Update of Portuguese translation

[geany-mirror.git] / src / spawn.c

/*
 *      spawn.c - this file is part of Geany, a fast and lightweight IDE
 *
 *      Copyright 2013 Dimitar Toshkov Zhekov <dimitar(dot)zhekov(at)gmail(dot)com>
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License along
 *      with this program; if not, write to the Free Software Foundation, Inc.,
 *      51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/* An ongoing effort to improve the tool spawning situation under Windows.
 * In particular:
 *    - There is no g_shell_parse_argv() for windows. It's not hard to write one,
 *      but the command line recreated by mscvrt may be wrong.
 *    - GLib converts the argument vector to UNICODE. For non-UTF8 arguments,
 *      the result is often "Invalid string in argument vector at %d: %s: Invalid
 *      byte sequence in conversion input" (YMMV). Our tools (make, grep, gcc, ...)
 *      are "ANSI", so converting to UNICODE and then back only causes problems.
 *    - For various reasons, GLib uses an intermediate program to start children
 *      (see gspawn-win32.c), the result being that the grandchildren output (such
 *      as make -> gcc) is not captured.
 *    - With non-blocking pipes, the g_io_add_watch() callbacks are never invoked,
 *      while with blocking pipes, g_io_channel_read_line() blocks.
 *    - Some other problems are explained in separate comments below.
 *
 * Even under Unix, using g_io_channel_read_line() is not a good idea, since it may
 * buffer lines of unlimited length.
 *
 * This module does not depend on Geany when compiled for testing (-DSPAWN_TEST).
 */

/** @file spawn.h
 * Portable and convenient process spawning and communication.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <errno.h>
#include <string.h>

#include "spawn.h"

#ifdef G_OS_WIN32
# include <ctype.h>    /* isspace() */
# include <fcntl.h>    /* _O_RDONLY, _O_WRONLY */
# include <io.h>       /* _open_osfhandle, _close */
# include <windows.h>
#else  /* G_OS_WIN32 */
# include <signal.h>
#endif  /* G_OS_WIN32 */

#ifdef SPAWN_TEST
# define _
# define GEANY_API_SYMBOL
#else
# include "support.h"
#endif

#ifdef G_OS_WIN32
/* Each 4KB under Windows seem to come in 2 portions, so 2K + 2K is more
   balanced than 4095 + 1. May be different on the latest Windows/glib? */
# define DEFAULT_IO_LENGTH 2048
#else
# define DEFAULT_IO_LENGTH 4096

/* helper function that cuts glib citing of the original text on bad quoting: it may be long,
   and only the caller knows whether it's UTF-8. Thought we lose the ' or " failed info. */
static gboolean spawn_parse_argv(const gchar *command_line, gint *argcp, gchar ***argvp,
        GError **error)
{
        GError *gerror = NULL;

        if (g_shell_parse_argv(command_line, argcp, argvp, &gerror))
                return TRUE;

        g_set_error_literal(error, gerror->domain, gerror->code,
                gerror->code == G_SHELL_ERROR_BAD_QUOTING ?
                _("Text ended before matching quote was found") : gerror->message);
        g_error_free(gerror);
        return FALSE;
}
#endif

#define G_IO_FAILURE (G_IO_ERR | G_IO_HUP | G_IO_NVAL)  /* always used together */


/*
 *  Checks whether a command line is syntactically valid and extracts the program name from it.
 *
 *  See @c spawn_check_command() for details.
 *
 *  @param command_line the command line to check and get the program name from.
 *  @param error return location for error.
 *
 *  @return allocated string with the program name on success, @c NULL on error.
 */
static gchar *spawn_get_program_name(const gchar *command_line, GError **error)
{
        gchar *program;

#ifdef G_OS_WIN32
        gboolean open_quote = FALSE;
        const gchar *s, *arguments;

        g_return_val_if_fail(command_line != NULL, FALSE);

        while (*command_line && strchr(" \t\r\n", *command_line))
                command_line++;

        if (!*command_line)
        {
                g_set_error_literal(error, G_SHELL_ERROR, G_SHELL_ERROR_EMPTY_STRING,
                        /* TL note: from glib */
                        _("Text was empty (or contained only whitespace)"));
                return FALSE;
        }

        /* To prevent Windows from doing something weird, we want to be 100% sure that the
           character after the program name is a delimiter, so we allow space and tab only. */

        if (*command_line == '"')
        {
                command_line++;
                /* Windows allows "foo.exe, but we may have extra arguments */
                if ((s = strchr(command_line, '"')) == NULL)
                {
                        g_set_error_literal(error, G_SHELL_ERROR, G_SHELL_ERROR_BAD_QUOTING,
                                _("Text ended before matching quote was found"));
                        return FALSE;
                }

                if (!strchr(" \t", s[1]))  /* strchr() catches s[1] == '\0' */
                {
                        g_set_error_literal(error, G_SHELL_ERROR, G_SHELL_ERROR_BAD_QUOTING,
                                _("A quoted Windows program name must be entirely inside the quotes"));
                        return FALSE;
                }
        }
        else
        {
                const gchar *quote = strchr(command_line, '"');

                /* strchr() catches *s == '\0', and the for body is empty */
                for (s = command_line; !strchr(" \t", *s); s++);

                if (quote && quote < s)
                {
                        g_set_error_literal(error, G_SHELL_ERROR, G_SHELL_ERROR_BAD_QUOTING,
                                _("A quoted Windows program name must be entirely inside the quotes"));
                        return FALSE;
                }
        }

        program = g_strndup(command_line, s - command_line);
        arguments = s + (*s == '"');

        for (s = arguments; *s; s++)
        {
                if (*s == '"')
                {
                        const char *slash;

