From dfb93e636657c59e89fc62002ac26dee1795b794 Mon Sep 17 00:00:00 2001
From: Andrew Clayton <ac@sigsegv.uk>
Date: Fri, 7 Mar 2025 00:49:45 +0000
Subject: Initial commit

Signed-off-by: Andrew Clayton <ac@sigsegv.uk>
---
 sptr.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 sptr.c

(limited to 'sptr.c')

diff --git a/sptr.c b/sptr.c
new file mode 100644
index 0000000..c275b8a
--- /dev/null
+++ b/sptr.c
@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+union sptr_u {
+	uint8_t base[1];
+	uint32_t offset;
+};
+typedef union sptr_u sptr_t;
+
+struct s {
+	uint8_t name1_len;
+	uint8_t name2_len;
+	uint8_t name3_len;
+
+	sptr_t name1;
+	sptr_t name2;
+	sptr_t name3;
+};
+
+static void sptr_set(sptr_t *sptr, void *ptr)
+{
+	sptr->offset = (uint8_t *)ptr - sptr->base;
+
+	printf("sptr->base   : %p\n", sptr->base);
+	printf("sptr->offset : %u\n", sptr->offset);
+}
+
+static void *sptr_get(sptr_t *sptr)
+{
+	return sptr->base + sptr->offset;
+}
+
+int main(void)
+{
+	static const char * const names[] = { "toor", "foobar", "baz" };
+	struct s *s = malloc(sizeof(struct s) +
+		             strlen(names[0]) + strlen(names[1]) +
+			     strlen(names[2]) + 3);
+	char *p = (char *)(s) + sizeof(struct s);
+
+	printf("s : %p\n", s);
+
+	s->name1_len = strlen(names[0]);
+	sptr_set(&s->name1, p);
+	p = stpcpy(p, names[0]);
+
+	p++;
+	s->name2_len = strlen(names[1]);
+	sptr_set(&s->name2, p);
+	p = stpcpy(p, names[1]);
+
+	p++;
+	s->name3_len = strlen(names[2]);
+	sptr_set(&s->name3, p);
+	p = stpcpy(p, names[2]);
+
+	printf("name1 : %s\n", (const char *)sptr_get(&s->name1));
+	printf("name2 : %s\n", (const char *)sptr_get(&s->name2));
+	printf("name3 : %s\n", (const char *)sptr_get(&s->name3));
+
+	free(s);
+
+	exit(EXIT_SUCCESS);
+}
-- 
cgit