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catm.c
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catm.c
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/* Copyright (C) 2019 Jeremiah Orians
* This file is part of mescc-tools
*
* mescc-tools is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* mescc-tools is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with mescc-tools. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#define BUFFER_SIZE 4096
/********************************************************************************
* the reason why we are using read and write instead of fread and fwrite is *
* because it is much faster and involves less copying of values around *
********************************************************************************/
int main(int argc, char** argv)
{
if(2 > argc)
{
fputs("catm requires 2 or more arguments\n", stderr);
exit(EXIT_FAILURE);
}
/* create a new file with read/write permissions only */
int output = open(argv[1], O_TRUNC | O_CREAT | O_WRONLY , 0600);
if(-1 == output)
{
fputs("The file: ", stderr);
fputs(argv[1], stderr);
fputs(" is not a valid output file name\n", stderr);
exit(EXIT_FAILURE);
}
int i;
int bytes;
char* buffer = calloc(BUFFER_SIZE + 1, sizeof(char));
int input;
for(i = 2; i < argc ; i = i + 1)
{
input = open(argv[i], 0, 0);
if(-1 == input)
{
fputs("The file: ", stderr);
fputs(argv[i], stderr);
fputs(" is not a valid input file name\n", stderr);
exit(EXIT_FAILURE);
}
keep:
bytes = read(input, buffer, BUFFER_SIZE);
write(output, buffer, bytes);
if(BUFFER_SIZE == bytes) goto keep;
}
free(buffer);
return EXIT_SUCCESS;
}