                        for (slash = s; slash > arguments && slash[-1] == '\\'; slash--);
                        if ((s - slash) % 2 == 0)
                                open_quote ^= TRUE;
                }
        }

        if (open_quote)
        {
                g_set_error_literal(error, G_SHELL_ERROR, G_SHELL_ERROR_BAD_QUOTING,
                        _("Text ended before matching quote was found"));
                g_free(program);
                return FALSE;
        }
#else  /* G_OS_WIN32 */
        int argc;
        char **argv;

        if (!spawn_parse_argv(command_line, &argc, &argv, error))
                return FALSE;

        /* empty string results in parse error, so argv[0] is not NULL */
        program = g_strdup(argv[0]);
        g_strfreev(argv);
#endif  /* G_OS_WIN32 */

        return program;
}


/**
 *  Checks whether a command line is valid.
 *
 *  Checks if @a command_line is syntactically valid.
 *
 *  All OS:
 *     - any leading spaces, tabs and new lines are skipped
 *     - an empty command is invalid
 *
 *  Unix:
 *     - the standard shell quoting and escaping rules are used, see @c g_shell_parse_argv()
 *     - as a consequence, an unqouted # at the start of an argument comments to the end of line
 *
 *  Windows:
 *     - leading carriage returns are skipped too
 *     - a quoted program name must be entirely inside the quotes. No "C:\Foo\Bar".pdf or
 *       "C:\Foo\Bar".bat, which would be executed by Windows as `C:\Foo\Bar.exe`
 *     - an unquoted program name may not contain spaces. `Foo Bar Qux` will not be considered
 *       `"Foo Bar.exe" Qux` or `"Foo Bar Qux.exe"`, depending on what executables exist, as
 *       Windows normally does.
 *     - the program name must be separated from the arguments by at least one space or tab
 *     - the standard Windows quoting and escaping rules are used: double quote is escaped with
 *       backslash, and any literal backslashes before a double quote must be duplicated.
 *
 *  If @a execute is TRUE, also checks, using @c g_find_program_in_path(), if the program
 *  specified in @a command_line exists and is executable.
 *
 *  @param command_line the command line to check.
 *  @param execute whether to check if the command line is really executable.
 *  @param error return location for error.
 *
 *  @return @c TRUE on success, @c FALSE on error.
 *
 *  @since 1.25
 **/
GEANY_API_SYMBOL
gboolean spawn_check_command(const gchar *command_line, gboolean execute, GError **error)
{
        gchar *program = spawn_get_program_name(command_line, error);

        if (!program)
                return FALSE;

        if (execute)
        {
                gchar *executable = g_find_program_in_path(program);

                if (!executable)
                {
                        g_set_error_literal(error, G_SHELL_ERROR, G_SHELL_ERROR_FAILED,
                                _("Program not found"));
                        g_free(program);
                        return FALSE;
                }

                g_free(executable);
        }

        g_free(program);
        return TRUE;
}


/**
 *  Kills a process.
 *
 *  @param pid id of the process to kill.
 *  @param error return location for error.
 *
 *  On Unix, sends a SIGTERM to the process.
 *
 *  On Windows, terminates the process with exit code 255 (used sometimes as "generic"
 *  error code, or for programs terminated with Ctrl+C / Ctrl+Break).
 *
 *  @return @c TRUE on success, @c FALSE on error.
 *
 *  @since 1.25
 **/
GEANY_API_SYMBOL
gboolean spawn_kill_process(GPid pid, GError **error)
{
#ifdef G_OS_WIN32
        if (!TerminateProcess(pid, 255))
        {
                gchar *message = g_win32_error_message(GetLastError());

                g_set_error_literal(error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED, message);
                g_free(message);
                return FALSE;
        }
#else
        if (kill(pid, SIGTERM))
        {
                g_set_error_literal(error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED, g_strerror(errno));
                return FALSE;
        }
#endif
        return TRUE;
}


#ifdef G_OS_WIN32
static gchar *spawn_create_process_with_pipes(char *command_line, const char *working_directory,
        void *environment, HANDLE *hprocess, int *stdin_fd, int *stdout_fd, int *stderr_fd)
{
        enum { WRITE_STDIN, READ_STDOUT, READ_STDERR, READ_STDIN, WRITE_STDOUT, WRITE_STDERR };
        STARTUPINFO startup;
        PROCESS_INFORMATION process;
        HANDLE hpipe[6] = { NULL, NULL, NULL, NULL, NULL, NULL };
        int *fd[3] = { stdin_fd, stdout_fd, stderr_fd };
        const char *failed;     /* failed WIN32/CRTL function, if any */
        gchar *message = NULL;  /* glib WIN32/CTRL error message */
        gchar *failure = NULL;  /* full error text */
        gboolean pipe_io;
        int i;

        ZeroMemory(&startup, sizeof startup);
        startup.cb = sizeof startup;
        pipe_io = stdin_fd || stdout_fd || stderr_fd;

        if (pipe_io)
        {
                startup.dwFlags |= STARTF_USESTDHANDLES;

                /* not all programs accept mixed NULL and non-NULL hStd*, so we create all */
                for (i = 0; i < 3; i++)
                {
                        static int pindex[3][2] = { { READ_STDIN, WRITE_STDIN },
                                        { READ_STDOUT, WRITE_STDOUT }, { READ_STDERR, WRITE_STDERR } };

                        if (!CreatePipe(&hpipe[pindex[i][0]], &hpipe[pindex[i][1]], NULL, 0))
                        {
                                hpipe[pindex[i][0]] = hpipe[pindex[i][1]] = NULL;
                                failed = "create pipe";
                                goto leave;
                        }

                        if (fd[i])
                        {
                                static int mode[3] = { _O_WRONLY, _O_RDONLY, _O_RDONLY };

                                if ((*fd[i] = _open_osfhandle((intptr_t) hpipe[i], mode[i])) == -1)
                                {
                                        failed = "convert pipe handle to file descriptor";
                                        message = g_strdup(g_strerror(errno));
                                        goto leave;
                                }
                        }
                        else if (!CloseHandle(hpipe[i]))
                        {
                                failed = "close pipe";
                                goto leave;
                        }

