# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1318567544 -10800
# Node ID 29d89c00e61184a1dc4b2da764bd28cac0480531

simple partition table reading test

diff -r 000000000000 -r 29d89c00e611 Makefile
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Makefile	Fri Oct 14 07:45:44 2011 +0300
@@ -0,0 +1,13 @@
+src = $(wildcard *.c)
+obj = $(src:.c=.o)
+bin = lspart
+
+CC = gcc
+CFLAGS = -pedantic -Wall -g
+
+$(bin): $(obj)
+	$(CC) -o $@ $(obj) $(LDFLAGS)
+
+.PHONY: clean
+clean:
+	rm -f $(obj) $(bin)
diff -r 000000000000 -r 29d89c00e611 lspart.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lspart.c	Fri Oct 14 07:45:44 2011 +0300
@@ -0,0 +1,228 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include "ptype.h"
+
+#define PATTR_ACT_BIT	(1 << 9)
+#define PATTR_PRIM_BIT	(1 << 10)
+
+#define PTYPE(attr)		((attr) & 0xff)
+#define IS_ACT(attr)	((attr) & PATTR_ACT_BIT)
+#define IS_PRIM(attr)	((attr) & PATTR_PRIM_BIT)
+
+struct partition {
+	uint32_t start_sect;
+	size_t size_sect;
+
+	unsigned int attr;
+
+	struct partition *next;
+};
+
+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 void print_parlist(struct partition *plist);
+
+static struct partition *load_parlist(void);
+static uint16_t bootsig(const char *sect);
+static int read_sector(void *buf, uint32_t sector);
+static const char *printsz(unsigned int sz);
+static const char *ptype_name(int type);
+
+int bdev;
+
+int main(int argc, char **argv)
+{
+	struct partition *plist;
+
+	if(argc != 2) {
+		fprintf(stderr, "usage: %s <block device>\n", argv[0]);
+		return 1;
+	}
+
+	if((bdev = open(argv[1], O_RDONLY)) == -1) {
+		fprintf(stderr, "failed to open %s: %s\n", argv[1], strerror(errno));
+		return 1;
+	}
+
+	if((plist = load_parlist())) {
+		printf("partitions:\n");
+		print_parlist(plist);
+	}
+
+	return 0;
+}
+
+static void print_parlist(struct partition *plist)
+{
+	int idx = 0;
+
+	while(plist) {
+		printf("%d%c ", idx++, IS_ACT(plist->attr) ? '*' : ' ');
+		printf("(%s) %-20s ", IS_PRIM(plist->attr) ? "pri" : "log", ptype_name(PTYPE(plist->attr)));
+		printf("start: %-10lu ", (unsigned long)plist->start_sect);
+		printf("size: %-10lu [%s]\n", (unsigned long)plist->size_sect, printsz(plist->size_sect));
+		plist = plist->next;
+	}
+}
+
+
+#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))
+static struct partition *load_parlist(void)
+{
+	char *sect;
+	struct partition *phead = 0, *ptail = 0;
+	uint32_t sidx = 0;
+	uint32_t first_ebr_offs = 0;
+	int i, num_bootrec = 0;
+
+	if(!(sect = malloc(512))) {
+		perror("failed to allocate sector buffer");
+		return 0;
+	}
+
+
+	do {
+		int num_rec;
+		struct part_record *prec;
+
+		if(IS_FIRST_EBR) {
+			first_ebr_offs = sidx;
+		}
+
+		if(read_sector(sect, sidx) == -1) {
+			goto err;
+		}
+		if(bootsig(sect) != BOOTSIG) {
+			fprintf(stderr, "invalid/corrupted partition table, sector %lu has no magic\n", (unsigned long)sidx);
+			goto err;
+		}
+		prec = (struct part_record*)(sect + PTABLE_OFFS);
+
+		/* MBR has 4 records, EBRs have 2 */
+		num_rec = IS_MBR ? 4 : 2;
+
+		for(i=0; i<num_rec; i++) {
+			struct partition *pnode;
+
+			/* ignore empty partitions in the MBR, stop if encountered 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 afterwards.
