diff options
Diffstat (limited to 'src/basic/memory-util.c')
-rw-r--r-- | src/basic/memory-util.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/src/basic/memory-util.c b/src/basic/memory-util.c new file mode 100644 index 0000000..fcedae2 --- /dev/null +++ b/src/basic/memory-util.c @@ -0,0 +1,41 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <unistd.h> + +#include "memory-util.h" +#include "missing_threads.h" + +size_t page_size(void) { + static thread_local size_t pgsz = 0; + long r; + + if (_likely_(pgsz > 0)) + return pgsz; + + r = sysconf(_SC_PAGESIZE); + assert(r > 0); + + pgsz = (size_t) r; + return pgsz; +} + +bool memeqbyte(uint8_t byte, const void *data, size_t length) { + /* Does the buffer consist entirely of the same specific byte value? + * Copied from https://github.com/systemd/casync/, copied in turn from + * https://github.com/rustyrussell/ccan/blob/master/ccan/mem/mem.c#L92, + * which is licensed CC-0. + */ + + const uint8_t *p = data; + + /* Check first 16 bytes manually */ + for (size_t i = 0; i < 16; i++, length--) { + if (length == 0) + return true; + if (p[i] != byte) + return false; + } + + /* Now we know first 16 bytes match, memcmp() with self. */ + return memcmp(data, p + 16, length) == 0; +} |