opendev(3) tweak

[Marc Espie]

Already shown to a few people, but since pledge(2) aborts on non-dev, let's
check upfront that we're of the right type.

I don't think this requires a bump. It doesn't really change the interface,
just makes it stricter.

Index: opendev.3
===================================================================
RCS file: /build/data/openbsd/cvs/src/lib/libutil/opendev.3,v
retrieving revision 1.22
diff -u -p -r1.22 opendev.3
--- opendev.3   15 Jan 2015 19:06:32 -0000      1.22
+++ opendev.3   10 Mar 2016 11:51:27 -0000
@@ -93,7 +93,9 @@ it is modified to point at the fully exp
 The
 .Fn opendev
 return value and errors are the same as the return value and errors of
-.Xr open 2 .
+.Xr open 2 ,
+plus
+.Er EFTYPE .
 .Sh SEE ALSO
 .Xr open 2 ,
 .Xr getrawpartition 3 ,
Index: opendev.c
===================================================================
RCS file: /build/data/openbsd/cvs/src/lib/libutil/opendev.c,v
retrieving revision 1.15
diff -u -p -r1.15 opendev.c
--- opendev.c   30 Jun 2011 15:04:58 -0000      1.15
+++ opendev.c   8 Mar 2016 22:30:44 -0000
@@ -38,6 +38,7 @@
 #include <sys/limits.h>
 #include <sys/disk.h>
 #include <sys/dkio.h>
+#include <sys/stat.h>
 
 #include "util.h"
 
@@ -50,6 +51,7 @@ opendev(const char *path, int oflags, in
 {
        static char namebuf[PATH_MAX];
        struct dk_diskmap dm;
+       struct stat st;
        char *slash, *prefix;
        int fd;
 
@@ -106,5 +108,17 @@ opendev(const char *path, int oflags, in
        if (realpath)
                *realpath = namebuf;
 
+       if (fd != -1) {
+               if (fstat(fd, &st) == -1) {
+                       close(fd);
+                       return (-1);
+               }
+               if ((dflags & OPENDEV_BLCK) ? !S_ISBLK(st.st_mode) :
+                   !S_ISCHR(st.st_mode)) {
+                       close(fd);
+                       errno = EFTYPE;
+                       return (-1);
+               }
+       }
        return (fd);
 }