+			 */
+			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;
+			}
+
+			if(!(pnode = malloc(sizeof *pnode))) {
+				perror("failed to allocate partition list node");
+				goto err;
+			}
+
+			pnode->attr = prec[i].type;
+
+			if(prec[i].stat & 0x80) {
+				pnode->attr |= PATTR_ACT_BIT;
+			}
+			if(IS_MBR) {
+				pnode->attr |= PATTR_PRIM_BIT;
+			}
+			pnode->start_sect = prec[i].first_lba + first_ebr_offs;
+			pnode->size_sect = prec[i].nsect_lba;
+			pnode->next = 0;
+
+			/* append to the list */
+			if(!phead) {
+				phead = ptail = pnode;
+			} else {
+				ptail->next = pnode;
+				ptail = pnode;
+			}
+		}
+
+		num_bootrec++;
+	} while(sidx > 0);
+
+	free(sect);
+	return phead;
+
+err:
+	free(sect);
+	while(phead) {
+		void *tmp = phead;
+		phead = phead->next;
+		free(tmp);
+	}
+	return 0;
+}
+
+static uint16_t bootsig(const char *sect)
+{
+	return *(uint16_t*)(sect + BOOTSIG_OFFS);
+}
+
+static int read_sector(void *buf, uint32_t sector)
+{
+	if(lseek(bdev, (off_t)sector * 512, SEEK_SET) == -1) {
+		fprintf(stderr, "read_sector: failed to seek: %s\n", strerror(errno));
+		return -1;
+	}
+	if(read(bdev, buf, 512) != 512) {
+		fprintf(stderr, "failed to read sector %lu: %s\n", (unsigned long)sector, strerror(errno));
+		return -1;
+	}
+	return 0;
+}
+
+const char *printsz(unsigned int sz)
+{
+	int i = 0;
+	const char *suffix[] = { "kb", "mb", "gb", "tb", "pb", 0 };
+	static char buf[512];
+
+	while(sz > 1024 && suffix[i + 1]) {
+		sz /= 1024;
+		i++;
+	}
+
+	sprintf(buf, "%u %s", sz, suffix[i]);
+	return buf;
+}
+
+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";
+}
diff -r 000000000000 -r 29d89c00e611 ptype.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ptype.h	Fri Oct 14 07:45:44 2011 +0300
@@ -0,0 +1,83 @@
+#ifndef PTYPE_H_
+#define PTYPE_H_
+
+
+#define PTYPE_EXT		0x5
+#define PTYPE_EXT_LBA	0xf
+
+
+#define PTYPES_SIZE		(sizeof partypes / sizeof *partypes)
+
+struct {
+	int type;
+	const char *name;
+} partypes[] = {
+	{0, "empty"},
+	{0x01, "fat12"},
+	{0x02, "xenix root"},
+	{0x03, "xenix usr"},
+	{0x04, "fat16 (small)"},
+	{0x05, "extended"},
+	{0x06, "fat16"},
+	{0x07, "hpfs/ntfs"},
+	{0x08, "aix"},
+	{0x09, "aix bootable"},
+	{0x0a, "os/2 boot manager"},
+	{0x0b, "fat32 (chs)"},
+	{0x0c, "fat32 (lba)"},
+	{0x0e, "fat16 (lba)"},
+	{0x0f, "extended (lba)"},
+	{0x11, "hidden fat12"},
+	{0x12, "compaq diagnostics"},
+	{0x14, "hidden fat16 (small)"},
+	{0x16, "hidden fat16"},
+	{0x17, "hidden hpfs/ntfs"},
+	{0x1b, "hidden fat32"},
+	{0x1c, "hidden fat32 (lba)"},
+	{0x1d, "hidden fat16 (lba)"},
+	{0x24, "nec dos"},
+	{0x27, "windows recovery"},
+	{0x39, "plan 9"},
+	{0x3c, "partition magic"},
+	{0x4d, "qnx"},
+	{0x4e, "qnx 2nd"},
+	{0x4f, "qnx 3rd"},
+	{0x52, "cp/m"},
+	{0x63, "hurd/sysv"},
+	{0x64, "netware 286"},
+	{0x65, "netware 386"},
+	{0x80, "minix (old)"},
+	{0x81, "minix"},
+	{0x82, "linux swap/solaris"},
+	{0x83, "linux"},
+	{0x84, "windows suspend"},
+	{0x85, "linux extended"},
+	{0x86, "ntfs volume?"},
+	{0x87, "ntfs volume?"},
+	{0x88, "linux plaintext"},
+	{0x8e, "linux lvm"},
+	{0x9f, "bsd/os"},
+	{0xa0, "laptop diagnostic"},
+	{0xa5, "freebsd slice"},
+	{0xa6, "openbsd slice"},
+	{0xa7, "nextstep"},
+	{0xa8, "darwin ufs"},
+	{0xa9, "netbsd slice"},
+	{0xab, "darwin boot"},
+	{0xaf, "hfs/hfs+"},
+	{0xb7, "bsdi"},
+	{0xb8, "bsdi swap"},
+	{0xbe, "solaris boot"},
+	{0xbf, "solaris"},
+	{0xde, "dell diagnostic"},
+	{0xeb, "beos"},
+	{0xee, "gpt"},
+	{0xef, "efi (fat)"},
+	{0xf0, "linux/pa-risc boot"},
+	{0xf2, "dos secondary"},
+	{0xfb, "vmware vmfs"},
+	{0xfc, "vmware vmkcore"},
+	{0xfd, "linux raid auto"}
+};
+
+#endif	/* PTYPE_H_ */