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authorDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2019-10-07 11:20:55 +0200
committerDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2019-10-07 12:22:05 +0200
commita68eb730558fb90bc8d9524564d8f9e58f3ccac1 (patch)
treede7a678b28786ec2e47e4956d8cdb0f4466f3d5c /lib/sqfs/comp/compressor.c
parentc7fdb2b305ed8b4deb67bfc6ef3257e7e6773397 (diff)
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 <david.oberhollenzer@sigma-star.at>
Diffstat (limited to 'lib/sqfs/comp/compressor.c')
-rw-r--r--lib/sqfs/comp/compressor.c30
1 files changed, 30 insertions, 0 deletions
diff --git a/lib/sqfs/comp/compressor.c b/lib/sqfs/comp/compressor.c
index bfc20b7..902ce92 100644
--- a/lib/sqfs/comp/compressor.c
+++ b/lib/sqfs/comp/compressor.c
@@ -87,12 +87,42 @@ bool sqfs_compressor_exists(E_SQFS_COMPRESSOR id)
sqfs_compressor_t *sqfs_compressor_create(const sqfs_compressor_config_t *cfg)
{
+ sqfs_u8 padd0[sizeof(cfg->opt)];
+ int ret;
+
if (cfg == NULL || cfg->id < SQFS_COMP_MIN || cfg->id > SQFS_COMP_MAX)
return NULL;
if (compressors[cfg->id] == NULL)
return NULL;
+ memset(padd0, 0, sizeof(padd0));
+
+ switch (cfg->id) {
+ case SQFS_COMP_XZ:
+ ret = memcmp(cfg->opt.xz.padd0, padd0,
+ sizeof(cfg->opt.xz.padd0));
+ break;
+ case SQFS_COMP_LZO:
+ ret = memcmp(cfg->opt.lzo.padd0, padd0,
+ sizeof(cfg->opt.lzo.padd0));
+ break;
+ case SQFS_COMP_ZSTD:
+ ret = memcmp(cfg->opt.zstd.padd0, padd0,
+ sizeof(cfg->opt.zstd.padd0));
+ break;
+ case SQFS_COMP_GZIP:
+ ret = memcmp(cfg->opt.gzip.padd0, padd0,
+ sizeof(cfg->opt.gzip.padd0));
+ break;
+ default:
+ ret = memcmp(cfg->opt.padd0, padd0, sizeof(cfg->opt.padd0));
+ break;
+ }
+
+ if (ret != 0)
+ return NULL;
+
return compressors[cfg->id](cfg);
}