1 files changed, 134 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/libfat/fatchain.c b/contrib/syslinux-4.02/libfat/fatchain.c
new file mode 100644
index 0000000..9853a72
--- /dev/null
+++ b/contrib/syslinux-4.02/libfat/fatchain.c
@@ -0,0 +1,134 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
+ *
+ *   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, Inc., 53 Temple Place Ste 330,
+ *   Boston MA 02111-1307, USA; either version 2 of the License, or
+ *   (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * fatchain.c
+ *
+ * Follow a FAT chain
+ */
+
+#include "libfatint.h"
+#include "ulint.h"
+
+/*
+ * Convert a cluster number (or 0 for the root directory) to a
+ * sector number.  Return -1 on failure.
+ */
+libfat_sector_t libfat_clustertosector(const struct libfat_filesystem *fs,
+				       int32_t cluster)
+{
+    if (cluster == 0)
+	cluster = fs->rootcluster;
+
+    if (cluster == 0)
+	return fs->rootdir;
+    else if (cluster < 2 || cluster >= fs->endcluster)
+	return -1;
+    else
+	return fs->data + ((libfat_sector_t) (cluster - 2) << fs->clustshift);
+}
+
+/*
+ * Get the next sector of either the root directory or a FAT chain.
+ * Returns 0 on end of file and -1 on error.
+ */
+
+libfat_sector_t libfat_nextsector(struct libfat_filesystem * fs,
+				  libfat_sector_t s)
+{
+    int32_t cluster, nextcluster;
+    uint32_t fatoffset;
+    libfat_sector_t fatsect;
+    uint8_t *fsdata;
+    uint32_t clustmask = fs->clustsize - 1;
+    libfat_sector_t rs;
+
+    if (s < fs->data) {
+	if (s < fs->rootdir)
+	    return -1;
+
+	/* Root directory */
+	s++;
+	return (s < fs->data) ? s : 0;
+    }
+
+    rs = s - fs->data;
+
+    if (~rs & clustmask)
+	return s + 1;		/* Next sector in cluster */
+
+    cluster = 2 + (rs >> fs->clustshift);
+
+    if (cluster >= fs->endcluster)
+	return -1;
+
+    switch (fs->fat_type) {
+    case FAT12:
+	/* Get first byte */
+	fatoffset = cluster + (cluster >> 1);
+	fatsect = fs->fat + (fatoffset >> LIBFAT_SECTOR_SHIFT);
+	fsdata = libfat_get_sector(fs, fatsect);
+	if (!fsdata)
+	    return -1;
+	nextcluster = fsdata[fatoffset & LIBFAT_SECTOR_MASK];
+
+	/* Get second byte */
+	fatoffset++;
+	fatsect = fs->fat + (fatoffset >> LIBFAT_SECTOR_SHIFT);
+	fsdata = libfat_get_sector(fs, fatsect);
+	if (!fsdata)
+	    return -1;
+	nextcluster |= fsdata[fatoffset & LIBFAT_SECTOR_MASK] << 8;
+
+	/* Extract the FAT entry */
+	if (cluster & 1)
+	    nextcluster >>= 4;
+	else
+	    nextcluster &= 0x0FFF;
+
+	if (nextcluster >= 0x0FF8)
+	    return 0;
+	break;
+
+    case FAT16:
+	fatoffset = cluster << 1;
+	fatsect = fs->fat + (fatoffset >> LIBFAT_SECTOR_SHIFT);
+	fsdata = libfat_get_sector(fs, fatsect);
+	if (!fsdata)
+	    return -1;
+	nextcluster =
+	    read16((le16_t *) & fsdata[fatoffset & LIBFAT_SECTOR_MASK]);
+
+	if (nextcluster >= 0x0FFF8)
+	    return 0;
+	break;
+
+    case FAT28:
+	fatoffset = cluster << 2;
+	fatsect = fs->fat + (fatoffset >> LIBFAT_SECTOR_SHIFT);
+	fsdata = libfat_get_sector(fs, fatsect);
+	if (!fsdata)
+	    return -1;
+	nextcluster =
+	    read32((le32_t *) & fsdata[fatoffset & LIBFAT_SECTOR_MASK]);
+	nextcluster &= 0x0FFFFFFF;
+
+	if (nextcluster >= 0x0FFFFFF8)
+	    return 0;
+	break;
+
+    default:
+	return -1;		/* WTF? */
+    }
+
+    return libfat_clustertosector(fs, nextcluster);
+}