diff --git a/defs.h b/defs.h
index fb48700a633a87398fa0ba0b8231774293d1fea9..9babf92b9a102aa40dee42cd986643e24dc59543 100644
--- a/defs.h
+++ b/defs.h
@@ -16,7 +16,7 @@ struct jmpbuf;
void setupsegs(struct proc*);
struct proc* copyproc(struct proc*);
struct spinlock;
-uint growproc(int);
+int growproc(int);
void sleep(void*, struct spinlock*);
void wakeup(void*);
void scheduler(void);
@@ -43,10 +43,10 @@ int strncmp(const char*, const char*, uint);
// syscall.c
void syscall(void);
int fetchint(struct proc*, uint, int*);
-int fetchbyte(struct proc*, uint, char*);
-int fetcharg(int, void*);
-int checkstring(uint);
-int putint(struct proc*, uint, int);
+int fetchstr(struct proc*, uint, char**);
+int argint(int, int*);
+int argptr(int, char**, int);
+int argstr(int, char**);
// picirq.c
extern ushort irq_mask_8259A;
@@ -99,7 +99,6 @@ int pipe_read(struct pipe*, char*, int);
// file.c
struct stat;
void fileinit(void);
-int fdalloc(void);
struct file* filealloc(void);
void fileclose(struct file*);
int fileread(struct file*, char*, int n);
diff --git a/file.c b/file.c
index 29f07cc69e0be6205233f45f55dc65488573b2d7..4c314eca27890dfef9d4d5465359e59d340c6167 100644
--- a/file.c
+++ b/file.c
@@ -22,19 +22,7 @@ fileinit(void)
initlock(&fd_table_lock, "fd_table");
}
-// Allocate a file descriptor number for curproc.
-int
-fdalloc(void)
-{
- int fd;
- struct proc *p = curproc[cpu()];
- for(fd = 0; fd < NOFILE; fd++)
- if(p->ofile[fd] == 0)
- return fd;
- return -1;
-}
-
-// Allocate a file descriptor structure
+// Allocate a file structure
struct file*
filealloc(void)
{
diff --git a/syscall.c b/syscall.c
index ee22d09bf879e54061f44a926c617e266952af61..8f7350fa851dc47df27e9ab531f8c184dcf6723b 100644
--- a/syscall.c
+++ b/syscall.c
@@ -21,64 +21,71 @@
// library system call function. The saved user %esp points
// to a saved program counter, and then the first argument.
-// Fetch 32 bits from a user-supplied pointer.
-// Returns 0 if addr was OK, -1 if illegal.
+// Fetch the int at addr from process p.
int
fetchint(struct proc *p, uint addr, int *ip)
{
- *ip = 0;
-
- if(addr > p->sz - 4)
+ if(addr >= p->sz || addr+4 > p->sz)
return -1;
*ip = *(int*)(p->mem + addr);
return 0;
}
-// Fetch byte from a user-supplied pointer.
-// Returns 0 on success, -1 if pointer is illegal.
+// Fetch the nul-terminated string at addr from process p.
+// Doesn't actually copy the string - just sets *pp to point at it.
+// Returns length of string, not including nul.
int
-fetchbyte(struct proc *p, uint addr, char *c)
+fetchstr(struct proc *p, uint addr, char **pp)
{
+ char *cp, *ep;
+
if(addr >= p->sz)
return -1;
- *c = *(p->mem + addr);
- return 0;
+ *pp = p->mem + addr;
+ ep = p->mem + p->sz;
+ for(cp = *pp; cp < ep; cp++)
+ if(*cp == 0)
+ return cp - *pp;
+ return -1;
}
+// Fetch the argno'th word-sized system call argument as an integer.
int
-fetcharg(int argno, void *ip)
+argint(int argno, int *ip)
{
- uint esp;
+ struct proc *p = curproc[cpu()];
- esp = (uint) curproc[cpu()]->tf->esp;
- return fetchint(curproc[cpu()], esp + 4 + 4*argno, ip);
+ return fetchint(p, p->tf->esp + 4 + 4*argno, ip);
}
-// Check that an entire string is valid in user space.
-// Returns the length, not including null, or -1.
+// Fetch the nth word-sized system call argument as a pointer
+// to a block of memory of size n bytes. Check that the pointer
+// lies within the process address space.
int
-checkstring(uint s)
+argptr(int argno, char **pp, int size)
{
- char c;
- int len = 0;
-
- for(;;){
- if(fetchbyte(curproc[cpu()], s, &c) < 0)
- return -1;
- if(c == '\0')
- return len;
- len++;
- s++;
- }
+ int i;
+ struct proc *p = curproc[cpu()];
+
+ if(argint(argno, &i) < 0)
+ return -1;
+ if((uint)i >= p->sz || (uint)i+size >= p->sz)
+ return -1;
+ *pp = p->mem + i;
+ return 0;
}
+// Fetch the nth word-sized system call argument as a string pointer.
