From b3bebfce8a790975ba941d346e6bcff1b5afecf9 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@swtch.com>
Date: Mon, 13 Jul 2009 09:34:45 -0700
Subject: [PATCH] exec tweaks
---
exec.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/exec.c b/exec.c
index 1c653de..3be3eed 100644
--- a/exec.c
+++ b/exec.c
@@ -16,19 +16,21 @@ exec(char *path, char **argv)
struct inode *ip;
struct proghdr ph;
+ mem = 0;
+ sz = 0;
+
if((ip = namei(path)) == 0)
return -1;
ilock(ip);
- // Compute memory size of new process.
- mem = 0;
- sz = 0;
-
- // Program segments.
+ // Check ELF header
if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
goto bad;
if(elf.magic != ELF_MAGIC)
goto bad;
+
+ // Compute memory size of new process.
+ // Program segments.
for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){
if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))
goto bad;
@@ -44,7 +46,10 @@ exec(char *path, char **argv)
for(argc=0; argv[argc]; argc++)
arglen += strlen(argv[argc]) + 1;
arglen = (arglen+3) & ~3;
- sz += arglen + 4*(argc+1);
+ sz += arglen;
+ sz += 4*(argc+1); // argv data
+ sz += 4; // argv
+ sz += 4; // argc
// Stack.
sz += PAGE;
--
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