tests/lapi: add sysprof test

The patch adds a test for sysprof built into LuaJIT and
Tarantool's sysprof.

Author: ligurio

.luacheckrc

@@ -1,3 +1,6 @@
+-- Tarantool introduces a global for misc API namespace.
+read_globals = { "misc" }
+
 -- Defined functions is unused in preamble,
 -- but could be used by generated Lua programs.
 files["tests/capi/luaL_loadbuffer_proto/preamble.lua"] = {

tests/lapi/misc_sysprof_test.lua

@@ -0,0 +1,97 @@
+--[[
+SPDX-License-Identifier: ISC
+Copyright (c) 2025, Sergey Bronnikov.
+
+LuaJIT platform profiler,
+https://luajit.org/ext_profiler.html
+https://www.tarantool.io/en/doc/latest/tooling/luajit_sysprof/
+]]
+
+local luzer = require("luzer")
+local test_lib = require("lib")
+
+local MAX_INT = test_lib.MAX_INT
+local MIN_INT = test_lib.MIN_INT
+
+local has_tnt_sysprof, sysprof = pcall(require, "misc.sysprof")
+if not has_tnt_sysprof then
+    sysprof = require("jit.profile")
+end
+
+local SYSPROF_OPTIONS = {
+    "f", -- Profile with precision down to the function level.
+    "l", -- Profile with precision down to the line level.
+    "i", -- Sampling interval in milliseconds (default 10ms).
+}
+
+local SYSPROF_DEFAULT_INTERVAL = 10 -- ms
+
+local function sysprof_start(fdp)
+    if has_tnt_sysprof then
+        local mode = fdp:oneof({"D", "L", "C"})
+        local _, err = misc.sysprof.start({
+            interval = SYSPROF_DEFAULT_INTERVAL,
+            mode = mode,
+            path = "/dev/null",
+        })
+        assert(err)
+    else
+        local option = fdp:oneof(SYSPROF_OPTIONS)
+        if option == "i" then
+            option = ("i%d"):format(SYSPROF_DEFAULT_INTERVAL)
+        end
+        local cb = function(_thread, _samples, _vmstate)
+            -- Nope.
+        end
+        sysprof.start(option, cb)
+    end
+end
+
+local function sysprof_report()
+    if has_tnt_sysprof then
+		misc.sysprof.report()
+    end
+end
+
+local DUMPSTACK_FMT = {
+    "p", -- Preserve the full path for module names.
+    "f", -- Dump the function name if it can be derived.
+    "F", -- Ditto, but dump module:name.
+    "l", -- Dump module:line.
+    "Z", -- Zap the following characters for the last dumped frame.
+}
+
+local function sysprof_dumpstack(fdp)
+    if not has_tnt_sysprof then
+		local fmt = fdp:oneof(DUMPSTACK_FMT)
+		local depth = fdp:consume_integer(MIN_INT, MAX_INT)
+        local dump = sysprof.dumpstack(fmt, depth)
+        assert(dump)
+    end
+end
+
+local function sysprof_stop()
+    sysprof.stop()
+end
+
+local function TestOneInput(buf)
+    local fdp = luzer.FuzzedDataProvider(buf)
+    local mode = fdp:oneof({"t", "b"})
+    -- LuaJIT ASSERT lj_bcread.c:123: bcread_byte: buffer read
+    -- overflow.
+    if test_lib.lua_version() == "LuaJIT" then
+        mode = "t"
+    end
+    local chunk = fdp:consume_string(test_lib.MAX_STR_LEN)
+    local func = load(chunk, "luzer", mode)
+    sysprof_start(fdp)
+    pcall(func)
+    sysprof_report()
+    sysprof_dumpstack(fdp)
+    sysprof_stop()
+end
+
+local args = {
+    artifact_prefix = "misc_sysprof_",
+}
+luzer.Fuzz(TestOneInput, nil, args)