                        if (!SetHandleInformation(hpipe[i + 3], HANDLE_FLAG_INHERIT,
                                HANDLE_FLAG_INHERIT))
                        {
                                failed = "set pipe handle to inheritable";
                                goto leave;
                        }
                }
        }

        startup.hStdInput = hpipe[READ_STDIN];
        startup.hStdOutput = hpipe[WRITE_STDOUT];
        startup.hStdError = hpipe[WRITE_STDERR];

        if (!CreateProcess(NULL, command_line, NULL, NULL, TRUE, pipe_io ? CREATE_NO_WINDOW : 0,
                environment, working_directory, &startup, &process))
        {
                failed = "";  /* report the message only */
                /* further errors will not be reported */
        }
        else
        {
                failed = NULL;
                CloseHandle(process.hThread);  /* we don't need this */

                if (hprocess)
                        *hprocess = process.hProcess;
                else
                        CloseHandle(process.hProcess);
        }

leave:
        if (failed)
        {
                if (!message)
                {
                        size_t len;

                        message = g_win32_error_message(GetLastError());
                        len = strlen(message);

                        /* unlike g_strerror(), the g_win32_error messages may include a final '.' */
                        if (len > 0 && message[len - 1] == '.')
                                message[len - 1] = '\0';
                }

                if (*failed == '\0')
                        failure = message;
                else
                {
                        failure = g_strdup_printf("Failed to %s (%s)", failed, message);
                        g_free(message);
                }
        }

        if (pipe_io)
        {
                for (i = 0; i < 3; i++)
                {
                        if (failed)
                        {
                                if (fd[i] && *fd[i] != -1)
                                        _close(*fd[i]);
                                else if (hpipe[i])
                                        CloseHandle(hpipe[i]);
                        }

                        if (hpipe[i + 3])
                                CloseHandle(hpipe[i + 3]);
                }
        }

        return failure;
}


static void spawn_append_argument(GString *command, const char *text)
{
        const char *s;

        if (command->len)
                g_string_append_c(command, ' ');

        for (s = text; *s; s++)
        {
                /* g_ascii_isspace() fails for '\v', and locale spaces (if any) will do no harm */
                if (*s == '"' || isspace(*s))
                        break;
        }

        if (*text && !*s)
                g_string_append(command, text);
        else
        {
                g_string_append_c(command, '"');

                for (s = text; *s; s++)
                {
                        const char *slash;

                        for (slash = s; *slash == '\\'; slash++);

                        if (slash > s)
                        {
                                g_string_append_len(command, s, slash - s);

                                if (!*slash || *slash == '"')
                                {
                                        g_string_append_len(command, s, slash - s);

                                        if (!*slash)
                                                break;
                                }

                                s = slash;
                        }

                        if (*s == '"')
                                g_string_append_c(command, '\\');

                        g_string_append_c(command, *s);
                }

                g_string_append_c(command, '"');
        }
}
#endif /* G_OS_WIN32 */


/*
 *  Executes a child program asynchronously and setups pipes.
 *
 *  This is the low-level spawning function. Please use @c spawn_with_callbacks() unless
 *  you need to setup specific event source(s).
 *
 *  A command line or an argument vector must be passed. If both are present, the argument
 *  vector is appended to the command line. An empty command line is not allowed.
 *
 *  Under Windows, if the child is a console application, and at least one file descriptor is
 *  specified, the new child console (if any) will be hidden.
 *
 *  If a @a child_pid is passed, it's your responsibility to invoke @c g_spawn_close_pid().
 *
 *  @param working_directory child's current working directory, or @c NULL.
 *  @param command_line child program and arguments, or @c NULL.
 *  @param argv child's argument vector, or @c NULL.
 *  @param envp child's environment, or @c NULL.
 *  @param child_pid return location for child process ID, or @c NULL.
 *  @param stdin_fd return location for file descriptor to write to child's stdin, or @c NULL.
 *  @param stdout_fd return location for file descriptor to read child's stdout, or @c NULL.
 *  @param stderr_fd return location for file descriptor to read child's stderr, or @c NULL.
 *  @param error return location for error.
 *
 *  @return @c TRUE on success, @c FALSE on error.
 */
static gboolean spawn_async_with_pipes(const gchar *working_directory, const gchar *command_line,
        gchar **argv, gchar **envp, GPid *child_pid, gint *stdin_fd, gint *stdout_fd,
        gint *stderr_fd, GError **error)
{
        g_return_val_if_fail(command_line != NULL || argv != NULL, FALSE);

#ifdef G_OS_WIN32
        GString *command;
        GArray *environment;
        gchar *failure;

        if (command_line)
        {
                gchar *program = spawn_get_program_name(command_line, error);
                const gchar *arguments;

                if (!program)
                        return FALSE;

                command = g_string_new(NULL);
                arguments = strstr(command_line, program) + strlen(program);

                if (*arguments == '"')
                {
                        g_string_append(command, program);
                        arguments++;
                }
                else
                {
                        /* quote the first token, to avoid Windows attemps to run two or more
                           unquoted tokens as a program until an existing file name is found */
                        g_string_printf(command, "\"%s\"", program);
                }

                g_string_append(command, arguments);
                g_free(program);
        }
        else
                command = g_string_new(NULL);

        environment = g_array_new(TRUE, FALSE, sizeof(char));

        while (argv && *argv)
                spawn_append_argument(command, *argv++);

