summaryrefslogtreecommitdiffstats
path: root/src/basic/memory-util.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:35:18 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:35:18 +0000
commitb750101eb236130cf056c675997decbac904cc49 (patch)
treea5df1a06754bdd014cb975c051c83b01c9a97532 /src/basic/memory-util.c
parentInitial commit. (diff)
downloadsystemd-b750101eb236130cf056c675997decbac904cc49.tar.xz
systemd-b750101eb236130cf056c675997decbac904cc49.zip
Adding upstream version 252.22.upstream/252.22upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--src/basic/memory-util.c59
1 files changed, 59 insertions, 0 deletions
diff --git a/src/basic/memory-util.c b/src/basic/memory-util.c
new file mode 100644
index 0000000..84b5b2d
--- /dev/null
+++ b/src/basic/memory-util.c
@@ -0,0 +1,59 @@
+/* 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;
+}
+
+#if !HAVE_EXPLICIT_BZERO
+/*
+ * The pointer to memset() is volatile so that compiler must de-reference the pointer and can't assume that
+ * it points to any function in particular (such as memset(), which it then might further "optimize"). This
+ * approach is inspired by openssl's crypto/mem_clr.c.
+ */
+typedef void *(*memset_t)(void *,int,size_t);
+
+static volatile memset_t memset_func = memset;
+
+void* explicit_bzero_safe(void *p, size_t l) {
+ if (l > 0)
+ memset_func(p, '\0', l);
+
+ return p;
+}
+#endif