Various cleanup:
- Got rid of dummy proc[0]. Now proc[0] is init. - Added initcode.S to exec /init, so that /init is just a regular binary. - Moved exec out of sysfile to exec.c - Moved code dealing with fs guts (like struct inode) from sysfile.c to fs.c. Code dealing with system call arguments stays in sysfile.c - Refactored directory routines in fs.c; should be simpler. - Changed iget to return *unlocked* inode structure. This solves the lookup-then-use race in namei without introducing deadlocks. It also enabled getting rid of the dummy proc[0].
This commit is contained in:
rsc
parent
2d61a40b20
commit
f32f3638f4
12 changed files with 456 additions and 415 deletions
221
sysfile.c
221
sysfile.c
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@ -114,42 +114,22 @@ sys_close(void)
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int
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sys_open(void)
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{
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struct inode *ip, *dp;
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char *path, *name;
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int namelen;
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int omode;
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int fd, dev;
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uint inum;
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char *path;
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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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if(argstr(0, &path) < 0 || argint(1, &omode) < 0)
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return -1;
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switch(omode & O_CREATE){
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default:
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case 0: // regular open
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if((ip = namei(path)) == 0)
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return -1;
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break;
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case O_CREATE:
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if((dp = nameiparent(path, &name, &namelen)) == 0)
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return -1;
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if(dirlookup(dp, name, namelen, 0, &inum) >= 0){
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dev = dp->dev;
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iput(dp);
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ip = iget(dev, inum);
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}else{
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if((ip = dircreat(dp, name, namelen, T_FILE, 0, 0)) == 0){
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iput(dp);
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return -1;
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}
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iput(dp);
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}
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break;
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}
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if(omode & O_CREATE)
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ip = create(path);
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else
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ip = namei(path);
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if(ip == 0)
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return -1;
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if(ip->type == T_DIR && (omode & (O_RDWR|O_WRONLY|O_CREATE))){
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if(ip->type == T_DIR && (omode & (O_RDWR|O_WRONLY))){
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iput(ip);
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return -1;
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}
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@ -194,6 +174,7 @@ sys_mknod(void)
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argint(2, &major) < 0 || argint(3, &minor) < 0)
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return -1;
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// XXX why this check?
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if(len >= DIRSIZ)
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return -1;
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@ -206,45 +187,11 @@ sys_mknod(void)
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int
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sys_mkdir(void)
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{
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struct inode *nip;
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struct inode *dp;
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char *name, *path;
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struct dirent de;
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int namelen;
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char *path;
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if(argstr(0, &path) < 0)
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return -1;
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dp = nameiparent(path, &name, &namelen);
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if(dp == 0)
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return -1;
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if(dirlookup(dp, name, namelen, 0, 0) >= 0){
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iput(dp);
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return -1;
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}
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nip = dircreat(dp, name, namelen, T_DIR, 0, 0);
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if(nip == 0){
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iput(dp);
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return -1;
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}
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dp->nlink++;
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iupdate(dp);
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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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de.inum = dp->inum;
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de.name[1] = '.';
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writei(nip, (char*) &de, sizeof(de), sizeof(de));
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iput(dp);
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iput(nip);
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return 0;
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return mkdir(path);
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}
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int
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@ -315,132 +262,30 @@ sys_link(void)
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return link(old, new);
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}
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#define ARGMAX 10
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int
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sys_exec(void)
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{
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uint 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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char *path, *s, *last;
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uint argv;
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if(argstr(0, &path) < 0 || argint(1, (int*)&argv) < 0)
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char *path, *argv[ARGMAX];
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int i;
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uint uargv, uarg;
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if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0)
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return -1;
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if((ip = namei(path)) == 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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nargs = 0;
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argbytes = 0;
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for(i = 0;; i++){
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if(fetchint(cp, argv + 4*i, (int*)&ap) < 0)
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goto bad;
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if(ap == 0)
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memset(argv, 0, sizeof argv);
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for(i=0;; i++){
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if(i >= ARGMAX)
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return -1;
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if(fetchint(cp, uargv+4*i, (int*)&uarg) < 0)
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return -1;
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if(uarg == 0){
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argv[i] = 0;
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break;
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len = fetchstr(cp, ap, &s);
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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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if(fetchstr(cp, uarg, &argv[i]) < 0)
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return -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, argv + 4*i, (int*)&ap);
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len = fetchstr(cp, ap, &s);
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memmove(mem + p2, s, 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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// Save name for debugging.
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for(last=s=path; *s; s++)
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if(*s == '/')
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last = s+1;
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safestrcpy(cp->name, last, sizeof cp->name);
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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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}
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iput(ip);
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cp->tf->eip = elf.entry;
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cp->tf->esp = sp;
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setupsegs(cp);
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return 0;
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bad:
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if(mem)
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kfree(mem, sz);
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iput(ip);
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return -1;
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bad2:
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iput(ip);
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proc_exit();
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return 0;
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return exec(path, argv);
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}
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