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@@ -0,0 +1,204 @@
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+#include <string.h>
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+#include <stdio.h>
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+#include <sys/types.h>
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+#include <stdlib.h>
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+
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+#include "crypto.h"
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+#include "compat.h"
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+
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+#undef MIN
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+#define MIN(a,b) ( ((a)<(b)) ? (a) : (b) )
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+
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+static unsigned fill_a_buffer_memset(void) __attribute__((noinline));
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+static unsigned fill_a_buffer_memwipe(void) __attribute__((noinline));
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+static unsigned fill_a_buffer_nothing(void) __attribute__((noinline));
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+static unsigned fill_heap_buffer_memset(void) __attribute__((noinline));
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+static unsigned fill_heap_buffer_memwipe(void) __attribute__((noinline));
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+static unsigned fill_heap_buffer_nothing(void) __attribute__((noinline));
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+static unsigned check_a_buffer(void) __attribute__((noinline));
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+
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+const char *s = NULL;
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+
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+#define FILL_BUFFER_IMPL() \
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+ unsigned int i; \
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+ unsigned sum = 0; \
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+ \
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+ /* Fill up a 1k buffer with a recognizable pattern. */ \
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+ for (i = 0; i < 2048; i += strlen(s)) { \
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+ memcpy(buf+i, s, MIN(strlen(s), 2048-i)); \
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+ } \
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+ \
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+ /* Use the buffer as input to a computation so the above can't get */ \
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+ /* optimized away. */ \
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+ for (i = 0; i < 2048; ++i) { \
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+ sum += (unsigned char)buf[i]; \
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+ }
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+
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+static unsigned
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+fill_a_buffer_memset(void)
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+{
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+ char buf[2048];
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+ FILL_BUFFER_IMPL()
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+ memset(buf, 0, sizeof(buf));
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+ return sum;
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+}
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+
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+static unsigned
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+fill_a_buffer_memwipe(void)
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+{
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+ char buf[2048];
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+ FILL_BUFFER_IMPL()
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+ memwipe(buf, 0, sizeof(buf));
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+ return sum;
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+}
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+
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+static unsigned
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+fill_a_buffer_nothing(void)
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+{
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+ char buf[2048];
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+ FILL_BUFFER_IMPL()
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+ return sum;
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+}
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+
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+static INLINE int
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+vmemeq(volatile char *a, const char *b, size_t n)
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+{
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+ while (n--) {
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+ if (*a++ != *b++)
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+ return 0;
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+ }
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+ return 1;
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+}
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+
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+static unsigned
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+check_a_buffer(void)
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+{
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+ unsigned int i;
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+ volatile char buf[1024];
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+ unsigned sum = 0;
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+
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+ /* See if this buffer has the string in it.
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+
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+ YES, THIS DOES INVOKE UNDEFINED BEHAVIOR BY READING FROM AN UNINITIALIZED
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+ BUFFER.
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+
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+ If you know a better way to figure out whether the compiler eliminated
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+ the memset/memwipe calls or not, please let me know.
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+ */
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+ for (i = 0; i < sizeof(buf); ++i) {
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+ if (vmemeq(buf+i, s, strlen(s)))
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+ ++sum;
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+ }
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+
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+ return sum;
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+}
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+
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+static char *heap_buf = NULL;
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+
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+static unsigned
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+fill_heap_buffer_memset(void)
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+{
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+ char *buf = heap_buf = malloc(2048);
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+ FILL_BUFFER_IMPL()
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+ memset(buf, 0, 2048);
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+ free(buf);
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+ return sum;
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+}
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+
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+static unsigned
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+fill_heap_buffer_memwipe(void)
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+{
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+ char *buf = heap_buf = malloc(2048);
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+ FILL_BUFFER_IMPL()
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+ memwipe(buf, 0, 2048);
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+ free(buf);
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+ return sum;
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+}
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+
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+static unsigned
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+fill_heap_buffer_nothing(void)
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+{
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+ char *buf = heap_buf = malloc(2048);
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+ FILL_BUFFER_IMPL()
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+ free(buf);
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+ return sum;
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+}
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+
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+static unsigned
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+check_heap_buffer(void)
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+{
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+ unsigned int i;
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+ unsigned sum = 0;
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+ volatile char *buf = heap_buf;
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+
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+ /* See if this buffer has the string in it.
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+
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+ YES, THIS DOES INVOKE UNDEFINED BEHAVIOR BY READING FROM A FREED BUFFER.
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+
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+ If you know a better way to figure out whether the compiler eliminated
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+ the memset/memwipe calls or not, please let me know.
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+ */
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+ for (i = 0; i < sizeof(buf); ++i) {
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+ if (vmemeq(buf+i, s, strlen(s)))
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+ ++sum;
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+ }
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+
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+ return sum;
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+}
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+
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+static struct testcase {
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+ const char *name;
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+ unsigned (*fill_fn)(void);
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+ unsigned (*check_fn)(void);
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+} testcases[] = {
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+ { "nil", fill_a_buffer_nothing, check_a_buffer },
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+ { "nil-heap", fill_heap_buffer_nothing, check_heap_buffer },
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+ { "memset", fill_a_buffer_memset, check_a_buffer },
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+ { "memset-heap", fill_heap_buffer_memset, check_heap_buffer },
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+ { "memwipe", fill_a_buffer_memwipe, check_a_buffer },
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+ { "memwipe-heap", fill_heap_buffer_memwipe, check_heap_buffer },
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+ { NULL, NULL, NULL }
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+};
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+
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+int
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+main(int argc, char **argv)
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+{
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+ unsigned x, x2;
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+ int i;
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+ int working = 1;
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+ unsigned found[6];
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+ (void) argc; (void) argv;
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+
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+ s = "squamous haberdasher gallimaufry";
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+
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+ memset(found, 0, sizeof(found));
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+
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+ for (i = 0; testcases[i].name; ++i) {
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+ x = testcases[i].fill_fn();
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+ found[i] = testcases[i].check_fn();
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+
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+ x2 = fill_a_buffer_nothing();
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+
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+ if (x != x2) {
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+ working = 0;
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+ }
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+ }
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+
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+ if (!working || !found[0] || !found[1]) {
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+ printf("It appears that this test case may not give you reliable "
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+ "information. Sorry.\n");
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+ }
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+
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+ if (!found[2] && !found[3]) {
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+ printf("It appears that memset is good enough on this platform. Good.\n");
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+ }
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+
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+ if (found[4] || found[5]) {
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+ printf("ERROR: memwipe does not wipe data!\n");
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+ return 1;
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+ } else {
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+ printf("OKAY: memwipe seems to work.");
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+ return 0;
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+ }
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+}
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+
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