--- /dev/null
+/*
+ (c) Marc Welz 2000, released under GPL, tested under Linux 2.2.17
+
+ Most of the stuff cribbed from the nbd package written by Pavel Machek
+
+ Unfortunately quite slow since zlib has to decompress all the stuff between
+ seeks, so only suited to smaller files
+
+ Could be a neat way to do userland encryption/steganography if you have
+ a crypto library which has a stdiolike interface to replace zlib
+
+ Usage
+
+ dd if=/dev/zero of=/tmp/image bs=1024 count=1024
+ mke2fs -f /tmp/image
+ mount -o loop /tmp/image /mnt/
+ cp /bin/ls /mnt/
+ umount /mnt
+ sync
+ gzip -9 /tmp/image
+ gznbd /dev/nbd0 /tmp/image.gz
+
+ gznbd does not background, from another terminal type
+
+ mount -o ro,nocheck /dev/nbd0 /mnt/
+ cd /mnt
+ ls
+ df
+
+ ro is important, since writes will fail horribly and nochecks
+ speeds the mount up nicely
+
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <zlib.h>
+#include <errno.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <netinet/in.h>
+
+/* asm/types defines __u??, at least on my system */
+#include <asm/types.h>
+
+#define u32 __u32
+#define u64 __u64
+
+#include <linux/nbd.h>
+
+#define BLOCK 1024
+
+/* don't ask me why this value, I only copied it */
+#define CHUNK BLOCK*20
+
+/* taken litterally from the original nbd */
+#ifdef WORDS_BIGENDIAN
+u64 ntohll(u64 a)
+{
+ return a;
+}
+#else
+u64 ntohll(u64 a)
+{
+ u32 lo = a & 0xffffffff;
+ u32 hi = a >> 32U;
+ lo = ntohl(lo);
+ hi = ntohl(hi);
+ return ((u64) lo) << 32U | hi;
+}
+#endif
+
+
+int main(int argc, char **argv)
+{
+ int pr[2];
+ int sk;
+ int nbd;
+ gzFile *gz;
+ int gzerr;
+
+ char chunk[CHUNK];
+ struct nbd_request request;
+ struct nbd_reply reply;
+
+ u64 size;
+ u64 from;
+ u32 len;
+
+ if(argc<3){
+ printf("Usage: %s nbdevice gzfile [size]\n",argv[0]);
+ exit(1);
+ }
+
+ gz=gzopen(argv[2], "rb");
+ if(gz==NULL){
+ fprintf(stderr,"%s: unable open compressed file %s\n",argv[0],argv[2]);
+ exit(1);
+ }
+
+ if(argc>3){
+ size=atol(argv[3]);
+ if((size==0)||(size%BLOCK)){
+ fprintf(stderr,"%s: %s does not appear to be a valid size\n",argv[0],argv[3]);
+ exit(1);
+ }
+ printf("%s: file=%s, size=%Ld\n",argv[0],argv[2],size);
+ } else {
+ char buffer[BLOCK];
+ int result;
+
+ size=0;
+ printf("%s: file=%s, seeking, ",argv[0],argv[2]);
+ fflush(stdout);
+
+ /* expensive seek to get file size */
+ while(BLOCK==(result=gzread(gz,buffer,BLOCK))){
+ size+=BLOCK;
+ }
+
+ if(result==0){
+ printf("size=%Ld\n",size);
+ } else {
+ printf("failed\n");
+ if(result<0){
+ fprintf(stderr,"%s: read failed: %s\n",argv[0],gzerror(gz,&gzerr));
+ } else {
+ fprintf(stderr,"%s: incomplete last read, file has to be a multiple of %d\n",argv[0],BLOCK);
