Added exec functions

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),

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);
+	}
+}