bread

iget
mkfs makes a file system image
put this in your .bochsrc:
ata0-slave: type=disk, mode=flat, path="fs.img", cylinders=1024, heads=1, spt=1

1 files changed, 140 insertions, 0 deletions

diff --git a/mkfs.c b/mkfs.c
new file mode 100644
index 0000000..033e064
--- /dev/null
+++ b/mkfs.c
@@ -0,0 +1,140 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include "types.h"
+#include "param.h"
+#include "fs.h"
+
+int nblocks = 1009;
+int ninodes = 100;
+
+int fd;
+struct superblock sb;
+char zeroes[512];
+uint freeblock;
+
+void wsect(uint, void *);
+void winode(uint, struct dinode *);
+void rsect(uint sec, void *buf);
+
+// convert to intel byte order
+ushort
+xshort(ushort x)
+{
+  ushort y;
+  uchar *a = &y;
+  a[0] = x;
+  a[1] = x >> 8;
+  return y;
+}
+
+uint
+xint(uint x)
+{
+  uint y;
+  uchar *a = &y;
+  a[0] = x;
+  a[1] = x >> 8;
+  a[2] = x >> 16;
+  a[3] = x >> 24;
+  return y;
+}
+
+main(int argc, char *argv[])
+{
+  int i;
+  struct dinode din;
+  char dbuf[512];
+
+  if(argc != 2){
+    fprintf(stderr, "Usage: mkfs fs.img\n");
+    exit(1);
+  }
+
+  if(sizeof(struct dinode) * IPB != 512){
+    fprintf(stderr, "sizeof(dinode) must divide 512\n");
+    exit(1);
+  }
+
+  fd = open(argv[1], O_RDWR|O_CREAT|O_TRUNC, 0666);
+  if(fd < 0){
+    perror(argv[1]);
+    exit(1);
+  }
+
+  sb.nblocks = xint(nblocks); // so whole disk is 1024 sectors
+  sb.ninodes = xint(ninodes);
+
+  freeblock = ninodes / IPB + 2;
+
+  for(i = 0; i < nblocks + (ninodes / IPB) + 3; i++)
+    wsect(i, zeroes);
+
+  wsect(1, &sb);
+
+  bzero(&din, sizeof(din));
+  din.type = xshort(T_DIR);
+  din.nlink = xshort(2);
+  din.size = xint(512);
+  din.addrs[0] = xint(freeblock++);
+  winode(1, &din);
+
+  bzero(dbuf, sizeof(dbuf));
+  ((struct dirent *) dbuf)[0].inum = xshort(1);
+  strcpy(((struct dirent *) dbuf)[0].name, ".");
+  ((struct dirent *) dbuf)[1].inum = xshort(1);
+  strcpy(((struct dirent *) dbuf)[1].name, "..");
+  wsect(din.addrs[0], dbuf);
+
+  exit(0);
+}
+
+void
+wsect(uint sec, void *buf)
+{
+  if(lseek(fd, sec * 512L, 0) != sec * 512L){
+    perror("lseek");
+    exit(1);
+  }
+  if(write(fd, buf, 512) != 512){
+    perror("write");
+    exit(1);
+  }
+}
+
+uint
+i2b(uint inum)
+{
+  return (inum / IPB) + 2;
+}
+
+void
+winode(uint inum, struct dinode *ip)
+{
+  char buf[512];
+  uint bn;
+  struct dinode *dip;
+
+  bn = i2b(inum);
+  rsect(bn, buf);
+  dip = ((struct dinode *) buf) + (inum % IPB);
+  *dip = *ip;
+  printf("bn %d off %d\n",
+         bn, (unsigned)dip - (unsigned) buf);
+  wsect(bn, buf);
+}
+
+void
+rsect(uint sec, void *buf)
+{
+  if(lseek(fd, sec * 512L, 0) != sec * 512L){
+    perror("lseek");
+    exit(1);
+  }
+  if(read(fd, buf, 512) != 512){
+    perror("read");
+    exit(1);
+  }
+}