12685309fSrsc #include "types.h" 2558ab49fSrsc #include "defs.h" 32685309fSrsc #include "param.h" 4558ab49fSrsc #include "stat.h" 52685309fSrsc #include "mmu.h" 62685309fSrsc #include "proc.h" 72685309fSrsc #include "fs.h" 82685309fSrsc #include "fsvar.h" 99936bffaSrsc #include "file.h" 102685309fSrsc #include "fcntl.h" 112685309fSrsc 12224f6598Srsc // Fetch the nth word-sized system call argument as a file descriptor 13224f6598Srsc // and return both the descriptor and the corresponding struct file. 14224f6598Srsc static int 1564c47374Srsc argfd(int n, int *pfd, struct file **pf) 16224f6598Srsc { 17224f6598Srsc int fd; 18224f6598Srsc struct file *f; 19224f6598Srsc 203a2310f7Srsc if(argint(n, &fd) < 0) 21224f6598Srsc return -1; 229583b476Srsc if(fd < 0 || fd >= NOFILE || (f=cp->ofile[fd]) == 0) 23224f6598Srsc return -1; 24224f6598Srsc if(pfd) 25224f6598Srsc *pfd = fd; 26224f6598Srsc if(pf) 27224f6598Srsc *pf = f; 28224f6598Srsc return 0; 29224f6598Srsc } 30224f6598Srsc 31224f6598Srsc // Allocate a file descriptor for the given file. 32224f6598Srsc // Takes over file reference from caller on success. 33224f6598Srsc static int 34224f6598Srsc fdalloc(struct file *f) 35224f6598Srsc { 36224f6598Srsc int fd; 379583b476Srsc 38224f6598Srsc for(fd = 0; fd < NOFILE; fd++){ 399583b476Srsc if(cp->ofile[fd] == 0){ 409583b476Srsc cp->ofile[fd] = f; 41224f6598Srsc return fd; 42224f6598Srsc } 43224f6598Srsc } 44224f6598Srsc return -1; 45224f6598Srsc } 46224f6598Srsc 472685309fSrsc int 48eaea18cbSrsc sys_read(void) 492685309fSrsc { 50eaea18cbSrsc struct file *f; 51eaea18cbSrsc int n; 52eaea18cbSrsc char *cp; 532685309fSrsc 54eaea18cbSrsc if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &cp, n) < 0) 552685309fSrsc return -1; 56eaea18cbSrsc return fileread(f, cp, n); 572685309fSrsc } 582685309fSrsc 592685309fSrsc int 602685309fSrsc sys_write(void) 612685309fSrsc { 62224f6598Srsc struct file *f; 63224f6598Srsc int n; 64224f6598Srsc char *cp; 652685309fSrsc 66224f6598Srsc if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &cp, n) < 0) 672685309fSrsc return -1; 68224f6598Srsc return filewrite(f, cp, n); 692685309fSrsc } 702685309fSrsc 712685309fSrsc int 728d2e9a48Srsc sys_dup(void) 732685309fSrsc { 74224f6598Srsc struct file *f; 758d2e9a48Srsc int fd; 762685309fSrsc 778d2e9a48Srsc if(argfd(0, 0, &f) < 0) 782685309fSrsc return -1; 798d2e9a48Srsc if((fd=fdalloc(f)) < 0) 808d2e9a48Srsc return -1; 811ccff18bSrsc filedup(f); 828d2e9a48Srsc return fd; 832685309fSrsc } 842685309fSrsc 852685309fSrsc int 862685309fSrsc sys_close(void) 872685309fSrsc { 882685309fSrsc int fd; 89224f6598Srsc struct file *f; 902685309fSrsc 91224f6598Srsc if(argfd(0, &fd, &f) < 0) 922685309fSrsc return -1; 93b6095304Srsc cp->ofile[fd] = 0; 94224f6598Srsc fileclose(f); 952685309fSrsc return 0; 962685309fSrsc } 972685309fSrsc 988d2e9a48Srsc int 998d2e9a48Srsc sys_fstat(void) 1008d2e9a48Srsc { 1018d2e9a48Srsc struct file *f; 1028d2e9a48Srsc struct stat *st; 1038d2e9a48Srsc 1048d2e9a48Srsc if(argfd(0, 0, &f) < 0 || argptr(1, (void*)&st, sizeof(*st)) < 0) 