add stack overflow example

Author: vladak

pmap/Makefile

@@ -1,10 +1,13 @@
-PROGS=proc-addr-space
+PROGS=proc-addr-space stack-overflow
 
 all: $(PROGS)
 
 proc-addr-space: proc-addr-space.o
 	$(CC) -o $@ $^
 
+stack-overflow: stack-overflow.o
+	$(CC) -o $@ $^
+
 clean:
 	rm -f *.o a.out $(PROGS)
 

pmap/stack-overflow.c

@@ -0,0 +1,55 @@
+/*
+ * Demonstrate the behavior of process stack size limit.
+ *
+ * Compile with:
+ *   cc stack-overflow.c
+ *
+ * The first argument is the max recursion depth.
+ *
+ * Run with e.g.:
+ *   ulimit -s
+ *   ./a.out 8000
+ *
+ * (c) [email protected]
+ */
+
+#define	_XOPEN_SOURCE	700
+
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <err.h>
+#include <signal.h>
+
+void
+recurse(size_t n)
+{
+	/* Intentionally unused variable to make the stack bigger */
+	char foo[1024];
+
+	/* To silence the compiler warning */
+	(void) foo;
+	printf("%zu ", n);
+	fflush(stdout);
+
+	if (n == 0) {
+		printf("\n");
+		return;
+	}
+
+	recurse(--n);
+}
+
+int
+main(int argc, char *argv[])
+{
+	if (argc != 2)
+		errx(1, "Usage: %s <iterations>", argv[0]);
+
+	/* Should have used strtoull(). */
+	recurse(atoi(argv[1]));
+
+	return (0);
+}