Fix two minor documentation issues.

[paraslash.git] / interactive.c

/*
 * Copyright (C) 2011-2012 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file interactive.c Readline abstraction for interactive sessions. */

#include <regex.h>
#include <stdbool.h>
#include <curses.h>
#include <readline/readline.h>
#include <readline/history.h>
#include <sys/ioctl.h>
#include <assert.h>
#include <signal.h>

#include "para.h"
#include "fd.h"
#include "buffer_tree.h"
#include "list.h"
#include "sched.h"
#include "interactive.h"
#include "string.h"
#include "error.h"

struct i9e_private {
        struct i9e_client_info *ici;
        FILE *stderr_stream;
        char empty_line[1000];
        struct task task;
        struct btr_node *stdout_btrn;
        bool line_handler_running;
        bool input_eof;
        bool caught_sigint;
};
static struct i9e_private i9e_private, *i9ep = &i9e_private;

static bool is_prefix(const char *partial, const char *full, size_t len)
{
        if (len == 0)
                len = strlen(partial);
        return !strncmp(partial, full, len);
}

/*
 * Generator function for command completion. STATE lets us know whether
 * to start from scratch; without any state (i.e. STATE == 0), then we
 * start at the top of the list.
 */
static char *command_generator(const char *text, int state)
{
        static int list_index, len;
        const char *name;
        struct i9e_client_info *ici = i9ep->ici;

        rl_attempted_completion_over = 1; /* disable filename completion */
        /*
         * If this is a new word to complete, initialize now. This includes
         * saving the length of TEXT for efficiency, and initializing the index
         * variable to 0.
         */
        if (state == 0) {
                list_index = 0;
                len = strlen(text);
        }
        /* Return the next name which partially matches from the command list. */
        while ((name = ici->completers[list_index].name)) {
                list_index++;
                if (is_prefix(text, name, len))
                        return para_strdup(name);
        }
        return NULL; /* no names matched */
}

static void reset_completion_result(struct i9e_completion_result *cr)
{
        cr->dont_append_space = false;
        cr->filename_completion_desired = false;
        cr->matches = NULL;
}

static void create_matches(struct i9e_completion_info *ci,
                struct i9e_completer *completers,
                struct i9e_completion_result *cr)
{
        int i, ret;

        reset_completion_result(cr);

        ret = create_argv(ci->buffer, " ", &ci->argv);
        if (ret < 0 || !ci->argv[0])
                return;

        ci->argc = ret;
        ci->word_num = compute_word_num(ci->buffer, " ", ci->point);
        for (i = 0; completers[i].name; i++) {
                if (strcmp(completers[i].name, ci->argv[0]) != 0)
                        continue;
                completers[i].completer(ci, cr);
                break;
        }
        PARA_DEBUG_LOG("current word: %d (%s)\n", ci->word_num,
                ci->argv[ci->word_num]);
        if (cr->matches)
                for (i = 0; cr->matches[i]; i++)
                        PARA_DEBUG_LOG("match %d: %s\n", i, cr->matches[i]);
}

static char *completion_generator(const char *word, int state)
{
        static int list_index;
        static char **argv, **matches;
        struct i9e_completer *completers = i9ep->ici->completers;
        struct i9e_completion_info ci = {
                .word = (char *)word,
                .point = rl_point,
                .buffer = rl_line_buffer,
        };
        struct i9e_completion_result cr = {.matches = NULL};

        if (state != 0)
                goto out;
        /* clean up previous matches and set defaults */
        free(matches);
        matches = NULL;
        free_argv(argv);
        argv = NULL;
        list_index = 0;
        rl_completion_append_character = ' ';
        rl_completion_suppress_append = false;
        rl_attempted_completion_over = true;

        create_matches(&ci, completers, &cr);

        matches = cr.matches;
        argv = ci.argv;
        rl_completion_suppress_append = cr.dont_append_space;
        rl_attempted_completion_over = !cr.filename_completion_desired;
out:
        if (!matches)
                return NULL;
        return matches[list_index++];
}

/*
 * Attempt to complete on the contents of TEXT. START and END bound the
 * region of rl_line_buffer that contains the word to complete.  TEXT is
 * the word to complete.  We can use the entire contents of rl_line_buffer
 * in case we want to do some simple parsing. Return the array of matches,
 * or NULL if there aren't any.
 */
static char **i9e_completer(const char *text, int start, __a_unused int end)
{
        struct i9e_client_info *ici = i9ep->ici;

        if (!ici->completers)
                return NULL;
        /* Complete on command names if this is the first word in the line. */
        if (start == 0)
                return rl_completion_matches(text, command_generator);
        return rl_completion_matches(text, completion_generator);
}

