1 files changed, 135 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/com32/gpllib/disk/read.c b/contrib/syslinux-4.02/com32/gpllib/disk/read.c
new file mode 100644
index 0000000..7a6cc43
--- /dev/null
+++ b/contrib/syslinux-4.02/com32/gpllib/disk/read.c
@@ -0,0 +1,135 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2009 Pierre-Alexandre Meyer
+ *
+ *   Some parts borrowed from chain.c32:
+ *
+ *   Copyright 2003-2009 H. Peter Anvin - All Rights Reserved
+ *   Copyright 2009 Intel Corporation; author: H. Peter Anvin
+ *
+ *   This file is part of Syslinux, and is made available under
+ *   the terms of the GNU General Public License version 2.
+ *
+ * ----------------------------------------------------------------------- */
+
+#include <com32.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <disk/errno_disk.h>
+#include <disk/geom.h>
+#include <disk/read.h>
+#include <disk/util.h>
+#include <disk/common.h>
+
+/*
+ * TODO: implement file descriptors to cache metadata (geometry, ...)
+ */
+
+/**
+ * read_mbr - return a pointer to a malloced buffer containing the mbr
+ * @drive:	Drive number
+ * @buf:	Pre-allocated buffer for output
+ *
+ * Return the number of sectors read on success or -1 on failure.
+ * errno_disk contains the error number.
+ **/
+int read_mbr(int drive, void *buf)
+{
+    struct driveinfo drive_info;
+    drive_info.disk = drive;
+
+    /* MBR: lba = 0, 1 sector */
+    return read_sectors(&drive_info, buf, 0, 1);
+}
+
+/**
+ * dev_read - read from a drive
+ * @drive:	Drive number
+ * @buf:	Pre-allocated buffer for output
+ * @lba:	Position to start reading from
+ * @sectors:	Number of sectors to read
+ *
+ * High-level routine to read from a hard drive.
+ * Return the number of sectors read on success or -1 on failure.
+ * errno_disk contains the error number.
+ **/
+int dev_read(int drive, void *buf, unsigned int lba, int sectors)
+{
+    struct driveinfo drive_info;
+    drive_info.disk = drive;
+
+    return read_sectors(&drive_info, buf, lba, sectors);
+}
+
+/**
+ * read_sectors - read several sectors from disk
+ * @drive_info:		driveinfo struct describing the disk
+ * @data:		Pre-allocated buffer for output
+ * @lba:		Position to read
+ * @sectors:		Number of sectors to read
+ *
+ * Return the number of sectors read on success or -1 on failure.
+ * errno_disk contains the error number.
+ **/
+int read_sectors(struct driveinfo *drive_info, void *data,
+		 const unsigned int lba, const int sectors)
+{
+    com32sys_t inreg, outreg;
+    struct ebios_dapa *dapa = __com32.cs_bounce;
+    void *buf = (char *)__com32.cs_bounce + sectors * SECTOR;
+    char *bufp = data;
+
+    if (get_drive_parameters(drive_info) == -1)
+	return -1;
+
+    memset(&inreg, 0, sizeof inreg);
+
+    if (drive_info->ebios) {
+	dapa->len = sizeof(*dapa);
+	dapa->count = sectors;
+	dapa->off = OFFS(buf);
+	dapa->seg = SEG(buf);
+	dapa->lba = lba;
+
+	inreg.esi.w[0] = OFFS(dapa);
+	inreg.ds = SEG(dapa);
+	inreg.edx.b[0] = drive_info->disk;
+	inreg.eax.b[1] = 0x42;	/* Extended read */
+    } else {
+	unsigned int c, h, s;
+
+	if (!drive_info->cbios) {	// XXX errno
+	    /* We failed to get the geometry */
+	    if (lba)
+		return -1;	/* Can only read MBR */
+
+	    s = 1;
+	    h = 0;
+	    c = 0;
+	} else
+	    lba_to_chs(drive_info, lba, &s, &h, &c);
+
+	// XXX errno
+	if (s > 63 || h > 256 || c > 1023)
+	    return -1;
+
+	inreg.eax.w[0] = 0x0201;	/* Read one sector */
+	inreg.ecx.b[1] = c & 0xff;
+	inreg.ecx.b[0] = s + (c >> 6);
+	inreg.edx.b[1] = h;
+	inreg.edx.b[0] = drive_info->disk;
+	inreg.ebx.w[0] = OFFS(buf);
+	inreg.es = SEG(buf);
+    }
+
+    /* Perform the read */
+    if (int13_retry(&inreg, &outreg)) {
+	errno_disk = outreg.eax.b[1];
+	return -1;		/* Give up */
+    }
+
+    memcpy(bufp, buf, sectors * SECTOR);
+
+    return sectors;
+}