[PATCH i-g-t v3 1/6] igt_hook: Add feature

Gustavo Sousa gustavo.sousa at intel.com
Thu Jul 25 14:19:34 UTC 2024


For development purposes, sometimes it is useful to have a way of
running custom scripts at certain points of test executions. A
real-world example I bumped into recently is to collect information from
sysfs before and after running each entry of a testlist.

While it is possible for the user to handcraft a script that calls each
test with the correct actions before and after execution, we can provide
a better experience by adding built-in support for running hooks during
test execution.

That would be even better when adding the same kind of support for
igt_runner (which is done in an upcoming change), since the user can
also nicely resume with igt_resume with the hook already setup in case a
crash happens during execution of the test list.

As such provide implement support for hooks, integrate it into
igt_core and expose the functionality via --hook CLI option on test
executables.

v2:
  - s/igt_hook_init/igt_hook_create/ (Lucas)
  - Use SPDX License Identifier instead of license text. (Lucas)
  - Do not rely on hard-coded length 3 when generating full test name.
    (Lucas)
  - Do not pollute current environment variables when running hooks.
    (Lucas)
  - Change hook string in run_tests_and_match_env() to use "printf"
    instead of "echo" to be compatible with CI environment.

v3:
  - igt_hook_create() only errors out for invalid input.
  - Use igt_hook_free() instead of simply free() in the error path for
    common_init().
  - Go back to the simpler logic for calling hooks instead of using
    fork: setenv() calls followed by system().
  - Change igt_hook_create() to return error number and receive
    reference to destination pointer instead of the opposite. (Lucas)
  - Remove checks for non-existing negative return of igt_hook_create().
    (Lucas)
  - s/igt_hook_push_evt/igt_hook_event_notify/. (Lucas)
  - Simplify call sites for igt_hook_event_notify() by allowing argument
    to igt_hook to be NULL and using compount literals for the event
    struct. (Lucas)
  - Fix style for igt_hook_calc_test_fullname_size(). (Lucas)

Signed-off-by: Gustavo Sousa <gustavo.sousa at intel.com>
---
 .../igt-gpu-tools/igt-gpu-tools-docs.xml      |   1 +
 lib/igt_core.c                                |  78 ++-
 lib/igt_hook.c                                | 470 ++++++++++++++++++
 lib/igt_hook.h                                |  69 +++
 lib/meson.build                               |   1 +
 lib/tests/igt_hook.c                          | 157 ++++++
 lib/tests/igt_hook_integration.c              | 281 +++++++++++
 lib/tests/meson.build                         |   2 +
 8 files changed, 1052 insertions(+), 7 deletions(-)
 create mode 100644 lib/igt_hook.c
 create mode 100644 lib/igt_hook.h
 create mode 100644 lib/tests/igt_hook.c
 create mode 100644 lib/tests/igt_hook_integration.c

diff --git a/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml b/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml
index 9085eb924e85..11458c68124b 100644
--- a/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml
+++ b/docs/reference/igt-gpu-tools/igt-gpu-tools-docs.xml
@@ -32,6 +32,7 @@
     <xi:include href="xml/igt_fb.xml"/>
     <xi:include href="xml/igt_frame.xml"/>
     <xi:include href="xml/igt_gt.xml"/>
+    <xi:include href="xml/igt_hook.xml"/>
     <xi:include href="xml/igt_io.xml"/>
     <xi:include href="xml/igt_kmod.xml"/>
     <xi:include href="xml/igt_kms.xml"/>
diff --git a/lib/igt_core.c b/lib/igt_core.c
index 3ff3e0392316..51141722c89b 100644
--- a/lib/igt_core.c
+++ b/lib/igt_core.c
@@ -70,6 +70,7 @@
 
 #include "igt_core.h"
 #include "igt_aux.h"
+#include "igt_hook.h"
 #include "igt_sysfs.h"
 #include "igt_sysrq.h"
 #include "igt_rc.h"
@@ -241,6 +242,9 @@
  * - '*,!basic*' match any subtest not starting basic
  * - 'basic*,!basic-render*' match any subtest starting basic but not starting basic-render
  *
+ * It is possible to run a shell script at certain points of test execution with
+ * "--hook". See the usage description with "--help-hook" for details.
+ *
  * # Configuration
  *
  * Some of IGT's behavior can be configured through a configuration file.
@@ -273,6 +277,8 @@ static unsigned int exit_handler_count;
 const char *igt_interactive_debug;
 bool igt_skip_crc_compare;
 
+static struct igt_hook *igt_hook = NULL;
+
 /* subtests helpers */
 static bool show_testlist = false;
 static bool list_subtests = false;
@@ -338,6 +344,8 @@ enum {
 	OPT_INTERACTIVE_DEBUG,
 	OPT_SKIP_CRC,
 	OPT_TRACE_OOPS,
+	OPT_HOOK,
+	OPT_HELP_HOOK,
 	OPT_DEVICE,
 	OPT_VERSION,
 	OPT_HELP = 'h'
@@ -810,6 +818,8 @@ static void common_exit_handler(int sig)
 		bind_fbcon(true);
 	}
 
