On 17 Aug 2016 10:47, Jeff Layton wrote: > The Linux kernel expects a flock64 structure whenever you use OFD locks > with fcntl64. Unfortunately, you can currently build a 32-bit program > that passes in a struct flock when it calls fcntl64. > > Only define the F_OFD_* constants when __USE_FILE_OFFSET64 is also > defined, so that the build fails in this situation rather than > producing a broken binary. this seems to be going against the glibc API/guarantees we've provided before (or at least tried to promise), and what the fcntl(2) man page says now. namely, we haven't documented F_GETLK64 or struct flock64, with the expectation that the user just calls fcntl() with a struct flock. in fact, the man page even goes so far as to discourage people from using the *64 variants. it should be possible using our existing LFS framework to make the OFD cmds available even to 32-bit apps (where sizeof(off_t) == 32). but maybe the usage of F_GETLK64/struct flock64/etc... in the real world has made it hard to put that genie back in the bottle ? we'd have to version the current fcntl symbol, create a new fcntl symbol that does 32->64 munging, and add a new fcntl64 symbol that we'd transparently rewrite to when LFS is turned on. -mike
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