1 files changed, 117 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/libfat/open.c b/contrib/syslinux-4.02/libfat/open.c
new file mode 100644
index 0000000..7281e03
--- /dev/null
+++ b/contrib/syslinux-4.02/libfat/open.c
@@ -0,0 +1,117 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   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.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * open.c
+ *
+ * Open a FAT filesystem and compute some initial values; return NULL
+ * on failure.
+ */
+
+#include <stdlib.h>
+#include "libfatint.h"
+#include "ulint.h"
+
+struct libfat_filesystem *
+libfat_open(int (*readfunc) (intptr_t, void *, size_t, libfat_sector_t),
+	    intptr_t readptr)
+{
+    struct libfat_filesystem *fs = NULL;
+    struct fat_bootsect *bs;
+    int i;
+    uint32_t sectors, fatsize, minfatsize, rootdirsize;
+    uint32_t nclusters;
+
+    fs = malloc(sizeof(struct libfat_filesystem));
+    if (!fs)
+	goto barf;
+
+    fs->sectors = NULL;
+    fs->read = readfunc;
+    fs->readptr = readptr;
+
+    bs = libfat_get_sector(fs, 0);
+    if (!bs)
+	goto barf;
+
+    if (read16(&bs->bsBytesPerSec) != LIBFAT_SECTOR_SIZE)
+	goto barf;
+
+    for (i = 0; i <= 8; i++) {
+	if ((uint8_t) (1 << i) == read8(&bs->bsSecPerClust))
+	    break;
+    }
+    if (i > 8)
+	goto barf;
+    fs->clustsize = 1 << i;	/* Treat 0 as 2^8 = 64K */
+    fs->clustshift = i;
+
+    sectors = read16(&bs->bsSectors);
+    if (!sectors)
+	sectors = read32(&bs->bsHugeSectors);
+
+    fs->end = sectors;
+
+    fs->fat = read16(&bs->bsResSectors);
+    fatsize = read16(&bs->bsFATsecs);
+    if (!fatsize)
+	fatsize = read32(&bs->u.fat32.bpb_fatsz32);
+
+    fs->rootdir = fs->fat + fatsize * read8(&bs->bsFATs);
+
+    rootdirsize = ((read16(&bs->bsRootDirEnts) << 5) + LIBFAT_SECTOR_MASK)
+	>> LIBFAT_SECTOR_SHIFT;
+    fs->data = fs->rootdir + rootdirsize;
+
+    /* Sanity checking */
+    if (fs->data >= fs->end)
+	goto barf;
+
+    /* Figure out how many clusters */
+    nclusters = (fs->end - fs->data) >> fs->clustshift;
+    fs->endcluster = nclusters + 2;
+
+    if (nclusters <= 0xff4) {
+	fs->fat_type = FAT12;
+	minfatsize = fs->endcluster + (fs->endcluster >> 1);
+    } else if (nclusters <= 0xfff4) {
+	fs->fat_type = FAT16;
+	minfatsize = fs->endcluster << 1;
+    } else if (nclusters <= 0xffffff4) {
+	fs->fat_type = FAT28;
+	minfatsize = fs->endcluster << 2;
+    } else
+	goto barf;		/* Impossibly many clusters */
+
+    minfatsize = (minfatsize + LIBFAT_SECTOR_SIZE - 1) >> LIBFAT_SECTOR_SHIFT;
+
+    if (minfatsize > fatsize)
+	goto barf;		/* The FATs don't fit */
+
+    if (fs->fat_type == FAT28)
+	fs->rootcluster = read32(&bs->u.fat32.bpb_rootclus);
+    else
+	fs->rootcluster = 0;
+
+    return fs;			/* All good */
+
+barf:
+    if (fs)
+	free(fs);
+    return NULL;
+}
+
+void libfat_close(struct libfat_filesystem *fs)
+{
+    libfat_flush(fs);
+    free(fs);
+}