+	igt_hook_free(igt_hook);
+
 	/* When not killed by a signal check that igt_exit() has been properly
 	 * called. */
 	assert(sig != 0 || igt_exit_called || igt_is_aborting);
@@ -907,6 +917,8 @@ static void print_usage(const char *help_str, bool output_on_stderr)
 		   "  --interactive-debug[=domain]\n"
 		   "  --skip-crc-compare\n"
 		   "  --trace-on-oops\n"
+		   "  --hook [<events>:]<cmd>\n"
+		   "  --help-hook\n"
 		   "  --help-description\n"
 		   "  --describe\n"
 		   "  --device filters\n"
@@ -1090,6 +1102,8 @@ static int common_init(int *argc, char **argv,
 		{"interactive-debug", optional_argument, NULL, OPT_INTERACTIVE_DEBUG},
 		{"skip-crc-compare",  no_argument,       NULL, OPT_SKIP_CRC},
 		{"trace-on-oops",     no_argument,       NULL, OPT_TRACE_OOPS},
+		{"hook",              required_argument, NULL, OPT_HOOK},
+		{"help-hook",         no_argument,       NULL, OPT_HELP_HOOK},
 		{"device",            required_argument, NULL, OPT_DEVICE},
 		{"version",           no_argument,       NULL, OPT_VERSION},
 		{"help",              no_argument,       NULL, OPT_HELP},
@@ -1225,6 +1239,24 @@ static int common_init(int *argc, char **argv,
 		case OPT_TRACE_OOPS:
 			show_ftrace = true;
 			break;
+		case OPT_HOOK:
+			assert(optarg);
+			if (igt_hook) {
+				igt_warn("Overriding previous hook descriptor\n");
+				igt_hook_free(igt_hook);
+			}
+			ret = igt_hook_create(optarg, &igt_hook);
+			if (ret) {
+				igt_critical("Failed to initialize hook data: %s\n",
+					     igt_hook_error_str(ret));
+				ret = -2;
+				goto out;
+			}
+			break;
+		case OPT_HELP_HOOK:
+			igt_hook_print_help(stdout, "--hook");
+			ret = -1;
+			goto out;
 		case OPT_DEVICE:
 			assert(optarg);
 			/* if set by env IGT_DEVICE we need to free it */
@@ -1274,9 +1306,15 @@ out:
 			exit(IGT_EXIT_INVALID);
 	}
 
-	if (ret < 0)
+	if (ret < 0) {
+		if (igt_hook) {
+			igt_hook_free(igt_hook);
+			igt_hook = NULL;
+		}
+
 		/* exit with no error for -h/--help */
 		exit(ret == -1 ? 0 : IGT_EXIT_INVALID);
+	}
 
 	if (!igt_only_list_subtests()) {
 		bind_fbcon(false);
@@ -1284,6 +1322,10 @@ out:
 		print_version();
 		igt_srandom();
 
+		igt_hook_event_notify(igt_hook, &(struct igt_hook_evt){
+			.evt_type = IGT_HOOK_PRE_TEST,
+			.target_name = command_str });
+
 		sync();
 		oom_adjust_for_doom();
 		ftrace_dump_on_oops(show_ftrace);
@@ -1487,6 +1529,11 @@ bool __igt_run_subtest(const char *subtest_name, const char *file, const int lin
 	igt_thread_clear_fail_state();
 
 	igt_gettime(&subtest_time);
+
+	igt_hook_event_notify(igt_hook, &(struct igt_hook_evt){
+		.evt_type = IGT_HOOK_PRE_SUBTEST,
+		.target_name = subtest_name });
+
 	return (in_subtest = subtest_name);
 }
 
@@ -1517,6 +1564,11 @@ bool __igt_run_dynamic_subtest(const char *dynamic_subtest_name)
 	_igt_dynamic_tests_executed++;
 
 	igt_gettime(&dynamic_subtest_time);
+
+	igt_hook_event_notify(igt_hook, &(struct igt_hook_evt){
+		.evt_type = IGT_HOOK_PRE_DYN_SUBTEST,
+		.target_name = dynamic_subtest_name });
+
 	return (in_dynamic_subtest = dynamic_subtest_name);
 }
 
@@ -1602,6 +1654,12 @@ __noreturn static void exit_subtest(const char *result)
 	struct timespec *thentime = in_dynamic_subtest ? &dynamic_subtest_time : &subtest_time;
 	jmp_buf *jmptarget = in_dynamic_subtest ? &igt_dynamic_jmpbuf : &igt_subtest_jmpbuf;
 
+	igt_hook_event_notify(igt_hook, &(struct igt_hook_evt){
+		.evt_type = (in_dynamic_subtest
+				? IGT_HOOK_POST_DYN_SUBTEST
+				: IGT_HOOK_POST_SUBTEST),
+		.result = result });
+
 	if (!igt_thread_is_main()) {
 		igt_thread_fail();
 		pthread_exit(NULL);
@@ -2274,6 +2332,7 @@ void __igt_abort(const char *domain, const char *file, const int line,
 void igt_exit(void)
 {
 	int tmp;
+	const char *result;
 
 	if (!test_with_subtests)
 		igt_thread_assert_no_failures();
@@ -2318,12 +2377,7 @@ void igt_exit(void)
 
 	assert(waitpid(-1, &tmp, WNOHANG) == -1 && errno == ECHILD);
 
-	if (!test_with_subtests) {
-		struct timespec now;
-		const char *result;
-
-		igt_gettime(&now);
-
+	if (!test_with_subtests || igt_hook) {
 		switch (igt_exitcode) {
 			case IGT_EXIT_SUCCESS:
 				result = "SUCCESS";
@@ -2334,6 +2388,12 @@ void igt_exit(void)
 			default:
 				result = "FAIL";
 		}
+	}
+
+	if (!test_with_subtests) {
+		struct timespec now;
+
+		igt_gettime(&now);
 
 		if (test_multi_fork_child) /* parent will do the yelling */
 			_log_line_fprintf(stdout, "dyn_child pid:%d (%.3fs) ends with err=%d\n",
@@ -2344,6 +2404,10 @@ void igt_exit(void)
 					  result, igt_time_elapsed(&subtest_time, &now));
 	}
 
+	igt_hook_event_notify(igt_hook, &(struct igt_hook_evt){
+		.evt_type = IGT_HOOK_POST_TEST,
+		.result = result });
+
 	exit(igt_exitcode);
 }
 
diff --git a/lib/igt_hook.c b/lib/igt_hook.c
new file mode 100644
index 000000000000..b9350fdd78b1
--- /dev/null
+++ b/lib/igt_hook.c
@@ -0,0 +1,470 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright(c) 2024 Intel Corporation. All rights reserved.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "igt_hook.h"
+
+/**
+ * SECTION:igt_hook
+ * @short_description: Support for running a hook script on test execution
+ * @title: Hook support
+ *
+ * IGT provides support for running a hook script when executing tests. This
+ * support is provided to users via CLI option `--hook` available in test
+ * binaries. Users should use `--help-hook` for detailed usaged description of
+ * the feature.
+ *
+ * The sole user of the exposed API is `igt_core`, which calls @igt_hook_create()
+ * when initializing a test case, then calls @igt_hook_event_notify() for each
+ * event that occurs during that test's execution and finally calls
+ * @igt_hook_free() to clean up at the end.
+ */
+
+#define TEST_NAME_INITIAL_SIZE 16
+
+typedef uint16_t evt_mask_t;
+
+struct igt_hook {
+	evt_mask_t evt_mask;
+	char *cmd;
+	char *test_name;
+	size_t test_name_size;
+	char *subtest_name;
+	size_t subtest_name_size;
+	char *dyn_subtest_name;
+	size_t dyn_subtest_name_size;
+	char *test_fullname;
+};
+
+enum igt_hook_error {
+	IGT_HOOK_EVT_EMPTY_NAME = 1,
+	IGT_HOOK_EVT_NO_MATCH,
+};
+
+static_assert(IGT_HOOK_NUM_EVENTS <= sizeof(evt_mask_t) * CHAR_BIT,
+	      "Number of event types does not fit event type mask");
+
+static const char *igt_hook_evt_type_to_name(enum igt_hook_evt_type evt_type)
+{
+	switch (evt_type) {
+	case IGT_HOOK_PRE_TEST:
+		return "pre-test";
+	case IGT_HOOK_PRE_SUBTEST:
+		return "pre-subtest";
+	case IGT_HOOK_PRE_DYN_SUBTEST:
+		return "pre-dyn-subtest";
+	case IGT_HOOK_POST_DYN_SUBTEST:
+		return "post-dyn-subtest";
+	case IGT_HOOK_POST_SUBTEST:
+		return "post-subtest";
+	case IGT_HOOK_POST_TEST:
+		return "post-test";
+	case IGT_HOOK_NUM_EVENTS:
+		break;
+	/* No "default:" case, to force a warning from -Wswitch in case we miss
+	 * any new event type. */
+	}
+	return "?";
+}
+
+static int igt_hook_parse_hook_str(const char *hook_str, evt_mask_t *evt_mask, const char **cmd)
+{
+	const char *s;
+
+	if (!strchr(hook_str, ':')) {
+		*evt_mask = ~0;
+		*cmd = hook_str;
+		return 0;
+	}
+
+	s = hook_str;
+	*evt_mask = 0;
+
+	while (1) {
+		const char *evt_name;
+		bool has_match;
+		bool is_star;
+		enum igt_hook_evt_type evt_type;
+
+		evt_name = s;
+
+		while (*s != ':' && *s != ',')
+			s++;
+
+		if (evt_name == s)
+			return IGT_HOOK_EVT_EMPTY_NAME;
+
+		has_match = false;
+		is_star = *evt_name == '*' && evt_name + 1 == s;
+
+		for (evt_type = IGT_HOOK_PRE_TEST; evt_type < IGT_HOOK_NUM_EVENTS; evt_type++) {
+			if (!is_star) {
+				const char *this_event_name = igt_hook_evt_type_to_name(evt_type);
+				size_t len = s - evt_name;
+
+				if (len != strlen(this_event_name))
+					continue;
+
+				if (strncmp(evt_name, this_event_name, len))
+					continue;
+			}
+
+			*evt_mask |= 1 << evt_type;
+			has_match = true;
+
+			if (!is_star)
+				break;
+		}
+
+		if (!has_match)
+			return IGT_HOOK_EVT_NO_MATCH;
+
+		if (*s++ == ':')
+			break;
+	}
+
+	*cmd = s;
+
+	return 0;
+}
+
+static size_t igt_hook_calc_test_fullname_size(struct igt_hook *igt_hook)
+{
+	/* The maximum size of test_fullname will be the maximum length of
+	 * "igt@<test_name>@<subtest_name>@<dyn_subtest_name>" plus 1 for the
+	 * null byte. */
+	return igt_hook->test_name_size + igt_hook->subtest_name_size + igt_hook->dyn_subtest_name_size + 4;
+}
+
+static void igt_hook_update_test_fullname(struct igt_hook *igt_hook)
+{
+	int i;
+	char *s;
+	const char *values[] = {
+		igt_hook->test_name,
+		igt_hook->subtest_name,
+		igt_hook->dyn_subtest_name,
+		NULL,
+	};
+
+	if (igt_hook->test_name[0] == '\0') {
+		igt_hook->test_fullname[0] = '\0';
+		return;
+	}
+
+	s = stpcpy(igt_hook->test_fullname, "igt");
+	for (i = 0; values[i] && values[i][0] != '\0'; i++) {
+		*s++ = '@';
+		s = stpcpy(s, values[i]);
+	}
+}
+
+/**
+ * igt_hook_create:
+ * @hook_str: Hook descriptor string.
+ * @igt_hook_ptr: Destination of the struct igt_hook pointer.
+ *
+ * Allocate and initialize an #igt_hook structure.
+ *
+ * This function parses the hook descriptor in @hook_str and initializes the
+ * struct. The pointer to the allocated structure is stored in @igt_hook_ptr.
+ *
+ * The hook descriptor comes from the argument to `--hook` of the test
+ * executable being run.
+ *
+ * If an error happens, the returned error number can be passed to
+ * @igt_hook_error_str() to get a human-readable error message.
+ *
+ * Returns: Zero on success and a non-zero value on error.
+ */
+int igt_hook_create(const char *hook_str, struct igt_hook **igt_hook_ptr)
+{
+	int ret;
+	evt_mask_t evt_mask;
+	const char *cmd;
+	struct igt_hook *igt_hook = NULL;
+
+	ret = igt_hook_parse_hook_str(hook_str, &evt_mask, &cmd);
+	if (ret)
+		goto out;
+
+	igt_hook = calloc(1, sizeof(*igt_hook));
+	igt_hook->evt_mask = evt_mask;
+	igt_hook->cmd = strdup(cmd);
+	igt_hook->test_name = malloc(TEST_NAME_INITIAL_SIZE);
+	igt_hook->test_name_size = TEST_NAME_INITIAL_SIZE;
+	igt_hook->subtest_name = malloc(TEST_NAME_INITIAL_SIZE);
+	igt_hook->subtest_name_size = TEST_NAME_INITIAL_SIZE;
+	igt_hook->dyn_subtest_name = malloc(TEST_NAME_INITIAL_SIZE);
+	igt_hook->dyn_subtest_name_size = TEST_NAME_INITIAL_SIZE;
+	igt_hook->test_fullname = malloc(igt_hook_calc_test_fullname_size(igt_hook));
+
+	igt_hook->test_name[0] = '\0';
+	igt_hook->subtest_name[0] = '\0';
+	igt_hook->dyn_subtest_name[0] = '\0';
+	igt_hook->test_fullname[0] = '\0';
+
+out:
+	if (ret)
+		igt_hook_free(igt_hook);
+	else
+		*igt_hook_ptr = igt_hook;
+
+	return ret;
+}
+
+/**
+ * igt_hook_free:
+ * @igt_hook: The igt_hook struct.
+ *
+ * De-initialize an igt_hook struct returned by @igt_hook_create().
+ *
+ * This is a no-op if @igt_hook is #NULL.
+ */
+void igt_hook_free(struct igt_hook *igt_hook)
+{
+	if (!igt_hook)
+		return;
+
+	free(igt_hook->cmd);
+	free(igt_hook->test_name);
+	free(igt_hook->subtest_name);
+	free(igt_hook->dyn_subtest_name);
+	free(igt_hook);
+}
+
+static void igt_hook_update_test_name_pre_call(struct igt_hook *igt_hook, struct igt_hook_evt *evt)
+{
+	char **name_ptr;
+	size_t *size_ptr;
+	size_t len;
+
+	switch (evt->evt_type) {
+	case IGT_HOOK_PRE_TEST:
+		name_ptr = &igt_hook->test_name;
+		size_ptr = &igt_hook->test_name_size;
+		break;
+	case IGT_HOOK_PRE_SUBTEST:
+		name_ptr = &igt_hook->subtest_name;
+		size_ptr = &igt_hook->subtest_name_size;
+		break;
+	case IGT_HOOK_PRE_DYN_SUBTEST:
+		name_ptr = &igt_hook->dyn_subtest_name;
+		size_ptr = &igt_hook->dyn_subtest_name_size;
+		break;
+	default:
+		return;
+	}
+
+	len = strlen(evt->target_name);
+	if (len + 1 > *size_ptr) {
+		size_t fullname_size;
+
+		*size_ptr *= 2;
+		*name_ptr = realloc(*name_ptr, *size_ptr);
+
+		fullname_size = igt_hook_calc_test_fullname_size(igt_hook);
+		igt_hook->test_fullname = realloc(igt_hook->test_fullname, fullname_size);
+	}
+
+	strcpy(*name_ptr, evt->target_name);
+	igt_hook_update_test_fullname(igt_hook);
+}
+
+static void igt_hook_update_test_name_post_call(struct igt_hook *igt_hook, struct igt_hook_evt *evt)
+{
+	switch (evt->evt_type) {
+	case IGT_HOOK_POST_TEST:
+		igt_hook->test_name[0] = '\0';
+		break;
+	case IGT_HOOK_POST_SUBTEST:
+		igt_hook->subtest_name[0] = '\0';
+		break;
+	case IGT_HOOK_POST_DYN_SUBTEST:
+		igt_hook->dyn_subtest_name[0] = '\0';
+		break;
+	default:
+		return;
+	}
+
+	igt_hook_update_test_fullname(igt_hook);
+}
+
+static void igt_hook_update_env_vars(struct igt_hook *igt_hook, struct igt_hook_evt *evt)
+{
+	setenv("IGT_HOOK_EVENT", igt_hook_evt_type_to_name(evt->evt_type), 1);
+	setenv("IGT_HOOK_TEST_FULLNAME", igt_hook->test_fullname, 1);
+	setenv("IGT_HOOK_TEST", igt_hook->test_name, 1);
+	setenv("IGT_HOOK_SUBTEST", igt_hook->subtest_name, 1);
+	setenv("IGT_HOOK_DYN_SUBTEST", igt_hook->dyn_subtest_name, 1);
+	setenv("IGT_HOOK_RESULT", evt->result ?: "", 1);
+}
+
+/**
+ * igt_hook_event_notify:
+ * @igt_hook: The igt_hook structure.
+ * @evt: The event to be pushed.
+ *
+ * Push a new igt_hook event.
+ *
+ * The argument to @igt_hook can be #NULL, which is equivalent to a no-op.
+ *
+ * This function must be used to notify on a new igt_hook event. Calling it will
+ * cause execution of the hook script if the event type matches the filters
+ * provided during initialization of @igt_hook.
+ */
+void igt_hook_event_notify(struct igt_hook *igt_hook, struct igt_hook_evt *evt)
+{
+	evt_mask_t evt_bit;
+
+	if (!igt_hook)
+		return;
+
+	evt_bit = (1 << evt->evt_type);
+	igt_hook_update_test_name_pre_call(igt_hook, evt);
+
+	if ((evt_bit & igt_hook->evt_mask)) {
+		igt_hook_update_env_vars(igt_hook, evt);
+		system(igt_hook->cmd);
+	}
+
+	igt_hook_update_test_name_post_call(igt_hook, evt);
+}
+
+/**
+ * igt_hook_error_str:
+ * @error: Non-zero error number.
+ *