1058d2e9a48Srsc return -1; 1068d2e9a48Srsc return filestat(f, st); 1078d2e9a48Srsc } 1088d2e9a48Srsc 109eaea18cbSrsc // Create the path new as a link to the same inode as old. 110eaea18cbSrsc int 111eaea18cbSrsc sys_link(void) 112eaea18cbSrsc { 113eaea18cbSrsc char name[DIRSIZ], *new, *old; 114eaea18cbSrsc struct inode *dp, *ip; 115eaea18cbSrsc 116eaea18cbSrsc if(argstr(0, &old) < 0 || argstr(1, &new) < 0) 117eaea18cbSrsc return -1; 11807090dd7Srsc if((ip = namei(old)) == 0) 119eaea18cbSrsc return -1; 12007090dd7Srsc ilock(ip); 121eaea18cbSrsc if(ip->type == T_DIR){ 12207090dd7Srsc iunlockput(ip); 123eaea18cbSrsc return -1; 124eaea18cbSrsc } 125eaea18cbSrsc ip->nlink++; 126eaea18cbSrsc iupdate(ip); 12707090dd7Srsc iunlock(ip); 128eaea18cbSrsc 12907090dd7Srsc if((dp = nameiparent(new, name)) == 0) 13007090dd7Srsc goto bad; 13107090dd7Srsc ilock(dp); 13207090dd7Srsc if(dp->dev != ip->dev || dirlink(dp, name, ip->inum) < 0) 13307090dd7Srsc goto bad; 13407090dd7Srsc iunlockput(dp); 13507090dd7Srsc iput(ip); 13607090dd7Srsc return 0; 13707090dd7Srsc 13807090dd7Srsc bad: 139eaea18cbSrsc if(dp) 14007090dd7Srsc iunlockput(dp); 14107090dd7Srsc ilock(ip); 142eaea18cbSrsc ip->nlink--; 143eaea18cbSrsc iupdate(ip); 14407090dd7Srsc iunlockput(ip); 145eaea18cbSrsc return -1; 146eaea18cbSrsc } 147eaea18cbSrsc 148eaea18cbSrsc // Is the directory dp empty except for "." and ".." ? 149eaea18cbSrsc static int 150eaea18cbSrsc isdirempty(struct inode *dp) 151eaea18cbSrsc { 152eaea18cbSrsc int off; 153eaea18cbSrsc struct dirent de; 154eaea18cbSrsc 155eaea18cbSrsc for(off=2*sizeof(de); off<dp->size; off+=sizeof(de)){ 156eaea18cbSrsc if(readi(dp, (char*)&de, off, sizeof(de)) != sizeof(de)) 157eaea18cbSrsc panic("isdirempty: readi"); 158eaea18cbSrsc if(de.inum != 0) 159eaea18cbSrsc return 0; 160eaea18cbSrsc } 161eaea18cbSrsc return 1; 162eaea18cbSrsc } 163eaea18cbSrsc 1648d2e9a48Srsc //PAGEBREAK! 165eaea18cbSrsc int 166eaea18cbSrsc sys_unlink(void) 167eaea18cbSrsc { 168eaea18cbSrsc struct inode *ip, *dp; 169eaea18cbSrsc struct dirent de; 170eaea18cbSrsc char name[DIRSIZ], *path; 171eaea18cbSrsc uint off; 172eaea18cbSrsc 173eaea18cbSrsc if(argstr(0, &path) < 0) 174eaea18cbSrsc return -1; 17507090dd7Srsc if((dp = nameiparent(path, name)) == 0) 176eaea18cbSrsc return -1; 17707090dd7Srsc ilock(dp); 178eaea18cbSrsc 179eaea18cbSrsc // Cannot unlink "." or "..". 180eaea18cbSrsc if(namecmp(name, ".") == 0 || namecmp(name, "..") == 0){ 18107090dd7Srsc iunlockput(dp); 182eaea18cbSrsc return -1; 183eaea18cbSrsc } 184eaea18cbSrsc 18507090dd7Srsc if((ip = dirlookup(dp, name, &off)) == 0){ 18607090dd7Srsc iunlockput(dp); 187eaea18cbSrsc return -1; 188eaea18cbSrsc } 18907090dd7Srsc ilock(ip); 190eaea18cbSrsc 191eaea18cbSrsc if(ip->nlink < 1) 192eaea18cbSrsc panic("unlink: nlink < 1"); 193eaea18cbSrsc if(ip->type == T_DIR && !isdirempty(ip)){ 19407090dd7Srsc iunlockput(ip); 19507090dd7Srsc iunlockput(dp); 196eaea18cbSrsc return -1; 197eaea18cbSrsc } 198eaea18cbSrsc 199eaea18cbSrsc memset(&de, 0, sizeof(de)); 200eaea18cbSrsc if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de)) 