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/*
* 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/StdLibExtras.h>
#include <LibCore/ArgsParser.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int head(const String& filename, bool print_filename, int line_count, int char_count);
int main(int argc, char** argv)
{
if (pledge("stdio rpath", nullptr) < 0) {
perror("pledge");
return 1;
}
int line_count = 0;
int char_count = 0;
bool never_print_filenames = false;
bool always_print_filenames = false;
Vector<const char*> files;
Core::ArgsParser args_parser;
args_parser.set_general_help("Print the beginning ('head') of a file.");
args_parser.add_option(line_count, "Number of lines to print (default 10)", "lines", 'n', "number");
args_parser.add_option(char_count, "Number of characters to print", "characters", 'c', "number");
args_parser.add_option(never_print_filenames, "Never print file names", "quiet", 'q');
args_parser.add_option(always_print_filenames, "Always print file names", "verbose", 'v');
args_parser.add_positional_argument(files, "File to process", "file", Core::ArgsParser::Required::No);
args_parser.parse(argc, argv);
if (line_count == 0 && char_count == 0) {
line_count = 10;
}
bool print_filenames = files.size() > 1;
if (always_print_filenames)
print_filenames = true;
else if (never_print_filenames)
print_filenames = false;
if (files.is_empty()) {
return head("", print_filenames, line_count, char_count);
}
int rc = 0;
for (auto& file : files) {
if (head(file, print_filenames, line_count, char_count) != 0) {
rc = 1;
}
}
return rc;
}
int head(const String& filename, bool print_filename, int line_count, int char_count)
{
bool is_stdin = false;
FILE* fp = nullptr;
if (filename == "" || filename == "-") {
fp = stdin;
is_stdin = true;
} else {
fp = fopen(filename.characters(), "r");
if (!fp) {
fprintf(stderr, "can't open %s for reading: %s\n", filename.characters(), strerror(errno));
return 1;
}
}
if (print_filename) {
if (is_stdin) {
puts("==> standard input <==");
} else {
printf("==> %s <==\n", filename.characters());
}
}
if (line_count) {
for (int line = 0; line < line_count; ++line) {
char buffer[BUFSIZ];
auto* str = fgets(buffer, sizeof(buffer), fp);
if (!str)
break;
// specifically use fputs rather than puts, because fputs doesn't add
// its own newline.
fputs(str, stdout);
}
} else if (char_count) {
char buffer[BUFSIZ];
while (char_count) {
int nread = fread(buffer, 1, min(BUFSIZ, char_count), fp);
if (nread > 0) {
int ncomplete = 0;
while (ncomplete < nread) {
int nwrote = fwrite(&buffer[ncomplete], 1, nread - ncomplete, stdout);
if (nwrote > 0)
ncomplete += nwrote;
if (feof(stdout)) {
fprintf(stderr, "unexpected eof writing to stdout\n");
return 1;
}
if (ferror(stdout)) {
fprintf(stderr, "error writing to stdout\n");
return 1;
}
}
}
char_count -= nread;
if (feof(fp))
break;
if (ferror(fp)) {
fprintf(stderr, "error reading input\n");
break;
}
}
}
fclose(fp);
if (print_filename) {
puts("");
}
return 0;
}
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