--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/ctype.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/zalloc.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <subcmd/exec-cmd.h>
+#include <subcmd/parse-options.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include "builtin.h"
+#include "builtin-test-list.h"
+#include "color.h"
+#include "debug.h"
+#include "hist.h"
+#include "intlist.h"
+#include "string2.h"
+#include "symbol.h"
+#include "tests.h"
+#include "util/rlimit.h"
+
+
+/*
+ * As this is a singleton built once for the run of the process, there is
+ * no value in trying to free it and just let it stay around until process
+ * exits when it's cleaned up.
+ */
+static size_t files_num = 0;
+static struct script_file *files = NULL;
+static int files_max_width = 0;
+
+static const char *shell_tests__dir(char *path, size_t size)
+{
+       const char *devel_dirs[] = { "./tools/perf/tests", "./tests", };
+       char *exec_path;
+       unsigned int i;
+
+       for (i = 0; i < ARRAY_SIZE(devel_dirs); ++i) {
+               struct stat st;
+
+               if (!lstat(devel_dirs[i], &st)) {
+                       scnprintf(path, size, "%s/shell", devel_dirs[i]);
+                       if (!lstat(devel_dirs[i], &st))
+                               return path;
+               }
+       }
+
+       /* Then installed path. */
+       exec_path = get_argv_exec_path();
+       scnprintf(path, size, "%s/tests/shell", exec_path);
+       free(exec_path);
+       return path;
+}
+
+static const char *shell_test__description(char *description, size_t size,
+                                           const char *path, const char *name)
+{
+       FILE *fp;
+       char filename[PATH_MAX];
+       int ch;
+
+       path__join(filename, sizeof(filename), path, name);
+       fp = fopen(filename, "r");
+       if (!fp)
+               return NULL;
+
+       /* Skip first line - should be #!/bin/sh Shebang */
+       do {
+               ch = fgetc(fp);
+       } while (ch != EOF && ch != '\n');
+
+       description = fgets(description, size, fp);
+       fclose(fp);
+
+       /* Assume first char on line is omment everything after that desc */
+       return description ? strim(description + 1) : NULL;
+}
+
+/* Is this full file path a shell script */
+static bool is_shell_script(const char *path)
+{
+       const char *ext;
+
+       ext = strrchr(path, '.');
+       if (!ext)
+               return false;
+       if (!strcmp(ext, ".sh")) { /* Has .sh extension */
+               if (access(path, R_OK | X_OK) == 0) /* Is executable */
+                       return true;
+       }
+       return false;
+}
+
+/* Is this file in this dir a shell script (for test purposes) */
+static bool is_test_script(const char *path, const char *name)
+{
+       char filename[PATH_MAX];
+
+       path__join(filename, sizeof(filename), path, name);
+       if (!is_shell_script(filename)) return false;
+       return true;
+}
+
+/* Duplicate a string and fall over and die if we run out of memory */
+static char *strdup_check(const char *str)
+{
+       char *newstr;
+
+       newstr = strdup(str);
+       if (!newstr) {
+               pr_err("Out of memory while duplicating test script string\n");
+               abort();
+       }
+       return newstr;
+}
+
+static void append_script(const char *dir, const char *file, const char *desc)
+{
+       struct script_file *files_tmp;
+       size_t files_num_tmp;
+       int width;
+
+       files_num_tmp = files_num + 1;
+       if (files_num_tmp >= SIZE_MAX) {
+               pr_err("Too many script files\n");
+               abort();
+       }
+       /* Realloc is good enough, though we could realloc by chunks, not that
+        * anyone will ever measure performance here */
+       files_tmp = realloc(files,
+                           (files_num_tmp + 1) * sizeof(struct script_file));
+       if (files_tmp == NULL) {
+               pr_err("Out of memory while building test list\n");
+               abort();
+       }
+       /* Add file to end and NULL terminate the struct array */
+       files = files_tmp;
+       files_num = files_num_tmp;
+       files[files_num - 1].dir = strdup_check(dir);
+       files[files_num - 1].file = strdup_check(file);
+       files[files_num - 1].desc = strdup_check(desc);
+       files[files_num].dir = NULL;
+       files[files_num].file = NULL;
+       files[files_num].desc = NULL;
+
+       width = strlen(desc); /* Track max width of desc */
+       if (width > files_max_width)
+               files_max_width = width;
+}
+
+static void append_scripts_in_dir(const char *path)
+{
+       struct dirent **entlist;
+       struct dirent *ent;
+       int n_dirs, i;
+       char filename[PATH_MAX];
+
+       /* List files, sorted by alpha */
+       n_dirs = scandir(path, &entlist, NULL, alphasort);
+       if (n_dirs == -1)
+               return;
+       for (i = 0; i < n_dirs && (ent = entlist[i]); i++) {
+               if (ent->d_name[0] == '.')
+                       continue; /* Skip hidden files */
+               if (is_test_script(path, ent->d_name)) { /* It's a test */
+                       char bf[256];
+                       const char *desc = shell_test__description
+                               (bf, sizeof(bf), path, ent->d_name);
+
+                       if (desc) /* It has a desc line - valid script */
+                               append_script(path, ent->d_name, desc);
+               } else if (is_directory(path, ent)) { /* Scan the subdir */
+                       path__join(filename, sizeof(filename),
+                                  path, ent->d_name);
+                       append_scripts_in_dir(filename);
+               }
+       }
+       for (i = 0; i < n_dirs; i++) /* Clean up */
+               zfree(&entlist[i]);
+       free(entlist);
+}
+
+const struct script_file *list_script_files(void)
+{
+       char path_dir[PATH_MAX];
+       const char *path;
+
+       if (files)
+               return files; /* Singleton - we already know our list */
+
+       path = shell_tests__dir(path_dir, sizeof(path_dir)); /* Walk  dir */
+       append_scripts_in_dir(path);
+
+       return files;
+}
+
+int list_script_max_width(void)
+{
+       list_script_files(); /* Ensure we have scanned all scripts */
+       return files_max_width;
+}
 
