char *p = RSTRING_PTR(self);

/* Move original content to the end */

/* Move original content to the end. The original self data now lives

at p + total_prepend_len, which we use as the source for any

self-referencing arguments (e.g., s.prepend(s, s)) to avoid reading

data that has already been overwritten by earlier copies. */

memmove(p + total_prepend_len, p, self_len);

/* Copy prepended strings in order */

mrb_int offset = 0;

for (mrb_int i = 0; i < argc; i++) {

mrb_int arg_len = RSTRING_LEN(argv[i]);

const char *src;

mrb_int arg_len;

if (mrb_obj_eq(mrb, self, argv[i])) {

src = p + total_prepend_len;

arg_len = self_len;

}

else {

src = RSTRING_PTR(argv[i]);

arg_len = RSTRING_LEN(argv[i]);

}

if (arg_len > 0) {

memcpy(p + offset, RSTRING_PTR(argv[i]), arg_len);

memcpy(p + offset, src, arg_len);

offset += arg_len;

}

}

g = "world"

assert_equal "hello world", g.prepend("", "hello ", "")

assert_equal "hello world", g

# Self-referencing arguments (GHSA-3hgj-g76g-878c)

h = "A" * 100

h.prepend(h, h)

assert_equal 300, h.length

assert_equal "A" * 300, h

# Mixed self-reference and literal

i = "AB"

i.prepend("XYZ", i)

assert_equal "XYZABAB", i

j = "AB"

j.prepend(j, "X", j)

assert_equal "ABXABAB", j

end

assert('String#ljust') do