X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=bootcensus;a=blobdiff_plain;f=src%2Fpart.c;fp=src%2Fpart.c;h=df007eee0cbc705747ee6d2390c4b52a04c02531;hp=0000000000000000000000000000000000000000;hb=137aca58851528e77004dc3909826f24bbdbde87;hpb=81c11bdd80190ec319a82b0402173cfb65fcbf72

diff --git a/src/part.c b/src/part.c
new file mode 100644
index 0000000..df007ee
--- /dev/null
+++ b/src/part.c
@@ -0,0 +1,158 @@
+/*
+pcboot - bootable PC demo/game kernel
+Copyright (C) 2018-2019  John Tsiombikas <nuclear@member.fsf.org>
+
+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 <https://www.gnu.org/licenses/>.
+*/
+#include <stdio.h>
+#include "part.h"
+#include "boot.h"
+#include "bootdev.h"
+#include "ptype.h"
+
+struct part_record {
+	uint8_t stat;
+	uint8_t first_head, first_cyl, first_sect;
+	uint8_t type;
+	uint8_t last_head, last_cyl, last_sect;
+	uint32_t first_lba;
+	uint32_t nsect_lba;
+} __attribute__((packed));
+
+static int read_sector(int dev, uint64_t sidx);
+static const char *ptype_name(int type);
+
+static unsigned char sectdata[512];
+
+#define BOOTSIG_OFFS	510
+#define PTABLE_OFFS		0x1be
+
+#define BOOTSIG			0xaa55
+
+#define IS_MBR			(sidx == 0)
+#define IS_FIRST_EBR	(!IS_MBR && (first_ebr_offs == 0))
+
+int read_partitions(int dev, struct partition *ptab, int ptabsz)
+{
+	int i, num_rec, nparts = 0;
+	int num_bootrec = 0;
+	struct partition *part = ptab;
+	struct part_record *prec;
+	uint64_t sidx = 0;
+	uint64_t first_ebr_offs = 0;
+
+	if(ptabsz <= 0) {
+		ptab = 0;
+	}
+
+	do {
+		if(IS_FIRST_EBR) {
+			first_ebr_offs = sidx;
+		}
+
+		if(read_sector(dev, sidx) == -1) {
+			printf("failed to read sector %llu\n", (unsigned long long)sidx);
+			return -1;
+		}
+		if(*(uint16_t*)(sectdata + BOOTSIG_OFFS) != BOOTSIG) {
+			printf("invalid partitionm table, sector %llu has no magic\n", (unsigned long long)sidx);
+			return -1;
+		}
+		prec = (struct part_record*)(sectdata + PTABLE_OFFS);
+
+		/* MBR has 4 records, EBRs have 2 */
+		num_rec = IS_MBR ? 4 : 2;
+
+		for(i=0; i<num_rec; i++) {
+			/* ignore empty partitions in the MBR, stop on empty partitions in an EBR */
+			if(prec[i].type == 0) {
+				if(num_bootrec > 0) {
+					sidx = 0;
+					break;
+				}
+				continue;
+			}
+
+			/* ignore extended partitions and setup sector index to read the
+			 * next logical partition.
+			 */
+			if(prec[i].type == PTYPE_EXT || prec[i].type == PTYPE_EXT_LBA) {
+				/* all EBR start fields are relative to the first EBR offset */
+				sidx = first_ebr_offs + prec[i].first_lba;
+				continue;
+			}
+
+			/* found a proper partition */
+			nparts++;
+
+			if(ptab) {
+				part->attr = prec[i].type;
+
+				if(prec[i].stat & 0x80) {
+					part->attr |= PART_ACT_BIT;
+				}
+				if(IS_MBR) {
+					part->attr |= PART_PRIM_BIT;
+				}
+				part->start_sect = prec[i].first_lba + first_ebr_offs;
+				part->size_sect = prec[i].nsect_lba;
+				part++;
+			}
+		}
+
+		num_bootrec++;
+	} while(sidx > 0 && (!ptab || nparts < ptabsz));
+
+	return nparts;
+}
+
+void print_partition_table(struct partition *ptab, int npart)
+{
+	int i;
+	struct partition *p = ptab;
+
+	printf("Found %d partitions\n", npart);
+	for(i=0; i<npart; i++) {
+		printf("%d%c ", i, PART_IS_ACT(p->attr) ? '*' : ' ');
+		printf("(%s) %-20s ", PART_IS_PRIM(p->attr) ? "pri" : "log", ptype_name(PART_TYPE(p->attr)));
+		printf("start: %-10llu ", (unsigned long long)p->start_sect);
+		printf("size: %-10llu\n", (unsigned long long)p->size_sect);
+		p++;
+	}
+}
+
+static int read_sector(int dev, uint64_t sidx)
+{
+	if(dev == -1 || dev == boot_drive_number) {
+		if(bdev_read_sect(sidx, sectdata) == -1) {
+			return -1;
+		}
+		return 0;
+	}
+
+	printf("BUG: reading partitions of drives other than the boot drive not implemented yet\n");
+	return -1;
+}
+
+static const char *ptype_name(int type)
+{
+	int i;
+
+	for(i=0; i<PTYPES_SIZE; i++) {
+		if(partypes[i].type == type) {
+			return partypes[i].name;
+		}
+	}
+	return "unknown";
+}