kernel: Add string view and string builder

This makes write/read calls that use strings to communicate much
simpler and less error prone.

1 files changed, 14 insertions, 0 deletions

diff --git a/kernel/libc/string/memmove.c b/kernel/libc/string/memmove.c
new file mode 100644
index 0000000..5fc49f7
--- /dev/null
+++ b/kernel/libc/string/memmove.c
@@ -0,0 +1,14 @@
+#include <string.h>
+
+// copy bytes in memory with overlapping areas
+// https://pubs.opengroup.org/onlinepubs/9699919799/functions/memmove.html
+void *memmove(void *s1, const void *s2, size_t n) {
+  // Copying takes place as if the n bytes from the object pointed to by s2 are
+  // first copied into a temporary array of n bytes that does not overlap the
+  // objects pointed to by s1 and s2, and then the n bytes from the temporary
+  // array are copied into the object pointed to by s1.
+  unsigned char tmp[n];
+  memcpy(tmp, s2, n);
+  memcpy(s1, tmp, n);
+  return s1;
+}