#include "cache.h"
#include "run-command.h"
#include "exec_cmd.h"

static inline void close_pair(int fd[2])
{
        close(fd[0]);
        close(fd[1]);
}

static inline void dup_devnull(int to)
{
        int fd = open("/dev/null", O_RDWR);
        dup2(fd, to);
        close(fd);
}

int start_command(struct child_process *cmd)
{
        int need_in, need_out, need_err;
        int fdin[2], fdout[2], fderr[2];

        /*
         * In case of errors we must keep the promise to close FDs
         * that have been passed in via ->in and ->out.
         */

        need_in = !cmd->no_stdin && cmd->in < 0;
        if (need_in) {
                if (pipe(fdin) < 0) {
                        if (cmd->out > 0)
                                close(cmd->out);
                        return -ERR_RUN_COMMAND_PIPE;
                }
                cmd->in = fdin[1];
        }

        need_out = !cmd->no_stdout
                && !cmd->stdout_to_stderr
                && cmd->out < 0;
        if (need_out) {
                if (pipe(fdout) < 0) {
                        if (need_in)
                                close_pair(fdin);
                        else if (cmd->in)
                                close(cmd->in);
                        return -ERR_RUN_COMMAND_PIPE;
                }
                cmd->out = fdout[0];
        }

        need_err = !cmd->no_stderr && cmd->err < 0;
        if (need_err) {
                if (pipe(fderr) < 0) {
                        if (need_in)
                                close_pair(fdin);
                        else if (cmd->in)
                                close(cmd->in);
                        if (need_out)
                                close_pair(fdout);
                        else if (cmd->out)
                                close(cmd->out);
                        return -ERR_RUN_COMMAND_PIPE;
                }
                cmd->err = fderr[0];
        }

        cmd->pid = fork();
        if (cmd->pid < 0) {
                if (need_in)
                        close_pair(fdin);
                else if (cmd->in)
                        close(cmd->in);
                if (need_out)
                        close_pair(fdout);
                else if (cmd->out)
                        close(cmd->out);
                if (need_err)
                        close_pair(fderr);
                return -ERR_RUN_COMMAND_FORK;
        }

        if (!cmd->pid) {
                if (cmd->no_stdin)
                        dup_devnull(0);
                else if (need_in) {
                        dup2(fdin[0], 0);
                        close_pair(fdin);
                } else if (cmd->in) {
                        dup2(cmd->in, 0);
                        close(cmd->in);
                }

                if (cmd->no_stderr)
                        dup_devnull(2);
                else if (need_err) {
                        dup2(fderr[1], 2);
                        close_pair(fderr);
                }

                if (cmd->no_stdout)
                        dup_devnull(1);
                else if (cmd->stdout_to_stderr)
                        dup2(2, 1);
                else if (need_out) {
                        dup2(fdout[1], 1);
                        close_pair(fdout);
                } else if (cmd->out > 1) {
                        dup2(cmd->out, 1);
                        close(cmd->out);
                }

                if (cmd->dir && chdir(cmd->dir))
                        die("exec %s: cd to %s failed (%s)", cmd->argv[0],
                            cmd->dir, strerror(errno));
                if (cmd->env) {
                        for (; *cmd->env; cmd->env++) {
                                if (strchr(*cmd->env, '='))
                                        putenv((char*)*cmd->env);
                                else
                                        unsetenv(*cmd->env);
                        }
                }
                if (cmd->git_cmd) {
                        execv_git_cmd(cmd->argv);
                } else {
                        execvp(cmd->argv[0], (char *const*) cmd->argv);
                }
                die("exec %s failed.", cmd->argv[0]);
        }

        if (need_in)
                close(fdin[0]);
        else if (cmd->in)
                close(cmd->in);

        if (need_out)
                close(fdout[1]);
        else if (cmd->out)
                close(cmd->out);

        if (need_err)
                close(fderr[1]);

        return 0;
}

static int wait_or_whine(pid_t pid)
{
        for (;;) {
                int status, code;
                pid_t waiting = waitpid(pid, &status, 0);

                if (waiting < 0) {
                        if (errno == EINTR)
                                continue;
                        error("waitpid failed (%s)", strerror(errno));
                        return -ERR_RUN_COMMAND_WAITPID;
                }
                if (waiting != pid)
                        return -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
                if (WIFSIGNALED(status))
                        return -ERR_RUN_COMMAND_WAITPID_SIGNAL;

                if (!WIFEXITED(status))
                        return -ERR_RUN_COMMAND_WAITPID_NOEXIT;
                code = WEXITSTATUS(status);
                if (code)
                        return -code;
                return 0;
        }
}

int finish_command(struct child_process *cmd)
{
        return wait_or_whine(cmd->pid);
}

int run_command(struct child_process *cmd)
{
        int code = start_command(cmd);
        if (code)
                return code;
        return finish_command(cmd);
}

static void prepare_run_command_v_opt(struct child_process *cmd,
                                      const char **argv,
                                      int opt)
{
        memset(cmd, 0, sizeof(*cmd));
        cmd->argv = argv;
        cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
        cmd->git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
        cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
}

int run_command_v_opt(const char **argv, int opt)
{
        struct child_process cmd;
        prepare_run_command_v_opt(&cmd, argv, opt);
        return run_command(&cmd);
}

int run_command_v_opt_cd(const char **argv, int opt, const char *dir)
{
        struct child_process cmd;
        prepare_run_command_v_opt(&cmd, argv, opt);
        cmd.dir = dir;
        return run_command(&cmd);
}

int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
{
        struct child_process cmd;
        prepare_run_command_v_opt(&cmd, argv, opt);
        cmd.dir = dir;
        cmd.env = env;
        return run_command(&cmd);
}

int start_async(struct async *async)
{
        int pipe_out[2];

        if (pipe(pipe_out) < 0)
                return error("cannot create pipe: %s", strerror(errno));

        async->pid = fork();
        if (async->pid < 0) {
                error("fork (async) failed: %s", strerror(errno));
                close_pair(pipe_out);
                return -1;
        }
        if (!async->pid) {
                close(pipe_out[0]);
                exit(!!async->proc(pipe_out[1], async->data));
        }
        async->out = pipe_out[0];
        close(pipe_out[1]);
        return 0;
}

int finish_async(struct async *async)
{
        int ret = 0;

        if (wait_or_whine(async->pid))
                ret = error("waitpid (async) failed");
        return ret;
}