Pipe and file write test

foo.c

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

int main() {

	int c, i;
	i = 0;
        char buffer[256];
        FILE *file;

	printf("Reading from stdin.\n");

	while ((c = fgetc(stdin)) != EOF) buffer[i++] = c;
	    buffer[i] = '\0';

	if ((file = fopen("file1.txt", "w")) == NULL) {

            printf("fopen failed with errno %d", errno);
	    return 1;
        }

	fputs(buffer, file);
	fclose(file);

    return 0;
}

pipedata.c

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

int main() {

    FILE *stream;
    int fds[2];
    int status;
    pid_t pid;
    char *cmd[] = { "foo", NULL };

    pipe(fds);
    pid = fork();

    if (pid < 0) {
        fprintf(stderr, "Fork failed\n");
        return 1;
    }
    if (pid > 0) {
        // Parent process
        close(fds[0]);
        stream = fdopen(fds[1], "w");
        fprintf(stream, "some string\n");
        fflush(stream);
        close(fds[1]);
        waitpid(pid, &status, 0);
        if (WIFEXITED(status) == 0 || WEXITSTATUS(status) < 0)
            return 1;
    }
    else {
        // Child process
        close(fds[1]);
        dup2(fds[0], STDIN_FILENO);

        execv("foo", cmd);
        return 1;
    }

    return 0;
}