Implemented checksum verification on node creation.

git-svn-id: http://exfat.googlecode.com/svn/trunk@38 60bc1c72-a15a-11de-b98f-4500b42dc123

diff --git a/libexfat/node.c b/libexfat/node.c
index 95c0be6..67bd617 100644 (file)
--- a/libexfat/node.c
+++ b/libexfat/node.c
@@ -74,6 +74,8 @@ static int readdir(struct exfat* ef, const struct exfat_node* parent,
        const struct exfat_label* label;
        uint8_t continuations = 0;
        le16_t* namep = NULL;
+       uint16_t reference_checksum = 0;
+       uint16_t actual_checksum = 0;
 
        *node = NULL;
 
@@ -125,6 +127,8 @@ static int readdir(struct exfat* ef, const struct exfat_node* parent,
                                exfat_error("too few continuations (%hhu)", continuations);
                                return -EIO;
                        }
+                       reference_checksum = le16_to_cpu(file->checksum);
+                       actual_checksum = exfat_start_checksum(file);
                        *node = malloc(sizeof(struct exfat_node));
                        if (*node == NULL)
                        {
@@ -147,6 +151,7 @@ static int readdir(struct exfat* ef, const struct exfat_node* parent,
                                goto error;
                        }
                        file_info = (const struct exfat_file_info*) entry;
+                       actual_checksum = exfat_add_checksum(entry, actual_checksum);
                        (*node)->size = le64_to_cpu(file_info->size);
                        (*node)->start_cluster = le32_to_cpu(file_info->start_cluster);
                        if (file_info->flag == EXFAT_FLAG_CONTIGUOUS)
@@ -161,10 +166,20 @@ static int readdir(struct exfat* ef, const struct exfat_node* parent,
                                goto error;
                        }
                        file_name = (const struct exfat_file_name*) entry;
+                       actual_checksum = exfat_add_checksum(entry, actual_checksum);
+
                        memcpy(namep, file_name->name, EXFAT_ENAME_MAX * sizeof(le16_t));
                        namep += EXFAT_ENAME_MAX;
                        if (--continuations == 0)
+                       {
+                               if (actual_checksum != reference_checksum)
+                               {
+                                       exfat_error("invalid checksum (0x%hx != 0x%hx)",
+                                                       actual_checksum, reference_checksum);
+                                       return -EIO;
+                               }
                                return 0; /* entry completed */
+                       }
                        break;
 
                case EXFAT_ENTRY_UPCASE: