libc: implement err/warn functions

1 files changed, 17 insertions, 12 deletions

diff --git a/bin/echo/echo.c b/bin/echo/echo.c
index b5ceee1c..ee932898 100644
--- a/bin/echo/echo.c
+++ b/bin/echo/echo.c
@@ -1,30 +1,35 @@
+#include <alloca.h>  // for alloca
+#include <err.h>     // for errx
 #include <string.h>  // for strlen
 #include <sys/uio.h> // for iovec, writev
 #include <unistd.h>  // for STDOUT_FILENO
 
 int main(int argc, char **argv)
 {
+	struct iovec *iov;
+	int n_iov;
+
 	if (argc <= 1)
 		return 0;
 
-	struct iovec iov[2 * argc - 2];
-	int iovcnt = 0;
+	iov = alloca(sizeof(struct iovec) * (int)(2 * argc));
+	n_iov = 0;
 
 	for (int i = 1; i < argc; i++) {
-		iov[iovcnt].iov_base = argv[i];
-		iov[iovcnt].iov_len = strlen(argv[i]);
-		iovcnt++;
+		iov[n_iov].iov_base = argv[i];
+		iov[n_iov++].iov_len = strlen(argv[i]);
 
 		if (i < argc - 1) {
-			iov[iovcnt].iov_base = " ";
-			iov[iovcnt].iov_len = 1;
-			iovcnt++;
+			iov[n_iov].iov_base = " ";
+			iov[n_iov++].iov_len = 1;
 		}
 	}
 
-	iov[iovcnt].iov_base = "\n";
-	iov[iovcnt].iov_len = 1;
-	iovcnt++;
+	iov[n_iov].iov_base = "\n";
+	iov[n_iov++].iov_len = 1;
+
+	if (writev(STDOUT_FILENO, iov, n_iov) < 0)
+		err(1, "writev");
 
-	return writev(STDOUT_FILENO, iov, iovcnt) < 0 ? 1 : 0;
+	return 0;
 }