#ifdef SPAWN_TEST
        g_message("full spawn command line: %s\n", command->str);
#endif

        while (envp && *envp)
        {
                g_array_append_vals(environment, *envp, strlen(*envp) + 1);
                envp++;
        }

        failure = spawn_create_process_with_pipes(command->str, working_directory,
                envp ? environment->data : NULL, child_pid, stdin_fd, stdout_fd, stderr_fd);

        g_string_free(command, TRUE);
        g_array_free(environment, TRUE);

        if (failure)
        {
                g_set_error_literal(error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED, failure);
                g_free(failure);
                return FALSE;
        }

        return TRUE;
#else  /* G_OS_WIN32 */
        int cl_argc;
        char **full_argv;
        gboolean spawned;
        GError *gerror = NULL;

        if (command_line)
        {
                int argc = 0;
                char **cl_argv;

                if (!spawn_parse_argv(command_line, &cl_argc, &cl_argv, error))
                        return FALSE;

                if (argv)
                        for (argc = 0; argv[argc]; argc++);

                full_argv = g_renew(gchar *, cl_argv, cl_argc + argc + 1);
                memcpy(full_argv + cl_argc, argv, argc * sizeof(gchar *));
                full_argv[cl_argc + argc] = NULL;
        }
        else
                full_argv = argv;

        spawned = g_spawn_async_with_pipes(working_directory, full_argv, envp,
                G_SPAWN_SEARCH_PATH | (child_pid ? G_SPAWN_DO_NOT_REAP_CHILD : 0), NULL, NULL,
                child_pid, stdin_fd, stdout_fd, stderr_fd, &gerror);

        if (!spawned)
        {
                gint en = 0;
                const gchar *message = gerror->message;

                /* try to cut glib citing of the program name or working directory: they may be long,
                   and only the caller knows whether they're UTF-8. We lose the exact chdir error. */
                switch (gerror->code)
                {
                #ifdef EACCES
                        case G_SPAWN_ERROR_ACCES : en = EACCES; break;
                #endif
                #ifdef EPERM
                        case G_SPAWN_ERROR_PERM : en = EPERM; break;
                #endif
                #ifdef E2BIG
                        case G_SPAWN_ERROR_TOO_BIG : en = E2BIG; break;
                #endif
                #ifdef ENOEXEC
                        case G_SPAWN_ERROR_NOEXEC : en = ENOEXEC; break;
                #endif
                #ifdef ENAMETOOLONG
                        case G_SPAWN_ERROR_NAMETOOLONG : en = ENAMETOOLONG; break;
                #endif
                #ifdef ENOENT
                        case G_SPAWN_ERROR_NOENT : en = ENOENT; break;
                #endif
                #ifdef ENOMEM
                        case G_SPAWN_ERROR_NOMEM : en = ENOMEM; break;
                #endif
                #ifdef ENOTDIR
                        case G_SPAWN_ERROR_NOTDIR : en = ENOTDIR; break;
                #endif
                #ifdef ELOOP
                        case G_SPAWN_ERROR_LOOP : en = ELOOP; break;
                #endif
                #ifdef ETXTBUSY
                        case G_SPAWN_ERROR_TXTBUSY : en = ETXTBUSY; break;
                #endif
                #ifdef EIO
                        case G_SPAWN_ERROR_IO : en = EIO; break;
                #endif
                #ifdef ENFILE
                        case G_SPAWN_ERROR_NFILE : en = ENFILE; break;
                #endif
                #ifdef EMFILE 
                        case G_SPAWN_ERROR_MFILE : en = EMFILE; break;
                #endif
                #ifdef EINVAL
                        case G_SPAWN_ERROR_INVAL : en = EINVAL; break;
                #endif
                #ifdef EISDIR
                        case G_SPAWN_ERROR_ISDIR : en = EISDIR; break;
                #endif
                #ifdef ELIBBAD
                        case G_SPAWN_ERROR_LIBBAD : en = ELIBBAD; break;
                #endif
                        case G_SPAWN_ERROR_CHDIR :
                        {
                                message = _("Failed to change to the working directory");
                                break;
                        }
                        case G_SPAWN_ERROR_FAILED :
                        {
                                message = _("Unknown error executing child process");
                                break;
                        }
                }

                if (en)
                        message = g_strerror(en);

                g_set_error_literal(error, gerror->domain, gerror->code, message);
                g_error_free(gerror);
        }

        if (full_argv != argv)
        {
                full_argv[cl_argc] = NULL;
                g_strfreev(full_argv);
        }

        return spawned;
#endif  /* G_OS_WIN32 */
}


/**
 *  Executes a child asynchronously.
 *
 *  A command line or an argument vector must be passed. If both are present, the argument
 *  vector is appended to the command line. An empty command line is not allowed.
 *
 *  If a @a child_pid is passed, it's your responsibility to invoke @c g_spawn_close_pid().
 *
 *  @param working_directory child's current working directory, or @c NULL.
 *  @param command_line child program and arguments, or @c NULL.
 *  @param argv child's argument vector, or @c NULL.
 *  @param envp child's environment, or @c NULL.
 *  @param child_pid return location for child process ID, or @c NULL.
 *  @param error return location for error.
 *
 *  @return @c TRUE on success, @c FALSE on error.
 *
 *  @since 1.25
 **/
GEANY_API_SYMBOL
gboolean spawn_async(const gchar *working_directory, const gchar *command_line, gchar **argv,
        gchar **envp, GPid *child_pid, GError **error)
{
        return spawn_async_with_pipes(working_directory, command_line, argv, envp, child_pid,
                NULL, NULL, NULL, error);
}


/*
 * Spawn with callbacks - general event sequence:
 *
 * - Launch the child.
 * - Setup any I/O callbacks and a child watch callback.
 * - On sync execution, run a main loop.
 * - Wait for the child to terminate.
 * - Check for active I/O sources. If any, add a timeout source to watch them, they should
 *   become inactive real soon now that the child is dead. Otherwise, finalize immediately.
 * - In the timeout source: check for active I/O sources and finalize if none.
 */

typedef struct _SpawnChannelData
{
        GIOChannel *channel;  /* NULL if not created / already destroyed */
        union
        {
                GIOFunc write;
                SpawnReadFunc read;
        } cb;
        gpointer cb_data;
        /* stdout/stderr only */
        GString *buffer;       /* NULL if recursive */
        GString *line_buffer;  /* NULL if char buffered */
        gsize max_length;
} SpawnChannelData;


static void spawn_destroy_cb(gpointer data)
{
        SpawnChannelData *sc = (SpawnChannelData *) data;