+// Check that the pointer is valid and the string is nul-terminated.
+// (There is no shared writable memory, so the string can't change
+// between this check and being used by the kernel.)
int
-putint(struct proc *p, uint addr, int x)
+argstr(int argno, char **pp)
{
- if(addr > p->sz - 4)
+ int addr;
+ if(argint(argno, &addr) < 0)
return -1;
- memmove(p->mem + addr, &x, 4);
- return 0;
+ return fetchstr(curproc[cpu()], addr, pp);
}
extern int sys_chdir(void);
diff --git a/syscall.h b/syscall.h
index a0279ae635e9c4bf18978d9a20869b4c72a3b242..c4e90ab8d81785b2694c17aa457d011691df6db9 100644
--- a/syscall.h
+++ b/syscall.h
@@ -1,3 +1,4 @@
+// System call numbers
#define SYS_fork 1
#define SYS_exit 2
#define SYS_wait 3
diff --git a/sysfile.c b/sysfile.c
index be09c43518ee48414ff499de48029407d4729825..912ca7fc8070f962c480265eab47aca40f9333f0 100644
--- a/sysfile.c
+++ b/sysfile.c
@@ -15,120 +15,117 @@
#include "file.h"
#include "fcntl.h"
-int
-sys_pipe(void)
+// Fetch the nth word-sized system call argument as a file descriptor
+// and return both the descriptor and the corresponding struct file.
+static int
+argfd(int argno, int *pfd, struct file **pf)
{
- struct file *rfd = 0, *wfd = 0;
- int f1 = -1, f2 = -1;
+ int fd;
+ struct file *f;
struct proc *p = curproc[cpu()];
- uint fdp;
-
- if(pipe_alloc(&rfd, &wfd) < 0)
- goto oops;
- if((f1 = fdalloc()) < 0)
- goto oops;
- p->ofile[f1] = rfd;
- if((f2 = fdalloc()) < 0)
- goto oops;
- 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;
+
+ if(argint(argno, &fd) < 0)
+ return -1;
+ if(fd < 0 || fd >= NOFILE || (f=p->ofile[fd]) == 0)
+ return -1;
+ if(pfd)
+ *pfd = fd;
+ if(pf)
+ *pf = f;
return 0;
+}
- oops:
- if(rfd)
- fileclose(rfd);
- if(wfd)
- fileclose(wfd);
- if(f1 >= 0)
- p->ofile[f1] = 0;
- if(f2 >= 0)
- p->ofile[f2] = 0;
+// Allocate a file descriptor for the given file.
+// Takes over file reference from caller on success.
+static int
+fdalloc(struct file *f)
+{
+ int fd;
+ struct proc *p = curproc[cpu()];
+ for(fd = 0; fd < NOFILE; fd++){
+ if(p->ofile[fd] == 0){
+ p->ofile[fd] = f;
+ return fd;
+ }
+ }
return -1;
}
int
-sys_write(void)
+sys_pipe(void)
{
- int fd, n, ret;
- uint addr;
+ int *fd;
+ struct file *rf = 0, *wf = 0;
+ int fd0, fd1;
struct proc *p = curproc[cpu()];
- if(fetcharg(0, &fd) < 0 ||
- fetcharg(1, &addr) < 0 ||
- fetcharg(2, &n) < 0)
- return -1;
- if(fd < 0 || fd >= NOFILE)
+ if(argptr(0, (void*)&fd, 2*sizeof fd[0]) < 0)
return -1;
- if(p->ofile[fd] == 0)
+ if(pipe_alloc(&rf, &wf) < 0)
return -1;
- if(addr + n > p->sz)
+ fd0 = -1;
+ if((fd0 = fdalloc(rf)) < 0 || (fd1 = fdalloc(wf)) < 0){
+ if(fd0 >= 0)
+ p->ofile[fd0] = 0;
+ fileclose(rf);
+ fileclose(wf);
return -1;
+ }
+ return 0;
+}
+
+int
+sys_write(void)
+{
+ struct file *f;
+ int n;
+ char *cp;
- ret = filewrite(p->ofile[fd], p->mem + addr, n);
- return ret;
+ if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &cp, n) < 0)
+ return -1;
+ return filewrite(f, cp, n);
}
int
sys_read(void)
{
- int fd, n, ret;
- uint addr;
- struct proc *p = curproc[cpu()];
+ struct file *f;
+ int n;
+ char *cp;
- if(fetcharg(0, &fd) < 0 ||
- fetcharg(1, &addr) < 0 ||
- fetcharg(2, &n) < 0)
- return -1;
- if(fd < 0 || fd >= NOFILE)
- return -1;
- if(p->ofile[fd] == 0)
