Add mkexfatfs (utility that creates an exFAT file system).

[android-x86/external-exfat.git] / mkfs / fat.c

diff --git a/mkfs/fat.c b/mkfs/fat.c
new file mode 100644 (file)
index 0000000..ecbe822
--- /dev/null
+++ b/mkfs/fat.c
@@ -0,0 +1,80 @@
+/*
+       fat.c (09.11.10)
+       File Allocation Table creation code.
+
+       Copyright (C) 2009, 2010  Andrew Nayenko
+
+       This program is free software: you can redistribute it and/or modify
+       it under the terms of the GNU General Public License as published by
+       the Free Software Foundation, either version 3 of the License, or
+       (at your option) any later version.
+
+       This program is distributed in the hope that it will be useful,
+       but WITHOUT ANY WARRANTY; without even the implied warranty of
+       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+       GNU General Public License for more details.
+
+       You should have received a copy of the GNU General Public License
+       along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <unistd.h>
+#include <inttypes.h>
+#include <errno.h>
+#include "mkexfat.h"
+#include "cbm.h"
+#include "uct.h"
+#include "rootdir.h"
+
+off_t fat_alignment(void)
+{
+       return (off_t) le32_to_cpu(sb.fat_block_start) * BLOCK_SIZE(sb);
+}
+
+off_t fat_size(void)
+{
+       return (off_t) le32_to_cpu(sb.cluster_count) * sizeof(cluster_t);
+}
+
+static cluster_t fat_write_entry(cluster_t cluster, cluster_t value, int fd)
+{
+       le32_t fat_entry = cpu_to_le32(value);
+       if (write(fd, &fat_entry, sizeof(fat_entry)) == -1)
+               return 0;
+       return cluster + 1;
+}
+
+static cluster_t fat_write_entries(cluster_t cluster, uint64_t length, int fd)
+{
+       cluster_t end = cluster + DIV_ROUND_UP(length, CLUSTER_SIZE(sb));
+
+       while (cluster < end - 1)
+       {
+               cluster = fat_write_entry(cluster, cluster + 1, fd);
+               if (cluster == 0)
+                       return 0;
+       }
+       return fat_write_entry(cluster, EXFAT_CLUSTER_END, fd);
+}
+
+int fat_write(off_t base, int fd)
+{
+       cluster_t c = 0;
+
+       if (base != le32_to_cpu(sb.fat_block_start) * BLOCK_SIZE(sb))
+               exfat_bug("unexpected FAT location: %"PRIu64" (expected %u)",
+                               base, le32_to_cpu(sb.fat_block_start) * BLOCK_SIZE(sb));
+
+       if (!(c = fat_write_entry(c, 0xfffffff8, fd))) /* media type */
+               return errno;
+       if (!(c = fat_write_entry(c, 0xffffffff, fd))) /* some weird constant */
+               return errno;
+       if (!(c = fat_write_entries(c, cbm_size(), fd)))
+               return errno;
+       if (!(c = fat_write_entries(c, uct_size(), fd)))
+               return errno;
+       if (!(c = fat_write_entries(c, rootdir_size(), fd)))
+               return errno;
+
+       return 0;
+}