diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-29 04:40:20 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-29 04:40:20 +0000 |
commit | 2dba2525fb35dcfc79aad5bdf6c92e790d69635c (patch) | |
tree | ac8ac7d3960922094733bac6d9a5300da7171c56 /ccan/ccan/build_assert | |
parent | Initial commit. (diff) | |
download | libnvme-upstream.tar.xz libnvme-upstream.zip |
Adding upstream version 1.3.upstream/1.3upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'ccan/ccan/build_assert')
l--------- | ccan/ccan/build_assert/LICENSE | 1 | ||||
-rw-r--r-- | ccan/ccan/build_assert/_info | 49 | ||||
-rw-r--r-- | ccan/ccan/build_assert/build_assert.h | 40 |
3 files changed, 90 insertions, 0 deletions
diff --git a/ccan/ccan/build_assert/LICENSE b/ccan/ccan/build_assert/LICENSE new file mode 120000 index 0000000..b7951da --- /dev/null +++ b/ccan/ccan/build_assert/LICENSE @@ -0,0 +1 @@ +../../licenses/CC0
\ No newline at end of file diff --git a/ccan/ccan/build_assert/_info b/ccan/ccan/build_assert/_info new file mode 100644 index 0000000..97ebe6c --- /dev/null +++ b/ccan/ccan/build_assert/_info @@ -0,0 +1,49 @@ +#include "config.h" +#include <stdio.h> +#include <string.h> + +/** + * build_assert - routines for build-time assertions + * + * This code provides routines which will cause compilation to fail should some + * assertion be untrue: such failures are preferable to run-time assertions, + * but much more limited since they can only depends on compile-time constants. + * + * These assertions are most useful when two parts of the code must be kept in + * sync: it is better to avoid such cases if possible, but seconds best is to + * detect invalid changes at build time. + * + * For example, a tricky piece of code might rely on a certain element being at + * the start of the structure. To ensure that future changes don't break it, + * you would catch such changes in your code like so: + * + * Example: + * #include <stddef.h> + * #include <ccan/build_assert/build_assert.h> + * + * struct foo { + * char string[5]; + * int x; + * }; + * + * static char *foo_string(struct foo *foo) + * { + * // This trick requires that the string be first in the structure + * BUILD_ASSERT(offsetof(struct foo, string) == 0); + * return (char *)foo; + * } + * + * License: CC0 (Public domain) + * Author: Rusty Russell <rusty@rustcorp.com.au> + */ +int main(int argc, char *argv[]) +{ + if (argc != 2) + return 1; + + if (strcmp(argv[1], "depends") == 0) + /* Nothing. */ + return 0; + + return 1; +} diff --git a/ccan/ccan/build_assert/build_assert.h b/ccan/ccan/build_assert/build_assert.h new file mode 100644 index 0000000..b9ecd84 --- /dev/null +++ b/ccan/ccan/build_assert/build_assert.h @@ -0,0 +1,40 @@ +/* CC0 (Public domain) - see LICENSE file for details */ +#ifndef CCAN_BUILD_ASSERT_H +#define CCAN_BUILD_ASSERT_H + +/** + * BUILD_ASSERT - assert a build-time dependency. + * @cond: the compile-time condition which must be true. + * + * Your compile will fail if the condition isn't true, or can't be evaluated + * by the compiler. This can only be used within a function. + * + * Example: + * #include <stddef.h> + * ... + * static char *foo_to_char(struct foo *foo) + * { + * // This code needs string to be at start of foo. + * BUILD_ASSERT(offsetof(struct foo, string) == 0); + * return (char *)foo; + * } + */ +#define BUILD_ASSERT(cond) \ + do { (void) sizeof(char [1 - 2*!(cond)]); } while(0) + +/** + * BUILD_ASSERT_OR_ZERO - assert a build-time dependency, as an expression. + * @cond: the compile-time condition which must be true. + * + * Your compile will fail if the condition isn't true, or can't be evaluated + * by the compiler. This can be used in an expression: its value is "0". + * + * Example: + * #define foo_to_char(foo) \ + * ((char *)(foo) \ + * + BUILD_ASSERT_OR_ZERO(offsetof(struct foo, string) == 0)) + */ +#define BUILD_ASSERT_OR_ZERO(cond) \ + (sizeof(char [1 - 2*!(cond)]) - 1) + +#endif /* CCAN_BUILD_ASSERT_H */ |