root/tools/lib/subcmd/help.c
// SPDX-License-Identifier: GPL-2.0
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <linux/string.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>
#include <assert.h>
#include "subcmd-util.h"
#include "help.h"
#include "exec-cmd.h"

void add_cmdname(struct cmdnames *cmds, const char *name, size_t len)
{
        struct cmdname *ent = malloc(sizeof(*ent) + len + 1);
        if (!ent)
                return;

        ent->len = len;
        memcpy(ent->name, name, len);
        ent->name[len] = 0;

        ALLOC_GROW(cmds->names, cmds->cnt + 1, cmds->alloc);
        cmds->names[cmds->cnt++] = ent;
}

void clean_cmdnames(struct cmdnames *cmds)
{
        unsigned int i;

        for (i = 0; i < cmds->cnt; ++i)
                zfree(&cmds->names[i]);
        zfree(&cmds->names);
        cmds->cnt = 0;
        cmds->alloc = 0;
}

int cmdname_compare(const void *a_, const void *b_)
{
        struct cmdname *a = *(struct cmdname **)a_;
        struct cmdname *b = *(struct cmdname **)b_;
        return strcmp(a->name, b->name);
}

void uniq(struct cmdnames *cmds)
{
        unsigned int i, j;

        if (!cmds->cnt)
                return;

        for (i = 1; i < cmds->cnt; i++) {
                if (!strcmp(cmds->names[i]->name, cmds->names[i-1]->name))
                        zfree(&cmds->names[i - 1]);
        }
        for (i = 0, j = 0; i < cmds->cnt; i++) {
                if (cmds->names[i]) {
                        if (i == j)
                                j++;
                        else
                                cmds->names[j++] = cmds->names[i];
                }
        }
        cmds->cnt = j;
        while (j < i)
                cmds->names[j++] = NULL;
}

void exclude_cmds(struct cmdnames *cmds, struct cmdnames *excludes)
{
        size_t ci, cj, ei;
        int cmp;

        if (!excludes->cnt)
                return;

        ci = cj = ei = 0;
        while (ci < cmds->cnt && ei < excludes->cnt) {
                cmp = strcmp(cmds->names[ci]->name, excludes->names[ei]->name);
                if (cmp < 0) {
                        if (ci == cj) {
                                ci++;
                                cj++;
                        } else {
                                cmds->names[cj++] = cmds->names[ci];
                                cmds->names[ci++] = NULL;
                        }
                } else if (cmp == 0) {
                        zfree(&cmds->names[ci]);
                        ci++;
                        ei++;
                } else if (cmp > 0) {
                        ei++;
                }
        }
        while (ci < cmds->cnt) {
                if (ci != cj) {
                        cmds->names[cj] = cmds->names[ci];
                        cmds->names[ci] = NULL;
                }
                ci++;
                cj++;
        }
        for (ci = cj; ci < cmds->cnt; ci++)
                assert(cmds->names[ci] == NULL);
        cmds->cnt = cj;
}

static void get_term_dimensions(struct winsize *ws)
{
        char *s = getenv("LINES");

        if (s != NULL) {
                ws->ws_row = atoi(s);
                s = getenv("COLUMNS");
                if (s != NULL) {
                        ws->ws_col = atoi(s);
                        if (ws->ws_row && ws->ws_col)
                                return;
                }
        }
#ifdef TIOCGWINSZ
        if (ioctl(1, TIOCGWINSZ, ws) == 0 &&
            ws->ws_row && ws->ws_col)
                return;
#endif
        ws->ws_row = 25;
        ws->ws_col = 80;
}

static void pretty_print_string_list(struct cmdnames *cmds, int longest)
{
        int cols = 1, rows;
        int space = longest + 1; /* min 1 SP between words */
        struct winsize win;
        int max_cols;
        int i, j;

        get_term_dimensions(&win);
        max_cols = win.ws_col - 1; /* don't print *on* the edge */

        if (space < max_cols)
                cols = max_cols / space;
        rows = (cmds->cnt + cols - 1) / cols;

        for (i = 0; i < rows; i++) {
                printf("  ");

                for (j = 0; j < cols; j++) {
                        unsigned int n = j * rows + i;
                        unsigned int size = space;

