diff options
Diffstat (limited to 'lib')
-rw-r--r-- | lib/fuse_lowlevel.c | 64 |
1 files changed, 57 insertions, 7 deletions
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c index c7efc3d..baa6d2b 100644 --- a/lib/fuse_lowlevel.c +++ b/lib/fuse_lowlevel.c @@ -459,17 +459,67 @@ int fuse_reply_canonical_path(fuse_req_t req, const char *path) return send_reply_ok(req, path, strlen(path) + 1); } +enum { + FUSE_PASSTHROUGH_API_UNAVAILABLE, + FUSE_PASSTHROUGH_API_V0, + FUSE_PASSTHROUGH_API_V1, + FUSE_PASSTHROUGH_API_STABLE, +}; + +/* + * Requests the FUSE passthrough feature to be enabled on a specific file + * through the passed fd. + * This function returns an identifier that must be used as passthrough_fh + * when the open/create_open request reply is sent back to /dev/fuse. + * As for the current FUSE passthrough implementation, passthrough_fh values + * are only valid if > 0, so in case the FUSE passthrough open ioctl returns + * a value <= 0, this must be considered an error and is returned as-is by + * this function. + */ int fuse_passthrough_enable(fuse_req_t req, unsigned int fd) { - struct fuse_passthrough_out out = {}; - int ret; + static sig_atomic_t passthrough_version = FUSE_PASSTHROUGH_API_STABLE; + int ret = 0; /* values <= 0 represent errors in FUSE passthrough */ - out.fd = fd; + /* + * The interface of FUSE passthrough is still unstable in the kernel, + * so the following solution is to search for the most updated API + * version and, if not found, fall back to an older one. + * This happens when ioctl() returns -1 and errno is set to ENOTTY, + * an error code that corresponds to the lack of a specific ioctl. + */ + switch (passthrough_version) { + case FUSE_PASSTHROUGH_API_STABLE: + /* There is not a stable API yet */ + passthrough_version = FUSE_PASSTHROUGH_API_V1; + case FUSE_PASSTHROUGH_API_V1: { + struct fuse_passthrough_out_v0 out = {}; + out.fd = fd; + + ret = ioctl(req->se->fd, FUSE_DEV_IOC_PASSTHROUGH_OPEN_V1, &out); + if (ret == -1 && errno == ENOTTY) + passthrough_version = FUSE_PASSTHROUGH_API_V0; + else + break; + } + case FUSE_PASSTHROUGH_API_V0: { + struct fuse_passthrough_out_v0 out = {}; + out.fd = fd; - ret = ioctl(req->se->fd, FUSE_DEV_IOC_PASSTHROUGH_OPEN, &out); - if (ret <= 0) - fuse_log(FUSE_LOG_ERR, "fuse: passthrough_enable: %s\n", strerror(errno)); + ret = ioctl(req->se->fd, FUSE_DEV_IOC_PASSTHROUGH_OPEN_V0, &out); + if (ret == -1 && errno == ENOTTY) + passthrough_version = FUSE_PASSTHROUGH_API_UNAVAILABLE; + else + break; + } + default: + fuse_log(FUSE_LOG_ERR, "fuse: passthrough_enable no valid API\n"); + return -ENOTTY; + } + + if (ret <= 0) + fuse_log(FUSE_LOG_ERR, "fuse: passthrough_enable: %s\n", strerror(errno)); - return ret; + return ret; } int fuse_reply_open(fuse_req_t req, const struct fuse_file_info *f) |