+ * Return a human-readable string containing a description of an error number
+ * generated by one of the `igt_hook_*` functions.
+ *
+ * The string will be the result of strerror() for errors from the C standard
+ * library or a custom description specific to igt_hook.
+ */
+const char *igt_hook_error_str(int error)
+{
+	if (!error)
+		return "No error";
+
+	switch (error) {
+	case IGT_HOOK_EVT_EMPTY_NAME:
+		return "Empty name in event descriptor";
+	case IGT_HOOK_EVT_NO_MATCH:
+		return "Event name in event descriptor does not match any event type";
+	default:
+		return "Unknown error";
+	}
+}
+
+/**
+ * igt_hook_print_help:
+ * @f: File pointer where to write the output.
+ * @option_name: Name of the CLI option that accepts the hook descriptor.
+ *
+ * Print a detailed user help text on hook usage.
+ */
+void igt_hook_print_help(FILE *f, const char *option_name)
+{
+	fprintf(f, "\
+The option %1$s receives as argument a \"hook descriptor\" and allows the\n\
+execution of a shell command at different points during execution of tests. Each\n\
+such a point is called a \"hook event\".\n\
+\n\
+Examples:\n\
+\n\
+  # Prints hook-specic env vars for every event.\n\
+  %1$s 'printenv | grep ^IGT_HOOK_'\n\
+\n\
+  # Equivalent to the above. Useful if command contains ':'.\n\
+  %1$s '*:printenv | grep ^IGT_HOOK_'\n\
+\n\
+  # Adds a line to out.txt containing the result of each test case.\n\
+  %1$s 'post-test:echo $IGT_HOOK_TEST_FULLNAME $IGT_HOOK_RESULT >> out.txt'\n\
+\n\
+The accepted format for a hook descriptor is `[<events>:]<cmd>`, where:\n\
+\n\
+  - <events> is a comma-separated list of event descriptors, which defines the\n\
+    set of events be tracked. If omitted, all events are tracked.\n\
+\n\
+  - <cmd> is a shell command to be executed on the occurrence each tracked\n\
+    event. If the command contains ':', then passing <events> is required,\n\
+    otherwise part of the command would be treated as an event descriptor.\n\
+\n\
+", option_name);
+
+	fprintf(f, "\
+An \"event descriptor\" is either the name of an event or the string '*'. The\n\
+latter matches all event names. The list of possible event names is provided\n\
+below:\n\
+\n\
+");
+
+	for (enum igt_hook_evt_type et = 0; et < IGT_HOOK_NUM_EVENTS; et++) {
+		const char *desc;
+
+		switch (et) {
+		case IGT_HOOK_PRE_TEST:
+			desc = "Occurs before a test case starts.";
+			break;
+		case IGT_HOOK_PRE_SUBTEST:
+			desc = "Occurs before the execution of a subtest.";
+			break;
+		case IGT_HOOK_PRE_DYN_SUBTEST:
+			desc = "Occurs before the execution of a dynamic subtest.";
+			break;
+		case IGT_HOOK_POST_DYN_SUBTEST:
+			desc = "Occurs after the execution of a dynamic subtest.";
+			break;
+		case IGT_HOOK_POST_SUBTEST:
+			desc = "Occurs after the execution of a subtest.";
+			break;
+		case IGT_HOOK_POST_TEST:
+			desc = "Occurs after a test case has finished.";
+			break;
+		default:
+			desc = "MISSING DESCRIPTION";
+		}
+
+		fprintf(f, "  %s\n  %s\n\n", igt_hook_evt_type_to_name(et), desc);
+	}
+
+	fprintf(f, "\
+For each event matched by <events>, <cmd> is executed as a shell command. The\n\
+exit status of the command is ignored. The following environment variables are\n\
+available to the command:\n\
+\n\
+  IGT_HOOK_EVENT\n\
+  Name of the current event.\n\
+\n\
+  IGT_HOOK_TEST_FULLNAME\n\
+  Full name of the test in the format `igt@<test>[@<subtest>[@<dyn_subtest>]]`.\n\
+\n\
+  IGT_HOOK_TEST\n\
+  Name of the current test.\n\
+\n\
+  IGT_HOOK_SUBTEST\n\
+  Name of the current subtest. Will be the empty string if not running a\n\
+  subtest.\n\
+\n\
+  IGT_HOOK_DYN_SUBTEST\n\
+  Name of the current dynamic subtest. Will be the empty string if not running a\n\
+  dynamic subtest.\n\
+\n\
+  IGT_HOOK_RESULT\n\
+  String representing the result of the test/subtest/dynamic subtest. Possible\n\
+  values are: SUCCESS, SKIP or FAIL. This is only applicable on \"post-*\"\n\
+  events and will be the empty string for other types of events.\n\
+\n\
+");
+}
diff --git a/lib/igt_hook.h b/lib/igt_hook.h
new file mode 100644
index 000000000000..83722cbb2f2b
--- /dev/null
+++ b/lib/igt_hook.h
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright(c) 2024 Intel Corporation. All rights reserved.
+ */
+
+#ifndef IGT_HOOK_H
+#define IGT_HOOK_H
+
+#include <stdio.h>
+
+/**
+ * igt_hook:
+ *
+ * Opaque struct to hold data related to hook support.
+ */
+struct igt_hook;
+
+/**
+ * igt_hook_evt_type:
+ * @IGT_HOOK_PRE_TEST: Occurs before a test case (executable) starts the
+ * test code.
+ * @IGT_HOOK_PRE_SUBTEST: Occurs before the execution of a subtest.
