From 9d59eb015141697da616a4b98ac27cf4269cd780 Mon Sep 17 00:00:00 2001
From: Austin Clements <amdragon@mit.edu>
Date: Fri, 17 Feb 2012 23:20:13 -0500
Subject: [PATCH] Make fetchint and fetchstr use proc instead of taking a
 struct proc

Previously, these were inconsistent: they used their struct proc
argument for bounds checking, but always copied the argument from the
current address space (and hence the current process).  Drop the
struct proc argument and always use the current proc.

Suggested by Carmi Merimovich.
---
 defs.h    |  4 ++--
 syscall.c | 18 +++++++++---------
 sysfile.c |  4 ++--
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/defs.h b/defs.h
index efbbe3d..7f1e88d 100644
--- a/defs.h
+++ b/defs.h
@@ -142,8 +142,8 @@ char*           strncpy(char*, const char*, int);
 int             argint(int, int*);
 int             argptr(int, char**, int);
 int             argstr(int, char**);
-int             fetchint(struct proc*, uint, int*);
-int             fetchstr(struct proc*, uint, char**);
+int             fetchint(uint, int*);
+int             fetchstr(uint, char**);
 void            syscall(void);
 
 // timer.c
diff --git a/syscall.c b/syscall.c
index 0918da7..45f758e 100644
--- a/syscall.c
+++ b/syscall.c
@@ -13,28 +13,28 @@
 // library system call function. The saved user %esp points
 // to a saved program counter, and then the first argument.
 
-// Fetch the int at addr from process p.
+// Fetch the int at addr from the current process.
 int
-fetchint(struct proc *p, uint addr, int *ip)
+fetchint(uint addr, int *ip)
 {
-  if(addr >= p->sz || addr+4 > p->sz)
+  if(addr >= proc->sz || addr+4 > proc->sz)
     return -1;
   *ip = *(int*)(addr);
   return 0;
 }
 
-// Fetch the nul-terminated string at addr from process p.
+// Fetch the nul-terminated string at addr from the current process.
 // Doesn't actually copy the string - just sets *pp to point at it.
 // Returns length of string, not including nul.
 int
-fetchstr(struct proc *p, uint addr, char **pp)
+fetchstr(uint addr, char **pp)
 {
   char *s, *ep;
 
-  if(addr >= p->sz)
+  if(addr >= proc->sz)
     return -1;
   *pp = (char*)addr;
-  ep = (char*)p->sz;
+  ep = (char*)proc->sz;
   for(s = *pp; s < ep; s++)
     if(*s == 0)
       return s - *pp;
@@ -45,7 +45,7 @@ fetchstr(struct proc *p, uint addr, char **pp)
 int
 argint(int n, int *ip)
 {
-  return fetchint(proc, proc->tf->esp + 4 + 4*n, ip);
+  return fetchint(proc->tf->esp + 4 + 4*n, ip);
 }
 
 // Fetch the nth word-sized system call argument as a pointer
@@ -74,7 +74,7 @@ argstr(int n, char **pp)
   int addr;
   if(argint(n, &addr) < 0)
     return -1;
-  return fetchstr(proc, addr, pp);
+  return fetchstr(addr, pp);
 }
 
 extern int sys_chdir(void);
diff --git a/sysfile.c b/sysfile.c
index e6d08e8..64f2b33 100644
--- a/sysfile.c
+++ b/sysfile.c
@@ -388,13 +388,13 @@ sys_exec(void)
   for(i=0;; i++){
     if(i >= NELEM(argv))
       return -1;
-    if(fetchint(proc, uargv+4*i, (int*)&uarg) < 0)
+    if(fetchint(uargv+4*i, (int*)&uarg) < 0)
       return -1;
     if(uarg == 0){
       argv[i] = 0;
       break;
     }
-    if(fetchstr(proc, uarg, &argv[i]) < 0)
+    if(fetchstr(uarg, &argv[i]) < 0)
       return -1;
   }
   return exec(path, argv);