diff options
| -rw-r--r-- | toys/posix/ls.c | 32 |
1 files changed, 21 insertions, 11 deletions
diff --git a/toys/posix/ls.c b/toys/posix/ls.c index 84149e41..6429ce60 100644 --- a/toys/posix/ls.c +++ b/toys/posix/ls.c @@ -181,24 +181,34 @@ static int filter(struct dirtree *new) if (flags & FLAG_Z) { if (!CFG_TOYBOX_LSM_NONE) { - // In theory we can just openat(O_PATH|O_NOFOLLOW) and getcontext() on - // that filehandle, but the kernel won't let us read this "metadata" - // unless we have permission to read the data, so we do these elaborate - // bug workarounds instead. - if (S_ISLNK(new->st.st_mode) && !(toys.optflags & FLAG_L)) { + int fd; + + // Why not just openat(O_PATH|(O_NOFOLLOW*!!(toys.optflags&FLAG_L))) and + // lsm_fget_context() on that filehandle? Because the kernel is broken, + // and won't let us read this "metadata" from the filehandle unless we + // have permission to read the data. We _can_ read the same data in + // by path, we just can't do it through an O_PATH filehandle, because + // reasons. So as a bug workaround for the broken kernel, we do it + // both ways. + // + // The O_NONBLOCK is there to avoid triggering automounting (there's + // a rush of nostalgia for you) on directories we don't descend into, + // which O_PATH would have done for us but see "the kernel is broken". + if (S_ISSOCK(new->st.st_mode) || + (S_ISLNK(new->st.st_mode) && !(toys.optflags & FLAG_L)) || + -1 == (fd = openat(dirtree_parentfd(new), new->name, + O_RDONLY|O_NONBLOCK|O_NOATIME))) + { char *path; // Wouldn't it be nice if the lsm functions worked like openat(), - // fchmodat(), mknodat(), readlinkat()... but no, this is 1990's tech. + // fchmodat(), mknodat(), readlinkat() so we could do this without + // even O_PATH? But no, this is 1990's tech. path = dirtree_path(new, 0); lsm_lget_context(path, (char **)&new->extra); free(path); } else { - // Why O_NONBLOCK? No idea. Why not O_PATH|O_NOFOLLOW? Kernel's broken. - int fd = openat(dirtree_parentfd(new), new->name, - O_RDONLY|O_NONBLOCK|O_NOATIME); - - if (fd != -1) lsm_fget_context(fd, (char **)&new->extra); + lsm_fget_context(fd, (char **)&new->extra); close(fd); } } |