+ * @IGT_HOOK_PRE_DYN_SUBTEST: Occurs before the execution of a dynamic subtest.
+ * @IGT_HOOK_POST_DYN_SUBTEST: Occurs after the execution of a dynamic subtest.
+ * @IGT_HOOK_POST_SUBTEST: Occurs after the execution of a subtest..
+ * @IGT_HOOK_POST_TEST: Occurs after a test case (executable) is finished with
+ * the test code.
+ * @IGT_HOOK_NUM_EVENTS: This is not really an event and represents the number
+ * of possible events tracked by igt_hook.
+ *
+ * Events tracked by igt_hook. Those events occur at specific points during the
+ * execution of a test.
+ */
+enum igt_hook_evt_type {
+	IGT_HOOK_PRE_TEST,
+	IGT_HOOK_PRE_SUBTEST,
+	IGT_HOOK_PRE_DYN_SUBTEST,
+	IGT_HOOK_POST_DYN_SUBTEST,
+	IGT_HOOK_POST_SUBTEST,
+	IGT_HOOK_POST_TEST,
+	IGT_HOOK_NUM_EVENTS /* This must always be the last one. */
+};
+
+/**
+ * igt_hook_evt:
+ * @evt_type: Type of event.
+ * @target_name: A string pointing to the name of the test, subtest or dynamic
+ * subtest, depending on @evt_type.
+ * @result: A string containing the result of the test, subtest or dynamic
+ * subtest. This is only applicable for the `IGT_HOOK_POST_\*' event types;
+ * other types must initialize this to #NULL.
+ *
+ * An event tracked by igt_hook, which is done with @@igt_hook_event_notify().
+ * This must be zero initialized and fields relevant to the event type must be
+ * set before passing its reference to @igt_hook_event_notify().
+ */
+struct igt_hook_evt {
+	enum igt_hook_evt_type evt_type;
+	const char *target_name;
+	const char *result;
+};
+
+int igt_hook_create(const char *hook_str, struct igt_hook **igt_hook_ptr);
+void igt_hook_free(struct igt_hook *igt_hook);
+void igt_hook_event_notify(struct igt_hook *igt_hook, struct igt_hook_evt *evt);
+const char *igt_hook_error_str(int error);
+void igt_hook_print_help(FILE *f, const char *option_name);
+
+#endif /* IGT_HOOK_H */
diff --git a/lib/meson.build b/lib/meson.build
index f711e60a736a..ab4cf9c7a2ba 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -110,6 +110,7 @@ lib_sources = [
 	'veboxcopy_gen12.c',
 	'igt_msm.c',
 	'igt_dsc.c',
+	'igt_hook.c',
 	'xe/xe_gt.c',
 	'xe/xe_ioctl.c',
 	'xe/xe_mmio.c',
diff --git a/lib/tests/igt_hook.c b/lib/tests/igt_hook.c
new file mode 100644
index 000000000000..0d71909e676a
--- /dev/null
+++ b/lib/tests/igt_hook.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright(c) 2024 Intel Corporation. All rights reserved.
+ */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "igt_core.h"
+#include "igt_hook.h"
+
+static const char *env_var_names[] = {
+	"IGT_HOOK_EVENT",
+	"IGT_HOOK_TEST_FULLNAME",
+	"IGT_HOOK_TEST",
+	"IGT_HOOK_SUBTEST",
+	"IGT_HOOK_DYN_SUBTEST",
+	"IGT_HOOK_RESULT",
+};
+
+#define num_env_vars (sizeof(env_var_names) / sizeof(env_var_names[0]))
+
+static int env_var_name_lookup(char *line)
+{
+	int i;
+	char *c;
+
+	c = strchr(line, '=');
+	if (c)
+		*c = '\0';
+
+	for (i = 0; i < num_env_vars; i++)
+		if (!strcmp(line, env_var_names[i]))
+			goto out;
+
+	i = -1;
+out:
+	if (c)
+		*c = '=';
+
+	return i;
+}
+
+static void test_invalid_hook_descriptors(void)
+{
+	struct {
+		const char *name;
+		const char *hook_desc;
+	} invalid_cases[] = {
+		{"invalid-event-name", "invalid-event:echo hello"},
+		{"invalid-empty-event-name", ":echo hello"},
+		{"invalid-colon-in-cmd", "echo hello:world"},
+		{},
+	};
+
+	for (int i = 0; invalid_cases[i].name; i++) {
+		igt_subtest(invalid_cases[i].name) {
+			int err;
+			struct igt_hook *igt_hook;
+
+			err = igt_hook_create(invalid_cases[i].hook_desc, &igt_hook);
+			igt_assert(err != 0);
+		}
+	}
+}
+
+static void test_print_help(void)
+{
+	char *buf;
+	size_t len;
+	FILE *f;
+	const char expected_initial_text[] = "The option --hook receives as argument a \"hook descriptor\"";
+
+	f = open_memstream(&buf, &len);
+	igt_assert(f);
+
+	igt_hook_print_help(f, "--hook");
+	fclose(f);
+
+	igt_assert(!strncmp(buf, expected_initial_text, sizeof(expected_initial_text) - 1));
+
+	/* This is an extra check to catch a case where an event type is added
+	 * without a proper description. */
+	igt_assert(!strstr(buf, "MISSING DESCRIPTION"));
+
+	free(buf);
+}
+
+static void test_all_env_vars(void)
+{
+	struct igt_hook_evt evt = {
+		.evt_type = IGT_HOOK_PRE_SUBTEST,
+		.target_name = "foo",
+	};
+	bool env_vars_checklist[num_env_vars] = {};
+	struct igt_hook *igt_hook;
+	char *hook_str;
+	FILE *f;
+	int pipefd[2];
+	int ret;
+	int i;
+	char *line;
+	size_t line_size;
+
+	ret = pipe(pipefd);
+	igt_assert(ret == 0);
+
+	/* Use grep to filter only env var set by us. This should ensure that