 #include <subcmd/exec-cmd.h>
 #include <linux/zalloc.h>
 
+#include "builtin-test-list.h"
+
 static bool dont_fork;
 
 struct test_suite *__weak arch_tests[] = {
        return err;
 }
 
-static const char *shell_test__description(char *description, size_t size,
-                                          const char *path, const char *name)
-{
-       FILE *fp;
-       char filename[PATH_MAX];
-       int ch;
-
-       path__join(filename, sizeof(filename), path, name);
-       fp = fopen(filename, "r");
-       if (!fp)
-               return NULL;
-
-       /* Skip shebang */
-       do {
-               ch = fgetc(fp);
-       } while (ch != EOF && ch != '\n');
-
-       description = fgets(description, size, fp);
-       fclose(fp);
-
-       return description ? strim(description + 1) : NULL;
-}
-
-#define for_each_shell_test(entlist, nr, base, ent)                    \
-       for (int __i = 0; __i < nr && (ent = entlist[__i]); __i++)      \
-               if (!is_directory(base, ent) && \
-                       is_executable_file(base, ent) && \
-                       ent->d_name[0] != '.')
-
-static const char *shell_tests__dir(char *path, size_t size)
-{
-       const char *devel_dirs[] = { "./tools/perf/tests", "./tests", };
-        char *exec_path;
-       unsigned int i;
-
-       for (i = 0; i < ARRAY_SIZE(devel_dirs); ++i) {
-               struct stat st;
-               if (!lstat(devel_dirs[i], &st)) {
-                       scnprintf(path, size, "%s/shell", devel_dirs[i]);
-                       if (!lstat(devel_dirs[i], &st))
-                               return path;
-               }
-       }
-
-        /* Then installed path. */
-        exec_path = get_argv_exec_path();
-        scnprintf(path, size, "%s/tests/shell", exec_path);
-       free(exec_path);
-       return path;
-}
-
-static int shell_tests__max_desc_width(void)
-{
-       struct dirent **entlist;
-       struct dirent *ent;
-       int n_dirs, e;
-       char path_dir[PATH_MAX];
-       const char *path = shell_tests__dir(path_dir, sizeof(path_dir));
-       int width = 0;
-
-       if (path == NULL)
-               return -1;
-
-       n_dirs = scandir(path, &entlist, NULL, alphasort);
-       if (n_dirs == -1)
-               return -1;
-
-       for_each_shell_test(entlist, n_dirs, path, ent) {
-               char bf[256];
-               const char *desc = shell_test__description(bf, sizeof(bf), path, ent->d_name);
-
-               if (desc) {
-                       int len = strlen(desc);
-
-                       if (width < len)
-                               width = len;
-               }
-       }
-
-       for (e = 0; e < n_dirs; e++)
-               zfree(&entlist[e]);
-       free(entlist);
-       return width;
-}
-
 struct shell_test {
        const char *dir;
        const char *file;
 static int run_shell_tests(int argc, const char *argv[], int i, int width,
                                struct intlist *skiplist)
 {
-       struct dirent **entlist;
-       struct dirent *ent;
-       int n_dirs, e;
-       char path_dir[PATH_MAX];
-       struct shell_test st = {
-               .dir = shell_tests__dir(path_dir, sizeof(path_dir)),
-       };
-
-       if (st.dir == NULL)
-               return -1;
+       struct shell_test st;
+       const struct script_file *files, *file;
 
