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pwc.c

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/wait.h>

static void die(const char *msg) {
	perror(msg);
	exit(EXIT_FAILURE);
}


static unsigned int wordcount(const char *file) {

	FILE *fp = fopen(file, "r");
	if (fp == NULL) {
		die(file);
	}

	unsigned int words = 0;
	int trennzeichen = 1; // Randfall: Anfang

	while (1) {

		int c = fgetc(fp);
		if (c == EOF) {
			if (trennzeichen == 0) { // Randfall: Ende
				words++;
			}
			break;
		}

		if (c == ' ' || c == '\n' || c == '\t') {
			if (trennzeichen == 0) {
				trennzeichen = 1;
				words++;
			}
		} else {
			trennzeichen = 0;
		}

	}
	if (ferror(fp)) {
		die(file);
	}

	fclose(fp);
	return words;
}

int main(int argc, char *argv[]) {
	if (argc == 1) {
		fprintf(stderr, "Syntax: %s <file...>\n", argv[0]);
		exit(EXIT_FAILURE);
	}

	for (int i = 1; i < argc; i++) {
		pid_t pid = fork();
		if (pid == -1) {
			die("fork");
		}
		if (pid == 0) {
			unsigned int wc = wordcount(argv[i]);
			printf("%s: %u\n", argv[i], wc);
			exit(EXIT_SUCCESS);
		}
	}

	int ok = 1;
	for (int i = 1; i < argc; i++) {
		int status = 0;
		pid_t p = wait(&status);
		if (p < 0) {
			die("wait");
		}
		if (WIFEXITED(status) && WEXITSTATUS(status) != EXIT_SUCCESS) {
			ok = 0;
		}
	}

	if (ok == 0) {
		fprintf(stderr, "Fehler!\n");
		exit(EXIT_FAILURE);
	}

	return EXIT_SUCCESS;

}