test.lua: Port the `test_uprobes` suite

tests/lua/test_uprobes.lua

+require("test_helper")
+local ffi = require("ffi")
+
+ffi.cdef[[
+  int getpid(void);
+  void malloc_stats(void);
+]]
+
+TestUprobes = {}
+
+function TestUprobes:test_simple_library()
+  local text = [[
+#include <uapi/linux/ptrace.h>
+BPF_TABLE("array", int, u64, stats, 1);
+static void incr(int idx) {
+    u64 *ptr = stats.lookup(&idx);
+    if (ptr)
+        ++(*ptr);
+}
+int count(struct pt_regs *ctx) {
+    u32 pid = bpf_get_current_pid_tgid();
+    if (pid == PID)
+        incr(0);
+    return 0;
+}]]
+
+  local pid = tonumber(ffi.C.getpid())
+  local text = text:gsub("PID", tostring(pid))
+
+  local b = BPF:new{text=text}
+  b:attach_uprobe{name="c", sym="malloc_stats", fn_name="count"}
+  b:attach_uprobe{name="c", sym="malloc_stats", fn_name="count", retprobe=true}
+
+  assert_equals(BPF.num_open_uprobes(), 2)
+
+  ffi.C.malloc_stats()
+
+  local stats = b:get_table("stats")
+  assert_equals(tonumber(stats:get(0)), 2)
+end
+
+function TestUprobes:test_simple_binary()
+  local text = [[
+#include <uapi/linux/ptrace.h>
+BPF_TABLE("array", int, u64, stats, 1);
+static void incr(int idx) {
+    u64 *ptr = stats.lookup(&idx);
+    if (ptr)
+        ++(*ptr);
+}
+int count(struct pt_regs *ctx) {
+    u32 pid = bpf_get_current_pid_tgid();
+    incr(0);
+    return 0;
+}]]
+
+  local b = BPF:new{text=text}
+  b:attach_uprobe{name="/usr/bin/python", sym="main", fn_name="count"}
+  b:attach_uprobe{name="/usr/bin/python", sym="main", fn_name="count", retprobe=true}
+
+  os.spawn("/usr/bin/python -V")
+
+  local stats = b:get_table("stats")
+  assert_true(tonumber(stats:get(0)) >= 2)
+end
+
+function TestUprobes:teardown()
+  BPF.cleanup_probes()
+end
+
+os.exit(LuaUnit.run())