        g_io_channel_shutdown(sc->channel, FALSE, NULL);
        sc->channel = NULL;

        if (sc->buffer)
                g_string_free(sc->buffer, TRUE);

        if (sc->line_buffer)
                g_string_free(sc->line_buffer, TRUE);
}


static gboolean spawn_write_cb(GIOChannel *channel, GIOCondition condition, gpointer data)
{
        SpawnChannelData *sc = (SpawnChannelData *) data;

        if (!sc->cb.write(channel, condition, sc->cb_data))
                return FALSE;

        return !(condition & G_IO_FAILURE);
}


static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpointer data)
{
        SpawnChannelData *sc = (SpawnChannelData *) data;
        GString *line_buffer = sc->line_buffer;
        GString *buffer = sc->buffer ? sc->buffer : g_string_sized_new(sc->max_length);
        GIOCondition input_cond = condition & (G_IO_IN | G_IO_PRI);
        GIOCondition failure_cond = condition & G_IO_FAILURE;
        /*
         * - Normally, read only once. With IO watches, our data processing must be immediate,
         *   which may give the child time to emit more data, and a read loop may combine it into
         *   large stdout and stderr portions. Under Windows, looping blocks.
         * - On failure, read in a loop. It won't block now, there will be no more data, and the
         *   IO watch is not guaranteed to be called again (under Windows this is the last call).
         */
        if (input_cond)
        {
                gsize chars_read;
                GIOStatus status;

                if (line_buffer)
                {
                        gsize n = line_buffer->len;

                        while ((status = g_io_channel_read_chars(channel, line_buffer->str + n,
                                DEFAULT_IO_LENGTH, &chars_read, NULL)) == G_IO_STATUS_NORMAL)
                        {
                                g_string_set_size(line_buffer, n + chars_read);

                                while (n < line_buffer->len)
                                {
                                        gsize line_len = 0;

                                        if (n == sc->max_length)
                                                line_len = n;
                                        else if (strchr("\n", line_buffer->str[n]))  /* '\n' or '\0' */
                                                line_len = n + 1;
                                        else if (n < line_buffer->len - 1 && line_buffer->str[n] == '\r')
                                                line_len = n + 1 + (line_buffer->str[n + 1] == '\n');

                                        if (!line_len)
                                                n++;
                                        else
                                        {
                                                g_string_append_len(buffer, line_buffer->str, line_len);
                                                g_string_erase(line_buffer, 0, line_len);
                                                /* input only, failures are reported separately below */
                                                sc->cb.read(buffer, input_cond, sc->cb_data);
                                                g_string_truncate(buffer, 0);
                                                n = 0;
                                        }
                                }

                                if (!failure_cond)
                                        break;
                        }
                }
                else
                {
                        while ((status = g_io_channel_read_chars(channel, buffer->str, sc->max_length,
                                &chars_read, NULL)) == G_IO_STATUS_NORMAL)
                        {
                                g_string_set_size(buffer, chars_read);
                                /* input only, failures are reported separately below */
                                sc->cb.read(buffer, input_cond, sc->cb_data);

                                if (!failure_cond)
                                        break;
                        }
                }

                /* Under OSX, after child death, the read watches receive input conditions instead
                   of error conditions, so we convert the termination statuses into conditions.
                   Should not hurt the other OS. */
                if (status == G_IO_STATUS_ERROR)
                        failure_cond |= G_IO_ERR;
                else if (status == G_IO_STATUS_EOF)
                        failure_cond |= G_IO_HUP;
        }

        if (failure_cond)  /* we must signal the callback */
        {
                if (line_buffer && line_buffer->len)  /* flush the line buffer */
                {
                        g_string_append_len(buffer, line_buffer->str, line_buffer->len);
                        /* all data may be from a previous call */
                        if (!input_cond)
                                input_cond = G_IO_IN;
                }
                else
                {
                        input_cond = 0;
                        g_string_truncate(buffer, 0);
                }

                sc->cb.read(buffer, input_cond | failure_cond, sc->cb_data);
        }

        if (buffer != sc->buffer)
                g_string_free(buffer, TRUE);

        return !failure_cond;
}


typedef struct _SpawnWatcherData
{
        SpawnChannelData sc[3];       /* stdin, stdout, stderr */
        GChildWatchFunc exit_cb;
        gpointer exit_data;
        GPid pid;
        gint exit_status;
        GMainContext *main_context;  /* NULL if async execution */
        GMainLoop *main_loop;        /* NULL if async execution */
} SpawnWatcherData;


static void spawn_finalize(SpawnWatcherData *sw)
{
        if (sw->exit_cb)
                sw->exit_cb(sw->pid, sw->exit_status, sw->exit_data);

        if (sw->main_loop)
        {
                g_main_loop_quit(sw->main_loop);
                g_main_loop_unref(sw->main_loop);
        }

        g_spawn_close_pid(sw->pid);
        g_slice_free(SpawnWatcherData, sw);
}


static gboolean spawn_timeout_cb(gpointer data)
{
        SpawnWatcherData *sw = (SpawnWatcherData *) data;
        int i;

        for (i = 0; i < 3; i++)
                if (sw->sc[i].channel)
                        return TRUE;

        spawn_finalize(sw);
        return FALSE;
}


static void spawn_watch_cb(GPid pid, gint status, gpointer data)
{
        SpawnWatcherData *sw = (SpawnWatcherData *) data;
        int i;

        sw->pid = pid;
        sw->exit_status = status;

        for (i = 0; i < 3; i++)
        {
                if (sw->sc[i].channel)
                {
                        GSource *source = g_timeout_source_new(50);

