ref: 61cc0694649a4d4b109d168032f431751f57f083
dir: /sys/src/cmd/bzfs/mkext.c/
/*
* bzip2-based file system.
* the file system itself is just a bzipped2 xzipped mkfs archive
* prefixed with "bzfilesystem\n" and suffixed with
* a kilobyte of zeros.
*
* changes to the file system are only kept in
* memory, not written back to the disk.
*
* this is intended for use on a floppy boot disk.
* we assume the file is in the dos file system and
* contiguous on the disk: finding it amounts to
* looking at the beginning of each sector for
* "bzfilesystem\n". then we pipe it through
* bunzip2 and store the files in a file tree in memory.
* things are slightly complicated by the fact that
* devfloppy requires reads to be on a 512-byte
* boundary and be a multiple of 512 bytes; we
* fork a process to relieve bunzip2 of this restriction.
*/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <auth.h>
#include <fcall.h>
#include "bzfs.h"
enum{
NFLDS = 6, /* filename, modes, uid, gid, mtime, bytes */
};
void mkdirs(char*, char*);
void mkdir(char*, ulong, ulong, char*, char*);
void extract(char*, ulong, ulong, char*, char*, ulong);
void seekpast(ulong);
void error(char*, ...);
void warn(char*, ...);
void usage(void);
char *mtpt;
Biobuf bin;
void
usage(void)
{
fprint(2, "usage: bzfs [-m mtpt] [-s] [-f file] [-h]\n");
exits("usage");
}
/*
* floppy disks can only be read on 512-byte
* boundaries and in 512 byte multiples.
* feed one over a pipe to allow arbitrary reading.
*/
char zero[512];
int
blockread(int in, char *first, int nfirst)
{
int p[2], out, n, rv;
char blk[512];
if(pipe(p) < 0)
sysfatal("pipe: %r");
rv = p[0];
out = p[1];
switch(rfork(RFPROC|RFNOTEG|RFFDG)){
case -1:
sysfatal("fork: %r");
case 0:
close(rv);
break;
default:
close(in);
close(out);
return rv;
}
write(out, first, nfirst);
while((n=read(in, blk, sizeof blk)) > 0){
if(write(out, blk, n) != n)
break;
if(n == sizeof(blk) && memcmp(zero, blk, n) == n)
break;
}
_exits(0);
}
void
main(int argc, char **argv)
{
char *rargv[10];
int rargc;
char *fields[NFLDS], *p;
ulong mode, bytes, mtime;
char *file;
int i, n, stdin, fd, chatty;
char blk[512];
if(argc>1 && strcmp(argv[1], "RAMFS") == 0){
argv[1] = argv[0];
ramfsmain(argc-1, argv+1);
exits(nil);
}
if(argc>1 && strcmp(argv[1], "BUNZIP") == 0){
_unbzip(0, 1);
exits(nil);
}
rfork(RFNOTEG);
stdin = 0;
file = nil;
mtpt = "/root";
chatty = 0;
ARGBEGIN{
case 'd':
chatty = !chatty;
break;
case 'f':
file = ARGF();
break;
case 's':
stdin++;
break;
case 'm':
mtpt = ARGF();
break;
default:
usage();
}ARGEND
if(argc != 0)
usage();
if(file == nil) {
fprint(2, "must specify -f file\n");
usage();
}
if((fd = open(file, OREAD)) < 0) {
fprint(2, "cannot open \"%s\": %r\n", file);
exits("open");
}
rargv[0] = "ramfs";
rargc = 1;
if(stdin)
rargv[rargc++] = "-i";
rargv[rargc++] = "-m";
rargv[rargc++] = mtpt;
rargv[rargc] = nil;
ramfsmain(rargc, rargv);
if(1 || strstr(file, "disk")) { /* search for archive on block boundary */
if(chatty) fprint(2, "searching for bz\n");
for(i=0;; i++){
if((n = readn(fd, blk, sizeof blk)) != sizeof blk)
sysfatal("read %d gets %d: %r\n", i, n);
if(strncmp(blk, "bzfilesystem\n", 13) == 0)
break;
}
if(chatty) fprint(2, "found at %d\n", i);
}
if(chdir(mtpt) < 0)
error("chdir %s: %r", mtpt);
fd = unbflz(unbzip(blockread(fd, blk+13, sizeof(blk)-13)));
Binit(&bin, fd, OREAD);
while((p = Brdstr(&bin, '\n', 1)) != nil){
if(chatty) fprint(2, "%s\n", p);
if(strcmp(p, "end of archive") == 0)
_exits(0);
if(getfields(p, fields, NFLDS, 0, " \t") != NFLDS){
warn("too few fields in file header");
continue;
}
mode = strtoul(fields[1], 0, 8);
mtime = strtoul(fields[4], 0, 10);
bytes = strtoul(fields[5], 0, 10);
if(mode & DMDIR)
mkdir(fields[0], mode, mtime, fields[2], fields[3]);
else
extract(fields[0], mode, mtime, fields[2], fields[3], bytes);
free(p);
}
fprint(2, "premature end of archive\n");
exits("premature end of archive");
}
char buf[IOUNIT];
int
ffcreate(char *name, ulong mode, char *uid, char *gid, ulong mtime, int length)
{
int fd, om;
Dir nd;
snprint(buf, sizeof buf, "%s/%s", mtpt, name);
om = ORDWR;
if(mode&DMDIR)
om = OREAD;
if((fd = create(buf, om, (mode&DMDIR)|0666)) < 0)
error("create %s: %r", buf);
nulldir(&nd);
nd.mode = mode;
nd.uid = uid;
nd.gid = gid;
nd.mtime = mtime;
if(length)
nd.length = length;
if(dirfwstat(fd, &nd) < 0)
error("fwstat %s: %r", buf);
return fd;
}
void
mkdir(char *name, ulong mode, ulong mtime, char *uid, char *gid)
{
close(ffcreate(name, mode, uid, gid, mtime, 0));
}
void
extract(char *name, ulong mode, ulong mtime, char *uid, char *gid, ulong bytes)
{
int fd, tot, n;
fd = ffcreate(name, mode, uid, gid, mtime, bytes);
for(tot = 0; tot < bytes; tot += n){
n = sizeof buf;
if(tot + n > bytes)
n = bytes - tot;
n = Bread(&bin, buf, n);
if(n <= 0)
error("premature eof reading %s", name);
if(write(fd, buf, n) != n)
error("short write writing %s", name);
}
close(fd);
}
void
error(char *fmt, ...)
{
char buf[1024];
va_list arg;
sprint(buf, "%s: ", argv0);
va_start(arg, fmt);
vseprint(buf+strlen(buf), buf+sizeof(buf), fmt, arg);
va_end(arg);
fprint(2, "%s\n", buf);
exits(0);
}
void
warn(char *fmt, ...)
{
char buf[1024];
va_list arg;
sprint(buf, "%s: ", argv0);
va_start(arg, fmt);
vseprint(buf+strlen(buf), buf+sizeof(buf), fmt, arg);
va_end(arg);
fprint(2, "%s\n", buf);
}
int
_efgfmt(Fmt*)
{
return -1;
}