From: Martin Mares <mj@ucw.cz>
Date: Tue, 27 Mar 2001 17:41:01 +0000 (+0000)
Subject: Mapping of zero-length files returns just a random non-zero address.
X-Git-Tag: holmes-import~1497
X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=271f4aa1f1334277cd5e052003fc795d4e3ebbc8;p=libucw.git

Mapping of zero-length files returns just a random non-zero address.

With this fix, empty indices are generated correctly.
---

diff --git a/lib/mmap.c b/lib/mmap.c
index e461e1ee..87a2047f 100644
--- a/lib/mmap.c
+++ b/lib/mmap.c
@@ -32,9 +32,14 @@ mmap_file(byte *name, unsigned *len, int writeable)
     {
       if (len)
 	*len = st.st_size;
-      x = mmap(NULL, st.st_size, writeable ? (PROT_READ | PROT_WRITE) : PROT_READ, MAP_SHARED, fd, 0);
-      if (x == MAP_FAILED)
-	x = NULL;
+      if (st.st_size)
+	{
+	  x = mmap(NULL, st.st_size, writeable ? (PROT_READ | PROT_WRITE) : PROT_READ, MAP_SHARED, fd, 0);
+	  if (x == MAP_FAILED)
+	    x = NULL;
+	}
+      else	/* For empty file, we can return any non-zero address */
+	return "";
     }
   close(fd);
   return x;