+ }
+ exit(1);
+ }
+
+ if(gzrewind(gz)!=0){
+ fprintf(stderr,"%s: unable to rewind gzfile\n",argv[0]);
+ exit(1);
+ }
+
+ }
+
+ if(socketpair(AF_UNIX, SOCK_STREAM, 0, pr)){
+ fprintf(stderr,"%s: unable to create socketpair: %s\n",argv[0],strerror(errno));
+ exit(1);
+ }
+
+ switch(fork()){
+ case -1 :
+ fprintf(stderr,"%s: unable to fork: %s\n",argv[0],strerror(errno));
+ exit(1);
+ break;
+ case 0 : /* child */
+ gzclose(gz);
+
+ close(pr[0]);
+
+ sk=pr[1];
+
+ nbd=open(argv[1], O_RDWR);
+ if(nbd<0){
+ fprintf(stderr,"%s: unable to open %s: %s\n",argv[0],argv[1],strerror(errno));
+ exit(1);
+ }
+
+ if(ioctl(nbd,NBD_SET_SIZE,size)<0){
+ fprintf(stderr,"%s: failed to set size for %s: %s\n",argv[0],argv[1],strerror(errno));
+ exit(1);
+ }
+
+ ioctl(nbd, NBD_CLEAR_SOCK);
+
+ if(ioctl(nbd,NBD_SET_SOCK,sk)<0){
+ fprintf(stderr,"%s: failed to set socket for %s: %s\n",argv[0],argv[1],strerror(errno));
+ exit(1);
+ }
+
+ if(ioctl(nbd,NBD_DO_IT)<0){
+ fprintf(stderr,"%s: block device %s terminated: %s\n",argv[0],argv[1],strerror(errno));
+ }
+
+ ioctl(nbd, NBD_CLEAR_QUE);
+ ioctl(nbd, NBD_CLEAR_SOCK);
+
+ exit(0);
+
+ break;
+ }
+
+ /* only parent here, child always exits */
+
+ close(pr[1]);
+ sk=pr[0];
+
+ reply.magic=htonl(NBD_REPLY_MAGIC);
+ reply.error=htonl(0);
+
+ while(1){
+
+ if(read(sk,&request,sizeof(request))!=sizeof(request)){
+ fprintf(stderr,"%s: incomplete request\n",argv[0]);
+ }
+
+ memcpy(reply.handle,request.handle,sizeof(reply.handle));
+
+ len=ntohl(request.len);
+ from=ntohll(request.from);
+
+#ifdef TRACE
+fprintf(stderr,"%s: len=%d, from=%Ld\n",argv[0],len,from);
+#endif
+
+ if(request.magic!=htonl(NBD_REQUEST_MAGIC)){
+ fprintf(stderr,"%s: bad magic\n",argv[0]);
+ reply.error=htonl(EIO); /* is that the right way of doing things ? */
+ }
+
+ if(ntohl(request.type)){
+ fprintf(stderr,"%s: unsupported write request\n",argv[0]);
+ reply.error=htonl(EROFS);
+ }
+
+ if(len+sizeof(struct nbd_reply)>CHUNK){
+ fprintf(stderr,"%s: request too long\n",argv[0]);
+ reply.error=htonl(EIO);
+ }
+
+ if(len+from>size){
+ fprintf(stderr,"%s: request outside range\n",argv[0]);
+ reply.error=htonl(EIO);
+ }
+
+ if(reply.error==htonl(0)){
+ gzseek(gz,from,0);
+ if(gzread(gz,chunk+sizeof(struct nbd_reply),len)!=len){
+ fprintf(stderr,"%s: unable to read\n",argv[0]);
+ reply.error=htonl(EIO);
+ len=0;
+ }
+ } else {
+ len=0;
+ }
+
+ memcpy(chunk,&reply,sizeof(struct nbd_reply));
+ if(write(sk,chunk,len+sizeof(struct nbd_reply))!=(len+sizeof(struct nbd_reply))){
+ fprintf(stderr,"%s: write failed: %s\n",argv[0],strerror(errno));
+ }
+ }
+
+ gzclose(gz);
+
+ return 0;
+}
projects / nbd.git / commitdiff