libblkid: Support for Atari partitioning scheme

Addresses: https://github.com/karelzak/util-linux/issues/517
Signed-off-by: Vaclav Dolezal <vdolezal@redhat.com>

4 files changed, 263 insertions, 1 deletions

diff --git a/libblkid/src/Makemodule.am b/libblkid/src/Makemodule.am
index 1046be100..0e1c765fb 100644
--- a/libblkid/src/Makemodule.am
+++ b/libblkid/src/Makemodule.am
@@ -29,6 +29,7 @@ libblkid_la_SOURCES = \
 	\
 	libblkid/src/partitions/aix.c \
 	libblkid/src/partitions/aix.h \
+	libblkid/src/partitions/atari.c \
 	libblkid/src/partitions/bsd.c \
 	libblkid/src/partitions/dos.c \
 	libblkid/src/partitions/gpt.c \
diff --git a/libblkid/src/partitions/atari.c b/libblkid/src/partitions/atari.c
new file mode 100644
index 000000000..eb3604088
--- /dev/null
+++ b/libblkid/src/partitions/atari.c
@@ -0,0 +1,259 @@
+/*
+ * atari partitions parsing code
+ *
+ * Copyright (C) 2018 Vaclav Dolezal <vdolezal@redhat.com>
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ *
+ * Based on Linux kernel implementation and atari-fdisk
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#include "partitions.h"
+
+struct atari_part_def {
+	/*
+	 * flags:
+	 * 0 (LSB): active
+	 * 1-6:     (reserved)
+	 * 7 (MSB): bootable
+	 */
+	unsigned char flags;
+	char id[3];
+	uint32_t start;
+	uint32_t size;
+} __attribute__((packed));
+
+struct atari_rootsector {
+	char unused0[0x156]; /* boot code */
+	struct atari_part_def icd_part[8]; /* ICD partition entries */
+	char unused1[0xc];
+	uint32_t hd_size;
+	struct atari_part_def part[4]; /* primary partition entries */
+	uint32_t bsl_start; /* bad sector list start */
+	uint32_t bsl_len; /* bad sector list length */
+	uint16_t checksum;
+} __attribute__((packed));
+
+
+/*
+ * Generated using linux kernel ctype.{c,h}
+ *
+ * Since kernel uses isalnum() to detect whether it is Atari PT, we need same
+ * definition of alnum character to be consistent with kernel.
+ */
+static const unsigned char _linux_isalnum[] = {
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,
+0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
+1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,
+0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
+1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
+1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,1,
+1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
+1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,1
+};
+
+static int linux_isalnum(unsigned char c) {
+	return _linux_isalnum[c];
+}
+
+#define isalnum linux_isalnum
+
+#define IS_ACTIVE(partdef) ((partdef).flags & 1)
+
+#define IS_PARTDEF_VALID(partdef) \
+	( \
+		(partdef).flags & 1 && \
+		isalnum((partdef).id[0]) && \
+		isalnum((partdef).id[1]) && \
+		isalnum((partdef).id[2]) \
+	)
+
+static int is_id_common(char *id)
+{
+	const char *ids[] = {"GEM", "BGM", "LNX", "SWP", "RAW", };
+	unsigned i;
+
+	for (i = 0; i < ARRAY_SIZE(ids); i++) {
+		if (!memcmp(ids[i], id, 3))
+			return 1;
+	}
+	return 0;
+}
+
+static int parse_partition(blkid_partlist ls, blkid_parttable tab,
+	struct atari_part_def *part, uint32_t offset)
+{
+	blkid_partition par;
+	uint32_t start;
+	uint32_t size;
+
+	start = be32_to_cpu(part->start) + offset;
+	size = be32_to_cpu(part->size);
+
+	par = blkid_partlist_add_partition(ls, tab, start, size);
+	if (!par)
+		return -ENOMEM;
+
+	blkid_partition_set_type_string(par, (unsigned char *) part->id,
+					sizeof(part->id));
+	return 1;
+}
+
+/*
+ * \return 1: OK, 0: bad format or -errno
+ */
+static int parse_extended(blkid_probe pr, blkid_partlist ls,
+	blkid_parttable tab, struct atari_part_def *part)
+{
+	uint32_t x0start, xstart;
+	unsigned i = 0;
+	int rc;
+
+	x0start = xstart = be32_to_cpu(part->start);
+	while (1) {
+		struct atari_rootsector *xrs;
+		xrs = (struct atari_rootsector *) blkid_probe_get_sector(pr, xstart);
+		if (!rs) {
+			if (errno)
+				return -errno;
+			return 0;
+		}
+
+		/*
+		 * There must be data partition followed by reference to next
+		 * XGM or inactive entry.
+		 */
+		for (i=0; ; i++) {
+			if (i >= ARRAY_SIZE(xrs->part) - 1)
+				return 0;
+			if (IS_ACTIVE(xrs->part[i]))
+				break;
+		}
+
+		if (!memcmp(xrs->part[i].id, "XGM", 3))
+			return 0;
+
+		rc = parse_partition(ls, tab, &xrs->part[i], xstart);
+		if (rc < 0)
+			return rc;
+
+		if (!IS_ACTIVE(xrs->part[i+1]))
+			break;
+
+		if (memcmp(xrs->part[i+1].id, "XGM", 3))
+			return 0;
+
+		xstart = x0start + be32_to_cpu(xrs->part[i+1].start);
+	}
+
+	return 1;
+}
+
+static int probe_atari_pt(blkid_probe pr,
+		const struct blkid_idmag *mag __attribute__((__unused__)))
+{
+	struct atari_rootsector *rs;
+
+	blkid_parttable tab = NULL;
+	blkid_partlist ls;
+
+	unsigned i;
+	int has_xgm = 0;
+	int rc = 0;
+
+	rs = (struct atari_rootsector *) blkid_probe_get_sector(pr, 0);
+	if (!rs) {
+		if (errno)
+			return -errno;
+		goto nothing;
+	}
+
+	/* Look for validly looking primary partition */
+	for (i = 0; ; i++) {
+		if (i >= ARRAY_SIZE(rs->part))
+			goto nothing;
+
+		if (IS_PARTDEF_VALID(rs->part[i])) {
+			blkid_probe_set_magic(pr,
+				offsetof(struct atari_rootsector, part[i]),
+				sizeof(rs->part[i].flags) + sizeof(rs->part[i].id),
+				(unsigned char *) &rs->part[i]);
+			break;
+		}
+	}
+
+	if (blkid_partitions_need_typeonly(pr))
+		/* caller does not ask for details about partitions */
+		return BLKID_PROBE_OK;
+
+	ls = blkid_probe_get_partlist(pr);
+	if (!ls)
+		goto nothing;
+
+	tab = blkid_partlist_new_parttable(ls, "atari", 0);
+	if (!tab)
+		goto err;
+
+	for (i = 0; i < ARRAY_SIZE(rs->part); i++) {
+		struct atari_part_def *p = &rs->part[i];
+
+		if (!IS_ACTIVE(*p)) {
+			blkid_partlist_increment_partno(ls);
+			continue;
+		}
+
+		if (!memcmp(p->id, "XGM", 3)) {
+			has_xgm = 1;
+			rc = parse_extended(pr, ls, tab, p);
+		} else {
+			rc = parse_partition(ls, tab, p, 0);
+		}
+		if (rc < 0)
+			return rc;
+	}
+
+	/* if there are no XGM partitions, we can try ICD format */
+	/* if first ICD partition ID is not valid, assume no ICD format */
+	if (!has_xgm && is_id_common(rs->icd_part[0].id)) {
+		for (i = 0; i < ARRAY_SIZE(rs->icd_part); i++) {
+			struct atari_part_def *p = &rs->icd_part[i];
+
+			if (!IS_ACTIVE(*p) || !is_id_common(p->id)) {
+				blkid_partlist_increment_partno(ls);
+				continue;
+			}
+
+			rc = parse_partition(ls, tab, p, 0);
+			if (rc < 0)
+				return rc;
+		}
+	}
+
+	return BLKID_PROBE_OK;
+
+nothing:
+	return BLKID_PROBE_NONE;
+err:
+	return -ENOMEM;
+}
+
+const struct blkid_idinfo atari_pt_idinfo =
+{
+	.name		= "atari",
+	.probefunc	= probe_atari_pt,
+	.magics		= BLKID_NONE_MAGIC
+};
diff --git a/libblkid/src/partitions/partitions.c b/libblkid/src/partitions/partitions.c
index d8fc8e3c8..1f1fc4515 100644
--- a/libblkid/src/partitions/partitions.c
+++ b/libblkid/src/partitions/partitions.c
@@ -133,7 +133,8 @@ static const struct blkid_idinfo *idinfos[] =
 	&bsd_pt_idinfo,
 	&unixware_pt_idinfo,
 	&solaris_x86_pt_idinfo,
-	&minix_pt_idinfo
+	&minix_pt_idinfo,
+	&atari_pt_idinfo
 };
 
 /*
diff --git a/libblkid/src/partitions/partitions.h b/libblkid/src/partitions/partitions.h
index 1d99fb6a3..4a718f4ea 100644
--- a/libblkid/src/partitions/partitions.h
+++ b/libblkid/src/partitions/partitions.h
@@ -69,5 +69,6 @@ extern const struct blkid_idinfo minix_pt_idinfo;
 extern const struct blkid_idinfo gpt_pt_idinfo;
 extern const struct blkid_idinfo pmbr_pt_idinfo;
 extern const struct blkid_idinfo ultrix_pt_idinfo;
+extern const struct blkid_idinfo atari_pt_idinfo;
 
 #endif /* BLKID_PARTITIONS_H */