From fc9f632a219decea427271dc5a77654f6aaa9610 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 14 Aug 2018 21:37:02 +0200 Subject: [PATCH] passthrough_ll: add *xattr() operations The extended attribute functionality is enabled with the "xattr" option (default) and disabled with the "no_xatt" option. New operations added: - getxattr - listxattr - setxattr - removexattr Caveat: none of these operations will work on a symbolic link, because it's difficult to implement that without races that can result in incorrect operation. Signed-off-by: Miklos Szeredi --- example/passthrough_ll.c | 186 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 186 insertions(+) diff --git a/example/passthrough_ll.c b/example/passthrough_ll.c index ba0f4af..c46057d 100644 --- a/example/passthrough_ll.c +++ b/example/passthrough_ll.c @@ -52,6 +52,7 @@ #include #include #include +#include /* We are re-using pointers to our `struct lo_inode` and `struct lo_dirp` elements as inodes. This means that we must be able to @@ -81,6 +82,7 @@ struct lo_data { int debug; int writeback; int flock; + int xattr; const char *source; struct lo_inode root; /* protected by lo->mutex */ }; @@ -96,6 +98,10 @@ static const struct fuse_opt lo_opts[] = { offsetof(struct lo_data, flock), 1 }, { "no_flock", offsetof(struct lo_data, flock), 0 }, + { "xattr", + offsetof(struct lo_data, xattr), 1 }, + { "no_xattr", + offsetof(struct lo_data, xattr), 0 }, FUSE_OPT_END }; @@ -910,6 +916,182 @@ static void lo_flock(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, fuse_reply_err(req, res == -1 ? errno : 0); } +static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name, + size_t size) +{ + char *value = NULL; + char procname[64]; + struct lo_inode *inode = lo_inode(req, ino); + ssize_t ret; + int saverr; + + saverr = ENOSYS; + if (!lo_data(req)->xattr) + goto out; + + if (lo_debug(req)) { + fprintf(stderr, "lo_getxattr(ino=%" PRIu64 ", name=%s size=%zd)\n", + ino, name, size); + } + + if (inode->is_symlink) { + /* Sorry, no race free way to getxattr on symlink. */ + saverr = EPERM; + goto out; + } + + sprintf(procname, "/proc/self/fd/%i", inode->fd); + + if (size) { + value = malloc(size); + if (!value) + goto out_err; + + ret = getxattr(procname, name, value, size); + if (ret == -1) + goto out_err; + saverr = 0; + if (ret == 0) + goto out; + + fuse_reply_buf(req, value, ret); + } else { + ret = getxattr(procname, name, NULL, 0); + if (ret == -1) + goto out_err; + + fuse_reply_xattr(req, ret); + } +out_free: + free(value); + return; + +out_err: + saverr = errno; +out: + fuse_reply_err(req, saverr); + goto out_free; +} + +static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) +{ + char *value = NULL; + char procname[64]; + struct lo_inode *inode = lo_inode(req, ino); + ssize_t ret; + int saverr; + + saverr = ENOSYS; + if (!lo_data(req)->xattr) + goto out; + + if (lo_debug(req)) { + fprintf(stderr, "lo_listxattr(ino=%" PRIu64 ", size=%zd)\n", + ino, size); + } + + if (inode->is_symlink) { + /* Sorry, no race free way to listxattr on symlink. */ + saverr = EPERM; + goto out; + } + + sprintf(procname, "/proc/self/fd/%i", inode->fd); + + if (size) { + value = malloc(size); + if (!value) + goto out_err; + + ret = listxattr(procname, value, size); + if (ret == -1) + goto out_err; + saverr = 0; + if (ret == 0) + goto out; + + fuse_reply_buf(req, value, ret); + } else { + ret = listxattr(procname, NULL, 0); + if (ret == -1) + goto out_err; + + fuse_reply_xattr(req, ret); + } +out_free: + free(value); + return; + +out_err: + saverr = errno; +out: + fuse_reply_err(req, saverr); + goto out_free; +} + +static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name, + const char *value, size_t size, int flags) +{ + char procname[64]; + struct lo_inode *inode = lo_inode(req, ino); + ssize_t ret; + int saverr; + + saverr = ENOSYS; + if (!lo_data(req)->xattr) + goto out; + + if (lo_debug(req)) { + fprintf(stderr, "lo_setxattr(ino=%" PRIu64 ", name=%s value=%s size=%zd)\n", + ino, name, value, size); + } + + if (inode->is_symlink) { + /* Sorry, no race free way to setxattr on symlink. */ + saverr = EPERM; + goto out; + } + + sprintf(procname, "/proc/self/fd/%i", inode->fd); + + ret = setxattr(procname, name, value, size, flags); + saverr = ret == -1 ? errno : 0; + +out: + fuse_reply_err(req, saverr); +} + +static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name) +{ + char procname[64]; + struct lo_inode *inode = lo_inode(req, ino); + ssize_t ret; + int saverr; + + saverr = ENOSYS; + if (!lo_data(req)->xattr) + goto out; + + if (lo_debug(req)) { + fprintf(stderr, "lo_removexattr(ino=%" PRIu64 ", name=%s)\n", + ino, name); + } + + if (inode->is_symlink) { + /* Sorry, no race free way to setxattr on symlink. */ + saverr = EPERM; + goto out; + } + + sprintf(procname, "/proc/self/fd/%i", inode->fd); + + ret = removexattr(procname, name); + saverr = ret == -1 ? errno : 0; + +out: + fuse_reply_err(req, saverr); +} + static struct fuse_lowlevel_ops lo_oper = { .init = lo_init, .lookup = lo_lookup, @@ -940,6 +1122,10 @@ static struct fuse_lowlevel_ops lo_oper = { .statfs = lo_statfs, .fallocate = lo_fallocate, .flock = lo_flock, + .getxattr = lo_getxattr, + .listxattr = lo_listxattr, + .setxattr = lo_setxattr, + .removexattr = lo_removexattr, }; int main(int argc, char *argv[]) -- 2.30.2