[PATCH bpf-next v2 6/6] selftests/bpf: Add a series of tests for bpf_snprintf

[Florent Revest <revest@chromium.org>]

This exercises most of the format specifiers when things go well.

Signed-off-by: Florent Revest <revest@chromium.org>
---
 .../selftests/bpf/prog_tests/snprintf.c       | 65 +++++++++++++++++++
 .../selftests/bpf/progs/test_snprintf.c       | 59 +++++++++++++++++
 2 files changed, 124 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_snprintf.c

diff --git a/tools/testing/selftests/bpf/prog_tests/snprintf.c b/tools/testing/selftests/bpf/prog_tests/snprintf.c
new file mode 100644
index 000000000000..948a05e6b2cb
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/snprintf.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Google LLC. */
+
+#include <test_progs.h>
+#include "test_snprintf.skel.h"
+
+#define EXP_NUM_OUT  "-8 9 96 -424242 1337 DABBAD00"
+#define EXP_NUM_RET  sizeof(EXP_NUM_OUT)
+
+#define EXP_IP_OUT   "127.000.000.001 0000:0000:0000:0000:0000:0000:0000:0001"
+#define EXP_IP_RET   sizeof(EXP_IP_OUT)
+
+/* The third specifier, %pB, depends on compiler inlining so don't check it */
+#define EXP_SYM_OUT  "schedule schedule+0x0/"
+#define MIN_SYM_RET  sizeof(EXP_SYM_OUT)
+
+/* The third specifier, %p, is a hashed pointer which changes on every reboot */
+#define EXP_ADDR_OUT "0000000000000000 ffff00000add4e55 "
+#define EXP_ADDR_RET sizeof(EXP_ADDR_OUT "unknownhashedptr")
+
+#define EXP_STR_OUT  "str1 longstr"
+#define EXP_STR_RET  sizeof(EXP_STR_OUT)
+
+#define EXP_OVER_OUT "%over"
+#define EXP_OVER_RET 10
+
+void test_snprintf(void)
+{
+	char exp_addr_out[] = EXP_ADDR_OUT;
+	char exp_sym_out[]  = EXP_SYM_OUT;
+	struct test_snprintf *skel;
+
+	skel = test_snprintf__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	if (!ASSERT_OK(test_snprintf__attach(skel), "skel_attach"))
+		goto cleanup;
+
+	/* trigger tracepoint */
+	usleep(1);
+
+	ASSERT_STREQ(skel->bss->num_out, EXP_NUM_OUT, "num_out");
+	ASSERT_EQ(skel->bss->num_ret, EXP_NUM_RET, "num_ret");
+
+	ASSERT_STREQ(skel->bss->ip_out, EXP_IP_OUT, "ip_out");
+	ASSERT_EQ(skel->bss->ip_ret, EXP_IP_RET, "ip_ret");
+
+	ASSERT_OK(memcmp(skel->bss->sym_out, exp_sym_out,
+			 sizeof(exp_sym_out) - 1), "sym_out");
+	ASSERT_LT(MIN_SYM_RET, skel->bss->sym_ret, "sym_ret");
+
+	ASSERT_OK(memcmp(skel->bss->addr_out, exp_addr_out,
+			 sizeof(exp_addr_out) - 1), "addr_out");
+	ASSERT_EQ(skel->bss->addr_ret, EXP_ADDR_RET, "addr_ret");
+
+	ASSERT_STREQ(skel->bss->str_out, EXP_STR_OUT, "str_out");
+	ASSERT_EQ(skel->bss->str_ret, EXP_STR_RET, "str_ret");
+
+	ASSERT_STREQ(skel->bss->over_out, EXP_OVER_OUT, "over_out");
+	ASSERT_EQ(skel->bss->over_ret, EXP_OVER_RET, "over_ret");
+
+cleanup:
+	test_snprintf__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_snprintf.c b/tools/testing/selftests/bpf/progs/test_snprintf.c
new file mode 100644
index 000000000000..e18709055fad
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_snprintf.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Google LLC. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_endian.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char num_out[64] = {};
+long num_ret = 0;
+
+char ip_out[64] = {};
+long ip_ret = 0;
+
+char sym_out[64] = {};
+long sym_ret = 0;
+
+char addr_out[64] = {};
+long addr_ret = 0;
+
+char str_out[64] = {};
+long str_ret = 0;
+
+char over_out[6] = {};
+long over_ret = 0;
+
+SEC("raw_tp/sys_enter")
+int handler(const void *ctx)
+{
+	/* Convenient values to pretty-print */
+	const __u8 ex_ipv4[] = {127, 0, 0, 1};
+	const __u8 ex_ipv6[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
+	const char str1[] = "str1";
+	const char longstr[] = "longstr";
+	extern const void schedule __ksym;
+
+	/* Integer types */
+	num_ret  = BPF_SNPRINTF(num_out, sizeof(num_out),
+				"%d %u %x %li %llu %lX",
+				-8, 9, 150, -424242, 1337, 0xDABBAD00);
+	/* IP addresses */
+	ip_ret   = BPF_SNPRINTF(ip_out, sizeof(ip_out), "%pi4 %pI6",
+				&ex_ipv4, &ex_ipv6);
+	/* Symbol lookup formatting */
+	sym_ret  = BPF_SNPRINTF(sym_out,  sizeof(sym_out), "%ps %pS %pB",
+				&schedule, &schedule, &schedule);
+	/* Kernel pointers */
+	addr_ret = BPF_SNPRINTF(addr_out, sizeof(addr_out), "%pK %px %p",
+				0, 0xFFFF00000ADD4E55, 0xFFFF00000ADD4E55);
+	/* Strings embedding */
+	str_ret  = BPF_SNPRINTF(str_out, sizeof(str_out), "%s %+05s",
+				str1, longstr);
+	/* Overflow */
+	over_ret = BPF_SNPRINTF(over_out, sizeof(over_out), "%%overflow");
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.31.0.291.g576ba9dcdaf-goog