316e79b1659Srsc f->readable = !(omode & O_WRONLY); 317e79b1659Srsc f->writable = (omode & O_WRONLY) || (omode & O_RDWR); 318224f6598Srsc return fd; 3192685309fSrsc } 3202685309fSrsc 3212685309fSrsc int 322f9a06440SRuss Cox sys_mkdir(void) 323f9a06440SRuss Cox { 324f9a06440SRuss Cox char *path; 325f9a06440SRuss Cox struct inode *ip; 326f9a06440SRuss Cox 3272e590463SRobert Morris begin_trans(); 3282e590463SRobert Morris if(argstr(0, &path) < 0 || (ip = create(path, T_DIR, 0, 0)) == 0){ 3292e590463SRobert Morris commit_trans(); 330f9a06440SRuss Cox return -1; 3312e590463SRobert Morris } 332f9a06440SRuss Cox iunlockput(ip); 3332e590463SRobert Morris commit_trans(); 334f9a06440SRuss Cox return 0; 335f9a06440SRuss Cox } 336f9a06440SRuss Cox 337f9a06440SRuss Cox int 3382685309fSrsc sys_mknod(void) 3392685309fSrsc { 340eaea18cbSrsc struct inode *ip; 341224f6598Srsc char *path; 342224f6598Srsc int len; 343aa6824abSrsc int major, minor; 3442685309fSrsc 3452e590463SRobert Morris begin_trans(); 34607090dd7Srsc if((len=argstr(0, &path)) < 0 || 34707090dd7Srsc argint(1, &major) < 0 || 34807090dd7Srsc argint(2, &minor) < 0 || 3492e590463SRobert Morris (ip = create(path, T_DEV, major, minor)) == 0){ 3502e590463SRobert Morris commit_trans(); 3512685309fSrsc return -1; 3522e590463SRobert Morris } 35307090dd7Srsc iunlockput(ip); 3542e590463SRobert Morris commit_trans(); 355224f6598Srsc return 0; 3562685309fSrsc } 3572685309fSrsc 3582685309fSrsc int 3592685309fSrsc sys_chdir(void) 3602685309fSrsc { 361eaea18cbSrsc char *path; 3622685309fSrsc struct inode *ip; 3632685309fSrsc 36407090dd7Srsc if(argstr(0, &path) < 0 || (ip = namei(path)) == 0) 3652685309fSrsc return -1; 36607090dd7Srsc ilock(ip); 3672685309fSrsc if(ip->type != T_DIR){ 36807090dd7Srsc iunlockput(ip); 3692685309fSrsc return -1; 3702685309fSrsc } 37107090dd7Srsc iunlock(ip); 37248755214SRuss Cox iput(proc->cwd); 37348755214SRuss Cox proc->cwd = ip; 3742685309fSrsc return 0; 3752685309fSrsc } 3762685309fSrsc 3772685309fSrsc int 3782685309fSrsc sys_exec(void) 3792685309fSrsc { 3804655d42eSRobert Morris char *path, *argv[MAXARG]; 381f32f3638Srsc int i; 382f32f3638Srsc uint uargv, uarg; 3832685309fSrsc 38440889627SFrans Kaashoek if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0){ 3852685309fSrsc return -1; 38640889627SFrans Kaashoek } 387eaea18cbSrsc memset(argv, 0, sizeof(argv)); 3882685309fSrsc for(i=0;; i++){ 389eaea18cbSrsc if(i >= NELEM(argv)) 3902685309fSrsc return -1; 39148755214SRuss Cox if(fetchint(proc, uargv+4*i, (int*)&uarg) < 0) 392f32f3638Srsc return -1; 393f32f3638Srsc if(uarg == 0){ 394f32f3638Srsc argv[i] = 0; 395f32f3638Srsc break; 3962685309fSrsc } 39748755214SRuss Cox if(fetchstr(proc, uarg, &argv[i]) < 0) 398f32f3638Srsc return -1; 399f32f3638Srsc } 400f32f3638Srsc return exec(path, argv); 401f32f3638Srsc } 402f32f3638Srsc 403eaea18cbSrsc int 404eaea18cbSrsc sys_pipe(void) 405eaea18cbSrsc { 406eaea18cbSrsc int *fd; 407eaea18cbSrsc struct file *rf, *wf; 408eaea18cbSrsc int fd0, fd1; 409eaea18cbSrsc 410eaea18cbSrsc if(argptr(0, (void*)&fd, 2*sizeof(fd[0])) < 0) 411eaea18cbSrsc return -1; 4127834cca6Srsc if(pipealloc(&rf, &wf) < 0) 413eaea18cbSrsc return -1; 414eaea18cbSrsc fd0 = -1; 415eaea18cbSrsc if((fd0 = fdalloc(rf)) < 0 || (fd1 = fdalloc(wf)) < 0){ 416eaea18cbSrsc if(fd0 >= 0) 41748755214SRuss Cox proc->ofile[fd0] = 0; 418eaea18cbSrsc fileclose(rf); 419eaea18cbSrsc fileclose(wf); 420eaea18cbSrsc return -1; 421eaea18cbSrsc } 422eaea18cbSrsc fd[0] = fd0; 423eaea18cbSrsc fd[1] = fd1; 424eaea18cbSrsc return 0; 425eaea18cbSrsc } 426