configure.ac: check for xattr support both in libc and in -lattr #753
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In 2015, the attr/xattr.h header was fully removed from upstream attr. In 2020, rsync started preferring the standard header, if it exists: RsyncProject#22 But the fix was incomplete. We still looked for the getxattr function in -lattr, and used it if -lattr exists. This was the case even if the system libc was sufficient to provide the needed functions. Result: overlinking to -lattr, if it happened to be installed for any other reason. ``` checking whether to support extended attributes... Using Linux xattrs checking for getxattr in -lattr... yes ``` Instead, use a different autoconf macro that first checks if the function is available for use without any libraries (e.g. it is in libc). Result: ``` checking whether to support extended attributes... Using Linux xattrs checking for library containing getxattr... none required ``` Signed-off-by: Eli Schwartz <[email protected]>
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When USE=xattr is enabled, the configure script checks for -lattr and attempts to link to it for good luck. It also checks for attr/xattr.h, but only includes it in an if/elif when sys/xattr.h doesn't exist -- this makes sense, since the former simply #includes the latter and then emits a #warning telling you to migrate to libc. Presumably, this is meant as a sort of infinite compatibility thing and "it's fine if you use --as-needed" in practice. rsync doesn't actually include any of libattr's non-deprecated headers, just xattr.h and at runtime libattr.so is not needed despite automagically detecting it during configure. Upstream fix for false detection: RsyncProject/rsync#753 Fixes: ``` * VDB: detected possibly incorrect RDEPEND (net-misc/rsync-3.3.0-r2) * sys-apps/attr < ``` No revbump, this package won't be depcleaned anyway so forcing a rebuild feels pointless. Signed-off-by: Eli Schwartz <[email protected]>
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In 2015, the attr/xattr.h header was fully removed from upstream attr.
In 2020, rsync started preferring the standard header, if it exists: #22
But the fix was incomplete. We still looked for the getxattr function in -lattr, and used it if -lattr exists. This was the case even if the system libc was sufficient to provide the needed functions. Result: overlinking to -lattr, if it happened to be installed for any other reason.
Instead, use a different autoconf macro that first checks if the function is available for use without any libraries (e.g. it is in libc).
Result: