Change fetchint, fetcharg, and putint to return -1 on error, 0 on success.

They had been returning 0 on error, 1 on success, but all the callers were checking for return value < 0.

Change fetchint, fetcharg, and putint to return -1 on error, 0 on success.
7f419a0d · rsc · 46bbd72f · 7f419a0d
--- a/syscall.c
+++ b/syscall.c
@@ -23,7 +23,7 @@ extern struct spinlock proc_table_lock;

 /*
 * fetch 32 bits from a user-supplied pointer.
- * returns 1 if addr was OK, 0 if illegal.
+ * returns 0 if addr was OK, -1 if illegal.
 */
 int
 fetchint(struct proc *p, unsigned addr, int *ip)
@@ -31,9 +31,9 @@ fetchint(struct proc *p, unsigned addr, int *ip)
  *ip = 0;

  if(addr > p->sz - 4)
-    return 0;
+    return -1;
  memcpy(ip, p->mem + addr, 4);
-  return 1;
+  return 0;
 }

 int
@@ -49,9 +49,9 @@ int
 putint(struct proc *p, unsigned addr, int ip)
 {
  if(addr > p->sz - 4)
-    return 0;
+    return -1;
  memcpy(p->mem + addr, &ip, 4);
-  return 1;
+  return 0;
 }

 int