Exemplo n.º 1
0
int mnt_context_setup_loopdev(struct libmnt_context *cxt)
{
	const char *backing_file, *optstr, *loopdev = NULL;
	char *val = NULL;
	size_t len;
	struct loopdev_cxt lc;
	int rc = 0, lo_flags = 0;
	uint64_t offset = 0, sizelimit = 0;

	assert(cxt->fs);
	assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));

	if (!cxt)
		return -EINVAL;

	backing_file = mnt_fs_get_srcpath(cxt->fs);
	if (!backing_file)
		return -EINVAL;

	DBG(CXT, ul_debugobj(cxt, "trying to setup loopdev for %s", backing_file));

	if (cxt->mountflags & MS_RDONLY) {
		DBG(CXT, ul_debugobj(cxt, "enabling READ-ONLY flag"));
		lo_flags |= LO_FLAGS_READ_ONLY;
	}

	rc = loopcxt_init(&lc, 0);
	if (rc)
		return rc;

	ON_DBG(CXT, loopcxt_enable_debug(&lc, 1));

	optstr = mnt_fs_get_user_options(cxt->fs);

	/*
	 * loop=
	 */
	if (rc == 0 && (cxt->user_mountflags & MNT_MS_LOOP) &&
	    mnt_optstr_get_option(optstr, "loop", &val, &len) == 0 && val) {

		val = strndup(val, len);
		rc = val ? loopcxt_set_device(&lc, val) : -ENOMEM;
		free(val);

		if (rc == 0)
			loopdev = loopcxt_get_device(&lc);
	}

	/*
	 * offset=
	 */
	if (rc == 0 && (cxt->user_mountflags & MNT_MS_OFFSET) &&
	    mnt_optstr_get_option(optstr, "offset", &val, &len) == 0) {
		rc = mnt_parse_offset(val, len, &offset);
		if (rc) {
			DBG(CXT, ul_debugobj(cxt, "failed to parse offset="));
			rc = -MNT_ERR_MOUNTOPT;
		}
	}

	/*
	 * sizelimit=
	 */
	if (rc == 0 && (cxt->user_mountflags & MNT_MS_SIZELIMIT) &&
	    mnt_optstr_get_option(optstr, "sizelimit", &val, &len) == 0) {
		rc = mnt_parse_offset(val, len, &sizelimit);
		if (rc) {
			DBG(CXT, ul_debugobj(cxt, "failed to parse sizelimit="));
			rc = -MNT_ERR_MOUNTOPT;
		}
	}

	/*
	 * encryption=
	 */
	if (rc == 0 && (cxt->user_mountflags & MNT_MS_ENCRYPTION) &&
	    mnt_optstr_get_option(optstr, "encryption", &val, &len) == 0) {
		DBG(CXT, ul_debugobj(cxt, "encryption no longer supported"));
		rc = -MNT_ERR_MOUNTOPT;
	}

	if (rc == 0 && is_mounted_same_loopfile(cxt,
				mnt_context_get_target(cxt),
				backing_file, offset))
		rc = -EBUSY;

	if (rc)
		goto done;

	/* since 2.6.37 we don't have to store backing filename to mtab
	 * because kernel provides the name in /sys.
	 */
	if (get_linux_version() >= KERNEL_VERSION(2, 6, 37) ||
	    !mnt_context_mtab_writable(cxt)) {
		DBG(CXT, ul_debugobj(cxt, "enabling AUTOCLEAR flag"));
		lo_flags |= LO_FLAGS_AUTOCLEAR;
	}

	do {
		/* found free device */
		if (!loopdev) {
			rc = loopcxt_find_unused(&lc);
			if (rc)
				goto done;
			DBG(CXT, ul_debugobj(cxt, "trying to use %s",
						loopcxt_get_device(&lc)));
		}

		/* set device attributes
		 * -- note that loopcxt_find_unused() resets "lc"
		 */
		rc = loopcxt_set_backing_file(&lc, backing_file);

		if (!rc && offset)
			rc = loopcxt_set_offset(&lc, offset);
		if (!rc && sizelimit)
			rc = loopcxt_set_sizelimit(&lc, sizelimit);
		if (!rc)
			loopcxt_set_flags(&lc, lo_flags);
		if (rc) {
			DBG(CXT, ul_debugobj(cxt, "failed to set loopdev attributes"));
			goto done;
		}

