bionic works around the fact that you can't use an O_PATH fd with fgetxattr(2), but glibc doesn't.
Fixes https://github.com/landley/toybox/issues/158. --- toys/posix/ls.c | 28 ++++++---------------------- 1 file changed, 6 insertions(+), 22 deletions(-)
From 8168cdb84ecd014a9029a637b6ce8f0895eaa2bc Mon Sep 17 00:00:00 2001 From: Elliott Hughes <[email protected]> Date: Wed, 8 Jan 2020 14:23:34 -0800 Subject: [PATCH] ls.c: just use getxattr()/lgetxattr(). bionic works around the fact that you can't use an O_PATH fd with fgetxattr(2), but glibc doesn't. Fixes https://github.com/landley/toybox/issues/158. --- toys/posix/ls.c | 28 ++++++---------------------- 1 file changed, 6 insertions(+), 22 deletions(-) diff --git a/toys/posix/ls.c b/toys/posix/ls.c index 8bf9f693..9b382590 100644 --- a/toys/posix/ls.c +++ b/toys/posix/ls.c @@ -187,29 +187,13 @@ static int filter(struct dirtree *new) if (FLAG(Z)) { if (!CFG_TOYBOX_LSM_NONE) { + // Linux doesn't support fgetxattr(2) on O_PATH file descriptors (though + // bionic works around that), and there are no *xattrat(2) calls, so we + // just use lgetxattr(2). + char *path = dirtree_path(new, 0); - // (Wouldn't it be nice if the lsm functions worked like openat(), - // fchmodat(), mknodat(), readlinkat() so we could do this without - // even O_PATH? But no, this is 1990's tech.) - int fd = openat(dirtree_parentfd(new), new->name, - O_PATH|(O_NOFOLLOW*!FLAG(L))); - - if (fd != -1) { - if (-1 == lsm_fget_context(fd, (char **)&new->extra) && errno == EBADF) - { - char hack[32]; - - // Work around kernel bug that won't let us read this "metadata" from - // the filehandle unless we have permission to read the data. (We can - // query the same data in by path, but can't do it through an O_PATH - // filehandle, because reasons. But for some reason, THIS is ok? If - // they ever fix the kernel, this should stop triggering.) - - sprintf(hack, "/proc/self/fd/%d", fd); - lsm_lget_context(hack, (char **)&new->extra); - } - close(fd); - } + (FLAG(L) ? lsm_get_context : lsm_lget_context)(path,(char **)&new->extra); + free(path); } if (CFG_TOYBOX_LSM_NONE || !new->extra) new->extra = (long)xstrdup("?"); } -- 2.25.0.rc1.283.g88dfdc4193-goog
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