Implemented fake downloader without log support

exercises/downloader/main.c

@@ -1,7 +1,41 @@
+#define _GNU_SOURCE
+#include <pthread.h>
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+static void *download(void *);
 
 int main(int argc, char *argv[])
 {
-	return EXIT_SUCCESS;
+	if (argc < 2) {
+		fprintf(stderr, "Usage: %s file1 file2...", argv[0]);
+		return 1;
+	}
+
+	const int nfile = argc - 1;
+	pthread_t workers[nfile];
+	for (int i = 0; i < nfile; i++) {
+		pthread_create(&workers[i], NULL, download, argv[i + 1]);
+	}
+
+	for (int i = 0; i < nfile; i++) {
+		pthread_join(workers[i], NULL);
+	}
+	printf("All downloads complete.\n");
+
+	return 0;
+}
+
+static void *download(void *arg)
+{
+	char *uri = (char *)arg;
+	int tid = syscall(SYS_gettid);
+	printf("[Thread %x] Starting download of %s\n", tid, uri);
+	sleep(rand() % 3 + 1);
+	printf("[Thread %x] Finished download of %s\n", tid, uri);
+	pthread_exit(0);
 }