		/* setup the device */
		rc = loopcxt_setup_device(&lc);
		if (!rc)
			break;		/* success */

		if (loopdev || rc != -EBUSY) {
			DBG(CXT, ul_debugobj(cxt, "failed to setup device"));
			rc = -MNT_ERR_LOOPDEV;
			goto done;
		}
		DBG(CXT, ul_debugobj(cxt, "loopdev stolen...trying again"));
	} while (1);

	if (!rc)
		rc = mnt_fs_set_source(cxt->fs, loopcxt_get_device(&lc));

	if (!rc) {
		/* success */
		cxt->flags |= MNT_FL_LOOPDEV_READY;

		if ((cxt->user_mountflags & MNT_MS_LOOP) &&
		    loopcxt_is_autoclear(&lc)) {
			/*
			 * autoclear flag accepted by the kernel, don't store
			 * the "loop=" option to mtab.
			 */
			cxt->user_mountflags &= ~MNT_MS_LOOP;
			mnt_optstr_remove_option(&cxt->fs->user_optstr, "loop");
		}

		if (!(cxt->mountflags & MS_RDONLY) &&
		    loopcxt_is_readonly(&lc))
			/*
			 * mount planned read-write, but loopdev is read-only,
			 * let's fix mount options...
			 */
			mnt_context_set_mflags(cxt, cxt->mountflags | MS_RDONLY);

		/* we have to keep the device open until mount(1),
		 * otherwise it will be auto-cleared by kernel
		 */
		cxt->loopdev_fd = loopcxt_get_fd(&lc);
		loopcxt_set_fd(&lc, -1, 0);
	}
done:
	loopcxt_deinit(&lc);
	return rc;
}
Exemplo n.º 2
0
int mnt_context_setup_loopdev(struct libmnt_context *cxt)
{
	const char *backing_file, *optstr, *loopdev = NULL;
	char *val = NULL, *loopval = NULL;
	size_t len;
	struct loopdev_cxt lc;
	int rc = 0, lo_flags = 0;
	uint64_t offset = 0, sizelimit = 0;

	assert(cxt);
	assert(cxt->fs);
	assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));

	backing_file = mnt_fs_get_srcpath(cxt->fs);
	if (!backing_file)
		return -EINVAL;

	DBG(LOOP, ul_debugobj(cxt, "trying to setup device for %s", backing_file));

	if (cxt->mountflags & MS_RDONLY) {
		DBG(LOOP, ul_debugobj(cxt, "enabling READ-ONLY flag"));
		lo_flags |= LO_FLAGS_READ_ONLY;
	}

	optstr = mnt_fs_get_user_options(cxt->fs);

	/*
	 * loop=
	 */
	if (rc == 0 && (cxt->user_mountflags & MNT_MS_LOOP) &&
	    mnt_optstr_get_option(optstr, "loop", &val, &len) == 0 && val) {
		loopval = strndup(val, len);
		rc = loopval ? 0 : -ENOMEM;
	}

	/*
	 * offset=
	 */
	if (rc == 0 && (cxt->user_mountflags & MNT_MS_OFFSET) &&
	    mnt_optstr_get_option(optstr, "offset", &val, &len) == 0) {
		rc = mnt_parse_offset(val, len, &offset);
		if (rc) {
			DBG(LOOP, ul_debugobj(cxt, "failed to parse offset="));
			rc = -MNT_ERR_MOUNTOPT;
		}
	}

	/*
	 * sizelimit=
	 */
	if (rc == 0 && (cxt->user_mountflags & MNT_MS_SIZELIMIT) &&
	    mnt_optstr_get_option(optstr, "sizelimit", &val, &len) == 0) {
		rc = mnt_parse_offset(val, len, &sizelimit);
		if (rc) {
			DBG(LOOP, ul_debugobj(cxt, "failed to parse sizelimit="));
			rc = -MNT_ERR_MOUNTOPT;
		}
	}

	/*
	 * encryption=
	 */
	if (rc == 0 && (cxt->user_mountflags & MNT_MS_ENCRYPTION) &&
	    mnt_optstr_get_option(optstr, "encryption", &val, &len) == 0) {
		DBG(LOOP, ul_debugobj(cxt, "encryption no longer supported"));
		rc = -MNT_ERR_MOUNTOPT;
	}

	if (rc == 0 && is_mounted_same_loopfile(cxt,
				mnt_context_get_target(cxt),
				backing_file, offset))
		rc = -EBUSY;

	if (rc)
		goto done_no_deinit;