201eaea18cbSrsc panic("unlink: writei"); 20207090dd7Srsc iunlockput(dp); 203eaea18cbSrsc 204eaea18cbSrsc ip->nlink--; 205eaea18cbSrsc iupdate(ip); 20607090dd7Srsc iunlockput(ip); 207eaea18cbSrsc return 0; 208eaea18cbSrsc } 209eaea18cbSrsc 210eaea18cbSrsc static struct inode* 211e79b1659Srsc create(char *path, int canexist, short type, short major, short minor) 212eaea18cbSrsc { 213eaea18cbSrsc uint off; 214eaea18cbSrsc struct inode *ip, *dp; 215eaea18cbSrsc char name[DIRSIZ]; 216eaea18cbSrsc 21707090dd7Srsc if((dp = nameiparent(path, name)) == 0) 218eaea18cbSrsc return 0; 21907090dd7Srsc ilock(dp); 220eaea18cbSrsc 22107090dd7Srsc if(canexist && (ip = dirlookup(dp, name, &off)) != 0){ 22207090dd7Srsc iunlockput(dp); 22307090dd7Srsc ilock(ip); 224eaea18cbSrsc if(ip->type != type || ip->major != major || ip->minor != minor){ 22507090dd7Srsc iunlockput(ip); 226eaea18cbSrsc return 0; 227eaea18cbSrsc } 228eaea18cbSrsc return ip; 229eaea18cbSrsc } 230eaea18cbSrsc 23107090dd7Srsc if((ip = ialloc(dp->dev, type)) == 0){ 23207090dd7Srsc iunlockput(dp); 233eaea18cbSrsc return 0; 234eaea18cbSrsc } 23507090dd7Srsc ilock(ip); 236eaea18cbSrsc ip->major = major; 237eaea18cbSrsc ip->minor = minor; 238603deefcSrsc ip->nlink = 1; 239eaea18cbSrsc iupdate(ip); 240eaea18cbSrsc 241eaea18cbSrsc if(dirlink(dp, name, ip->inum) < 0){ 242eaea18cbSrsc ip->nlink = 0; 24307090dd7Srsc iunlockput(ip); 24407090dd7Srsc iunlockput(dp); 245eaea18cbSrsc return 0; 246eaea18cbSrsc } 247eaea18cbSrsc 248eaea18cbSrsc if(type == T_DIR){ // Create . and .. entries. 249eaea18cbSrsc dp->nlink++; // for ".." 250eaea18cbSrsc iupdate(dp); 251eaea18cbSrsc // No ip->nlink++ for ".": avoid cyclic ref count. 252eaea18cbSrsc if(dirlink(ip, ".", ip->inum) < 0 || dirlink(ip, "..", dp->inum) < 0) 253e79b1659Srsc panic("create dots"); 254eaea18cbSrsc } 25507090dd7Srsc iunlockput(dp); 256eaea18cbSrsc return ip; 257eaea18cbSrsc } 258eaea18cbSrsc 2592685309fSrsc int 2602685309fSrsc sys_open(void) 2612685309fSrsc { 262f32f3638Srsc char *path; 263f32f3638Srsc int fd, omode; 264224f6598Srsc struct file *f; 265f32f3638Srsc struct inode *ip; 2662685309fSrsc 267224f6598Srsc if(argstr(0, &path) < 0 || argint(1, &omode) < 0) 2682685309fSrsc return -1; 2692685309fSrsc 270eaea18cbSrsc if(omode & O_CREATE){ 271e79b1659Srsc if((ip = create(path, 1, T_FILE, 0, 0)) == 0) 272e2a620daSrsc return -1; 273eaea18cbSrsc }else{ 27407090dd7Srsc if((ip = namei(path)) == 0) 275eaea18cbSrsc return -1; 27607090dd7Srsc ilock(ip); 277f32f3638Srsc if(ip->type == T_DIR && (omode & (O_RDWR|O_WRONLY))){ 27807090dd7Srsc iunlockput(ip); 2792685309fSrsc return -1; 2802685309fSrsc } 281eaea18cbSrsc } 2822685309fSrsc 283eaea18cbSrsc if((f = filealloc()) == 0 || (fd = fdalloc(f)) < 0){ 284eaea18cbSrsc if(f) 285224f6598Srsc fileclose(f); 28607090dd7Srsc iunlockput(ip); 2872685309fSrsc return -1; 2882685309fSrsc } 28907090dd7Srsc iunlock(ip); 2902685309fSrsc 291eaea18cbSrsc f->type = FD_INODE; 29207090dd7Srsc f->ip = ip; 293eaea18cbSrsc f->off = 0; 294e79b1659Srsc f->readable = !