fs: fat: handle deleted directory entries correctly
[oweals/u-boot.git] / fs / fat / fat.c
index 73ffdeae63ebb123bf206151ed6c7e27650222e1..68ce658386780af4494ff309c4cd0136080484b3 100644 (file)
@@ -145,7 +145,8 @@ static void get_name(dir_entry *dirent, char *s_name)
 }
 
 static int flush_dirty_fat_buffer(fsdata *mydata);
-#if !defined(CONFIG_FAT_WRITE)
+
+#if !CONFIG_IS_ENABLED(FAT_WRITE)
 /* Stub for read only operation */
 int flush_dirty_fat_buffer(fsdata *mydata)
 {
@@ -260,7 +261,7 @@ get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size)
        if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
                ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 
-               printf("FAT: Misaligned buffer address (%p)\n", buffer);
+               debug("FAT: Misaligned buffer address (%p)\n", buffer);
 
                while (size >= mydata->sect_size) {
                        ret = disk_read(startsect++, 1, tmpbuf);
@@ -300,14 +301,21 @@ 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
  */
-__u8 get_contents_vfatname_block[MAX_CLUSTSIZE]
-       __aligned(ARCH_DMA_MINALIGN);
-
 static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
                        __u8 *buffer, loff_t maxsize, loff_t *gotsize)
 {
@@ -337,8 +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;
        }
@@ -350,15 +358,24 @@ static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
 
        /* align to beginning of next cluster if any */
        if (pos) {
+               __u8 *tmp_buffer;
+
                actsize = min(filesize, (loff_t)bytesperclust);
-               if (get_cluster(mydata, curclust, get_contents_vfatname_block,
-                               (int)actsize) != 0) {
+               tmp_buffer = malloc_cache_aligned(actsize);
+               if (!tmp_buffer) {
+                       debug("Error: allocating buffer\n");
+                       return -1;
+               }
+
+               if (get_cluster(mydata, curclust, tmp_buffer, actsize) != 0) {
                        printf("Error reading cluster\n");
+                       free(tmp_buffer);
                        return -1;
                }
                filesize -= actsize;
                actsize -= pos;
-               memcpy(buffer, get_contents_vfatname_block + pos, actsize);
+               memcpy(buffer, tmp_buffer + pos, actsize);
+               free(tmp_buffer);
                *gotsize += actsize;
                if (!filesize)
                        return 0;
@@ -367,8 +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;
                }
        }
 
@@ -383,8 +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;
@@ -411,7 +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;
@@ -571,6 +588,17 @@ static int get_fs_info(fsdata *mydata)
                                mydata->sect_size, cur_part_info.blksz);
                return -1;
        }
+       if (mydata->clust_size == 0) {
+               printf("Error: FAT cluster size not set\n");
+               return -1;
+       }
+       if ((unsigned int)mydata->clust_size * mydata->sect_size >
+           MAX_CLUSTSIZE) {
+               printf("Error: FAT cluster size too big (cs=%u, max=%u)\n",
+                      (unsigned int)mydata->clust_size * mydata->sect_size,
+                      MAX_CLUSTSIZE);
+               return -1;
+       }
 
        if (mydata->fatsize == 32) {
                mydata->data_begin = mydata->rootdir_sect -
@@ -584,8 +612,13 @@ static int get_fs_info(fsdata *mydata)
                mydata->data_begin = mydata->rootdir_sect +
                                        mydata->rootdir_size -
                                        (mydata->clust_size * 2);
-               mydata->root_cluster =
-                       sect_to_clust(mydata, mydata->rootdir_sect);
+
+               /*
+                * The root directory is not cluster-aligned and may be on a
+                * "negative" cluster, this will be handled specially in
+                * next_cluster().
+                */
+               mydata->root_cluster = 0;
        }
 
        mydata->fatbufnum = -1;
@@ -715,20 +748,38 @@ static void fat_itr_child(fat_itr *itr, fat_itr *parent)
        itr->last_cluster = 0;
 }
 
-static void *next_cluster(fat_itr *itr)
+static void *next_cluster(fat_itr *itr, unsigned *nbytes)
 {
        fsdata *mydata = itr->fsdata;  /* for silly macros */
        int ret;
        u32 sect;
+       u32 read_size;
 
        /* have we reached the end? */
        if (itr->last_cluster)
                return NULL;
 
-       sect = clust_to_sect(itr->fsdata, itr->next_clust);
+       if (itr->is_root && itr->fsdata->fatsize != 32) {
+               /*
+                * The root directory is located before the data area and
+                * cannot be indexed using the regular unsigned cluster
+                * numbers (it may start at a "negative" cluster or not at a
+                * cluster boundary at all), so consider itr->next_clust to be
+                * a offset in cluster-sized units from the start of rootdir.
+                */
+               unsigned sect_offset = itr->next_clust * itr->fsdata->clust_size;
+               unsigned remaining_sects = itr->fsdata->rootdir_size - sect_offset;
+               sect = itr->fsdata->rootdir_sect + sect_offset;
+               /* do not read past the end of rootdir */
+               read_size = min_t(u32, itr->fsdata->clust_size,
+                                 remaining_sects);
+       } else {
+               sect = clust_to_sect(itr->fsdata, itr->next_clust);
+               read_size = itr->fsdata->clust_size;
+       }
 
-       debug("FAT read(sect=%d), clust_size=%d, DIRENTSPERBLOCK=%zd\n",
-             sect, itr->fsdata->clust_size, DIRENTSPERBLOCK);
+       debug("FAT read(sect=%d), clust_size=%d, read_size=%u, DIRENTSPERBLOCK=%zd\n",
+             sect, itr->fsdata->clust_size, read_size, DIRENTSPERBLOCK);
 