                        g_source_set_callback(source, spawn_timeout_cb, data, NULL);
                        g_source_attach(source, sw->main_context);
                        g_source_unref(source);
                        return;
                }
        }

        spawn_finalize(sw);
}


/**
 *  Executes a child program and setups callbacks.
 *
 *  A command line or an argument vector must be passed. If both are present, the argument
 *  vector is appended to the command line. An empty command line is not allowed.
 *
 *  The synchronous execution may not be combined with recursive callbacks.
 *
 *  In line buffered mode, the child input is broken on `\n`, `\r\n`, `\r`, `\0` and max length.
 *
 *  All I/O callbacks are guaranteed to be invoked at least once with @c G_IO_ERR, @c G_IO_HUP
 *  or @c G_IO_NVAL set (except for a @a stdin_cb which returns @c FALSE before that). For the
 *  non-recursive callbacks, this is guaranteed to be the last call, and may be used to free any
 *  resources associated with the callback.
 *
 *  The @a stdin_cb may write to @c channel only once per invocation, only if @c G_IO_OUT is
 *  set, and only a non-zero number of characters.
 *
 *  @c stdout_cb and @c stderr_cb may modify the received strings in any way, but must not
 *  free them.
 *
 *  The default max lengths are 24K for line buffered stdout, 8K for line buffered stderr,
 *  4K for unbuffered input under Unix, and 2K for unbuffered input under Windows.
 *
 *  @c exit_cb is always invoked last, after all I/O callbacks.
 *
 *  The @a child_pid will be closed automatically, after @a exit_cb is invoked.
 *
 *  @param working_directory child's current working directory, or @c NULL.
 *  @param command_line child program and arguments, or @c NULL.
 *  @param argv child's argument vector, or @c NULL.
 *  @param envp child's environment, or @c NULL.
 *  @param spawn_flags flags from SpawnFlags.
 *  @param stdin_cb callback to send data to childs's stdin, or @c NULL.
 *  @param stdin_data data to pass to @a stdin_cb.
 *  @param stdout_cb callback to receive child's stdout, or @c NULL.
 *  @param stdout_data data to pass to @a stdout_cb.
 *  @param stdout_max_length maximum data length to pass to stdout_cb, @c 0 = default.
 *  @param stderr_cb callback to receive child's stderr, or @c NULL.
 *  @param stderr_data data to pass to @a stderr_cb.
 *  @param stderr_max_length maximum data length to pass to stderr_cb, @c 0 = default.
 *  @param exit_cb callback to invoke when the child exits, or @c NULL.
 *  @param exit_data data to pass to @a exit_cb.
 *  @param child_pid return location for child process ID, or @c NULL.
 *  @param error return location for error.
 *
 *  @return @c TRUE on success, @c FALSE on error.
 *
 *  @since 1.25
 **/
GEANY_API_SYMBOL
gboolean spawn_with_callbacks(const gchar *working_directory, const gchar *command_line,
        gchar **argv, gchar **envp, SpawnFlags spawn_flags, GIOFunc stdin_cb, gpointer stdin_data,
        SpawnReadFunc stdout_cb, gpointer stdout_data, gsize stdout_max_length,
        SpawnReadFunc stderr_cb, gpointer stderr_data, gsize stderr_max_length,
        GChildWatchFunc exit_cb, gpointer exit_data, GPid *child_pid, GError **error)
{
        GPid pid;
        int pipe[3] = { -1, -1, -1 };

        g_return_val_if_fail(!(spawn_flags & SPAWN_RECURSIVE) || !(spawn_flags & SPAWN_SYNC),
                FALSE);

        if (spawn_async_with_pipes(working_directory, command_line, argv, envp, &pid,
                stdin_cb ? &pipe[0] : NULL, stdout_cb ? &pipe[1] : NULL,
                stderr_cb ? &pipe[2] : NULL, error))
        {
                SpawnWatcherData *sw = g_slice_new0(SpawnWatcherData);
                gpointer cb_data[3] = { stdin_data, stdout_data, stderr_data };
                GSource *source;
                int i;

                sw->main_context = spawn_flags & SPAWN_SYNC ? g_main_context_new() : NULL;

                if (child_pid)
                        *child_pid = pid;

                for (i = 0; i < 3; i++)
                {
                        SpawnChannelData *sc = &sw->sc[i];
                        GIOCondition condition;
                        GSourceFunc callback;

                        if (pipe[i] == -1)
                                continue;

                #ifdef G_OS_WIN32
                        sc->channel = g_io_channel_win32_new_fd(pipe[i]);
                #else
                        sc->channel = g_io_channel_unix_new(pipe[i]);
                        g_io_channel_set_flags(sc->channel, G_IO_FLAG_NONBLOCK, NULL);
                #endif
                        g_io_channel_set_encoding(sc->channel, NULL, NULL);
                        /* we have our own buffers, and GIO buffering blocks under Windows */
                        g_io_channel_set_buffered(sc->channel, FALSE);
                        sc->cb_data = cb_data[i];

                        if (i == 0)
                        {
                                sc->cb.write = stdin_cb;
                                condition = G_IO_OUT | G_IO_FAILURE;
                                callback = (GSourceFunc) spawn_write_cb;
                        }
                        else
                        {
                                gboolean line_buffered = !(spawn_flags &
                                        ((SPAWN_STDOUT_UNBUFFERED >> 1) << i));

                                condition = G_IO_IN | G_IO_PRI | G_IO_FAILURE;
                                callback = (GSourceFunc) spawn_read_cb;

                                if (i == 1)
                                {
                                        sc->cb.read = stdout_cb;
                                        sc->max_length = stdout_max_length ? stdout_max_length :
                                                line_buffered ? 24576 : DEFAULT_IO_LENGTH;
                                }
                                else
                                {
                                        sc->cb.read = stderr_cb;
                                        sc->max_length = stderr_max_length ? stderr_max_length :
                                                line_buffered ? 8192 : DEFAULT_IO_LENGTH;
                                }

                                if (line_buffered)
                                {
                                        sc->line_buffer = g_string_sized_new(sc->max_length +
                                                DEFAULT_IO_LENGTH);
                                }
                        }

                        source = g_io_create_watch(sc->channel, condition);
                        g_io_channel_unref(sc->channel);

