failtest: fix fascist warn_unused_result warnings

ccan/failtest/failtest.c

@@ -248,7 +248,8 @@ static struct saved_file *save_file(struct saved_file *next, int fd)
 	s->len = lseek(fd, 0, SEEK_END);
 	lseek(fd, 0, SEEK_SET);
 	s->contents = malloc(s->len);
-	read(fd, s->contents, s->len);
+	if (read(fd, s->contents, s->len) != s->len)
+		err(1, "Failed to save %zu bytes", (size_t)s->len);
 	lseek(fd, s->off, SEEK_SET);
 	return s;
 }
@@ -293,8 +294,11 @@ static void restore_files(struct saved_file *s)
 		struct saved_file *next = s->next;
 
 		lseek(s->fd, 0, SEEK_SET);
-		write(s->fd, s->contents, s->len);
-		ftruncate(s->fd, s->len);
+		if (write(s->fd, s->contents, s->len) != s->len)
+			err(1, "Failed to restore %zu bytes", (size_t)s->len);
+		if (ftruncate(s->fd, s->len) != 0)
+			err(1, "Failed to trim file to length %zu",
+			    (size_t)s->len);
 		free(s->contents);
 		lseek(s->fd, s->off, SEEK_SET);
 		free(s);
@@ -395,8 +399,8 @@ static bool should_fail(struct failtest_call *call)
 			signal(SIGUSR1, SIG_IGN);
 			sprintf(str, "xterm -e gdb /proc/%d/exe %d &",
 				getpid(), getpid());
-			system(str);
-			sleep(5);
+			if (system(str) == 0)
+				sleep(5);
 		}
 	}
 

ccan/failtest/test/run-open.c

@@ -15,13 +15,15 @@ int main(void)
 
 	plan_tests(12);
 
-	pipe(pfd);
+	if (pipe(pfd))
+		abort();
 	fd = failtest_open("run-open-scratchpad", "run-open.c", 1,
 			   O_RDWR|O_CREAT, 0600);
 	if (fd == -1) {
 		/* We are the child: write error code for parent to check. */
 		err = errno;
-		write(pfd[1], &err, sizeof(err));
+		if (write(pfd[1], &err, sizeof(err)) != sizeof(err))
+			abort();
 		failtest_exit(0);
 	}
 	/* Check it is read-write. */
@@ -46,12 +48,14 @@ int main(void)
 	close(pfd[1]);
 
 	/* Two-arg open. */
-	pipe(pfd);
+	if (pipe(pfd) != 0)
+		abort();
 	fd = failtest_open("run-open-scratchpad", "run-open.c", 1, O_RDONLY);
 	if (fd == -1) {
 		/* We are the child: write error code for parent to check. */
 		err = errno;
-		write(pfd[1], &err, sizeof(err));
+		if (write(pfd[1], &err, sizeof(err)) != sizeof(err))
+			abort();
 		failtest_exit(0);
 	}
 	/* Check it is read-only. */

ccan/failtest/test/run-write.c

@@ -21,7 +21,8 @@ int main(int argc, char *argv[])
 	/* Child will fail, ignore. */
 	if (fd < 0)
 		failtest_exit(0);
-	write(fd, buf, strlen(buf));
+	if (write(fd, buf, strlen(buf)) != strlen(buf))
+		abort();
 	ok1(lseek(fd, 0, SEEK_CUR) == strlen(buf));
 
 	p = failtest_malloc(100, __FILE__, __LINE__);