tvm_preprocess: update *src after (re)allocating memory

During preprocessing, we find directives, and if they specify including
other source files, we remove the directive, allocate a new block of
memory, copy the first block, append the new source file, and append the
second block.

Previously, the value of the source pointer was passed into the
preprocessing function. When the memory would be (re)allocated, the
pointer value could change, but the original pointer would not be
updated.

Now, the pointer is passed by address, and updated when the memory it
points to changes.

include/tvm/tvm_preprocessor.h

@@ -3,6 +3,6 @@
 
 #include "tvm_htab.h"
 
-int tvm_preprocess(char *src, int *src_len, struct tvm_htab_ctx *defines);
+int tvm_preprocess(char **src, int *src_len, struct tvm_htab_ctx *defines);
 
 #endif

libtvm/tvm.c

@@ -45,7 +45,7 @@ int tvm_vm_interpret(struct tvm_ctx *vm, char *filename)
 	tvm_fcopy(source, source_length, filp);
 	fclose(filp);
 
-	int err = tvm_preprocess(source, &source_length, vm->prog->defines);
+	int err = tvm_preprocess(&source, &source_length, vm->prog->defines);
 
 	/* The preprocessor encountered a problem. */
 	if (err < 0)

libtvm/tvm_preprocessor.c

@@ -1,27 +1,28 @@
 #include <tvm/tvm_preprocessor.h>
-#include <tvm/tvm_tokens.h>
 #include <tvm/tvm_file.h>
+#include <tvm/tvm_tokens.h>
 
+#include <unistd.h>
 #include <string.h>
 
 static int process_includes(
-	char *src, int *src_len, struct tvm_htab_ctx *defines)
+	char **src, int *src_len, struct tvm_htab_ctx *defines)
 {
-	char *pp_directive_delimiter = strstr(src, TOK_INCLUDE);
+	char *pp_directive_delimiter = strstr(*src, TOK_INCLUDE);
 
 	if (!pp_directive_delimiter)
 		return 0;
 
-	char *strbegin = pp_directive_delimiter,
-		 *strend = strchr(strbegin, '\n');
+	char *begin = pp_directive_delimiter,
+		 *end = strchr(begin, '\n');
 
-	if (!strend || !strbegin)
+	if (!end || !begin)
 		return 0;
 
-	int linelen = strend - strbegin;
+	int linelen = end - begin;
 	char *temp_str = calloc(linelen + 1, sizeof(char));
 
-	memcpy(temp_str, strbegin, linelen);
+	memcpy(temp_str, begin, linelen);
 
 	char *filename = (strchr(temp_str, ' ') + 1);
 	FILE *filp = tvm_fopen(filename, ".vm", "r");
@@ -39,31 +40,26 @@ static int process_includes(
 	tvm_fcopy(addition_str, addition_len, filp);
 	fclose(filp);
 
-	size_t first_block_len = (strbegin - src);
-	size_t second_block_len = ((src + *src_len) - strend);
+	size_t first_block_len = (begin - *src);
+	size_t second_block_len = ((*src + *src_len) - end);
 	size_t new_src_len = (
 		first_block_len + addition_len + second_block_len);
 
-	src = (char *)realloc((char *)src, sizeof(char) * new_src_len);
-	src[new_src_len] = 0;
+	char *new_src = (char *)calloc(sizeof(char), new_src_len);
+	strncpy(new_src, (*src), first_block_len);
+	strcat(new_src, addition_str);
+	strcat(new_src, end+1);
 
-	memmove(&src[first_block_len + addition_len], strend, second_block_len);
-	memcpy(&src[first_block_len], addition_str, addition_len);
-
-	/* Fuckin' hack */
-	for (int i = 0; i < new_src_len; i++) {
-		if (src[i] == 0)
-			src[i] = ' ';
-	}
-
-	*src_len = strlen(src);
+	free(*src);
+	*src = new_src;
+	*src_len = strlen(*src);
 	return 1;
 }
 
 static int process_defines(
-	char *src, int *src_len, struct tvm_htab_ctx *defines)
+	char **src, int *src_len, struct tvm_htab_ctx *defines)
 {
-	char *pp_directive_delimiter = strstr(src, TOK_DEFINE);
+	char *pp_directive_delimiter = strstr(*src, TOK_DEFINE);
 
 	if (!pp_directive_delimiter)
 		return 0;
@@ -111,20 +107,20 @@ static int process_defines(
 	}
 
 	/* Remove the define line so it is not processed again. */
-	size_t new_length = *src_len - (end - begin);
-	size_t first_block_len = begin - src;
-	size_t second_block_len = (src + *src_len) - end;
+	size_t new_src_len = *src_len - (end - begin);
+	size_t first_block_len = begin - *src;
+	size_t second_block_len = (*src + *src_len) - end;
 
-	memmove(&src[first_block_len], end, second_block_len);
+	memmove(&(*src)[first_block_len], end, second_block_len);
 
-	src = realloc(src, sizeof(char) * new_length);
-	*src_len = new_length;
+	*src = realloc(*src, sizeof(char) * new_src_len);
+	*src_len = new_src_len;
 
 	return 1;
 }
 
 static int preprocess_pass(
-	char *src, int *src_len, struct tvm_htab_ctx *defines)
+	char **src, int *src_len, struct tvm_htab_ctx *defines)
 {
 	int ret = 0;
 
@@ -134,7 +130,7 @@ static int preprocess_pass(
 }
 
 
-int tvm_preprocess(char *src, int *src_len, struct tvm_htab_ctx *defines)
+int tvm_preprocess(char **src, int *src_len, struct tvm_htab_ctx *defines)
 {
 	int ret = 1;