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#define _XOPEN_SOURCE 700
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
int
head(FILE *f, int n) {
int i;
ssize_t bytes;
char *buf = NULL;
size_t len = 0;
for (i = 0; i < n; i++) {
bytes = getline(&buf, &len, f);
if (bytes == -1) {
if (ferror(f)) {
fprintf(stderr, "head: %s\n", strerror(errno));
return 1;
}
if (feof(f))
break;
}
if (write(1, buf, bytes) == -1) {
fprintf(stderr, "head: %s\n", strerror(errno));
return 1;
}
}
free(buf);
return 0;
}
int
main(int argc, char **argv) {
int n = 10;
int ret = 0;
int c;
while ((c = getopt(argc, argv, ":n:")) != -1) {
switch (c) {
case 'n':
n = atoi(optarg);
if (n <= 0) {
fprintf(stderr, "head: invalid number '%s'\n", optarg);
return 1;
}
break;
case ':':
case '?':
fprintf(stderr, "usage: %s [-n num] [file...]\n", *argv);
return 1;
}
}
argc -= optind;
argv += optind - 1;
if (argc == 0)
return head(stdin, n);
FILE *f;
while (*++argv) {
if (**argv == '-' && *(*argv + 1) == '\0')
f = stdin;
else {
f = fopen(*argv, "r");
if (f == NULL) {
fprintf(stderr, "head: %s: %s\n", *argv, strerror(errno));
ret = 1;
continue;
}
}
if (head(f, n) != 0)
ret = 1;
if (f != stdin && fclose(f) == EOF) {
fprintf(stderr, "head: %s: %s\n", *argv, strerror(errno));
ret = 1;
continue;
}
}
return ret;
}
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