	/* It is possible to mount the same file more times. If we set more
	 * than one loop device referring to the same file, kernel has no
	 * mechanism to detect it. To prevent data corruption, the same loop
	 * device has to be recycled.
	*/
	if (backing_file) {
		rc = loopcxt_init(&lc, 0);
		if (rc)
			goto done_no_deinit;

		rc = loopcxt_find_overlap(&lc, backing_file, offset, sizelimit);
		switch (rc) {
		case 0: /* not found */
			DBG(LOOP, ul_debugobj(cxt, "not found overlaping loopdev"));
			loopcxt_deinit(&lc);
			break;

		case 1:	/* overlap */
			DBG(LOOP, ul_debugobj(cxt, "overlaping %s detected",
						loopcxt_get_device(&lc)));
			rc = -MNT_ERR_LOOPOVERLAP;
			goto done;

		case 2: /* overlap -- full size and offset match (reuse) */
		{
			uint32_t lc_encrypt_type;

			DBG(LOOP, ul_debugobj(cxt, "re-using existing loop device %s",
				loopcxt_get_device(&lc)));

			/* Once a loop is initialized RO, there is no
			 * way to change its parameters. */
			if (loopcxt_is_readonly(&lc)
			    && !(lo_flags & LO_FLAGS_READ_ONLY)) {
				DBG(LOOP, ul_debugobj(cxt, "%s is read-only",
						loopcxt_get_device(&lc)));
				rc = -EROFS;
				goto done;
			}

			/* This is no more supported, but check to be safe. */
			if (loopcxt_get_encrypt_type(&lc, &lc_encrypt_type) == 0
			    && lc_encrypt_type != LO_CRYPT_NONE) {
				DBG(LOOP, ul_debugobj(cxt, "encryption no longer supported for device %s",
					loopcxt_get_device(&lc)));
				rc = -MNT_ERR_LOOPOVERLAP;
				goto done;
			}
			rc = 0;
			goto success;
		}
		default: /* error */
			goto done;
		}
	}

	DBG(LOOP, ul_debugobj(cxt, "not found; create a new loop device"));
	rc = loopcxt_init(&lc, 0);
	if (rc)
		goto done_no_deinit;
	if (loopval) {
		rc = loopcxt_set_device(&lc, loopval);
		if (rc == 0)
			loopdev = loopcxt_get_device(&lc);
	}
	if (rc)
		goto done;

	/* since 2.6.37 we don't have to store backing filename to mtab
	 * because kernel provides the name in /sys.
	 */
	if (get_linux_version() >= KERNEL_VERSION(2, 6, 37) ||
	    !mnt_context_mtab_writable(cxt)) {
		DBG(LOOP, ul_debugobj(cxt, "enabling AUTOCLEAR flag"));
		lo_flags |= LO_FLAGS_AUTOCLEAR;
	}

	do {
		/* found free device */
		if (!loopdev) {
			rc = loopcxt_find_unused(&lc);
			if (rc)
				goto done;
			DBG(LOOP, ul_debugobj(cxt, "trying to use %s",
						loopcxt_get_device(&lc)));
		}

		/* set device attributes
		 * -- note that loopcxt_find_unused() resets "lc"
		 */
		rc = loopcxt_set_backing_file(&lc, backing_file);

		if (!rc && offset)
			rc = loopcxt_set_offset(&lc, offset);
		if (!rc && sizelimit)
			rc = loopcxt_set_sizelimit(&lc, sizelimit);
		if (!rc)
			loopcxt_set_flags(&lc, lo_flags);
		if (rc) {
			DBG(LOOP, ul_debugobj(cxt, "failed to set loop attributes"));
			goto done;
		}

		/* setup the device */
		rc = loopcxt_setup_device(&lc);
		if (!rc)
			break;		/* success */

		if (loopdev || rc != -EBUSY) {
			DBG(LOOP, ul_debugobj(cxt, "failed to setup device"));
			rc = -MNT_ERR_LOOPDEV;
			goto done;
		}
		DBG(LOOP, ul_debugobj(cxt, "device stolen...trying again"));
	} while (1);

success:
	if (!rc)
		rc = mnt_fs_set_source(cxt->fs, loopcxt_get_device(&lc));

	if (!rc) {
		/* success */
		cxt->flags |= MNT_FL_LOOPDEV_READY;

		if ((cxt->user_mountflags & MNT_MS_LOOP) &&
		    loopcxt_is_autoclear(&lc)) {
			/*
			 * autoclear flag accepted by the kernel, don't store
			 * the "loop=" option to mtab.
			 */
			DBG(LOOP, ul_debugobj(cxt, "removing unnecessary loop= from mtab"));
			cxt->user_mountflags &= ~MNT_MS_LOOP;
			mnt_optstr_remove_option(&cxt->fs->user_optstr, "loop");
		}

		if (!(cxt->mountflags & MS_RDONLY) &&
		    loopcxt_is_readonly(&lc))
			/*
			 * mount planned read-write, but loopdev is read-only,
			 * let's fix mount options...
			 */
			mnt_context_set_mflags(cxt, cxt->mountflags | MS_RDONLY);

