feat(mkfs.stpd): make filesystem bootable (WIP)

configure.ac

@@ -13,6 +13,10 @@ AM_PROG_AR
 AC_PROG_INSTALL
 AC_PROG_RANLIB
 AM_PROG_CC_C_O
+AC_CHECK_PROG([NASM], [nasm], [nasm])
+AS_IF([test -z "$NASM"], [
+	AC_MSG_ERROR([nasm is required])
+])
 
 AC_CONFIG_HEADERS([config.h])
 

libstpdfs/Makefile.am

@@ -1,2 +1,2 @@
 noinst_LIBRARIES = libstpdfs.a
-liblzp_a_SOURCES = super.c bio.c inode.c file.c dir.c
+libstpdfs_a_SOURCES = super.c bio.c inode.c file.c dir.c

tools/Makefile.am

@@ -4,7 +4,16 @@ LDADD = ../lib/libstpdfs.a
 bin_PROGRAMS = mkfs.stpd tools.stpd
 
 mkfs_stpd_SOURCES = mkfs/main.c
+mkfs_stpd_LDADD = ../lib/libstpdfs.a mkfs/bootsector.o
 
 tools_stpd_SOURCES = tools/main.c
 
-man_MANS = mkfs/mkfs.stpd.8 tools/tools.stpd.8
+mkfs/boot.o: mkfs/boot.asm
+	$(NASM) -fbin -o $@ $<
+
+mkfs/bootsector.o: mkfs/boot.o
+	ld -r -b binary -o $@ $<
+
+man_MANS = mkfs/mkfs.stpd.8 tools/tools.stpd.8
+
+CLEANFILES = mkfs/boot.o mkfs/bootsector.o

tools/mkfs/boot.asm

@@ -0,0 +1,134 @@
+	[BITS 16]
+	[ORG 0x7c00]
+
+	LOADER_BASE  equ 0x1000
+	DISK_BUFFER  equ 0x8000
+	STPDFS_MAGIC equ 0x44505453
+	INODE_SIZE   equ 34
+	INODE_ALLOCATED equ (1<<15)
+
+	struc inode
+		.mode:    resb 1
+		.nlink:   resb 1
+		.uid:     resb 1
+		.gid:     resb 1
+		.flags:   resb 1
+		.size:    resd 1
+		.zones:   resd 10
+		.actime:  resq 1
+		.modtime: resq 1
+	endstruc
+
+	jmp start
+	nop
+
+bpb:
+	db 0, 0, 0
+.oem_id:            db "STUPIDFS"
+.sector_size:       dw 512
+.sects_per_cluster: db 0
+.reserved_sects:    dw 0
+.fat_count:         db 0
+.root_dir_entries:  dw 0
+.sector_count:      dw 0
+.media_type:        db 0
+.sects_per_fat:     dw 0
+.sects_per_track:   dw 18
+.head_count:        dw 2
+.hidden_sects:      dd 0
+.sector_count_big:  dd 0
+.drive_num:         db 0
+.reserved:          db 0
+.signature:         db 0
+.volume_id:         dd 0
+.volume_label:      db "STPD.MKFS  "
+.filesystem_type:   times 8 db 0
+
+start:
+	cli
+	cld
+	jmp 0x0:.canonicalize_cs 
+
+.canonicalize_cs:
+	xor ax, ax
+	mov ds, ax
+	mov ss, ax
+	mov es, ax
+	mov sp, 0x7c00
+
+	mov [bpb.drive_num], dl
+
+	; ensure lba mode is supported
+	mov ah, 0x41
+	mov bx, 0x55AA
+	int 0x13
+	jc .err_lba
+
+	; reset disk
+.reset_disk:
+	mov dl, [bpb.drive_num]
+	xor ah, ah
+	int 0x13
+	jc .reset_disk
+
+	; read superblock
+	mov ax, DISK_BUFFER/10
+	mov es, ax
+
+	; load two sector in memory 
+	; superblock and first inodes
+	mov eax, 1
+	mov cx, 2
+	xor bx, bx
+	call disk_read_sectors
+
+	mov dword eax, [DISK_BUFFER]
+	cmp eax, STPDFS_MAGIC
+	jne .err_magic
+
+	; inode 0 bad
+	; inode 1 root dir
+	; inode 2 is loader, let's keep things easy
+	mov ax, word [DISK_BUFFER + 34 * 2 + inode.flags]
+	and ax, INODE_ALLOCATED
+	jz .err_no_loader
+
+	mov dword eax, [DISK_BUFFER + 34 * 2 + inode.size] ; size
+
+	mov eax, DISK_BUFFER + 34 * 2 + 14 ; first zone
+
+
+	jmp 0x0:LOADER_BASE
+
+.err_no_loader:
+.err_magic:
+.err_lba:
+	hlt
+	jmp $
+
+disk_read_sectors:
+	mov word [disk_packet.sectors], cx
+	mov word [disk_packet.segment], es
+	mov word [disk_packet.offset], bx
+	mov dword [disk_packet.lba], eax
+	mov ds, [disk_packet]
+	mov dl, [bpb.drive_num]
+	mov ah, 0x42
+	int 0x13
+	ret
+
+disk_packet:
+	db 0x10
+	db 0
+.sectors:
+	dw 0
+.segment:
+	dw 0
+.offset:
+	dw 0
+.lba:
+	dd 0
+	dd 0
+
+	times 510-($-$$) db 0
+	dw 0xAA55

