From a68eb730558fb90bc8d9524564d8f9e58f3ccac1 Mon Sep 17 00:00:00 2001 From: David Oberhollenzer Date: Mon, 7 Oct 2019 11:20:55 +0200 Subject: Improve ABI backward & forward compatibillity - Padd the compressor config union - 128 bytes aught to be enough for everyone, i.e. future compressors. - Insist that the padding space is initialized to 0. If a field gets added to an existing compressor, it can test for 0 as a sentinel value. - Add a size field to the hook structure, aka "the Microsoft way". - The explanation is in the comment. - Don't make the Microsoft mistake of checking for >=, insist on *exact* size match. Future users will need a fallback if their hooks are rejected. But at least they will be rejected instead of silently not being used. - Add an unsupported flag check to the dir tree reader. - Add a basic abi unit test that, for now, checks the size of the compressor config struct fields. Signed-off-by: David Oberhollenzer --- lib/sqfs/data_writer/common.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'lib/sqfs/data_writer/common.c') diff --git a/lib/sqfs/data_writer/common.c b/lib/sqfs/data_writer/common.c index 059ef41..a19eb6d 100644 --- a/lib/sqfs/data_writer/common.c +++ b/lib/sqfs/data_writer/common.c @@ -157,9 +157,13 @@ int sqfs_data_writer_write_fragment_table(sqfs_data_writer_t *proc, return 0; } -void sqfs_data_writer_set_hooks(sqfs_data_writer_t *proc, void *user_ptr, - const sqfs_block_hooks_t *hooks) +int sqfs_data_writer_set_hooks(sqfs_data_writer_t *proc, void *user_ptr, + const sqfs_block_hooks_t *hooks) { + if (hooks->size != sizeof(*hooks)) + return SQFS_ERROR_UNSUPPORTED; + proc->hooks = hooks; proc->user_ptr = user_ptr; + return 0; } -- cgit v1.2.3