-       n_dirs = scandir(st.dir, &entlist, NULL, alphasort);
-       if (n_dirs == -1) {
-               pr_err("failed to open shell test directory: %s\n",
-                       st.dir);
-               return -1;
-       }
-
-       for_each_shell_test(entlist, n_dirs, st.dir, ent) {
+       files = list_script_files();
+       if (!files)
+               return 0;
+       for (file = files; file->dir; file++) {
                int curr = i++;
-               char desc[256];
                struct test_case test_cases[] = {
                        {
-                               .desc = shell_test__description(desc,
-                                                               sizeof(desc),
-                                                               st.dir,
-                                                               ent->d_name),
+                               .desc = file->desc,
                                .run_case = shell_test__run,
                        },
                        { .name = NULL, }
                        .test_cases = test_cases,
                        .priv = &st,
                };
+               st.dir = file->dir;
 
                if (test_suite.desc == NULL ||
                    !perf_test__matches(test_suite.desc, curr, argc, argv))
                        continue;
 
-               st.file = ent->d_name;
+               st.file = file->file;
                pr_info("%3d: %-*s:", i, width, test_suite.desc);
 
                if (intlist__find(skiplist, i)) {
 
                test_and_print(&test_suite, 0);
        }
-
-       for (e = 0; e < n_dirs; e++)
-               zfree(&entlist[e]);
-       free(entlist);
        return 0;
 }
 
        struct test_suite *t;
        unsigned int j, k;
        int i = 0;
-       int width = shell_tests__max_desc_width();
+       int width = list_script_max_width();
 
        for_each_test(j, k, t) {
                int len = strlen(test_description(t, -1));
 
 static int perf_test__list_shell(int argc, const char **argv, int i)
 {
-       struct dirent **entlist;
-       struct dirent *ent;
-       int n_dirs, e;
-       char path_dir[PATH_MAX];
-       const char *path = shell_tests__dir(path_dir, sizeof(path_dir));
-
-       if (path == NULL)
-               return -1;
+       const struct script_file *files, *file;
 
-       n_dirs = scandir(path, &entlist, NULL, alphasort);
-       if (n_dirs == -1)
-               return -1;
-
-       for_each_shell_test(entlist, n_dirs, path, ent) {
+       files = list_script_files();
+       if (!files)
+               return 0;
+       for (file = files; file->dir; file++) {
                int curr = i++;
-               char bf[256];
                struct test_suite t = {
-                       .desc = shell_test__description(bf, sizeof(bf), path, ent->d_name),
+                       .desc = file->desc
                };
 
                if (!perf_test__matches(t.desc, curr, argc, argv))
                        continue;
 
                pr_info("%3d: %s\n", i, t.desc);
-
        }
-
-       for (e = 0; e < n_dirs; e++)
-               zfree(&entlist[e]);
-       free(entlist);
        return 0;
 }