        /*
         * NOTE: do_fat_read_at() had complicated logic to deal w/
@@ -739,18 +790,17 @@ static void *next_cluster(fat_itr *itr)
         * dent at a time and iteratively constructing the vfat long
         * name.
         */
-       ret = disk_read(sect, itr->fsdata->clust_size,
-                       itr->block);
+       ret = disk_read(sect, read_size, itr->block);
        if (ret < 0) {
                debug("Error: reading block\n");
                return NULL;
        }
 
+       *nbytes = read_size * itr->fsdata->sect_size;
        itr->clust = itr->next_clust;
        if (itr->is_root && itr->fsdata->fatsize != 32) {
                itr->next_clust++;
-               sect = clust_to_sect(itr->fsdata, itr->next_clust);
-               if (sect - itr->fsdata->rootdir_sect >=
+               if (itr->next_clust * itr->fsdata->clust_size >=
                    itr->fsdata->rootdir_size) {
                        debug("nextclust: 0x%x\n", itr->next_clust);
                        itr->last_cluster = 1;
@@ -769,9 +819,8 @@ static void *next_cluster(fat_itr *itr)
 static dir_entry *next_dent(fat_itr *itr)
 {
        if (itr->remaining == 0) {
-               struct dir_entry *dent = next_cluster(itr);
-               unsigned nbytes = itr->fsdata->sect_size *
-                       itr->fsdata->clust_size;
+               unsigned nbytes;
+               struct dir_entry *dent = next_cluster(itr, &nbytes);
 
                /* have we reached the last cluster? */
                if (!dent) {
@@ -807,6 +856,9 @@ static dir_entry *extract_vfat_name(fat_itr *itr)
 
                slot2str((dir_slot *)dent, buf, &idx);
 
+               if (n + idx >= sizeof(itr->l_name))
+                       return NULL;
+
                /* shift accumulated long-name up and copy new part in: */
                memmove(itr->l_name + idx, itr->l_name, n);
                memcpy(itr->l_name, buf, idx);
@@ -817,6 +869,14 @@ static dir_entry *extract_vfat_name(fat_itr *itr)
                        return NULL;
        }
 
+       /*
+        * We are now at the short file name entry.
+        * If it is marked as deleted, just skip it.
+        */
+       if (dent->name[0] == DELETED_FLAG ||
+           dent->name[0] == aRING)
+               return NULL;
+
        itr->l_name[n] = '\0';
 
        chksum = mkcksum(dent->name, dent->ext);
@@ -846,6 +906,16 @@ static int fat_itr_next(fat_itr *itr)
 
        itr->name = NULL;
 
+       /*
+        * One logical directory entry consist of following slots:
+        *                              name[0] Attributes
+        *   dent[N - N]: LFN[N - 1]    N|0x40  ATTR_VFAT
+        *   ...
+        *   dent[N - 2]: LFN[1]        2       ATTR_VFAT
+        *   dent[N - 1]: LFN[0]        1       ATTR_VFAT
+        *   dent[N]:     SFN                   ATTR_ARCH
+        */
+
        while (1) {
                dent = next_dent(itr);
                if (!dent)
@@ -858,7 +928,17 @@ static int fat_itr_next(fat_itr *itr)
                if (dent->attr & ATTR_VOLUME) {
                        if ((dent->attr & ATTR_VFAT) == ATTR_VFAT &&
                            (dent->name[0] & LAST_LONG_ENTRY_MASK)) {
+                               /* long file name */
                                dent = extract_vfat_name(itr);
+                               /*
+                                * If succeeded, dent has a valid short file
+                                * name entry for the current entry.
+                                * If failed, itr points to a current bogus
+                                * entry. So after fetching a next one,
+                                * it may have a short file name entry
+                                * for this bogus entry so that we can still
+                                * check for a short name.
+                                */
                                if (!dent)
                                        continue;
                                itr->name = itr->l_name;
@@ -867,8 +947,11 @@ static int fat_itr_next(fat_itr *itr)
                                /* Volume label or VFAT entry, skip */
                                continue;
                        }
-               }
+               } else if (!(dent->attr & ATTR_ARCH) &&
+                          !(dent->attr & ATTR_DIR))
+                       continue;
 
+               /* short file name */
                break;
        }
 
@@ -1092,11 +1175,12 @@ int fat_size(const char *filename, loff_t *size)
                 * expected to fail if passed a directory path:
                 */
                free(fsdata.fatbuf);
-               fat_itr_root(itr, &fsdata);
-               if (!fat_itr_resolve(itr, filename, TYPE_DIR)) {
+               ret = fat_itr_root(itr, &fsdata);
+               if (ret)
+                       goto out_free_itr;
+               ret = fat_itr_resolve(itr, filename, TYPE_DIR);
+               if (!ret)
                        *size = 0;
-                       ret = 0;
-               }
                goto out_free_both;
        }
 
@@ -1127,7 +1211,11 @@ int file_fat_read_at(const char *filename, loff_t pos, void *buffer,
                goto out_free_both;
 
        debug("reading %s at pos %llu\n", filename, pos);
-       ret = get_contents(&fsdata, itr->dent, pos, buffer, maxsize, actread);
+
+       /* For saving default max clustersize memory allocated to malloc pool */
+       dir_entry *dentptr = itr->dent;
+
+       ret = get_contents(&fsdata, dentptr, pos, buffer, maxsize, actread);
 
 out_free_both:
        free(fsdata.fatbuf);