3 files changed, 20 insertions, 0 deletions
diff --git a/kernel/libc/ctype/isspace.c b/kernel/libc/ctype/isspace.c
new file mode 100644
index 0000000..a922d91
--- /dev/null
+++ b/kernel/libc/ctype/isspace.c
@@ -0,0 +1,5 @@
+#include <ctype.h>
+
+int isspace(int c) {
+  return c == ' ' || (unsigned)c - '\t' < 5;
+}
diff --git a/kernel/libc/include/string.h b/kernel/libc/include/string.h
index 89ea5ab..4425085 100644
--- a/kernel/libc/include/string.h
+++ b/kernel/libc/include/string.h
@@ -15,4 +15,5 @@ char *copy_and_allocate_string(const char *s);
 char *copy_and_allocate_user_string(const char *s);
 size_t strlcpy(char *dst, const char *src, size_t dsize);
 char *strcat(char *s1, const char *s2);
+void *memmove(void *s1, const void *s2, size_t n);
 #endif
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;
+}