diff --git a/Makefile b/Makefile index 31b5966..2859ef4 100644 --- a/Makefile +++ b/Makefile @@ -1,4 +1,4 @@ -TARGET := busexmp +TARGET := busexmp loopback LIBOBJS := buse.o OBJS := $(TARGET:=.o) $(LIBOBJS) STATIC_LIB := libbuse.a diff --git a/buse.c b/buse.c index db2dedb..3992cd3 100644 --- a/buse.c +++ b/buse.c @@ -132,7 +132,7 @@ int buse_main(int argc, char *argv[], const struct buse_operations *aop, void *u * and writes. */ case NBD_CMD_READ: - fprintf(stderr, "Request for read of size %d\n", len); + /* fprintf(stderr, "Request for read of size %d\n", len); */ chunk = malloc(len + sizeof(struct nbd_reply)); aop->read((char *)chunk + sizeof(struct nbd_reply), len, from); memcpy(chunk, &reply, sizeof(struct nbd_reply)); @@ -140,7 +140,7 @@ int buse_main(int argc, char *argv[], const struct buse_operations *aop, void *u free(chunk); break; case NBD_CMD_WRITE: - fprintf(stderr, "Request for write of size %d\n", len); + /* fprintf(stderr, "Request for write of size %d\n", len); */ chunk = malloc(len); read_all(sk, chunk, len); aop->write(chunk, len, from); diff --git a/loopback.c b/loopback.c new file mode 100644 index 0000000..86179e0 --- /dev/null +++ b/loopback.c @@ -0,0 +1,84 @@ +#define _GNU_SOURCE +#define _LARGEFILE64_SOURCE + +#include +#include +#include +#include +#include +#include +#include + +#include "buse.h" + +static int fd; + +static void usage(void) +{ + fprintf(stderr, "Usage: loopback \n"); +} + +static int loopback_read(void *buf, u_int32_t len, u_int64_t offset) +{ + int bytes_read; + + lseek64(fd, offset, SEEK_SET); + while (len > 0) { + bytes_read = read(fd, buf, len); + assert(bytes_read > 0); + len -= bytes_read; + buf = (char *) buf + bytes_read; + } + + return 0; +} + +static int loopback_write(const void *buf, u_int32_t len, u_int64_t offset) +{ + int bytes_written; + + lseek64(fd, offset, SEEK_SET); + while (len > 0) { + bytes_written = write(fd, buf, len); + assert(bytes_written > 0); + len -= bytes_written; + buf = (char *) buf + bytes_written; + } + + return 0; +} + +static struct buse_operations bop = { + .read = loopback_read, + .write = loopback_write +}; + +int main(int argc, char *argv[]) +{ + struct stat buf; + int err; + int64_t size; + + if (argc != 3) { + usage(); + return -1; + } + + fd = open(argv[1], O_RDWR|O_LARGEFILE); + assert(fd != -1); + + /* Let's verify that this file is actually a block device. We could support + * regular files, too, but we don't need to right now. */ + fstat(fd, &buf); + assert(S_ISBLK(buf.st_mode)); + + /* Figure out the size of the underlying block device. */ + err = ioctl(fd, BLKGETSIZE64, &size); + assert(err != -1); + fprintf(stderr, "The size of this device is %ld bytes.\n", size); + bop.size = size; + + buse_main(argc, argv, &bop, NULL); + + return 0; +}