1 files changed, 21 insertions, 25 deletions

diff --git a/kernel/syscall.c b/kernel/syscall.c
index c1b3670..ee94696 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -12,7 +12,7 @@ int
 fetchaddr(uint64 addr, uint64 *ip)
 {
   struct proc *p = myproc();
-  if(addr >= p->sz || addr+sizeof(uint64) > p->sz)
+  if(addr >= p->sz || addr+sizeof(uint64) > p->sz) // both tests needed, in case of overflow
     return -1;
   if(copyin(p->pagetable, (char *)ip, addr, sizeof(*ip)) != 0)
     return -1;
@@ -25,9 +25,8 @@ int
 fetchstr(uint64 addr, char *buf, int max)
 {
   struct proc *p = myproc();
-  int err = copyinstr(p->pagetable, buf, addr, max);
-  if(err < 0)
-    return err;
+  if(copyinstr(p->pagetable, buf, addr, max) < 0)
+    return -1;
   return strlen(buf);
 }
 
@@ -54,21 +53,19 @@ argraw(int n)
 }
 
 // Fetch the nth 32-bit system call argument.
-int
+void
 argint(int n, int *ip)
 {
   *ip = argraw(n);
-  return 0;
 }
 
 // Retrieve an argument as a pointer.
 // Doesn't check for legality, since
 // copyin/copyout will do that.
-int
+void
 argaddr(int n, uint64 *ip)
 {
   *ip = argraw(n);
-  return 0;
 }
 
 // Fetch the nth word-sized system call argument as a null-terminated string.
@@ -78,32 +75,31 @@ int
 argstr(int n, char *buf, int max)
 {
   uint64 addr;
-  if(argaddr(n, &addr) < 0)
-    return -1;
+  argaddr(n, &addr);
   return fetchstr(addr, buf, max);
 }
 
-extern uint64 sys_chdir(void);
-extern uint64 sys_close(void);
-extern uint64 sys_dup(void);
-extern uint64 sys_exec(void);
-extern uint64 sys_exit(void);
 extern uint64 sys_fork(void);
-extern uint64 sys_fstat(void);
-extern uint64 sys_getpid(void);
-extern uint64 sys_kill(void);
-extern uint64 sys_link(void);
-extern uint64 sys_mkdir(void);
-extern uint64 sys_mknod(void);
-extern uint64 sys_open(void);
+extern uint64 sys_exit(void);
+extern uint64 sys_wait(void);
 extern uint64 sys_pipe(void);
 extern uint64 sys_read(void);
+extern uint64 sys_kill(void);
+extern uint64 sys_exec(void);
+extern uint64 sys_fstat(void);
+extern uint64 sys_chdir(void);
+extern uint64 sys_dup(void);
+extern uint64 sys_getpid(void);
 extern uint64 sys_sbrk(void);
 extern uint64 sys_sleep(void);
-extern uint64 sys_unlink(void);
-extern uint64 sys_wait(void);
-extern uint64 sys_write(void);
 extern uint64 sys_uptime(void);
+extern uint64 sys_open(void);
+extern uint64 sys_write(void);
+extern uint64 sys_mknod(void);
+extern uint64 sys_unlink(void);
+extern uint64 sys_link(void);
+extern uint64 sys_mkdir(void);
+extern uint64 sys_close(void);
 
 static uint64 (*syscalls[])(void) = {
 [SYS_fork]    sys_fork,