+	 * writing to the pipe will not block due to capacity, since we only
+	 * read from the pipe after the shell command is done. */
+	ret = asprintf(&hook_str, "printenv -0 | grep -z ^IGT_HOOK >&%d", pipefd[1]);
+	igt_assert(ret > 0);
+
+	ret = igt_hook_create(hook_str, &igt_hook);
+	igt_assert(ret == 0);
+
+	igt_hook_event_notify(igt_hook, &evt);
+
+	close(pipefd[1]);
+	f = fdopen(pipefd[0], "r");
+	igt_assert(f);
+
+	line = NULL;
+	line_size = 0;
+
+	while (getdelim(&line, &line_size, '\0', f) != -1) {
+		ret = env_var_name_lookup(line);
+		igt_assert_f(ret >= 0, "Unexpected env var %s\n", line);
+		env_vars_checklist[ret] = true;
+	}
+
+	for (i = 0; i < num_env_vars; i++)
+		igt_assert_f(env_vars_checklist[i], "Missing env var %s\n", env_var_names[i]);
+
+	fclose(f);
+	igt_hook_free(igt_hook);
+	free(hook_str);
+	free(line);
+}
+
+igt_main
+{
+	test_invalid_hook_descriptors();
+
+	igt_subtest("help-description")
+		test_print_help();
+
+	igt_subtest_group {
+		igt_fixture {
+			igt_require_f(system(NULL), "Shell seems not to be available\n");
+		}
+
+		igt_subtest("all-env-vars")
+			test_all_env_vars();
+	}
+}
diff --git a/lib/tests/igt_hook_integration.c b/lib/tests/igt_hook_integration.c
new file mode 100644
index 000000000000..f5ba25e92897
--- /dev/null
+++ b/lib/tests/igt_hook_integration.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright(c) 2024 Intel Corporation. All rights reserved.
+ */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "igt_core.h"
+
+#include "igt_tests_common.h"
+
+char prog[] = "igt_hook_integration";
+char hook_opt[] = "--hook";
+char hook_str[128];
+char *fake_argv[] = {prog, hook_opt, hook_str};
+int fake_argc = sizeof(fake_argv) / sizeof(fake_argv[0]);
+
+#define ENV_ARRAY(evt_name, fullname_suffix, subtest, dyn_subtest, result) \
+{ \
+	"IGT_HOOK_EVENT=" evt_name, \
+	"IGT_HOOK_TEST_FULLNAME=igt at igt_hook_integration" fullname_suffix, \
+	"IGT_HOOK_TEST=igt_hook_integration", \
+	"IGT_HOOK_SUBTEST=" subtest, \
+	"IGT_HOOK_DYN_SUBTEST=" dyn_subtest, \
+	"IGT_HOOK_RESULT=" result, \
+}
+
+#define TEST_ENV(evt_name, result) \
+	ENV_ARRAY(evt_name, "", "", "", result)
+
+#define SUBTEST_ENV(evt_name, subtest, result) \
+	ENV_ARRAY(evt_name, "@" subtest, subtest, "", result)
+
+#define DYN_SUBTEST_ENV(evt_name, subtest, dyn_subtest, result) \
+	ENV_ARRAY(evt_name, "@" subtest "@" dyn_subtest, subtest, dyn_subtest, result)
+
+const char *pre_test_env[] = TEST_ENV("pre-test", "");
+const char *pre_subtest_a_env[] = SUBTEST_ENV("pre-subtest", "a", "");
+const char *pre_dyn_subtest_a_success_env[] = DYN_SUBTEST_ENV("pre-dyn-subtest", "a", "success", "");
+const char *post_dyn_subtest_a_success_env[] = DYN_SUBTEST_ENV("post-dyn-subtest", "a", "success", "SUCCESS");
+const char *pre_dyn_subtest_a_failed_env[] = DYN_SUBTEST_ENV("pre-dyn-subtest", "a", "failed", "");
+const char *post_dyn_subtest_a_failed_env[] = DYN_SUBTEST_ENV("post-dyn-subtest", "a", "failed", "FAIL");
+const char *pre_dyn_subtest_a_skipped_env[] = DYN_SUBTEST_ENV("pre-dyn-subtest", "a", "skipped", "");
+const char *post_dyn_subtest_a_skipped_env[] = DYN_SUBTEST_ENV("post-dyn-subtest", "a", "skipped", "SKIP");
+const char *post_subtest_a_env[] = SUBTEST_ENV("post-subtest", "a", "FAIL");
+const char *pre_subtest_b_env[] = SUBTEST_ENV("pre-subtest", "b", "");
+const char *post_subtest_b_env[] = SUBTEST_ENV("post-subtest", "b", "SUCCESS");
+const char *post_test_env[] = TEST_ENV("post-test", "FAIL");
+
+#define num_env_vars (sizeof(pre_test_env) / sizeof(pre_test_env[0]))
+
+__noreturn static void fake_main(void)
+{
+	igt_subtest_init(fake_argc, fake_argv);
+
+	igt_subtest_with_dynamic("a") {
+		igt_dynamic("success") {
+			igt_info("... at a@success\n");
+		}
+
+		igt_dynamic("failed") {
+			igt_assert_f(false, "Fail on purpose\n");
+			igt_info("... at a@failed\n");
+		}
+
+		igt_dynamic("skipped") {
+			igt_require_f(false, "Skip on purpose\n");
+			igt_info("... at a@skipped\n");
+		}
+	}
+
+	igt_subtest("b") {
+		igt_info("... at b\n");
+	}
+
+	igt_exit();
+}
+
+static void test_invalid_hook_str(void)
+{
+	int status;
+	pid_t pid;
+	static char err[4096];
+	int errfd;
+
+	sprintf(hook_str, "invalid-event:echo hello");
+
+	pid = do_fork_bg_with_pipes(fake_main, NULL, &errfd);
+
+	read_whole_pipe(errfd, err, sizeof(err));
+
+	internal_assert(safe_wait(pid, &status) != -1);
+	internal_assert_wexited(status, IGT_EXIT_INVALID);
+
+	internal_assert(strstr(err, "Failed to initialize hook data:"));
+
+	close(errfd);
+}
+
