first commit

installboot/Makefile

@@ -0,0 +1,15 @@
+PROG=installboot
+SRCS=$(wildcard *.c)
+OBJS=$(SRCS:.c=.o)
+
+CFLAGS = -g -Wall -Werror
+CPPFLAGS = -I $(IDIR)
+
+${PROG}: $(OBJS)
+	$(CC) $(CFLAGS) -o $(BDIR)/$(PROG) $^
+	cp filecopy.sh $(BDIR)
+
+$(OBJS): ../dat.h
+
+clean:
+	rm -rf $(PROG) *.o

installboot/elf32.h

@@ -0,0 +1,65 @@
+#include <elf.h>
+
+/* e_ident */
+#define IS_ELF(ehdr) ((ehdr).e_ident[EI_MAG0] == ELFMAG0 && \
+                      (ehdr).e_ident[EI_MAG1] == ELFMAG1 && \
+                      (ehdr).e_ident[EI_MAG2] == ELFMAG2 && \
+                      (ehdr).e_ident[EI_MAG3] == ELFMAG3)
+
+typedef Elf32_Ehdr Ehdr;
+typedef Elf32_Phdr Ephdr;
+typedef Elf32_Shdr Eshdr;
+typedef Elf32_Sym Esym;
+
+static Ehdr
+readEhdr(int fd)
+{
+	Ehdr h;	
+
+	assert(pread(fd, &h, sizeof(h), 0) == h.e_ehsize);
+	assert(IS_ELF(h) == 1);	
+	return h;
+}
+
+static Ephdr
+readEphdr(int fd, Ehdr h, int i)
+{
+	Ephdr ph;
+	int off;
+
+	off = h.e_phoff+i*h.e_phentsize;
+	assert(pread(fd, &ph, h.e_phentsize, off)
+			== sizeof(Ephdr));
+	return ph;
+}
+
+static Eshdr
+readEshdr(int fd, Ehdr h, int i)
+{
+	Eshdr sh;
+	int off;
+
+	off = h.e_shoff + i*h.e_shentsize;
+	assert(pread(fd, &sh, h.e_shentsize, off) == sizeof(sh));
+	return sh;
+}
+
+static void*
+readEcode(int fd, Ehdr h, Ephdr ph, void *dst)
+{
+	if(dst == NULL)
+		assert((dst = calloc(1, ph.p_filesz)) != NULL);
+	assert(pread(fd, dst, ph.p_filesz, ph.p_offset) ==
+			ph.p_filesz);
+	return dst;
+}
+
+static void*
+readsymtab(int fd, Eshdr sh, void *dst)
+{
+	if(dst == NULL)
+		assert((dst = calloc(1, sh.sh_size)) != NULL);
+	assert(pread(fd, dst, sh.sh_size, sh.sh_offset)
+			== sh.sh_size);
+	return dst;
+}

installboot/filecopy.sh

@@ -0,0 +1,34 @@
+#!/bin/sh
+
+abort()
+{
+	umount $dir 2>/dev/null
+	rm -rf $dir
+	echo >&2 "fail to install"
+    exit 0
+}
+
+trap 'abort' 0
+set -eu
+
+dir=$(mktemp -d)
+nsec=$((($(blockdev --getsz $1) - 64)/2))
+
+if [ ${nsec} -ge $((16*1024)) ]
+	then
+		nsec=$((16*1024-64/2))
+fi
+
+mkfs.fat -F16 -R 1 -r 512 -a -I --offset 64 $1 $nsec
+
+mount -o offset=$((512*64)) $1 $dir
+
+mkdir -p $dir/root
+
+cp -f build/boot  $dir/root/boot
+
+trap - 0
+umount $dir >&2
+rm -rf $dir
+sync
+exit 1