+ if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &cp, n) < 0)
return -1;
- if(addr + n > p->sz)
- return -1;
- ret = fileread(p->ofile[fd], p->mem + addr, n);
- return ret;
+ return fileread(f, cp, n);
}
int
sys_close(void)
{
int fd;
- struct proc *p = curproc[cpu()];
-
- if(fetcharg(0, &fd) < 0)
- return -1;
- if(fd < 0 || fd >= NOFILE)
+ struct file *f;
+
+ if(argfd(0, &fd, &f) < 0)
return -1;
- if(p->ofile[fd] == 0)
- return -1;
- fileclose(p->ofile[fd]);
- p->ofile[fd] = 0;
+ curproc[cpu()]->ofile[fd] = 0;
+ fileclose(f);
return 0;
}
int
sys_open(void)
{
- struct proc *cp = curproc[cpu()];
struct inode *ip, *dp;
- uint arg0, arg1;
- int ufd;
- struct file *fd;
- int l;
+ char *path;
+ int omode;
+ int fd;
+ struct file *f;
char *last;
- if(fetcharg(0, &arg0) < 0 || fetcharg(1, &arg1) < 0)
- return -1;
- if((l = checkstring(arg0)) < 0)
+ if(argstr(0, &path) < 0 || argint(1, &omode) < 0)
return -1;
- if(arg1 & O_CREATE){
- dp = namei(cp->mem + arg0, NAMEI_CREATE, 0, &last, &ip);
+ if(omode & O_CREATE){
+ dp = namei(path, NAMEI_CREATE, 0, &last, &ip);
if(dp){
ip = mknod1(dp, last, T_FILE, 0, 0);
iput(dp);
@@ -141,86 +138,77 @@ sys_open(void)
return -1;
}
} else {
- ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0, 0, 0);
+ ip = namei(path, NAMEI_LOOKUP, 0, 0, 0);
if(ip == 0)
return -1;
}
- if(ip->type == T_DIR && ((arg1 & O_RDWR) || (arg1 & O_WRONLY))){
+ if(ip->type == T_DIR && ((omode & O_RDWR) || (omode & O_WRONLY))){
iput(ip);
return -1;
}
- if((fd = filealloc()) == 0){
+ if((f = filealloc()) == 0){
iput(ip);
return -1;
}
- if((ufd = fdalloc()) < 0){
+ if((fd = fdalloc(f)) < 0){
iput(ip);
- fileclose(fd);
+ fileclose(f);
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;
+ f->type = FD_FILE;
+ if(omode & O_RDWR) {
+ f->readable = 1;
+ f->writable = 1;
+ } else if(omode & O_WRONLY) {
+ f->readable = 0;
+ f->writable = 1;
} else {
- fd->readable = 1;
- fd->writable = 0;
+ f->readable = 1;
+ f->writable = 0;
}
- fd->ip = ip;
- fd->off = 0;
- cp->ofile[ufd] = fd;
+ f->ip = ip;
+ f->off = 0;
- return ufd;
+ return fd;
}
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)
+ char *path;
+ int len;
+ int type, major, minor;
+
+ if((len=argstr(0, &path)) < 0 || argint(1, &type) < 0 ||
+ argint(2, &major) < 0 || argint(3, &minor) < 0)
return -1;
- if((l = checkstring(arg0)) < 0)
+ if(len >= DIRSIZ)
return -1;
- if(l >= DIRSIZ)
+ if((nip = mknod(path, type, major, minor)) == 0)
return -1;
-
- nip = mknod(cp->mem + arg0, (short) arg1, (short) arg2, (short) arg3);
- if(nip)
- iput(nip);
- return (nip == 0) ? -1 : 0;
+ iput(nip);
+ return 0;
}
int
sys_mkdir(void)
{
- struct proc *cp = curproc[cpu()];
struct inode *nip;
struct inode *dp;
- uint arg0;
- int l;
+ char *path;
struct dirent de;
char *last;
- if(fetcharg(0, &arg0) < 0)
- return -1;
-
- if((l = checkstring(arg0)) < 0)
+ if(argstr(0, &path) < 0)
return -1;
- dp = namei(cp->mem + arg0, NAMEI_CREATE, 0, &last, 0);
+ dp = namei(path, NAMEI_CREATE, 0, &last, 0);
if(dp == 0)
return -1;
@@ -248,25 +236,20 @@ sys_mkdir(void)
return 0;
}
-
int
sys_chdir(void)
{
- struct proc *cp = curproc[cpu()];
+ struct proc *p = curproc[cpu()];
struct inode *ip;
- uint arg0;
- int l;
-
- if(fetcharg(0, &arg0) < 0)
- return -1;
+ char *path;
