[PATCH v1 02/12] perf test: Truncate test description to fit terminal width

[Ian Rogers <irogers@google.com>]

The parallel test harness uses the carriage return delete escape sequence
`PERF_COLOR_DELETE_LINE` ("\033[A\33[2K\r") to erase and update the
"Running (X active)" progress lines.

However, if a test description is longer than the terminal width, the line
wraps around. When this happens, the cursor up escape sequence `\033[A` only
moves the cursor to the last wrapped row, leaving the top half of the description
printed on the previous line. This leads to name duplication and output corruption
spilling over multiple rows on consoles narrower than the maximum description length
(e.g., 101 columns wide).

Fix this by dynamically querying the terminal width using `get_term_dimensions`
and truncating the printed test descriptions using the `%-*.*s` printf format.
We reserve 35 characters for prefix, status, and spacing metrics to guarantee
the progress line never wraps.

Fixes: 0e036dcad4e6 ("perf test: Display number of active running tests")
Signed-off-by: Ian Rogers <irogers@google.com>
TAG=agy
CONV=7e7ee33a-e940-4a8a-8e64-878da6a68b59
---
 tools/perf/tests/builtin-test.c | 95 ++++++++++++++++++++++++---------
 1 file changed, 71 insertions(+), 24 deletions(-)

diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index afc06cec4954..51484e84d7c1 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -10,35 +10,39 @@
 #ifdef HAVE_BACKTRACE_SUPPORT
 #include <execinfo.h>
 #endif
-#include <poll.h>
-#include <unistd.h>
 #include <setjmp.h>
-#include <string.h>
 #include <stdlib.h>
-#include <sys/types.h>
+#include <string.h>
+
 #include <dirent.h>
-#include <sys/wait.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/zalloc.h>
+#include <poll.h>
+#include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <subcmd/exec-cmd.h>
+#include <subcmd/parse-options.h>
+#include <subcmd/run-command.h>
+
 #include "builtin.h"
+#include "color.h"
 #include "config.h"
+#include "debug.h"
 #include "hist.h"
 #include "intlist.h"
-#include "tests.h"
-#include "debug.h"
-#include "color.h"
-#include <subcmd/parse-options.h>
-#include <subcmd/run-command.h>
 #include "string2.h"
 #include "symbol.h"
+#include "tests-scripts.h"
+#include "tests.h"
 #include "util/rlimit.h"
 #include "util/strbuf.h"
-#include <linux/kernel.h>
-#include <linux/string.h>
-#include <subcmd/exec-cmd.h>
-#include <linux/zalloc.h>
-
-#include "tests-scripts.h"
+#include "util/term.h"
 
 static const char *junit_filename;
 static struct strbuf junit_xml_buf = STRBUF_INIT;
@@ -413,19 +417,52 @@ static char *xml_escape(const char *str)
 	return res ? res : strdup("");
 }
 
+static int get_max_desc_width(int width)
+{
+	struct winsize ws;
+	int cols = 80;
+	int max_desc_width;
+
+	get_term_dimensions(&ws);
+	if (ws.ws_col > 0)
+		cols = ws.ws_col;
+
+	/*
+	 * Limit description width to fit on a single line. We subtract 35
+	 * columns of headroom to allocate space for:
+	 * - The suite index prefix: e.g. " 10.100:" (9 characters).
+	 * - The colon separator and spaces: " : " (3 characters).
+	 * - The longest status results: e.g. "Skip (some metrics failed)" (26 characters)
+	 *   or "Running (XX active)" (20 characters).
+	 *
+	 * A minimum description width of 10 is enforced to ensure names are
+	 * legible even on very narrow consoles.
+	 */
+	max_desc_width = cols - 35;
+	if (max_desc_width < 10)
+		max_desc_width = 10;
+
+	return width > max_desc_width ? max_desc_width : width;
+}
+
 static int print_test_result(struct test_suite *t, int curr_suite, int curr_test_case,
 			     int result, int width, int running,
 			     const char *err_output, double elapsed)
 {
+	width = get_max_desc_width(width);
+
 	if (test_suite__num_test_cases(t) > 1) {
 		char prefix[32];
 		int len = snprintf(prefix, sizeof(prefix), "%3d.%1d:",
 				   curr_suite + 1, curr_test_case + 1);
 		int subw = len >= 4 ? width + 4 - len : width;
 