installboot/installboot.c

@@ -0,0 +1,244 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <ctype.h>
+#include <sys/mount.h>
+#include <sys/sysmacros.h>
+#include <sys/wait.h>
+#include <errno.h>
+#include <assert.h>
+#include "dat.h"
+#include "elf32.h"
+
+static char *devpath;
+static char *stage1 =  "build/biosboot";
+static char *shpath =  "build/filecopy.sh";
+static Disk dsk;
+static int btpart;
+static char btcode[512];
+
+// need patch
+static struct{
+	char *name;
+	u32 size;
+	u32 addr;
+	union{
+		u32 val;
+		struct{
+			u16 low;
+			u16 high;
+		};
+		u8 byte;
+	};
+}syms[] = {
+	{"start_cluster", 2},
+	{"dst_seg_off", 2},
+	{"spc_sqrt", 1},
+	{"clu_off", 2},
+	{"part_offset", 2},
+	{"shift_magic", 1},
+	{"and_magic", 2},
+};
+
+void
+usage(void)
+{
+	fprintf(stderr, "usgae: ./installboot device [bin]\n");
+	exit(1);
+}
+
+int
+streq(char *a, char *b)
+{
+	int la = strlen(a);
+	return la==strlen(b) && memcmp(a, b, la)==0;
+}
+
+void
+loadelf(char *fname)
+{
+	int fd;
+	char *tbbeg, *tbstr;
+	Ehdr h;
+	Ephdr ph;
+	Eshdr shsym, shstr;
+	Esym *tbsym;
+
+	assert((fd = open(fname, O_RDONLY))!=-1);
+	h = readEhdr(fd);
+	assert(h.e_phnum == 1); // only 1 program header
+	assert(h.e_shnum >= 2);
+	ph = readEphdr(fd, h, 0);
+	assert(ph.p_filesz == sizeof(btcode));
+
+	for(int i = 0; i < h.e_shnum; ++i)
+		if((shsym = readEshdr(fd, h, i)).sh_type == SHT_SYMTAB)
+			goto found;
+	assert(0 && "Can't find shymbol table\n");
+
+found:
+	shstr = readEshdr(fd, h, shsym.sh_link);
+	assert(shstr.sh_type == SHT_STRTAB);
+	assert((tbbeg = calloc(1, shstr.sh_size + shsym.sh_size))!=NULL);
+	tbstr = readsymtab(fd, shstr, tbbeg);
+	tbsym = readsymtab(fd, shsym, tbbeg+shstr.sh_size);
+
+	for(int i = 0; i < elem(syms); ++i){
+		for(int j = 0; j < shsym.sh_size/sizeof(*tbsym); ++j)
+			if(streq(syms[i].name, tbstr + tbsym[j].st_name)){
+				syms[i].addr = tbsym[j].st_value;
+				break;
+			}
+		assert(syms[i].addr != 0&& "Can't find symbol in symtab\n");
+	}
+
+	readEcode(fd, h, ph, btcode);
+	free(tbbeg);
+	close(fd);
+}
+
+void
+symset(char *name, u32 val)
+{
+	for(int i = 0; i < elem(syms); ++i){
+		if(streq(name, syms[i].name)){
+			syms[i].val = val;
+			return;
+		}
+	}
+	assert(0 && "symbol not exist");
+}
+
+uint
+tou32(u8 *str, int i)
+{
+	uint x = 0;
+
+	do{
+		x = x << 8;
+		x |= str[--i];
+	}while(i > 0);
+	return x;
+}
+
+u16
+exponent(u16 x)
+{
+	switch(x){
+	case 1: return 0;
+	case 2: return 1;
+	case 4: return 2;
+	case 8: return 4;
+	case 16: return 8;
+	case 32: return 16;
+	case 512: return 9;
+	case 1024: return 10;
+	case 2048: return 11;
+	case 4096: return 12;
+	default: assert(0);
+	}
+}
+
+void
+emit(u64 off)
+{
+	for(int i = 0; i < elem(syms); ++i){
+		switch(syms[i].size){
+		case 1:
+			btcode[syms[i].addr] = syms[i].byte;
+			break;
+		case 2:
+			*(u16*)&btcode[syms[i].addr] = syms[i].low;
+			break;
+		case 4:
+			*(u32*)&btcode[syms[i].addr] = syms[i].val;
+			break;
+		default:
+			assert(0);
+		}
+	}
+
+	assert(pwrite(dsk.fd, btcode+0x3c, sizeof(btcode)-0x3c, off+0x3c) ==
+			sizeof(btcode)-0x3c);
+}
+
+void
+setbootparam(int ino, int off, int sec)
+{
+	u8 buf[512];
+	u16	rdsecsz, dasec;
+
+	assert(sizeof(buf) == pread(dsk.fd, buf, sizeof(buf), off));
+
+	u32 bps = tou32(buf+0x0b, 2);
+	u32 spc = tou32(buf+0x0d, 1);
+	u32 res = tou32(buf+0x0e, 2);
+	u32 nfat = tou32(buf+0x10, 1);
+	u32 nrde = tou32(buf+0x11, 2);
+//	u32 nsec = tou32(buf+0x13, 2);
+	u32 nspf = tou32(buf+0x16, 2); // numberof sector per fat16
+	rdsecsz = (nrde*32 + (bps - 1))/bps;
+	dasec = res + (nspf*nfat) + rdsecsz;
+	assert(0xaa55 == tou32(buf+0x1fe, 2));
+
+	symset("dst_seg_off", bps>>4);
+	symset("start_cluster", ino);
+	symset("spc_sqrt", exponent(spc));
+	symset("clu_off", dasec - 2 * spc);
+	symset("part_offset", sec);
+	symset("shift_magic", exponent(bps)-3);
+	symset("and_magic", bps-1);
+}
+
+void
+catpath(char *dst, char *s1, char *s2)
+{
+	while(*s1)
+		*dst++ = *s1++;
+	*dst++ = '/';
+	while(*s2)
+		*dst++ = *s2++;
+	*dst = '\0';
+}
+
+void
+install(void)
+{
+	char *args[] = {shpath, devpath, NULL};
+	pid_t pid;
+	u64 beg;
+
+	switch(pid = fork()){
+	default:
+		assert(wait(NULL) == pid);
+		sync();
+		break;	
+	case 0:
+		assert(execvp(args[0], args) != -1);
+	case -1:
+		assert(0);
+	}
+	dsk = diskopen(devpath, O_RDWR);
+	for(int i = 0; i < elem(dsk.parts); ++i)
+		if(dsk.parts[i].type == DOSPTYP_FAT16 && dsk.parts[i].flag == DOSACTIVE){
+			btpart = i;
+			goto found;
+		}
+	assert(0);
+
+found:
+	beg = dsk.parts[btpart].beg * dsk.bps;
+	setbootparam(4, beg, dsk.parts[btpart].beg);
+	emit(beg);
+	close(dsk.fd);
+}
+
+int
+main(int argc, char *argv[])
+{
+	if(argc < 2 || argc > 3)
+		usage();
+	devpath = argv[1];
+	loadelf(stage1);
+	install();
+	return 0;
+}