cat.cpp

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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 <AK/Vector.h>
#include <LibCore/ArgsParser.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <string.h>
#include <unistd.h>

int main(int argc, char** argv)
{
    if (pledge("stdio rpath", nullptr) < 0) {
        perror("pledge");
        return 1;
    }

    Vector<const char*> paths;

    Core::ArgsParser args_parser;
    args_parser.add_positional_argument(paths, "File path", "path", Core::ArgsParser::Required::No);
    args_parser.parse(argc, argv);

    Vector<int> fds;
    if (!paths.is_empty()) {
        for (const char* path : paths) {
            int fd;
            if (StringView { path } == "-") {
                fd = 0;
            } else if ((fd = open(path, O_RDONLY)) == -1) {
                fprintf(stderr, "Failed to open %s: %s\n", path, strerror(errno));
                continue;
            }
            fds.append(fd);
        }
    } else {
        fds.append(0);
    }

    if (pledge("stdio", nullptr) < 0) {
        perror("pledge");
        return 1;
    }

    for (auto& fd : fds) {
        for (;;) {
            char buf[32768];
            ssize_t nread = read(fd, buf, sizeof(buf));
            if (nread == 0)
                break;
            if (nread < 0) {
                perror("read");
                return 2;
            }
            size_t already_written = 0;
            while (already_written < (size_t)nread) {
                ssize_t nwritten = write(1, buf + already_written, nread - already_written);
                if (nwritten < 0) {
                    perror("write");
                    return 3;
                }
                already_written += nwritten;
            }
        }
        close(fd);
    }

    return 0;
}