-		pr_info("%s %-*s:", prefix, subw, test_description(t, curr_test_case));
-	} else
-		pr_info("%3d: %-*s:", curr_suite + 1, width, test_description(t, curr_test_case));
+		pr_info("%s %-*.*s:", prefix, subw, subw,
+			test_description(t, curr_test_case));
+	} else {
+		pr_info("%3d: %-*.*s:", curr_suite + 1, width, width,
+			test_description(t, curr_test_case));
+	}
 
 	switch (result) {
 	case TEST_RUNNING:
@@ -695,6 +732,7 @@ static void finish_test(struct child_test **child_tests, int running_test, int c
 	int ret;
 	struct timespec end_time;
 	double elapsed;
+	width = get_max_desc_width(width);
 
 	if (child_test == NULL) {
 		/* Test wasn't started. */
@@ -709,7 +747,8 @@ static void finish_test(struct child_test **child_tests, int running_test, int c
 	 * sub test names.
 	 */
 	if (test_suite__num_test_cases(t) > 1 && curr_test_case == 0)
-		pr_info("%3d: %-*s:\n", curr_suite + 1, width, test_description(t, -1));
+		pr_info("%3d: %-*.*s:\n", curr_suite + 1, width, width,
+			test_description(t, -1));
 
 	/*
 	 * Busy loop reading from the child's stdout/stderr that are set to be
@@ -917,6 +956,8 @@ static int finish_tests_parallel(struct child_test **child_tests, size_t num_tes
 	int last_suite_printed = -1;
 	sigset_t set, oldset;
 
+	width = get_max_desc_width(width);
+
 	sigemptyset(&set);
 	sigaddset(&set, SIGINT);
 	sigaddset(&set, SIGTERM);
@@ -985,8 +1026,11 @@ static int finish_tests_parallel(struct child_test **child_tests, size_t num_tes
 			if (next_child) {
 				if (test_suite__num_test_cases(next_child->test) > 1 &&
 				    last_suite_printed != next_child->suite_num) {
-					pr_info("%3d: %-*s:\n", next_child->suite_num + 1, width,
-						test_description(next_child->test, -1));
+					pr_info("%3d: %-*.*s:\n",
+						next_child->suite_num + 1,
+						width, width,
+						test_description(
+							next_child->test, -1));
 					last_suite_printed = next_child->suite_num;
 				}
 				print_test_result(next_child->test, next_child->suite_num,
@@ -1049,7 +1093,8 @@ static int finish_tests_parallel(struct child_test **child_tests, size_t num_tes
 
 			if (test_suite__num_test_cases(child->test) > 1 &&
 			    last_suite_printed != child->suite_num) {
-				pr_info("%3d: %-*s:\n", child->suite_num + 1, width,
+				pr_info("%3d: %-*.*s:\n", child->suite_num + 1,
+					width, width,
 					test_description(child->test, -1));
 				last_suite_printed = child->suite_num;
 			}
@@ -1296,7 +1341,9 @@ static int __cmd_test(struct test_suite **suites, int argc, const char *argv[],
 
 			if (intlist__find(skiplist, curr_suite + 1)) {
 				if (pass == 1) {
-					pr_info("%3d: %-*s:", curr_suite + 1, width,
+					int max_width = get_max_desc_width(width);
+
+					pr_info("%3d: %-*.*s:", curr_suite + 1, max_width, max_width,
 						test_description(*t, -1));
 					color_fprintf(stderr, PERF_COLOR_YELLOW,
 						      " Skip (user override)\n");
-- 
2.54.0.1136.gdb2ca164c4-goog