cproof/src/tools/editor.c

/*
 * editor.c
 * vim: expandtab:ts=4:sts=4:sw=4
 *
 * Copyright (C) 2022 - 2026 Michael Vetter <jubalh@iodoru.org>
 * Copyright (C) 2022 MarcoPolo PasTonMolo <marcopolopastonmolo@protonmail.com>
 * Copyright (C) 2022 Steffen Jaeckel <jaeckel-floss@eyet-services.de>
 *
 * SPDX-License-Identifier: GPL-3.0-or-later WITH OpenSSL-exception
 */

#include <glib.h>
#include <errno.h>
#include <stdio.h>
#include <sys/wait.h>
#include <unistd.h>
#include <signal.h>

#include "config/files.h"
#include "config/preferences.h"
#include "editor.h"
#include "log.h"
#include "common.h"
#include "ncurses.h"
#include "ui/ui.h"
#include "xmpp/xmpp.h"

extern char** environ;

typedef struct EditorContext
{
    gchar* filename;
    void (*callback)(gchar* content, void* user_data);
    void* user_data;
} EditorContext;

static gboolean editor_active = FALSE; // re-entrancy guard
static pid_t editor_pid = 0;

static void
_editor_exit_cb(GPid pid, gint status, gpointer data)
{
    editor_active = FALSE;
    editor_pid = 0;

    EditorContext* ctx = data;
    gchar* contents = NULL;
    GError* error = NULL;

    ui_resume();
    ui_resize();

    if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
        if (g_file_get_contents(ctx->filename, &contents, NULL, &error)) {
            g_strchomp(contents);
            ctx->callback(contents, ctx->user_data);
            g_free(contents);
        } else {
            log_error("[Editor] could not read from %s: %s", ctx->filename, error->message);
            cons_show_error("Could not read edited content: %s", error->message);
            g_error_free(error);
        }
    } else if (WIFEXITED(status)) {
        cons_show_error("Editor exited with status %d", WEXITSTATUS(status));
    } else if (WIFSIGNALED(status)) {
        cons_show("Editor session cancelled.");
    }

    if (remove(ctx->filename) != 0) {
        log_error("[Editor] error during file deletion of %s", ctx->filename);
    }

    g_free(ctx->filename);
    g_free(ctx);
    g_spawn_close_pid(pid);
}

// Returns a message via callback once the editor is closed.
// Returns true if an error occurred.
gboolean
launch_editor(gchar* initial_content, void (*callback)(gchar* content, void* data), void* user_data)
{
    if (editor_active) {
        cons_show_error("An editor session is already active.");
        return TRUE;
    }

    auto_gchar gchar* filename = NULL;
    auto_gerror GError* glib_error = NULL;
    const char* jid = connection_get_barejid();
    if (jid) {
        filename = files_file_in_account_data_path(DIR_EDITOR, jid, "compose.md");
    } else {
        log_debug("[Editor] could not get JID");
        auto_gchar gchar* data_dir = files_get_data_path(DIR_EDITOR);
        if (!create_dir(data_dir)) {
            cons_show_error("Could not create editor directory.");
            return TRUE;
        }
        filename = g_strdup_printf("%s/compose.md", data_dir);
    }
    if (!filename) {
        log_error("[Editor] something went wrong while creating compose file");
        cons_show_error("Could not create compose file.");
        return TRUE;
    }

    gsize messagelen = 0;
    if (initial_content != NULL) {
        messagelen = strlen(initial_content);
    }

    if (!g_file_set_contents(filename, initial_content, messagelen, &glib_error)) {
        log_error("[Editor] could not write to %s: %s", filename, PROF_GERROR_MESSAGE(glib_error));
        cons_show_error("Could not write to compose file: %s", PROF_GERROR_MESSAGE(glib_error));
        return TRUE;
    }

    auto_gchar gchar* editor = prefs_get_string(PREF_COMPOSE_EDITOR);
    gchar** editor_argv = NULL;
    GError* error = NULL;

    auto_gchar gchar* full_cmd = g_strdup_printf("%s %s", editor, filename);
    if (!g_shell_parse_argv(full_cmd, NULL, &editor_argv, &error)) {
        log_error("[Editor] Failed to parse editor command: %s", error->message);
        cons_show_error("Failed to parse editor command: %s", error->message);
        g_error_free(error);
        return TRUE;
    }

