2011-03-15 Joel Sherrill <joel.sherrill@oarcorp.com>

	* libfs/src/dosfs/msdos_format.c: Address Coverity issue 183 which was
	where an expression evaluated to a constant and issue 185 which was a
	potential (although unlikely in expected usage) time-of-check,
	time-of-use race condition.

1 files changed, 16 insertions, 19 deletions

diff --git a/cpukit/libfs/src/dosfs/msdos_format.c b/cpukit/libfs/src/dosfs/msdos_format.c
index 71cd137f7e..1394f811c4 100644
--- a/cpukit/libfs/src/dosfs/msdos_format.c
+++ b/cpukit/libfs/src/dosfs/msdos_format.c
@@ -896,21 +896,29 @@ int msdos_format
   int                  i;
   msdos_format_param_t fmt_params;
 
-  msdos_format_printf (rqdata, MSDOS_FMT_INFO_LEVEL_INFO,
-                       "formating: %s\n", devname);
+  /*
+   * open device for writing
+   */
+  msdos_format_printf (rqdata, MSDOS_FMT_INFO_LEVEL_DETAIL, "open device\n");
+  fd = open(devname, O_RDWR);
+  if (fd == -1) {
+    ret_val= -1;
+  }
+
   /*
    * sanity check on device
    */
   msdos_format_printf (rqdata, MSDOS_FMT_INFO_LEVEL_DETAIL,
                        "stat check: %s\n", devname);
   if (ret_val == 0) {
-    rc = stat(devname, &stat_buf);
+    rc = fstat(fd, &stat_buf);
     ret_val = rc;
   }
 
+  msdos_format_printf (rqdata, MSDOS_FMT_INFO_LEVEL_INFO,
+                       "formating: %s\n", devname);
   /* rtems feature: no block devices, all are character devices */
-  if ((ret_val == 0) &&
-      (!S_ISBLK(stat_buf.st_mode))) {
+  if ((ret_val == 0) && (!S_ISBLK(stat_buf.st_mode))) {
     errno = ENOTTY;
     ret_val = -1;
   }
@@ -925,19 +933,6 @@ int msdos_format
   }
 
   /*
-   * open device for writing
-   */
-  if (ret_val == 0) {
-    msdos_format_printf (rqdata, MSDOS_FMT_INFO_LEVEL_DETAIL,
-                         "open device\n");
-    fd = open(devname, O_RDWR);
-    if (fd == -1)
-    {
-      ret_val= -1;
-    }
-  }
-
-  /*
    * compute formatting parameters
    */
   if (ret_val == 0) {
@@ -957,6 +952,7 @@ int msdos_format
        fmt_params.bytes_per_sector,
        0xe5);
   }
+
   /*
    * create master boot record
    */
@@ -1080,7 +1076,8 @@ int msdos_format
 
     case FAT_FAT16:
       /* FAT entry 0: 0xff00|media_type */
-      FAT_SET_VAL16(tmp_sec,0,0xff00|fmt_params.media_code);
+      FAT_SET_VAL8(tmp_sec,0,fmt_params.media_code);
+      FAT_SET_VAL8(tmp_sec,1,0xff);
       /* FAT entry 1: EOC */
       FAT_SET_VAL16(tmp_sec,2,FAT_FAT16_EOC);
       break;