From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sat, 8 Apr 2006 18:34:47 +0000 (+0000)
Subject: Don't read anything from the disk for a segment with p_filesz == 0.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=68d3a93433f506864f6c6cec8af0f5f4538a4a40;p=pintos-anon

Don't read anything from the disk for a segment with p_filesz == 0.
Thanks to Godmar Back for reporting this bug.
---

diff --git a/src/userprog/process.c b/src/userprog/process.c
index a81ca59..8c410ab 100644
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -333,7 +333,9 @@ load_segment (struct file *file, const struct Elf32_Phdr *phdr)
     return false; 
 
   /* Load the segment page-by-page into memory. */
-  filesz_left = phdr->p_filesz + (phdr->p_vaddr & PGMASK);
+  filesz_left = phdr->p_filesz;
+  if (filesz_left > 0)
+    filesz_left += phdr->p_vaddr & PGMASK;
   file_seek (file, ROUND_DOWN (phdr->p_offset, PGSIZE));
   for (upage = start; upage < (uint8_t *) end; upage += PGSIZE) 
     {