micro-utils/src/coreutils/cat/cat.c

#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include "config.h"

int cat(const char *path) {
	int fd = STDIN_FILENO;

	if (strcmp(path, "-"))
		fd = open(path, O_RDONLY);

	if (fd < 0) {
		fprintf(stderr, "cat: %s: %s\n", path, strerror(errno));
		return 1;
	}

	char buf[BUF_SIZE + 1];
	off_t len = 0;
	while ((len = read(fd, buf, sizeof(buf))) > 0)
		if (write(STDOUT_FILENO, buf, len) != len) {
			fprintf(stderr, "cat: %s\n", strerror(errno));
			return 1;
		}

	if (strcmp(path, "-"))
		close(fd);

	return 0;
}

int main(int argc, char **argv) {
	int opt;
	while ((opt = getopt(argc, argv, "")) != -1) {
		printf("cat [file1 file2...]\n");
		return 0;
	}

	argv += optind;
	argc -= optind;

	if (argc == 0)
		return cat("-");

	else {
		int ret = 0;
		for (int i = 0; i < argc; i++)
			if (cat(argv[i]))
				ret = 1;

		return ret;
	}
}