test-tool: extend trace2 helper with 400ancestry
Add a new test helper "400ancestry" to the trace2 test-tool that spawns a child process with a controlled trace2 environment, capturing only the child's trace2 output (including cmd_ancestry events) in isolation. The helper clears all inherited GIT_TRACE2* variables in the child and enables only the requested target (normal, perf, or event), directing output to a specified file. This gives the test suite a reliable way to capture cmd_ancestry events: the child always sees "test-tool" as its immediate parent in the process ancestry, providing a predictable value to verify in tests. Signed-off-by: Matthew John Cheetham <mjcheetham@outlook.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Matthew John Cheetham committed
Feb 13, 2026 at 19:54 UTC
b6a125b936bfb05de704243e1fa568d4a9ad9a11
1 file changed
+59
t/helper/test-trace2.c
+59
@@ -466,6 +466,63 @@ static int ut_303redact_def_param(int argc, const char **argv)
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return 0;
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}
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+/*
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+ * Run a child process with specific trace2 environment settings so that
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+ * we can capture its trace2 output (including cmd_ancestry) in isolation.
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+ *
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+ * test-tool trace2 400ancestry <target> <output_file> [<child_command_line>]
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+ *
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+ * <target> is one of: normal, perf, event
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+ *
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+ * For example:
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+ * test-tool trace2 400ancestry normal out.normal test-tool trace2 001return 0
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+ *
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+ * The child process inherits a controlled trace2 environment where only
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+ * the specified target is directed to <output_file>. The parent's trace2
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+ * environment variables are cleared in the child so that only the child's
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+ * events are captured.
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+ *
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+ * This is used by t0213-trace2-ancestry.sh to test cmd_ancestry events.
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+ * The child process will see "test-tool" as its immediate parent in the
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+ * process ancestry, giving us a predictable value to verify.
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+ */
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+static int ut_400ancestry(int argc, const char **argv)
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+{
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+ struct child_process cmd = CHILD_PROCESS_INIT;
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+ const char *target;
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+ const char *outfile;
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+ int result;
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+
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+ if (argc < 3)
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+ die("expect <target> <output_file> <child_command_line>");
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+
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+ target = argv[0];
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+ outfile = argv[1];
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+ argv += 2;
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+ argc -= 2;
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+
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+ /* Clear all trace2 environment variables in the child. */
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+ strvec_push(&cmd.env, "GIT_TRACE2=");
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+ strvec_push(&cmd.env, "GIT_TRACE2_PERF=");
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+ strvec_push(&cmd.env, "GIT_TRACE2_EVENT=");
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+ strvec_push(&cmd.env, "GIT_TRACE2_BRIEF=1");
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+
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+ /* Set only the requested target. */
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+ if (!strcmp(target, "normal"))
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+ strvec_pushf(&cmd.env, "GIT_TRACE2=%s", outfile);
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+ else if (!strcmp(target, "perf"))
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+ strvec_pushf(&cmd.env, "GIT_TRACE2_PERF=%s", outfile);
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+ else if (!strcmp(target, "event"))
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+ strvec_pushf(&cmd.env, "GIT_TRACE2_EVENT=%s", outfile);
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+ else
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+ die("invalid target '%s', expected: normal, perf, event",
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+ target);
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+
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+ strvec_pushv(&cmd.args, argv);
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+ result = run_command(&cmd);
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+ exit(result);
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+}
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+
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/*
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* Usage:
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* test-tool trace2 <ut_name_1> <ut_usage_1>
@@ -497,6 +554,8 @@ static struct unit_test ut_table[] = {
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{ ut_301redact_child_start, "301redact_child_start", "<argv...>" },
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{ ut_302redact_exec, "302redact_exec", "<exe> <argv...>" },
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{ ut_303redact_def_param, "303redact_def_param", "<key> <value>" },
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+
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+ { ut_400ancestry, "400ancestry", "<target> <output_file> [<child_command_line>]" },
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};
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/* clang-format on */
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