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#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define CAT_USAGE "Usage: cat [-u] [file...]\n"
#define STDIN_ARG "-"
#define BUFFER_SIZE 20480
static void close_file(int fd) {
if (fd != STDIN_FILENO) {
close(fd);
}
}
static bool print_file_content(const char *path) {
char buffer[BUFFER_SIZE];
int input = -1;
ssize_t ret = -1;
if (strcmp(path, STDIN_ARG) == 0) {
input = STDIN_FILENO;
} else {
if ((input = open(path, O_RDONLY)) == -1) {
fprintf(stderr,"Can't open file '%s': %s\n", path, strerror(errno));
return false;
}
}
do {
ret = read(input, buffer, BUFFER_SIZE);
if (ret > 0) {
write(STDOUT_FILENO, buffer, ret);
}
} while (ret > 0);
if (ret == -1) {
fprintf(stderr, "Failed to read file '%s': %s\n", path, strerror(errno));
}
close_file(input);
return ret == 0;
}
int cat_main(int argc, char *argv[]) {
int opt = 0;
bool ret = false;
while ((opt = getopt(argc, argv, "u")) != -1) {
if (opt != 'u') {
perror(CAT_USAGE);
return EXIT_FAILURE;
}
}
for (int i = optind; i < argc; i++) {
ret = print_file_content(argv[i]);
if (!ret) {
break;
}
}
/* If no argument was provided, we use stdin by default */
if (argc - optind == 0) {
ret = print_file_content(STDIN_ARG);
}
return ret ? EXIT_SUCCESS : EXIT_FAILURE;
}
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