redir.c

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/*
 * Copyright (c) 2009 Martin Decky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/types.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <str.h>
#include <stdio.h>
#include <task.h>
#include <str_error.h>
#include <errno.h>

#define NAME  "redir"

static void usage(void)
{
        printf("Usage: %s [-i <stdin>] [-o <stdout>] [-e <stderr>] -- <cmd> [args ...]\n",
            NAME);
}

static void reopen(FILE **stream, int fd, const char *path, int flags, const char *mode)
{
        if (fclose(*stream))
                return;
        
        *stream = NULL;
        
        int oldfd = open(path, flags);
        if (oldfd < 0)
                return;
        
        if (oldfd != fd) {
                if (dup2(oldfd, fd) != fd)
                        return;
                
                if (close(oldfd))
                        return;
        }
        
        *stream = fdopen(fd, mode);
}

static task_id_t spawn(int argc, char *argv[])
{
        const char **args;
        task_id_t id = 0;
        int rc;

        args = (const char **) calloc(argc + 1, sizeof(char *));
        if (!args) {
                printf("No memory available\n");
                return 0;
        }
        
        int i;
        for (i = 0; i < argc; i++)
                args[i] = argv[i];
        
        args[argc] = NULL;
        
        rc = task_spawnv(&id, argv[0], args);
        
        free(args);
        
        if (rc != EOK) {
                printf("%s: Error spawning %s (%s)\n", NAME, argv[0],
                    str_error(rc));
        }
        
        return id;
}

int main(int argc, char *argv[])
{
        if (argc < 3) {
                usage();
                return -1;
        }
        
        int i;
        for (i = 1; i < argc; i++) {
                if (str_cmp(argv[i], "-i") == 0) {
                        i++;
                        if (i >= argc) {
                                usage();
                                return -2;
                        }
                        reopen(&stdin, 0, argv[i], O_RDONLY, "r");
                } else if (str_cmp(argv[i], "-o") == 0) {
                        i++;
                        if (i >= argc) {
                                usage();
                                return -3;
                        }
                        reopen(&stdout, 1, argv[i], O_WRONLY | O_CREAT, "w");
                } else if (str_cmp(argv[i], "-e") == 0) {
                        i++;
                        if (i >= argc) {
                                usage();
                                return -4;
                        }
                        reopen(&stderr, 2, argv[i], O_WRONLY | O_CREAT, "w");
                } else if (str_cmp(argv[i], "--") == 0) {
                        i++;
                        break;
                }
        }
        
        if (i >= argc) {
                usage();
                return -5;
        }
        
        /*
         * FIXME: fdopen() should actually detect that we are opening a console
         * and it should set line-buffering mode automatically.
         */
        setvbuf(stdout, NULL, _IOLBF, BUFSIZ);
        
        task_id_t id = spawn(argc - i, argv + i);
        
        if (id != 0) {
                task_exit_t texit;
                int retval;
                task_wait(id, &texit, &retval);
                
                return retval;
        }
        
        return -6;
}

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