diff --git a/libXmd/build.sh b/libXmd/build.sh
index 0d821af..f23c380 100755
--- a/libXmd/build.sh
+++ b/libXmd/build.sh
@@ -1,9 +1,17 @@
 #!/bin/sh
 
 . ../scripts/flags.sh
+BUILDFLAGS="$CFLAGS -Iinclude"
+LINTCHECKS="-checks=-*,clang-analyzer-*,bugprone-*,portability-*,cert-*"
+SOURCE="src/*.c"
 
 function build() {
-	cc $CFLAGS -Iinclude -shared -o "lib/libXmd.so" src/*.c || \
+	cc $SOURCE -o "lib/libXmd.so" -shared $BUILDFLAGS || \
+	echo "XXX FAIL!"
+}
+
+function lint() {
+	clang-tidy $SOURCE $LINTCHECKS -- $BUILDFLAGS || \
 	echo "XXX FAIL!"
 }
 
@@ -21,6 +29,9 @@ install)
 clean)
 	clean
 	;;
+lint)
+	lint
+	;;
 *)
 	build
 esac
diff --git a/libXmd/include/Xmd/Buffer.h b/libXmd/include/Xmd/Buffer.h
index ce0f2db..a89f7c3 100644
--- a/libXmd/include/Xmd/Buffer.h
+++ b/libXmd/include/Xmd/Buffer.h
@@ -13,18 +13,20 @@ typedef struct _XmdBuffer XmdBuffer;
 #define XmdBufferNew(type) _XmdBufferNew(sizeof(type));
 XmdBuffer *_XmdBufferNew (Cardinal size);
 
-/* XmdBufferPush adds a new element to the buffer. */
+/* XmdBufferPush adds a new element to the buffer. If element is NULL, the new
+   element in the buffer is set to all zeros. */
 void XmdBufferPush (XmdBuffer *buffer, void *element);
 
 /* XmdBufferPop copies the last element into element, and removes it from the
-   buffer. */
+   buffer. If element is NULL, it removes the element without copying it. */
 void XmdBufferPop (XmdBuffer *buffer, void *element);
 
-/* XmdBufferPoke sets a single element of the buffer. */
+/* XmdBufferPoke sets a single element of the buffer. If element is NULL, the
+   element in the buffer is instead set to all zeros. */
 void XmdBufferPoke (XmdBuffer *buffer, Cardinal index, void *element);
 
 /* XmdBufferPeek copies the value of a single element of the buffer into
-   element.  */
+   element. If element is NULL, this function does nothing. */
 void XmdBufferPeek (XmdBuffer *buffer, Cardinal index, void *element);
 
 /* XmdBufferBreak frees the buffer without freeing its data. Its data is
diff --git a/libXmd/include/Xmd/Exec.h b/libXmd/include/Xmd/Exec.h
new file mode 100644
index 0000000..4c50ecf
--- /dev/null
+++ b/libXmd/include/Xmd/Exec.h
@@ -0,0 +1,12 @@
+#ifndef _XmdExec_h
+#define _XmdExec_h
+
+#include <X11/Intrinsic.h>
+#include <stdio.h>
+#include <sys/types.h>
+
+FILE *XmdVaPipedExecPath (const String file, pid_t *child, String mode, ...);
+
+FILE *XmdPipedExecPath (const String file, pid_t *child, String mode, String const argv[]);
+
+#endif
diff --git a/libXmd/src/Buffer.c b/libXmd/src/Buffer.c
index ac02b3a..a7078d6 100644
--- a/libXmd/src/Buffer.c
+++ b/libXmd/src/Buffer.c
@@ -40,17 +40,21 @@ void XmdBufferResize (XmdBuffer *buffer, Cardinal length) {
 
 void XmdBufferFit (XmdBuffer *buffer) {
 	if (buffer->length > buffer->capacity) {
-		puts("fitting");
 		buffer->capacity *= XmdBUFFER_GROWTH_FACTOR;
-		buffer->data = XtReallocArray (
+		void *data = XtReallocArray (
 			buffer->data,
 			buffer->capacity,
 			buffer->size);
+		if (data == NULL) {
+			/* TODO return error */
+		}
+		buffer->data = data;
 	}
 }
 
 void *XmdBufferOffset (XmdBuffer *buffer, Cardinal index) {
-	return buffer->data + (index * buffer->size);
+	char *data = buffer->data;
+	return (void *)(data + ((size_t)(index) * buffer->size));
 }
 
 void XmdBufferPush (XmdBuffer *buffer, void *element) {
@@ -67,14 +71,19 @@ void XmdBufferPop (XmdBuffer *buffer, void *element) {
 
 void XmdBufferPoke (XmdBuffer *buffer, Cardinal index, void *element) {
 	if (index > buffer->length) return;
-	memcpy (
-		XmdBufferOffset(buffer, index),
-		element,
-		buffer->size);
+	char *destination = XmdBufferOffset(buffer, index);
+	char *source      = element;
+	
+	if (source == NULL) {
+		memset(destination, 0, buffer->size);
+	} else {
+		memcpy(destination, source, buffer->size);
+	}
 }
 
 void XmdBufferPeek (XmdBuffer *buffer, Cardinal index, void *element) {
 	if (index > buffer->length) return;
+	if (element == NULL)        return;
 	memcpy (
 		element,
 		XmdBufferOffset(buffer, index),
diff --git a/libXmd/src/Exec.c b/libXmd/src/Exec.c
new file mode 100644
index 0000000..bfb1a73
--- /dev/null
+++ b/libXmd/src/Exec.c
@@ -0,0 +1,49 @@
+#define _POSIX_C_SOURCE 200112L
+
+#include <Xmd/Exec.h>
+#include <Xmd/Buffer.h>
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+FILE *XmdVaPipedExecPath (const String file, pid_t *child, String mode, ...) {
+	XmdBuffer *buffer = XmdBufferNew(String);
+	va_list argList;
+	va_start(argList, mode);
+	
+	while (1) {
+		String arg = va_arg(argList, String);
+		if (arg == NULL) break;
+		XmdBufferPush(buffer, &arg);
+	}
+	
+	va_end(argList);
+	String *args = XmdBufferBreak(buffer);
+	FILE* pipe = XmdPipedExecPath(file, child, mode, args);
+	XtFree((char *)(args));
+	return pipe;
+}
+
+FILE *XmdPipedExecPath (const String file, pid_t *child, String mode, String const argv[]) {
+	int pipes[2];
+	pipe(pipes);
+	
+	pid_t pid = fork();
+	switch (pid) {
+	case -1: /* fail */
+		return NULL;
+	case 0: /* child */
+		dup2(pipes[1], STDOUT_FILENO);
+		close(pipes[0]);
+		close(pipes[1]);
+		execvp(file, argv);
+		exit(EXIT_FAILURE);
+		return NULL;
+	default: /* parent */
+		close(pipes[1]);
+		*child = pid;
+		return fdopen(pipes[0], mode);
+	}
+}