tools/mkfs/main.c

@@ -23,12 +23,17 @@ static const char *prg_name;
 static int inodes = -1;
 static const char *device;
 static int blocks = -1;
+static int bootable = 0;
 static struct stpdfs_sb super;
 
+extern const char _binary_mkfs_boot_o_start[];
+extern const char _binary_mkfs_boot_o_end[];
+
 #ifdef HAVE_STRUCT_OPTION
 static struct option long_options[] = {
 	{"help", no_argument, 0, 'h'},
 	{"version", no_argument, 0, 'V'},
+	{"boot", no_argument, 0, 'b'},
 	{"inodes", required_argument, 0, 'i'},
 	{0, 0, 0, 0}
 };
@@ -45,6 +50,7 @@ usage(int retval)
 	{
 		printf("Usage: %s [options] /dev/name [blocks]\n\n", prg_name);
 		printf("Options:\n");
+		printf(" -b, --boot         make filesystem bootable\n");
 		printf(" -i, --inode <num>  number of inodes for the filesystem\n");
 		printf(" -h, --help         display this help\n");
 		printf(" -V, --version      display version\n\n");
@@ -168,6 +174,11 @@ mkfs()
 	super.state = STPDFS_CLEANLY_UNMOUNTED;
 	stpdfs_write(fd, 1, &super, sizeof(struct stpdfs_sb));
 
+	if (bootable)
+	{
+		stpdfs_write(fd, 0, (void *)_binary_mkfs_boot_o_start, STPDFS_BLOCK_SIZE);
+	}
+
 	/* we finished \o/  */
 	printf("StupidFS: %u blocks (%u Inodes)\n", super.fsize, super.isize);
 
@@ -189,9 +200,9 @@ main(int argc, char **argv)
 #endif /* HAVE_LIBGEN_H */
 
 #if defined(HAVE_GETOPT_LONG) && defined(HAVE_STRUCT_OPTION) 
-	while ((c = getopt_long(argc, argv, "hVi:", long_options, &idx)) != EOF)
+	while ((c = getopt_long(argc, argv, "hVbi:", long_options, &idx)) != EOF)
 #else
-	while ((c = getopt(argc, argv, "hVi:")) != EOF)
+	while ((c = getopt(argc, argv, "hVbi:")) != EOF)
 #endif /* HAVE_GETOPT_LONG && HAVE_STRUCT_OPTION */
 	{
 		switch (c)
@@ -202,6 +213,9 @@ main(int argc, char **argv)
 		case 'V':
 			version();
 			break;
+		case 'b':
+			bootable = 1;
+			break;
 		case 'i':
 			inodes = atoi(optarg);
 			break;