shithub: rgbds

Info  •  Files  •  Log  •  Branches

Implement a malloc-based readasciiz()

Instead of reading into a pre-sized buffer, this function now uses malloc to create a buffer, and resizes it if necessary.

This reduces the risk of memory issues if a long string (< 255 chars) was encountered.

--- a/src/link/object.c

+++ b/src/link/object.c

@@ -46,21 +46,41 @@

 	return (r);

 }

+

 /*

  * Read a NULL terminated string from a file

  *

  */

-

-SLONG 

-readasciiz(char *s, FILE * f)

+SLONG

+readasciiz(char **dest, FILE *f)

 {

 	SLONG r = 0;

-

-	while (((*s++) = fgetc(f)) != 0)

+	

+	size_t bufferLength = 16;

+	char *start = malloc(bufferLength);

+	char *s = start;

+	

+	if (!s) {

+		err(1, NULL);

+	}

+		

+	while (((*s++) = fgetc(f)) != 0) {

 		r += 1;

-

+		

+		if (r >= bufferLength) {

+			bufferLength *= 2;

+			start = realloc(start, bufferLength);

+			if (!start) {

+				err(1, NULL);

+			}

+			s = start + r;

+		}

+	}

+	

+	*dest = start;

 	return (r + 1);

 }

+

 /*

  * Allocate a new section and link it into the list

  *

@@ -97,7 +117,6 @@

 struct sSymbol *

 obj_ReadSymbol(FILE * f)

 {

-	char s[256];

 	struct sSymbol *pSym;

 	pSym = malloc(sizeof *pSym);

@@ -105,13 +124,7 @@

 		err(1, NULL);

 	}

-	readasciiz(s, f);

-	pSym->pzName = malloc(strlen(s) + 1);

-	if (!pSym->pzName) {

-		err(1, NULL);

-	}

-

-	strcpy(pSym->pzName, s);

+	readasciiz(&pSym->pzName, f);

 	if ((pSym->Type = (enum eSymbolType) fgetc(f)) != SYM_IMPORT) {

 		pSym->nSectionID = readlong(f);

 		pSym->nOffset = readlong(f);

@@ -153,7 +166,6 @@

 			SLONG nNumberOfPatches;

 			struct sPatch **ppPatch, *pPatch;

-			char s[256];

 			fread(pSection->pData, sizeof(UBYTE),

 			    pSection->nByteSize, f);

@@ -171,15 +183,8 @@

 				}

 				*ppPatch = pPatch;

-				readasciiz(s, f);

+				readasciiz(&pPatch->pzFilename, f);

-				pPatch->pzFilename = malloc(strlen(s) + 1);

-				if (!pPatch->pzFilename) {

-					err(1, NULL);

-				}

-

-				strcpy(pPatch->pzFilename, s);

-

 				pPatch->nLineNo =

 				    readlong(f);

 				pPatch->nOffset =

@@ -306,7 +311,6 @@

 			SLONG nNumberOfPatches;

 			struct sPatch **ppPatch, *pPatch;

-			char s[256];

 			fread(pSection->pData, sizeof(UBYTE),

 			    pSection->nByteSize, f);

@@ -324,13 +328,7 @@

 				}

 				*ppPatch = pPatch;

-				readasciiz(s, f);

-				pPatch->pzFilename = malloc(strlen(s) + 1);

-				if (!pPatch->pzFilename) {

-					err(1, NULL);

-				}

-

-				strcpy(pPatch->pzFilename, s);

+				readasciiz(&pPatch->pzFilename, f);

 				pPatch->nLineNo = readlong(f);

 				pPatch->nOffset = readlong(f);

 				pPatch->Type = (enum ePatchType) fgetc(f);

@@ -482,9 +480,9 @@

 	size = file_Length(f) - 4;

 	while (size) {

-		char name[256];

+		char *name;

-		size -= readasciiz(name, f);

+		size -= readasciiz(&name, f);

 		readword(f);

 		size -= 2;

 		readword(f);

@@ -492,5 +490,6 @@

 		size -= readlong(f);

 		size -= 4;

 		obj_ReadOpenFile(f, name);

+		free(name);

 	}

 }