                        if (n >= cmds->cnt)
                                break;
                        if (j == cols-1 || n + rows >= cmds->cnt)
                                size = 1;
                        printf("%-*s", size, cmds->names[n]->name);
                }
                putchar('\n');
        }
}

static int is_executable(const char *name)
{
        struct stat st;

        if (stat(name, &st) || /* stat, not lstat */
            !S_ISREG(st.st_mode))
                return 0;

        return st.st_mode & S_IXUSR;
}

static int has_extension(const char *filename, const char *ext)
{
        size_t len = strlen(filename);
        size_t extlen = strlen(ext);

        return len > extlen && !memcmp(filename + len - extlen, ext, extlen);
}

static void list_commands_in_dir(struct cmdnames *cmds,
                                         const char *path,
                                         const char *prefix)
{
        int prefix_len;
        DIR *dir = opendir(path);
        struct dirent *de;
        char *buf = NULL;

        if (!dir)
                return;
        if (!prefix)
                prefix = "perf-";
        prefix_len = strlen(prefix);

        astrcatf(&buf, "%s/", path);

        while ((de = readdir(dir)) != NULL) {
                int entlen;

                if (!strstarts(de->d_name, prefix))
                        continue;

                astrcat(&buf, de->d_name);
                if (!is_executable(buf))
                        continue;

                entlen = strlen(de->d_name) - prefix_len;
                if (has_extension(de->d_name, ".exe"))
                        entlen -= 4;

                add_cmdname(cmds, de->d_name + prefix_len, entlen);
        }
        closedir(dir);
        free(buf);
}

void load_command_list(const char *prefix,
                struct cmdnames *main_cmds,
                struct cmdnames *other_cmds)
{
        const char *env_path = getenv("PATH");
        char *exec_path = get_argv_exec_path();

        if (exec_path) {
                list_commands_in_dir(main_cmds, exec_path, prefix);
                qsort(main_cmds->names, main_cmds->cnt,
                      sizeof(*main_cmds->names), cmdname_compare);
                uniq(main_cmds);
        }

        if (env_path) {
                char *paths, *path, *colon;
                path = paths = strdup(env_path);
                while (1) {
                        if ((colon = strchr(path, ':')))
                                *colon = 0;
                        if (!exec_path || strcmp(path, exec_path))
                                list_commands_in_dir(other_cmds, path, prefix);

                        if (!colon)
                                break;
                        path = colon + 1;
                }
                free(paths);

                qsort(other_cmds->names, other_cmds->cnt,
                      sizeof(*other_cmds->names), cmdname_compare);
                uniq(other_cmds);
        }
        free(exec_path);
        exclude_cmds(other_cmds, main_cmds);
}

void list_commands(const char *title, struct cmdnames *main_cmds,
                   struct cmdnames *other_cmds)
{
        unsigned int i, longest = 0;

        for (i = 0; i < main_cmds->cnt; i++)
                if (longest < main_cmds->names[i]->len)
                        longest = main_cmds->names[i]->len;
        for (i = 0; i < other_cmds->cnt; i++)
                if (longest < other_cmds->names[i]->len)
                        longest = other_cmds->names[i]->len;

        if (main_cmds->cnt) {
                char *exec_path = get_argv_exec_path();
                printf("available %s in '%s'\n", title, exec_path);
                printf("----------------");
                mput_char('-', strlen(title) + strlen(exec_path));
                putchar('\n');
                pretty_print_string_list(main_cmds, longest);
                putchar('\n');
                free(exec_path);
        }

        if (other_cmds->cnt) {
                printf("%s available from elsewhere on your $PATH\n", title);
                printf("---------------------------------------");
                mput_char('-', strlen(title));
                putchar('\n');
                pretty_print_string_list(other_cmds, longest);
                putchar('\n');
        }
}

int is_in_cmdlist(struct cmdnames *c, const char *s)
{
        unsigned int i;

        for (i = 0; i < c->cnt; i++)
                if (!strcmp(s, c->names[i]->name))
                        return 1;
        return 0;
}