fs: fat: treat invalid FAT clusters as errors

When hitting an invalid FAT cluster while reading a file always print an
error message and return an error code.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index 29cae8d3914761cdd965b3ec536b807510e39fa0..2a5300d5019f7e8346ee949df4e5bc2450977826 100644 (file)
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -301,10 +301,20 @@ get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size)
        return 0;
 }
 
-/*
+/**
+ * get_contents() - read from file
+ *
  * Read at most 'maxsize' bytes from 'pos' in the file associated with 'dentptr'
- * into 'buffer'.
- * Update the number of bytes read in *gotsize or return -1 on fatal errors.
+ * into 'buffer'. Update the number of bytes read in *gotsize or return -1 on
+ * fatal errors.
+ *
+ * @mydata:    file system description
+ * @dentprt:   directory entry pointer
+ * @pos:       position from where to read
+ * @buffer:    buffer into which to read
+ * @maxsize:   maximum number of bytes to read
+ * @gotsize:   number of bytes actually read
+ * Return:     -1 on error, otherwise 0
  */
 static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
                        __u8 *buffer, loff_t maxsize, loff_t *gotsize)
@@ -335,8 +345,8 @@ static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
                curclust = get_fatent(mydata, curclust);
                if (CHECK_CLUST(curclust, mydata->fatsize)) {
                        debug("curclust: 0x%x\n", curclust);
-                       debug("Invalid FAT entry\n");
-                       return 0;
+                       printf("Invalid FAT entry\n");
+                       return -1;
                }
                actsize += bytesperclust;
        }
@@ -374,8 +384,8 @@ static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
                curclust = get_fatent(mydata, curclust);
                if (CHECK_CLUST(curclust, mydata->fatsize)) {
                        debug("curclust: 0x%x\n", curclust);
-                       debug("Invalid FAT entry\n");
-                       return 0;
+                       printf("Invalid FAT entry\n");
+                       return -1;
                }
        }
 
@@ -390,8 +400,8 @@ static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
                                goto getit;
                        if (CHECK_CLUST(newclust, mydata->fatsize)) {
                                debug("curclust: 0x%x\n", newclust);
-                               debug("Invalid FAT entry\n");
-                               return 0;
+                               printf("Invalid FAT entry\n");
+                               return -1;
                        }
                        endclust = newclust;
                        actsize += bytesperclust;
@@ -418,7 +428,7 @@ getit:
                if (CHECK_CLUST(curclust, mydata->fatsize)) {
                        debug("curclust: 0x%x\n", curclust);
                        printf("Invalid FAT entry\n");
-                       return 0;
+                       return -1;
                }
                actsize = bytesperclust;
                endclust = curclust;