                        if (spawn_flags & (SPAWN_STDIN_RECURSIVE << i))
                                g_source_set_can_recurse(source, TRUE);
                        else if (i)  /* to avoid new string on each call */
                                sc->buffer = g_string_sized_new(sc->max_length);

                        g_source_set_callback(source, callback, sc, spawn_destroy_cb);
                        g_source_attach(source, sw->main_context);
                        g_source_unref(source);
                }

                sw->exit_cb = exit_cb;
                sw->exit_data = exit_data;
                source = g_child_watch_source_new(pid);
                g_source_set_callback(source, (GSourceFunc) spawn_watch_cb, sw, NULL);
                g_source_attach(source, sw->main_context);
                g_source_unref(source);

                if (spawn_flags & SPAWN_SYNC)
                {
                        sw->main_loop = g_main_loop_new(sw->main_context, FALSE);
                        g_main_context_unref(sw->main_context);
                        g_main_loop_run(sw->main_loop);
                }

                return TRUE;
        }

        return FALSE;
}


/**
 *  Writes (a portion of) the data pointed by @a data->ptr to the @a channel.
 *
 *  If @c G_IO_OUT in @a condition is set, and the @a data->size is > 0, attempts to write
 *  @a data->ptr (or a portion of it, depending on the size) to the @a channel. On success,
 *  increases ptr and decreases size with the number of characters written.
 *
 *  This function may converted to @c GIOFunc and passed to @c spawn_with_callbacks() as
 *  @c stdin_cb, together with a @c SpawnWriteData for @c stdin_data. As with any other
 *  callback data, make sure that @c stdin_data exists while the child is being executed.
 *  (For example, on asynchronous execution, you can allocate the data in the heap, and free
 *  it in your @c spawn_with_callbacks() @c exit_cb callback.)
 *
 * @param channel the channel to write data to.
 * @param condition condition to check for @c G_IO_OUT.
 * @param data @c SpawnWriteData to write to @a channel.
 *
 *  @return @c TRUE if the remaining size is > 0 and @a condition does not indicate any error,
 *  @c FALSE otherwise.
 *
 *  @since 1.25
 **/
GEANY_API_SYMBOL
gboolean spawn_write_data(GIOChannel *channel, GIOCondition condition, SpawnWriteData *data)
{
        if ((condition & G_IO_OUT) && data->size)
        {
                gsize chars_written = 0;

                g_io_channel_write_chars(channel, data->ptr, data->size < DEFAULT_IO_LENGTH ?
                        data->size : DEFAULT_IO_LENGTH, &chars_written, NULL);

                /* "This can be nonzero even if the return value is not G_IO_STATUS_NORMAL." */
                if (chars_written)
                {
                        data->ptr += chars_written;
                        data->size -= chars_written;
                }
        }

        return data->size > 0 && !(condition & G_IO_FAILURE);
}


static void spawn_append_gstring_cb(GString *string, GIOCondition condition, gpointer data)
{
        if (condition & (G_IO_IN | G_IO_PRI))
                g_string_append_len((GString *) data, string->str, string->len);
}


static void spawn_get_exit_status_cb(G_GNUC_UNUSED GPid pid, gint status, gpointer exit_status)
{
        *(gint *) exit_status = status;
}


/**
 *  Executes a child synchronously.
 *
 *  A command line or an argument vector must be passed. If both are present, the argument
 *  vector is appended to the command line. An empty command line is not allowed.
 *
 *  The @a stdin_data is sent to the child with @c spawn_write_data().
 *
 *  All output from the child, including the nul characters, is stored in @a stdout_data and
 *  @a stderr_data (if non-NULL). Any existing data in these strings will be erased.
 *
 *  @param working_directory child's current working directory, or @c NULL.
 *  @param command_line child program and arguments, or @c NULL.
 *  @param argv child's argument vector, or @c NULL.
 *  @param envp child's environment, or @c NULL.
 *  @param stdin_data data to send to childs's stdin, or @c NULL.
 *  @param stdout_data GString location to receive the child's stdout, or NULL.
 *  @param stderr_data GString location to receive the child's stderr, or NULL.
 *  @param exit_status return location for the child exit code, or NULL.
 *  @param error return location for error.
 *
 *  @return @c TRUE on success, @c FALSE on error.
 *
 *  @since 1.25
 **/
GEANY_API_SYMBOL
gboolean spawn_sync(const gchar *working_directory, const gchar *command_line, gchar **argv,
        gchar **envp, SpawnWriteData *stdin_data, GString *stdout_data, GString *stderr_data,
        gint *exit_status, GError **error)
{
        g_string_truncate(stdout_data, 0);
        g_string_truncate(stderr_data, 0);

        return spawn_with_callbacks(working_directory, command_line, argv, envp, SPAWN_SYNC |
                SPAWN_UNBUFFERED, stdin_data ? (GIOFunc) spawn_write_data : NULL, stdin_data,
                stdout_data ? spawn_append_gstring_cb : NULL, stdout_data, 0,
                stderr_data ? spawn_append_gstring_cb : NULL, stderr_data, 0,
                exit_status ? spawn_get_exit_status_cb : NULL, exit_status, NULL, error);
}