    EditorContext* ctx = g_new0(EditorContext, 1);
    ctx->filename = g_steal_pointer(&filename);
    ctx->callback = callback;
    ctx->user_data = user_data;

    editor_active = TRUE;
    ui_suspend();

    // Force GLib to install its SIGCHLD handler before forking. Creating a
    // GChildWatchSource for our own pid is the documented trigger; we never
    // attach or dispatch it, just rely on the side effect.
    GSource* sigchld_warmup = g_child_watch_source_new(getpid());
    g_source_unref(sigchld_warmup);

    // Build the editor's env without LINES/COLUMNS pre-fork, so the child only
    // swaps environ (async-signal-safe) instead of calling unsetenv(). The
    // editor's (n)curses then reads the live window via ioctl(TIOCGWINSZ).
    gsize env_len = 0;
    while (environ[env_len]) {
        env_len++;
    }
    gchar** editor_env = g_new0(gchar*, env_len + 1);
    gsize env_kept = 0;
    for (gsize i = 0; i < env_len; i++) {
        if (g_str_has_prefix(environ[i], "LINES=") || g_str_has_prefix(environ[i], "COLUMNS=")) {
            continue;
        }
        editor_env[env_kept++] = environ[i];
    }

    pid_t pid = fork();
    if (pid == -1) {
        log_error("[Editor] Failed to fork: %s", strerror(errno));
        editor_active = FALSE;
        ui_resume();
        ui_resize();
        cons_show_error("Failed to start editor: %s", strerror(errno));
        g_strfreev(editor_argv);
        g_free(editor_env); // array only; strings are borrowed from environ
        g_free(ctx->filename);
        g_free(ctx);
        return TRUE;
    } else if (pid == 0) {
        // Child process: Inherits TTY from parent

        environ = editor_env; // live TIOCGWINSZ size, not the inherited LINES/COLUMNS

        // SIGTSTP=SIG_DFL lets vim's :stop / Ctrl-Z work; profanity catches
        // the STOPPED state via editor_check_stopped() and drops to the shell.
        signal(SIGINT, SIG_DFL);
        signal(SIGTSTP, SIG_DFL);
        signal(SIGPIPE, SIG_DFL);

        if (editor_argv && editor_argv[0]) {
            execvp(editor_argv[0], editor_argv);
        }
        _exit(EXIT_FAILURE);
    }

    // Parent process: Watch the child asynchronously
    editor_pid = pid;
    g_child_watch_add((GPid)pid, _editor_exit_cb, ctx);
    g_strfreev(editor_argv);
    g_free(editor_env); // array only; strings are borrowed from environ
    return FALSE;
}

void
editor_emergency_kill(void)
{
    if (!editor_active || editor_pid <= 0) {
        return;
    }
    log_warning("[Editor] aborting editor pid %d", editor_pid);
    kill(editor_pid, SIGCONT); // wake if STOPPED; no-op otherwise
    kill(editor_pid, SIGTERM);
    // _editor_exit_cb will restore the UI when the child reaps.
}

gboolean
editor_is_active(void)
{
    return editor_active;
}

gboolean
editor_check_stopped(void)
{
    // Poll for STOPPED without reaping (g_child_watch handles exit via its
    // own WNOHANG). Lets prof_run drop the group to the shell on Ctrl-Z.
    if (!editor_active || editor_pid <= 0) {
        return FALSE;
    }
    int status;
    pid_t r = waitpid(editor_pid, &status, WNOHANG | WUNTRACED);
    return (r == editor_pid && WIFSTOPPED(status));
}