		/* we have to keep the device open until mount(1),
		 * otherwise it will be auto-cleared by kernel
		 */
		cxt->loopdev_fd = loopcxt_get_fd(&lc);
		if (cxt->loopdev_fd < 0) {
			DBG(LOOP, ul_debugobj(cxt, "failed to get loopdev FD"));
			rc = -errno;
		} else
			loopcxt_set_fd(&lc, -1, 0);
	}
done:
	loopcxt_deinit(&lc);
done_no_deinit:
	free(loopval);
	return rc;
}
Exemplo n.º 3
0
int mnt_context_setup_loopdev(struct libmnt_context *cxt)
{
	const char *backing_file;
	char *loopdev = NULL;
	size_t len;
	struct loopdev_cxt lc;
	int rc, lo_flags = 0;

	assert(cxt);
	assert(cxt->fs);
	assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));

	backing_file = mnt_fs_get_srcpath(cxt->fs);
	if (!backing_file)
		return -EINVAL;

	DBG(CXT, mnt_debug_h(cxt, "trying to setup loopdev for %s", backing_file));

	if (cxt->mountflags & MS_RDONLY) {
		DBG(CXT, mnt_debug_h(cxt, "enabling READ-ONLY flag"));
		lo_flags |= LO_FLAGS_READ_ONLY;
	}
	loopcxt_init(&lc, 0);

	
	if ((cxt->user_mountflags & MNT_MS_LOOP) &&
	    mnt_fs_get_option(cxt->fs, "loop", &loopdev, &len) == 0 && loopdev) {

		char *tmp = strndup(loopdev, len);
		if (!tmp)
			rc = -ENOMEM;
		else {
			rc = loopcxt_set_device(&lc, tmp);
			free(tmp);
		}
	}

	/* since 2.6.37 we don't have to store backing filename to mtab
	 * because kernel provides the name in /sys.
	 */
	if (get_linux_version() >= KERNEL_VERSION(2, 6, 37) ||
	    !cxt->mtab_writable) {
		DBG(CXT, mnt_debug_h(cxt, "enabling AUTOCLEAR flag"));
		lo_flags |= LO_FLAGS_AUTOCLEAR;
	}

	do {
		/* found free device */
		if (!loopdev) {
			rc = loopcxt_find_unused(&lc);
			if (rc)
				goto done;
			DBG(CXT, mnt_debug_h(cxt, "trying to use %s",
						loopcxt_get_device(&lc)));
		}

		/* set device attributes */
		rc = loopcxt_set_backing_file(&lc, backing_file);
		if (rc)
			goto done;

		loopcxt_set_flags(&lc, lo_flags);

		/* setup the device */
		rc = loopcxt_setup_device(&lc);
		if (!rc)
			break;		/* success */

		if (loopdev || rc != -EBUSY) {
			DBG(CXT, mnt_debug_h(cxt, "failed to setup device"));
			break;
		}
		DBG(CXT, mnt_debug_h(cxt, "loopdev stolen...trying again"));
	} while (1);

	if (!rc)
		rc = mnt_fs_set_source(cxt->fs, loopcxt_get_device(&lc));

	if (!rc) {
		/* success */
		cxt->flags |= MNT_FL_LOOPDEV_READY;

		if ((cxt->user_mountflags & MNT_MS_LOOP) &&
		    loopcxt_is_autoclear(&lc))
			/*
			 * autoclear flag accepted by kernel, don't store
			 * the "loop=" option to mtab.
			 */
			cxt->user_mountflags &= ~MNT_MS_LOOP;

		if (!(cxt->mountflags & MS_RDONLY) &&
		    loopcxt_is_readonly(&lc))
			/*
			 * mount planned read-write, but loopdev is read-only,
			 * let's fix mount options...
			 */
			cxt->mountflags |= MS_RDONLY;


		/* we have to keep the device open until mount(1),
		 * otherwise it will auto-cleared by kernel
		 */
		cxt->loopdev_fd = loopcxt_get_fd(&lc);
		loopcxt_set_fd(&lc, -1, 0);
	}
done:
	loopcxt_deinit(&lc);
	return rc;
}