(omode & O_WRONLY); 295e79b1659Srsc f->writable = (omode & O_WRONLY) || (omode & O_RDWR); 2962685309fSrsc 297224f6598Srsc return fd; 2982685309fSrsc } 2992685309fSrsc 3002685309fSrsc int 3012685309fSrsc sys_mknod(void) 3022685309fSrsc { 303eaea18cbSrsc struct inode *ip; 304224f6598Srsc char *path; 305224f6598Srsc int len; 306aa6824abSrsc int major, minor; 3072685309fSrsc 30807090dd7Srsc if((len=argstr(0, &path)) < 0 || 30907090dd7Srsc argint(1, &major) < 0 || 31007090dd7Srsc argint(2, &minor) < 0 || 311e79b1659Srsc (ip = create(path, 0, T_DEV, major, minor)) == 0) 3122685309fSrsc return -1; 31307090dd7Srsc iunlockput(ip); 314224f6598Srsc return 0; 3152685309fSrsc } 3162685309fSrsc 3172685309fSrsc int 3182685309fSrsc sys_mkdir(void) 3192685309fSrsc { 320f32f3638Srsc char *path; 321eaea18cbSrsc struct inode *ip; 3222685309fSrsc 323e79b1659Srsc if(argstr(0, &path) < 0 || (ip = create(path, 0, T_DIR, 0, 0)) == 0) 3242685309fSrsc return -1; 32507090dd7Srsc iunlockput(ip); 326eaea18cbSrsc return 0; 3272685309fSrsc } 3282685309fSrsc 3292685309fSrsc int 3302685309fSrsc sys_chdir(void) 3312685309fSrsc { 332eaea18cbSrsc char *path; 3332685309fSrsc struct inode *ip; 3342685309fSrsc 33507090dd7Srsc if(argstr(0, &path) < 0 || (ip = namei(path)) == 0) 3362685309fSrsc return -1; 33707090dd7Srsc ilock(ip); 3382685309fSrsc if(ip->type != T_DIR) { 33907090dd7Srsc iunlockput(ip); 3402685309fSrsc return -1; 3412685309fSrsc } 34207090dd7Srsc iunlock(ip); 343eaea18cbSrsc iput(cp->cwd); 34407090dd7Srsc cp->cwd = ip; 3452685309fSrsc return 0; 3462685309fSrsc } 3472685309fSrsc 3482685309fSrsc int 3492685309fSrsc sys_exec(void) 3502685309fSrsc { 351eaea18cbSrsc char *path, *argv[20]; 352f32f3638Srsc int i; 353f32f3638Srsc uint uargv, uarg; 3542685309fSrsc 355f32f3638Srsc if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0) 3562685309fSrsc return -1; 357eaea18cbSrsc memset(argv, 0, sizeof(argv)); 3582685309fSrsc for(i=0;; i++){ 359eaea18cbSrsc if(i >= NELEM(argv)) 3602685309fSrsc return -1; 361f32f3638Srsc if(fetchint(cp, uargv+4*i, (int*)&uarg) < 0) 362f32f3638Srsc return -1; 363f32f3638Srsc if(uarg == 0){ 364f32f3638Srsc argv[i] = 0; 365f32f3638Srsc break; 3662685309fSrsc } 367f32f3638Srsc if(fetchstr(cp, uarg, &argv[i]) < 0) 368f32f3638Srsc return -1; 369f32f3638Srsc } 370f32f3638Srsc return exec(path, argv); 371f32f3638Srsc } 372f32f3638Srsc 373eaea18cbSrsc int 374eaea18cbSrsc sys_pipe(void) 375eaea18cbSrsc { 376eaea18cbSrsc int *fd; 377eaea18cbSrsc struct file *rf, *wf; 378eaea18cbSrsc int fd0, fd1; 379eaea18cbSrsc 380eaea18cbSrsc if(argptr(0, (void*)&fd, 2*sizeof(fd[0])) < 0) 381eaea18cbSrsc return -1; 382*7834cca6Srsc if(pipealloc(&rf, &wf) < 0) 383eaea18cbSrsc return -1; 384eaea18cbSrsc fd0 = -1; 385eaea18cbSrsc if((fd0 = fdalloc(rf)) < 0 || (fd1 = fdalloc(wf)) < 0){ 386eaea18cbSrsc if(fd0 >= 0) 387eaea18cbSrsc cp->ofile[fd0] = 0; 388eaea18cbSrsc fileclose(rf); 389eaea18cbSrsc fileclose(wf); 390eaea18cbSrsc return -1; 391eaea18cbSrsc } 392eaea18cbSrsc fd[0] = fd0; 393eaea18cbSrsc fd[1] = fd1; 394eaea18cbSrsc return 0; 395eaea18cbSrsc } 396