/**
 * Prepare writing to stdout.
 *
 * \param producer The buffer tree node which produces output.
 *
 * The i9e subsystem maintains a buffer tree node which may be attached to
 * another node which generates output (a "producer"). When attached, the i9e
 * buffer tree node copies the buffers generated by the producer to stdout.
 *
 * This function attaches the i9e input queue to an output queue of \a
 * producer.
 *
 * \return Standard.
 */
void i9e_attach_to_stdout(struct btr_node *producer)
{
        assert(!i9ep->stdout_btrn);
        i9ep->stdout_btrn = btr_new_node(&(struct btr_node_description)
                EMBRACE(.name = "interactive_stdout", .parent = producer));
}

/**
 * Reset the terminal and save the in-memory command line history.
 *
 * This should be called before the caller exits.
 */
void i9e_close(void)
{
        char *hf = i9ep->ici->history_file;

        rl_deprep_terminal();
        fprintf(i9ep->stderr_stream, "\n");
        if (hf)
                write_history(hf);
        fclose(i9ep->stderr_stream);
}

static void wipe_bottom_line(void)
{
        fprintf(i9ep->stderr_stream, "\r%s\r", i9ep->empty_line);
}

static void clear_bottom_line(void)
{
        int point;
        char *text;

        if (rl_point == 0 && rl_end == 0)
                return wipe_bottom_line();
        /*
         * We might have a multi-line input that needs to be wiped here, so the
         * simple printf("\r<space>\r") is insufficient. To workaround this, we
         * remove the whole line, redisplay and restore the killed text.
         */
        point = rl_point;
        text = rl_copy_text(0, rl_end);
        rl_kill_full_line(0, 0);
        rl_redisplay();
        wipe_bottom_line(); /* wipe out the prompt */
        rl_insert_text(text);
        rl_point = point;
}

static bool input_available(void)
{
        fd_set rfds;
        struct timeval tv = {0, 0};
        int ret;

        FD_ZERO(&rfds);
        FD_SET(i9ep->ici->fds[0], &rfds);
        ret = para_select(1, &rfds, NULL, &tv);
        return ret > 0;
}

static void i9e_line_handler(char *line)
{
        int ret;

        i9ep->line_handler_running = true;
        ret = i9ep->ici->line_handler(line);
        i9ep->line_handler_running = false;
        if (ret < 0)
                PARA_WARNING_LOG("%s\n", para_strerror(-ret));
        rl_set_prompt("");
        if (line) {
                if (!*line)
                        rl_set_prompt(i9ep->ici->prompt);
                else
                        add_history(line);
                free(line);
        } else {
                rl_set_prompt("");
                i9ep->input_eof = true;
        }
}

static void i9e_input(void)
{
        do {
                rl_callback_read_char();
        } while (input_available());
}

static void i9e_post_select(struct sched *s, struct task *t)
{
        int ret;
        struct btr_node *btrn = i9ep->stdout_btrn;
        struct i9e_client_info *ici = i9ep->ici;
        char *buf;
        size_t sz;

        if (i9ep->input_eof) {
                t->error = -E_I9E_EOF;
                return;
        }
        if (!btrn) {
                i9ep->caught_sigint = false;
                if (FD_ISSET(ici->fds[0], &s->rfds))
                        i9e_input();
                return;
        }
        if (i9ep->caught_sigint)
                goto rm_btrn;
        ret = btr_node_status(i9ep->stdout_btrn, 0, BTR_NT_LEAF);
        if (ret < 0)
                goto rm_btrn;
        sz = btr_next_buffer(btrn, &buf);
        if (sz == 0)
                goto out;
        ret = write_nonblock(ici->fds[1], buf, sz);
        if (ret < 0)
                goto rm_btrn;
        btr_consume(btrn, ret);
        goto out;
rm_btrn:
        btr_remove_node(btrn);
        btr_free_node(btrn);
        i9ep->stdout_btrn = NULL;
        rl_set_prompt(i9ep->ici->prompt);
        rl_forced_update_display();
out:
        t->error = 0;
}

static void i9e_pre_select(struct sched *s, __a_unused struct task *t)
{
        int ret;

        if (i9ep->input_eof || i9ep->caught_sigint) {
                sched_min_delay(s);
                return;
        }
        if (i9ep->stdout_btrn) {
                ret = btr_node_status(i9ep->stdout_btrn, 0, BTR_NT_LEAF);
                if (ret < 0) {
                        sched_min_delay(s);
                        return;
                }
                if (ret > 0)
                        para_fd_set(i9ep->ici->fds[1], &s->wfds, &s->max_fileno);
        }
        /*
         * fd[0] might have been reset to blocking mode if our job was moved to
         * the background due to CTRL-Z or SIGSTOP, so set the fd back to
         * nonblocking mode.
         */
        ret = mark_fd_nonblocking(i9ep->ici->fds[0]);
        if (ret < 0)
                PARA_WARNING_LOG("set to nonblock failed: (fd0 %d, %s)\n",
                        i9ep->ici->fds[0], para_strerror(-ret));
        para_fd_set(i9ep->ici->fds[0], &s->rfds, &s->max_fileno);
        return;
}

