From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 20 Feb 2018 11:46:14 +0000 (+0100)
Subject: xattr-util: support AT_EMPTY_PATH in fgetxattrat_fake()
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=4c5943104751a678b7ad886131806dd964618d2f;p=elogind.git

xattr-util: support AT_EMPTY_PATH in fgetxattrat_fake()

Let's expose fstatat() like behaviour if AT_EMPTY_PATH is defined.

Also, check the specified flags returning EINVAL on the flags we don't
emulate.
---

diff --git a/src/basic/xattr-util.c b/src/basic/xattr-util.c
index 1a309be2e..97387579d 100644
--- a/src/basic/xattr-util.c
+++ b/src/basic/xattr-util.c
@@ -31,6 +31,7 @@
 #include "macro.h"
 #include "sparse-endian.h"
 #include "stdio-util.h"
+//#include "string-util.h"
 #include "time-util.h"
 #include "xattr-util.h"
 
@@ -112,11 +113,21 @@ ssize_t fgetxattrat_fake(int dirfd, const char *filename, const char *attribute,
 
         /* The kernel doesn't have a fgetxattrat() command, hence let's emulate one */
 
-        fd = openat(dirfd, filename, O_CLOEXEC|O_PATH|(flags & AT_SYMLINK_NOFOLLOW ? O_NOFOLLOW : 0));
-        if (fd < 0)
-                return -errno;
+        if (flags & ~(AT_SYMLINK_NOFOLLOW|AT_EMPTY_PATH))
+                return -EINVAL;
+
+        if (isempty(filename)) {
+                if (!(flags & AT_EMPTY_PATH))
+                        return -EINVAL;
 
-        xsprintf(fn, "/proc/self/fd/%i", fd);
+                xsprintf(fn, "/proc/self/fd/%i", dirfd);
+        } else {
+                fd = openat(dirfd, filename, O_CLOEXEC|O_PATH|(flags & AT_SYMLINK_NOFOLLOW ? O_NOFOLLOW : 0));
+                if (fd < 0)
+                        return -errno;
+
+                xsprintf(fn, "/proc/self/fd/%i", fd);
+        }
 
         l = getxattr(fn, attribute, value, size);
         if (l < 0)