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author | Lennart Poettering <lennart@poettering.net> | 2018-03-22 16:53:26 +0100 |
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committer | Lennart Poettering <lennart@poettering.net> | 2018-03-22 20:21:42 +0100 |
commit | ae2a15bc14bc448e625ad93fd044bc077ede4b3f (patch) | |
tree | e503e6cf3b571d0a150dc2cea7d1838f55aaa6ab /src/basic/alloc-util.h | |
parent | 1147eef0b6a5937526247ff81ca1e5e45205ed16 (diff) | |
download | systemd-ae2a15bc14bc448e625ad93fd044bc077ede4b3f.tar.gz |
macro: introduce TAKE_PTR() macro
This macro will read a pointer of any type, return it, and set the
pointer to NULL. This is useful as an explicit concept of passing
ownership of a memory area between pointers.
This takes inspiration from Rust:
https://doc.rust-lang.org/std/option/enum.Option.html#method.take
and was suggested by Alan Jenkins (@sourcejedi).
It drops ~160 lines of code from our codebase, which makes me like it.
Also, I think it clarifies passing of ownership, and thus helps
readability a bit (at least for the initiated who know the new macro)
Diffstat (limited to 'src/basic/alloc-util.h')
-rw-r--r-- | src/basic/alloc-util.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/basic/alloc-util.h b/src/basic/alloc-util.h index ec7808c1f7..b1e0edbb7f 100644 --- a/src/basic/alloc-util.h +++ b/src/basic/alloc-util.h @@ -130,3 +130,12 @@ void* greedy_realloc0(void **p, size_t *allocated, size_t need, size_t size); _new_ = alloca_align(_size_, (align)); \ (void*)memset(_new_, 0, _size_); \ }) + +/* Takes inspiration from Rusts's Option::take() method: reads and returns a pointer, but at the same time resets it to + * NULL. See: https://doc.rust-lang.org/std/option/enum.Option.html#method.take */ +#define TAKE_PTR(ptr) \ + ({ \ + typeof(ptr) _ptr_ = (ptr); \ + (ptr) = NULL; \ + _ptr_; \ + }) |