static void update_winsize(void)
{
        struct winsize w;
        int ret = ioctl(i9ep->ici->fds[2], TIOCGWINSZ, (char *)&w);
        int num_columns = 80;

        if (ret >= 0) {
                assert(w.ws_col < sizeof(i9ep->empty_line));
                num_columns = w.ws_col;
        }
        memset(i9ep->empty_line, ' ', num_columns);
        i9ep->empty_line[num_columns] = '\0';
}

/**
 * Register the i9e task and initialize readline.
 *
 * \param ici The i9e configuration parameters set by the caller.
 * \param s The scheduler instance to add the i9e task to.
 *
 * The caller must allocate and initialize the structure \a ici points to.
 *
 * \return Standard.
 * \sa \ref register_task().
 */
int i9e_open(struct i9e_client_info *ici, struct sched *s)
{
        int ret;

        if (!isatty(ici->fds[0]))
                return -E_I9E_SETUPTERM;
        ret = mark_fd_nonblocking(ici->fds[0]);
        if (ret < 0)
                return ret;
        ret = mark_fd_nonblocking(ici->fds[1]);
        if (ret < 0)
                return ret;
        i9ep->task.pre_select = i9e_pre_select;
        i9ep->task.post_select = i9e_post_select;
        register_task(s, &i9ep->task);
        rl_readline_name = "para_i9e";
        rl_basic_word_break_characters = " ";
        rl_attempted_completion_function = i9e_completer;
        i9ep->ici = ici;
        i9ep->stderr_stream = fdopen(ici->fds[2], "w");

        if (ici->history_file)
                read_history(ici->history_file);
        update_winsize();
        rl_callback_handler_install(i9ep->ici->prompt, i9e_line_handler);
        return 1;
}

static void reset_line_state(void)
{
        if (i9ep->line_handler_running)
                return;
        rl_on_new_line();
        rl_reset_line_state();
        rl_forced_update_display();
}

/**
 * The log function of the i9e subsystem.
 *
 * \param ll Severity log level.
 * \param fmt Printf-like format string.
 *
 * This clears the bottom line of the terminal if necessary and writes the
 * string given by \a fmt to fd[2], where fd[] is the array provided earlier in
 * \ref i9e_open().
 */
__printf_2_3 void i9e_log(int ll, const char* fmt,...)
{
        va_list argp;

        if (ll < i9ep->ici->loglevel)
                return;
        if (i9ep->line_handler_running == false)
                clear_bottom_line();
        va_start(argp, fmt);
        vfprintf(i9ep->stderr_stream, fmt, argp);
        va_end(argp);
        reset_line_state();
}

/**
 * Tell i9e that the caller received a signal.
 *
 * \param sig_num The number of the signal received.
 *
 * Currently the function only cares about \p SIGINT, but this may change.
 */
void i9e_signal_dispatch(int sig_num)
{
        if (sig_num == SIGINT) {
                fprintf(i9ep->stderr_stream, "\n");
                rl_replace_line ("", false /* clear_undo */);
                reset_line_state();
                i9ep->caught_sigint = true;
        }
}

/**
 * Wrapper for select(2) which does not restart on interrupts.
 *
 * \param n \sa \ref para_select().
 * \param readfds \sa \ref para_select().
 * \param writefds \sa \ref para_select().
 * \param timeout_tv \sa \ref para_select().
 *
 * \return \sa \ref para_select().
 *
 * The only difference between this function and \ref para_select() is that
 * \ref i9e_select() returns zero if the select call returned \p EINTR.
 */
int i9e_select(int n, fd_set *readfds, fd_set *writefds,
                struct timeval *timeout_tv)
{
        int ret = select(n, readfds, writefds, NULL, timeout_tv);

        if (ret < 0) {
                if (errno == EINTR)
                        ret = 0;
                else
                        ret = -ERRNO_TO_PARA_ERROR(errno);
        }
        return ret;
}

/**
 * Return the possible completions for a given word.
 *
 * \param word The word to complete.
 * \param string_list All possible words in this context.
 * \param result String list is returned here.
 *
 * This function never fails. If no completion was found, a string list of
 * length zero is returned. In any case, the result must be freed by the caller
 * using \ref free_argv().
 *
 * This function is independent of readline and may be called before
 * i9e_open().
 *
 * \return The number of possible completions.
 */
int i9e_extract_completions(const char *word, char **string_list,
                char ***result)
{
        char **matches = para_malloc(sizeof(char *));
        int match_count = 0, matches_len = 1;
        char **p;
        int len = strlen(word);

        for (p = string_list; *p; p++) {
                if (!is_prefix(word, *p, len))
                        continue;
                match_count++;
                if (match_count >= matches_len) {
                        matches_len *= 2;
                        matches = para_realloc(matches,
                                matches_len * sizeof(char *));
                }
                matches[match_count - 1] = para_strdup(*p);
        }
        matches[match_count] = NULL;
        *result = matches;
        return match_count;
}