- if((l = checkstring(arg0)) < 0)
+ if(argstr(0, &path) < 0)
return -1;
- if((ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0, 0, 0)) == 0)
+ if((ip = namei(path, NAMEI_LOOKUP, 0, 0, 0)) == 0)
return -1;
- if(ip == cp->cwd) {
+ if(ip == p->cwd) {
iput(ip);
return 0;
}
@@ -276,100 +259,74 @@ sys_chdir(void)
return -1;
}
- idecref(cp->cwd);
- cp->cwd = ip;
- iunlock(cp->cwd);
+ idecref(p->cwd);
+ p->cwd = ip;
+ iunlock(p->cwd);
return 0;
}
int
sys_unlink(void)
{
- struct proc *cp = curproc[cpu()];
- uint arg0;
- int r;
-
- if(fetcharg(0, &arg0) < 0)
+ char *path;
+
+ if(argstr(0, &path) < 0)
return -1;
- if(checkstring(arg0) < 0)
- return -1;
- r = unlink(cp->mem + arg0);
- return r;
+ return unlink(path);
}
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;
- if(cp->ofile[fd] == 0)
- return -1;
- if(addr + sizeof(struct stat) > cp->sz)
+ struct file *f;
+ struct stat *st;
+
+ if(argfd(0, 0, &f) < 0 || argptr(1, (void*)&st, sizeof *st) < 0)
return -1;
- r = filestat(cp->ofile[fd], (struct stat*)(cp->mem + addr));
- return r;
+ return filestat(f, st);
}
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;
- if(cp->ofile[fd] == 0)
+ struct file *f;
+ int fd;
+
+ if(argfd(0, 0, &f) < 0)
return -1;
- if((ufd1 = fdalloc()) < 0)
+ if((fd=fdalloc(f)) < 0)
return -1;
- cp->ofile[ufd1] = cp->ofile[fd];
- fileincref(cp->ofile[ufd1]);
- return ufd1;
+ fileincref(f);
+ return fd;
}
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)
+ char *old, *new;
+
+ if(argstr(0, &old) < 0 || argstr(1, &new) < 0)
return -1;
- r = link(cp->mem + name1, cp->mem + name2);
- return r;
+ return link(old, new);
}
int
sys_exec(void)
{
struct proc *cp = curproc[cpu()];
- uint arg0, arg1, sz=0, ap, sp, p1, p2;
+ uint 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)
+ char *path, *s;
+ uint argv;
+
+ if(argstr(0, &path) < 0 || argint(1, (int*)&argv) < 0)
return -1;
- if(checkstring(arg0) < 0)
- return -1;
- ip = namei(cp->mem + arg0, NAMEI_LOOKUP, 0, 0, 0);
+
+ ip = namei(path, NAMEI_LOOKUP, 0, 0, 0);
if(ip == 0)
return -1;
@@ -399,15 +356,14 @@ sys_exec(void)
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)
+ for(i = 0;; i++){
+ if(fetchint(cp, argv + 4*i, (int*)&ap) < 0)
goto bad;
if(ap == 0)
break;
- len = checkstring(ap);
+ len = fetchstr(cp, ap, &s);
if(len < 0)
goto bad;
nargs++;
@@ -432,9 +388,9 @@ sys_exec(void)
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);
+ fetchint(cp, argv + 4*i, (int*)&ap);
+ len = fetchstr(cp, ap, &s);
+ memmove(mem + p2, s, len + 1);
*(uint*)(mem + p1) = p2;
p1 += 4;
p2 += len + 1;
diff --git a/sysproc.c b/sysproc.c
index 43ee973f416374d6451766ba4e1ca53b1f2a2ac9..14b85c5d057fd3c2e68608d78fddf681c6113b0e 100644
--- a/sysproc.c
+++ b/sysproc.c
@@ -44,7 +44,7 @@ sys_kill(void)
{
int pid;
- if(fetcharg(0, &pid) < 0)
+ if(argint(0, &pid) < 0)
return -1;
return proc_kill(pid);
}
@@ -52,20 +52,19 @@ sys_kill(void)
int
sys_getpid(void)
{
- struct proc *cp = curproc[cpu()];
- return cp->pid;
+ return curproc[cpu()]->pid;
}
int
sys_sbrk(void)
{
- uint addr;
+ int addr;
int n;
struct proc *cp = curproc[cpu()];
- if(fetcharg(0, &n) < 0)
+ if(argint(0, &n) < 0)
return -1;
- if((addr = growproc(n)) == 0xffffffff)
+ if((addr = growproc(n)) < 0)
return -1;
setupsegs(cp);
return addr;