/* tests, not part of the API */
#ifdef SPAWN_TEST
#include <stdio.h>


static gboolean read_line(const char *prompt, char *buffer, size_t size)
{
        fputs(prompt, stderr);
        *buffer = '\0';

        if (fgets(buffer, size, stdin))
        {
                char *s = strchr(buffer, '\n');

                if (s)
                        *s = '\0';
        }

        return *buffer;
}


static GString *read_string(const char *prompt)
{
        char buffer[0x1000];  /* larger portions for spawn < file */
        GString *string = g_string_sized_new(sizeof buffer);

        while (read_line(prompt, buffer, sizeof buffer))
        {
                if (string->len)
                        g_string_append_c(string, '\n');

                g_string_append(string, buffer);
        }

        if (!string->len)
        {
                g_string_free(string, TRUE);
                string = NULL;
        }

        return string;
}


static void print_cb(GString *string, GIOCondition condition, gpointer data)
{
        if (condition & (G_IO_IN | G_IO_PRI))
        {
                gsize i;

                printf("%s: ", (const gchar *) data);
                /*fputs(string->str, stdout);*/
                for (i = 0; i < string->len; i++)
                {
                        unsigned char c = (unsigned char) string->str[i];
                        printf(c >= ' ' && c < 0x80 ? "%c" : "\\x%02x", c);
                }
                putchar('\n');
        }
}


static void print_status(gint status)
{
        fputs("finished, ", stderr);

        if (SPAWN_WIFEXITED(status))
                fprintf(stderr, "exit code %d\n", SPAWN_WEXITSTATUS(status));
        else
                fputs("abnormal termination\n", stderr);
}


static void exit_cb(GPid pid, gint status, G_GNUC_UNUSED gpointer data)
{
        fprintf(stderr, "process %u ", (guint) pid);
        print_status(status);
}


static void watch_cb(GPid pid, gint status, gpointer data)
{
        g_spawn_close_pid(pid);
        exit_cb(pid, status, NULL);
        g_main_loop_quit((GMainLoop *) data);
}


int main(int argc, char **argv)
{
        char *test_type;

        if (argc != 2)
        {
                fputs("usage: spawn <test-type>\n", stderr);
                return 1;
        }

        test_type = argv[1];

        if (!strcmp(test_type, "syntax") || !strcmp(test_type, "syntexec"))
        {
                char command_line[0x100];

                while (read_line("command line: ", command_line, sizeof command_line))
                {
                        GError *error = NULL;

                        if (spawn_check_command(command_line, argv[1][4] == 'e', &error))
                                fputs("valid\n", stderr);
                        else
                        {
                                fprintf(stderr, "error: %s\n", error->message);
                                g_error_free(error);
                        }
                }
        }
        else if (!strcmp(test_type, "execute"))
        {
                char command_line[0x100];

                while (read_line("command line: ", command_line, sizeof command_line))
                {
                        char working_directory[0x100];
                        char args[4][0x100];
                        char envs[4][0x100];
                        char *argv[] = { args[0], args[1], args[2], args[3], NULL };
                        char *envp[] = { envs[0], envs[1], envs[2], envs[3], NULL };
                        int i;
                        GPid pid;
                        GError *error = NULL;

                        read_line("working directory: ", working_directory, sizeof working_directory);

                        fputs("up to 4 arguments\n", stderr);
                        for (i = 0; i < 4 && read_line("argument: ", args[i], sizeof args[i]); i++);
                        argv[i] = NULL;

                        fputs("up to 4 variables, or empty line for parent environment\n", stderr);
                        for (i = 0; i < 4 && read_line("variable: ", envs[i], sizeof envs[i]); i++);
                        envp[i] = NULL;

                        if (spawn_async_with_pipes(*working_directory ? working_directory : NULL,
                                *command_line ? command_line : NULL, argv, i ? envp : NULL, &pid, NULL,
                                NULL, NULL, &error))
                        {
                                GMainLoop *loop = g_main_loop_new(NULL, TRUE);

                                g_child_watch_add(pid, watch_cb, loop);
                                g_main_loop_run(loop);
                                g_main_loop_unref(loop);
                        }
                        else
                        {
                                fprintf(stderr, "error: %s\n", error->message);
                                g_error_free(error);
                        }
                }
        }
        else if (!strcmp(test_type, "redirect") || !strcmp(test_type, "redinput"))
        {
                char command_line[0x100];
                gboolean output = test_type[4] == 'r';

                while (read_line("command line: ", command_line, sizeof command_line))
                {
                        GString *stdin_text = read_string("text to send: ");
                        SpawnWriteData stdin_data;
                        GError *error = NULL;

                        if (stdin_text)
                        {
                                stdin_data.ptr = stdin_text->str;
                                stdin_data.size = stdin_text->len;
                        }

                        if (!spawn_with_callbacks(NULL, command_line, NULL, NULL, SPAWN_SYNC,
                                stdin_text ? (GIOFunc) spawn_write_data : NULL, &stdin_data,
                                output ? print_cb : NULL, "stdout", 0, output ? print_cb : NULL,
                                "stderr", 0, exit_cb, NULL, NULL, &error))
                        {
                                fprintf(stderr, "error: %s\n", error->message);
                                g_error_free(error);
                        }

                        if (stdin_text)
                                g_string_free(stdin_text, TRUE);
                }
        }
        else if (!strcmp(test_type, "capture"))
        {
                char command_line[0x100];

                while (read_line("command line: ", command_line, sizeof command_line))
                {
                        GString *stdin_text = read_string("text to send: ");
                        SpawnWriteData stdin_data = { NULL, 0 };
                        GString *stdout_data = g_string_sized_new(0x10000);  /* may grow */
                        GString *stderr_data = g_string_sized_new(0x1000);   /* may grow */
                        gint exit_status;
                        GError *error = NULL;

                        if (stdin_text)
                        {
                                stdin_data.ptr = stdin_text->str;
                                stdin_data.size = stdin_text->len;
                        }

                        if (spawn_sync(NULL, command_line, NULL, NULL, &stdin_data, stdout_data,
                                stderr_data, &exit_status, &error))
                        {
                                printf("stdout: %s\n", stdout_data->str);
                                printf("stderr: %s\n", stderr_data->str);
                                print_status(exit_status);
                        }
                        else
                        {
                                fprintf(stderr, "error: %s\n", error->message);
                                g_error_free(error);
                        }

                        if (stdin_text)
                                g_string_free(stdin_text, TRUE);

                        g_string_free(stdout_data, TRUE);
                        g_string_free(stderr_data, TRUE);
                }
        }
        else
        {
                fprintf(stderr, "spawn: unknown test type '%s'", argv[1]);
                return 1;
        }

        return 0;
}
#endif  /* SPAWN_TEST */