/**
 * Return the list of partially matching words.
 *
 * \param word The command to complete.
 * \param completers The array containing all command names.
 *
 * This is similar to \ref i9e_extract_completions(), but completes on the
 * command names in \a completers.
 *
 * \return See \ref i9e_extract_completions().
 */
char **i9e_complete_commands(const char *word, struct i9e_completer *completers)
{
        char **matches;
        const char *cmd;
        int i, match_count, len = strlen(word);

        /*
         * In contrast to completing against an arbitrary string list, here we
         * know all possible completions and expect that there will not be many
         * of them. So it should be OK to iterate twice over all commands which
         * simplifies the code a bit.
         */
        for (i = 0, match_count = 0; (cmd = completers[i].name); i++) {
                if (is_prefix(word, cmd, len))
                        match_count++;
        }
        matches = para_malloc((match_count + 1) * sizeof(*matches));
        for (i = 0, match_count = 0; (cmd = completers[i].name); i++)
                if (is_prefix(word, cmd, len))
                        matches[match_count++] = para_strdup(cmd);
        matches[match_count] = NULL;
        return matches;
}

/**
 * Complete according to the given options.
 *
 * \param opts All available options.
 * \param ci Information which was passed to the completer.
 * \param cr Result pointer.
 *
 * This convenience helper can be used to complete an option. The array of all
 * possible options is passed as the first argument. Flags, i.e. options
 * without an argument, are expected to be listed as strings of type "-X" in \a
 * opts while options which require an argument should be passed with a
 * trailing "=" character like "-X=".
 *
 * If the word can be uniquely completed to a flag option, an additional space
 * character is appended to the output. For non-flag options no space character
 * is appended.
 */
void i9e_complete_option(char **opts, struct i9e_completion_info *ci,
                struct i9e_completion_result *cr)
{
        int num_matches;

        num_matches = i9e_extract_completions(ci->word, opts, &cr->matches);
        if (num_matches == 1) {
                char *opt = cr->matches[0];
                char c = opt[strlen(opt) - 1];
                if (c == '=')
                        cr->dont_append_space = true;
        }
}

/**
 * Print possible completions to stdout.
 *
 * \param completers The array of completion functions.
 *
 * At the end of the output a line starting with "-o=", followed by the
 * (possibly empty) list of completion options is printed. Currently, the only
 * two completion options are "nospace" and "filenames". The former indicates
 * that no space should be appended even for a unique match while the latter
 * indicates that usual filename completion should be performed in addition to
 * the previously printed options.
 *
 * \return Standard.
 */
int i9e_print_completions(struct i9e_completer *completers)
{
        struct i9e_completion_result cr;
        struct i9e_completion_info ci;
        char *buf;
        const char *end, *p;
        int i, n, ret;

        reset_completion_result(&cr);
        buf = getenv("COMP_POINT");
        ci.point = buf? atoi(buf) : 0;
        ci.buffer = para_strdup(getenv("COMP_LINE"));

        ci.argc = create_argv(ci.buffer, " ", &ci.argv);
        ci.word_num = compute_word_num(ci.buffer, " ", ci.point);

        end = ci.buffer + ci.point;
        for (p = end; p > ci.buffer && *p != ' '; p--)
                ; /* nothing */
        if (*p == ' ')
                p++;

        n = end - p + 1;
        ci.word = para_malloc(n + 1);
        strncpy(ci.word, p, n);
        ci.word[n] = '\0';

        PARA_DEBUG_LOG("line: %s, point: %d (%c), wordnum: %d, word: %s\n",
                ci.buffer, ci.point, ci.buffer[ci.point], ci.word_num, ci.word);
        if (ci.word_num == 0)
                cr.matches = i9e_complete_commands(ci.word, completers);
        else
                create_matches(&ci, completers, &cr);
        ret = 0;
        if (cr.matches && cr.matches[0]) {
                for (i = 0; cr.matches[i]; i++)
                        printf("%s\n", cr.matches[i]);
                ret = 1;
        }
        printf("-o=");
        if (cr.dont_append_space)
                printf("nospace");
        if (cr.filename_completion_desired)
                printf(",filenames");
        printf("\n");
        free_argv(cr.matches);
        free_argv(ci.argv);
        free(ci.buffer);
        free(ci.word);
        return ret;
}