Re: MD5File and devices

[matthew patton <patton@netsec.net>]

Here is a proposed patch that seems to do what is needed with the minimum
of fuss. there's still the issue of directories and their returning a
constant value no matter what the path. By giving what appears to be a
valid MD5 hash IMO we're luring the user into a false sense of security.
Better to return EISDIR instead. The really important fix for the time
being though is the addition of the O_NONBLOCK flag to open(). I'm
surprised we didn't get bit by this sooner.


Also fixed a few "return 0;" where the return type is char* which as I'm
watching cvs log messages should be NULL's instead.

Index: mdXhl.c
===================================================================
RCS file: /cvs/src/lib/libc/md/mdXhl.c,v
retrieving revision 1.9
diff -u -p -r1.9 mdXhl.c
--- mdXhl.c     1999/08/17 09:13:12     1.9
+++ mdXhl.c     2000/01/17 19:14:52
@@ -16,6 +16,7 @@ static char rcsid[] = "$OpenBSD: mdXhl.c
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <sys/uio.h>
 #include <unistd.h>
 #include <mdX.h>
@@ -35,7 +36,7 @@ MDXEnd(ctx, buf)
        p = malloc(33);
     if (!p)
        return 0;
-    MDXFinal(digest,ctx);
+    MDXFinal(digest, ctx);
     for (i=0;i<16;i++) {
        p[i+i] = hex[digest[i] >> 4];
        p[i+i+1] = hex[digest[i] & 0x0f];
@@ -51,18 +52,26 @@ MDXFile (filename, buf)
 {
     unsigned char buffer[BUFSIZ];
     MDX_CTX ctx;
-    int f,i,j;
+    int f, i, j;
 
-    MDXInit(&ctx);
-    f = open(filename, O_RDONLY);
-    if (f < 0) return 0;
-    while ((i = read(f,buffer,sizeof buffer)) > 0) {
-       MDXUpdate(&ctx,buffer,i);
+    /* directories return a 'useless' constant value anyway,
+       might as well return NULL */
+    struct stat fsbuf;
+
+    if (stat(filename, &fsbuf) || (fsbuf.st_mode & S_IFDIR)) {
+       errno = EISDIR;
+       return NULL;
     }
+
+    MDXInit(&ctx);
+    if ((f = open(filename, O_RDONLY | O_NONBLOCK)) < 0)
+       return NULL;;
+    while ((i = read(f, buffer, sizeof buffer)) > 0)
+       MDXUpdate(&ctx, buffer, i);
     j = errno;
     close(f);
     errno = j;
-    if (i < 0) return 0;
+    if (i < 0) return NULL;
     return MDXEnd(&ctx, buf);
 }

-- 
Network Security Technologies Inc. - Commercial support for OpenBSD
www.netsec.net                            matthew.patton@netsec.net

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