mirror of
https://github.com/SerenityOS/serenity
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163 lines
5.1 KiB
C++
163 lines
5.1 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/StdLibExtras.h>
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#include <LibCore/ArgsParser.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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int head(const String& filename, bool print_filename, int line_count, int char_count);
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int main(int argc, char** argv)
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{
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if (pledge("stdio rpath", nullptr) < 0) {
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perror("pledge");
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return 1;
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}
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int line_count = 0;
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int char_count = 0;
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bool never_print_filenames = false;
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bool always_print_filenames = false;
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Vector<const char*> files;
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Core::ArgsParser args_parser;
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args_parser.set_general_help("Print the beginning ('head') of a file.");
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args_parser.add_option(line_count, "Number of lines to print (default 10)", "lines", 'n', "number");
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args_parser.add_option(char_count, "Number of characters to print", "characters", 'c', "number");
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args_parser.add_option(never_print_filenames, "Never print file names", "quiet", 'q');
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args_parser.add_option(always_print_filenames, "Always print file names", "verbose", 'v');
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args_parser.add_positional_argument(files, "File to process", "file", Core::ArgsParser::Required::No);
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args_parser.parse(argc, argv);
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if (line_count == 0 && char_count == 0) {
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line_count = 10;
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}
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bool print_filenames = files.size() > 1;
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if (always_print_filenames)
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print_filenames = true;
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else if (never_print_filenames)
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print_filenames = false;
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if (files.is_empty()) {
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return head("", print_filenames, line_count, char_count);
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}
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int rc = 0;
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for (auto& file : files) {
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if (head(file, print_filenames, line_count, char_count) != 0) {
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rc = 1;
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}
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}
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return rc;
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}
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int head(const String& filename, bool print_filename, int line_count, int char_count)
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{
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bool is_stdin = false;
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FILE* fp = nullptr;
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if (filename == "" || filename == "-") {
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fp = stdin;
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is_stdin = true;
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} else {
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fp = fopen(filename.characters(), "r");
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if (!fp) {
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fprintf(stderr, "can't open %s for reading: %s\n", filename.characters(), strerror(errno));
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return 1;
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}
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}
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if (print_filename) {
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if (is_stdin) {
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puts("==> standard input <==");
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} else {
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printf("==> %s <==\n", filename.characters());
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}
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}
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if (line_count) {
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for (int line = 0; line < line_count; ++line) {
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char buffer[BUFSIZ];
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auto* str = fgets(buffer, sizeof(buffer), fp);
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if (!str)
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break;
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// specifically use fputs rather than puts, because fputs doesn't add
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// its own newline.
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fputs(str, stdout);
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}
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} else if (char_count) {
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char buffer[BUFSIZ];
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while (char_count) {
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int nread = fread(buffer, 1, min(BUFSIZ, char_count), fp);
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if (nread > 0) {
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int ncomplete = 0;
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while (ncomplete < nread) {
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int nwrote = fwrite(&buffer[ncomplete], 1, nread - ncomplete, stdout);
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if (nwrote > 0)
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ncomplete += nwrote;
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if (feof(stdout)) {
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fprintf(stderr, "unexpected eof writing to stdout\n");
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return 1;
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}
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if (ferror(stdout)) {
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fprintf(stderr, "error writing to stdout\n");
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return 1;
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}
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}
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}
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char_count -= nread;
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if (feof(fp))
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break;
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if (ferror(fp)) {
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fprintf(stderr, "error reading input\n");
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break;
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}
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}
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}
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fclose(fp);
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if (print_filename) {
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puts("");
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}
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return 0;
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}
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