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* src: add free_const() and use it instead of xfree()Thomas Haller2023-11-091-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Almost everywhere xmalloc() and friends is used instead of malloc(). This is almost everywhere paired with xfree(). xfree() has two problems. First, it brings the wrong notion that xmalloc() should be paired with xfree(), as if xmalloc() would not use the plain malloc() allocator. In practices, xfree() just wraps free(), and it wouldn't make sense any other way. xfree() should go away. This will be addressed in the next commit. The problem addressed by this commit is that xfree() accepts a const pointer. Paired with the practice of almost always using xfree() instead of free(), all our calls to xfree() cast away constness of the pointer, regardless whether that is necessary. Declaring a pointer as const should help us to catch wrong uses. If the xfree() function always casts aways const, the compiler doesn't help. There are many places that rightly cast away const during free. But not all of them. Add a free_const() macro, which is like free(), but accepts const pointers. We should always make an intentional choice whether to use free() or free_const(). Having a free_const() macro makes this very common choice clearer, instead of adding a (void*) cast at many places. Note that we now pair xmalloc() allocations with a free() call (instead of xfree(). That inconsistency will be resolved in the next commit. Signed-off-by: Thomas Haller <thaller@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
* include: include <string.h> in <nft.h>Thomas Haller2023-09-281-0/+1
| | | | | | | | <string.h> provides strcmp(), as such it's very basic and used everywhere. Signed-off-by: Thomas Haller <thaller@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
* include: include <stdlib.h> in <nft.h>Thomas Haller2023-09-111-0/+1
| | | | | | | | | | | | | | It provides malloc()/free(), which is so basic that we need it everywhere. Include via <nft.h>. The ultimate purpose is to define more things in <nft.h>. While it has not corresponding C sources, <nft.h> can contain macros and static inline functions, and is a good place for things that we shall have everywhere. Since <stdlib.h> provides malloc()/free() and size_t, that is a very basic dependency, that will be needed for that. Signed-off-by: Thomas Haller <thaller@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
* include: include <std{bool,int}.h> via <nft.h>Thomas Haller2023-08-251-0/+3
| | | | | | | | | | | | | | | | | | | | There is a minimum base that all our sources will end up needing. This is what <nft.h> provides. Add <stdbool.h> and <stdint.h> there. It's unlikely that we want to implement anything, without having "bool" and "uint32_t" types available. Yes, this means the internal headers are not self-contained, with respect to what <nft.h> provides. This is the exception to the rule, and our internal headers should rely to have <nft.h> included for them. They should not include <nft.h> themselves, because <nft.h> needs always be included as first. So when an internal header would include <nft.h> it would be unnecessary, because the header is *always* included already. Signed-off-by: Thomas Haller <thaller@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
* configure: use AC_USE_SYSTEM_EXTENSIONS to get _GNU_SOURCEThomas Haller2023-08-251-2/+0
| | | | | | | | | | | | | | | | | Let "configure" detect which features are available. Also, nftables is a Linux project, so portability beyond gcc/clang and glibc/musl is less relevant. And even if it were, then feature detection by "configure" would still be preferable. Use AC_USE_SYSTEM_EXTENSIONS ([1]). Available since autoconf 2.60, from 2006 ([2]). [1] https://www.gnu.org/software/autoconf/manual/autoconf-2.67/html_node/Posix-Variants.html#index-AC_005fUSE_005fSYSTEM_005fEXTENSIONS-1046 [2] https://lists.gnu.org/archive/html/autoconf/2006-06/msg00111.html Signed-off-by: Thomas Haller <thaller@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
* src: add <nft.h> header and include it as firstThomas Haller2023-08-251-0/+9
<config.h> is generated by the configure script. As it contains our feature detection, it want to use it everywhere. Likewise, in some of our sources, we define _GNU_SOURCE. This defines the C variant we want to use. Such a define need to come before anything else, and it would be confusing if different source files adhere to a different C variant. It would be good to use autoconf's AC_USE_SYSTEM_EXTENSIONS, in which case we would also need to ensure that <config.h> is always included as first. Instead of going through all source files and include <config.h> as first, add a new header "include/nft.h", which is supposed to be included in all our sources (and as first). This will also allow us later to prepare some common base, like include <stdbool.h> everywhere. We aim that headers are self-contained, so that they can be included in any order. Which, by the way, already didn't work because some headers define _GNU_SOURCE, which would only work if the header gets included as first. <nft.h> is however an exception to the rule: everything we compile shall rely on having <nft.h> header included as first. This applies to source files (which explicitly include <nft.h>) and to internal header files (which are only compiled indirectly, by being included from a source file). Note that <config.h> has no include guards, which is at least ugly to include multiple times. It doesn't cause problems in practice, because it only contains defines and the compiler doesn't warn about redefining a macro with the same value. Still, <nft.h> also ensures to include <config.h> exactly once. Signed-off-by: Thomas Haller <thaller@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>