+static bool match_env(FILE *hook_out_stream, const char **expected_env)
+{
+	int i;
+	char hook_env_buf[4096];
+	size_t buf_len = 0;
+	char *line = NULL;
+	size_t line_size;
+	bool env_checklist[num_env_vars] = {};
+	bool has_unexpected = false;
+	bool has_missing = false;
+
+	/* Store env from hook so we can show it in case of errors */
+	while (getdelim(&line, &line_size, '\0', hook_out_stream) != -1) {
+		internal_assert(buf_len + strlen(line) + 1 <= sizeof(hook_env_buf));
+		strcpy(hook_env_buf + buf_len, line);
+		buf_len += strlen(line) + 1;
+
+		if (!strcmp(line, "---"))
+			break;
+	}
+
+	if (!expected_env && !buf_len) {
+		/* We have consumed everything and we are done now. */
+		return false;
+	}
+
+
+	if (!expected_env) {
+		printf("Detected unexpected hook execution\n");
+		has_unexpected = true;
+		goto out;
+	}
+
+	if (!buf_len) {
+		printf("Expected more hook execution, but none found\n");
+		has_missing = true;
+		goto out;
+	}
+
+
+	line = hook_env_buf;
+	while (strcmp(line, "---")) {
+		for (i = 0; i < num_env_vars; i++) {
+			if (!strcmp(line, expected_env[i])) {
+				env_checklist[i] = true;
+				break;
+			}
+		}
+
+		if (i == num_env_vars) {
+			printf("Unexpected envline from hook: %s\n", line);
+			has_unexpected = true;
+		}
+
+		line += strlen(line) + 1;
+	}
+
+	for (i = 0; i < num_env_vars; i++) {
+		if (!env_checklist[i]) {
+			has_missing = true;
+			printf("Missing expected envline: %s\n", expected_env[i]);
+		}
+	}
+
+out:
+	if (has_unexpected || has_missing) {
+		if (expected_env) {
+			printf("Expected environment:\n");
+			for (i = 0; i < num_env_vars; i++)
+				printf("  %s\n", expected_env[i]);
+		}
+
+		if (buf_len) {
+			printf("Environment from hook:\n");
+			line = hook_env_buf;
+			while (strcmp(line, "---")) {
+				printf("  %s\n", line);
+				line += strlen(line) + 1;
+			}
+		} else {
+			printf("No hook execution found\n");
+		}
+	}
+
+	internal_assert(!has_unexpected);
+	internal_assert(!has_missing);
+
+	/* Ready to consume next hook output. */
+	return true;
+}
+
+static void run_tests_and_match_env(const char *evt_descriptors, const char **expected_envs[])
+{
+	int i;
+	int ret;
+	int pipefd[2];
+	pid_t pid;
+	FILE *f;
+
+	ret = pipe(pipefd);
+	internal_assert(ret == 0);
+
+	/* Use grep to filter only env var set by us. This should ensure that
+	 * writing to the pipe will not block due to capacity, since we only
+	 * read from the pipe after the shell command is done. */
+	sprintf(hook_str,
+		"%1$s:printenv -0 | grep -z ^IGT_HOOK >&%2$d; printf -- ---\\\\00 >&%2$d",
+		evt_descriptors,
+		pipefd[1]);
+
+	pid = do_fork_bg_with_pipes(fake_main, NULL, NULL);
+	internal_assert(safe_wait(pid, &ret) != -1);
+	internal_assert_wexited(ret, IGT_EXIT_FAILURE);
+
+	close(pipefd[1]);
+	f = fdopen(pipefd[0], "r");
+	internal_assert(f);
+
+	i = 0;
+	while (match_env(f, expected_envs[i]))
+		i++;
+
+	fclose(f);
+
+}
+
+int main(int argc, char **argv)
+{
+	{
+		printf("Check invalid hook string\n");
+		test_invalid_hook_str();
+	}
+
+	{
+		const char **expected_envs[] = {
+			pre_test_env,
+			pre_subtest_a_env,
+			pre_dyn_subtest_a_success_env,
+			post_dyn_subtest_a_success_env,
+			pre_dyn_subtest_a_failed_env,
+			post_dyn_subtest_a_failed_env,
+			pre_dyn_subtest_a_skipped_env,
+			post_dyn_subtest_a_skipped_env,
+			post_subtest_a_env,
+			pre_subtest_b_env,
+			post_subtest_b_env,
+			post_test_env,
+			NULL,
+		};
+
+		printf("Check full event tracking\n");
+		run_tests_and_match_env("*", expected_envs);
+	}
+
+	{
+		const char **expected_envs[] = {
+			pre_dyn_subtest_a_success_env,
+			pre_dyn_subtest_a_failed_env,
+			pre_dyn_subtest_a_skipped_env,
+			NULL,
+		};
+
+		printf("Check single event type tracking\n");
+		run_tests_and_match_env("pre-dyn-subtest", expected_envs);
+	}
+
+	{
+		const char **expected_envs[] = {
+			pre_subtest_a_env,
+			post_dyn_subtest_a_success_env,
+			post_dyn_subtest_a_failed_env,
+			post_dyn_subtest_a_skipped_env,
+			pre_subtest_b_env,
+			NULL,
+		};
+
+		printf("Check multiple event types tracking\n");
+		run_tests_and_match_env("post-dyn-subtest,pre-subtest", expected_envs);
+	}
+}
diff --git a/lib/tests/meson.build b/lib/tests/meson.build
index fa3d81de6cef..df8092638eca 100644
--- a/lib/tests/meson.build
+++ b/lib/tests/meson.build
@@ -10,6 +10,8 @@ lib_tests = [
 	'igt_exit_handler',
 	'igt_fork',
 	'igt_fork_helper',
+	'igt_hook',
+	'igt_hook_integration',
         'igt_ktap_parser',
 	'igt_list_only',
 	'igt_invalid_subtest_name',
-- 
2.45.2



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