* generic/tclStringObj.c: Completed backports of fixes for

        [Bug 2494093] and [Bug 2553906].

2 files changed, 118 insertions, 66 deletions

diff --git a/ChangeLog b/ChangeLog
index f5360e2..a31480e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2009-04-07  Don Porter  <dgp@users.sourceforge.net>
+
+	* generic/tclStringObj.c:       Completed backports of fixes for
+	[Bug 2494093] and [Bug 2553906].
+
 2009-03-30  Don Porter  <dgp@users.sourceforge.net>
 
 	* doc/Alloc.3:	Size argument is "unsigned int".  [Bug 2556263]
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index 6490bc6..14f3bac 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -33,7 +33,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclStringObj.c,v 1.32.2.8 2009/03/30 17:47:09 dgp Exp $ */
+ * RCS: @(#) $Id: tclStringObj.c,v 1.32.2.9 2009/04/07 18:37:42 dgp Exp $ */
 
 #include "tclInt.h"
 
@@ -51,16 +51,17 @@ static void		AppendUtfToUnicodeRep _ANSI_ARGS_((Tcl_Obj *objPtr,
     			    CONST char *bytes, int numBytes));
 static void		AppendUtfToUtfRep _ANSI_ARGS_((Tcl_Obj *objPtr,
     			    CONST char *bytes, int numBytes));
-
-static void		FillUnicodeRep _ANSI_ARGS_((Tcl_Obj *objPtr));
-
-static void		FreeStringInternalRep _ANSI_ARGS_((Tcl_Obj *objPtr));
 static void		DupStringInternalRep _ANSI_ARGS_((Tcl_Obj *objPtr,
 			    Tcl_Obj *copyPtr));
+static void		FillUnicodeRep _ANSI_ARGS_((Tcl_Obj *objPtr));
+static void		FreeStringInternalRep _ANSI_ARGS_((Tcl_Obj *objPtr));
+static void		GrowUnicodeBuffer _ANSI_ARGS_((Tcl_Obj *objPtr,
+			    int needed));
 static int		SetStringFromAny _ANSI_ARGS_((Tcl_Interp *interp,
 			    Tcl_Obj *objPtr));
 static void		SetUnicodeObj(Tcl_Obj *objPtr,
 			    CONST Tcl_UniChar *unicode, int numChars);
+static int		UnicodeLength _ANSI_ARGS_((CONST Tcl_UniChar *unicode));
 static void		UpdateStringOfString _ANSI_ARGS_((Tcl_Obj *objPtr));
 
 /*
@@ -105,15 +106,25 @@ typedef struct String {
 				 * 'uallocated' field above. */
 } String;
 
+#define STRING_MAXCHARS \
+	(1 + (int)(((size_t)UINT_MAX - sizeof(String))/sizeof(Tcl_UniChar)))
 #define STRING_UALLOC(numChars)	\
-		((numChars) * sizeof(Tcl_UniChar))
+	((numChars) * sizeof(Tcl_UniChar))
 #define STRING_SIZE(ualloc) \
     ((unsigned) ((ualloc) \
-	? ((sizeof(String) - sizeof(Tcl_UniChar) + (ualloc) > INT_MAX) \
-	    ? Tcl_Panic("unable to alloc %u bytes", \
-	       sizeof(String) - sizeof(Tcl_UniChar) + (ualloc)), INT_MAX \
-	    : (sizeof(String) - sizeof(Tcl_UniChar) + (ualloc))) \
+	? (sizeof(String) - sizeof(Tcl_UniChar) + (ualloc)) \
 	: sizeof(String)))
+#define stringCheckLimits(numChars) \
+    if ((numChars) < 0 || (numChars) > STRING_MAXCHARS) { \
+	Tcl_Panic("max length for a Tcl unicode value (%d chars) exceeded", \
+		STRING_MAXCHARS); \
+    }
+#define stringRealloc(ptr, numChars) \
+	(String *) ckrealloc((char *) ptr, \
+		(unsigned) STRING_SIZE(STRING_UALLOC(numChars)) )
+#define stringAttemptRealloc(ptr, numChars) \
+	(String *) attemptckrealloc((char *) ptr, \
+		(unsigned) STRING_SIZE(STRING_UALLOC(numChars)) )
 #define GET_STRING(objPtr) \
 		((String *) (objPtr)->internalRep.otherValuePtr)
 #define SET_STRING(objPtr, stringPtr) \
@@ -157,6 +168,48 @@ typedef struct String {
 #define TCL_GROWTH_MIN_ALLOC	1024
 #endif
 
+static void
+GrowUnicodeBuffer(
+    Tcl_Obj *objPtr,
+    int needed)
+{
+    /* Pre-conditions:
+     *  objPtr->typePtr == &tclStringType
+     *  STRING_UALLOC(needed) > stringPtr->uallocated
+     *  needed < STRING_MAXCHARS
+     */
+    String *ptr = NULL, *stringPtr = GET_STRING(objPtr);
+    int attempt;
+
+    if (stringPtr->uallocated > 0) {
+	/* Subsequent appends - apply the growth algorithm. */
+	attempt = 2 * needed;
+	if (attempt >= 0 && attempt <= STRING_MAXCHARS) {
+	    ptr = stringAttemptRealloc(stringPtr, attempt);
+	}
+	if (ptr == NULL) {
+	    /*
+	     * Take care computing the amount of modest growth to avoid
+	     * overflow into invalid argument values for attempt.
+	     */
+	    unsigned int limit = STRING_MAXCHARS - needed;
+	    unsigned int extra = needed - stringPtr->numChars
+		    + TCL_GROWTH_MIN_ALLOC/sizeof(Tcl_UniChar);
+	    int growth = (int) ((extra > limit) ? limit : extra);
+	    attempt = needed + growth;
+	    ptr = stringAttemptRealloc(stringPtr, attempt);
+	}
+    }
+    if (ptr == NULL) {
+	/* First allocation - just big enough; or last chance fallback. */
+	attempt = needed;
+	ptr = stringRealloc(stringPtr, attempt);
+    }
+    stringPtr = ptr;
+    stringPtr->uallocated = STRING_UALLOC(attempt);
+    SET_STRING(objPtr, stringPtr);
+}
+
 
 /*
  *----------------------------------------------------------------------
@@ -797,9 +850,10 @@ Tcl_SetObjLength(objPtr, length)
     } else {
         /* Changing length of pure unicode string */
         size_t uallocated = STRING_UALLOC(length);
+
+	stringCheckLimits(length);
         if (uallocated > stringPtr->uallocated) {
-            stringPtr = (String *) ckrealloc((char*) stringPtr,
-                    STRING_SIZE(uallocated));
+	    stringPtr = stringRealloc(stringPtr, length);
             SET_STRING(objPtr, stringPtr);
             stringPtr->uallocated = uallocated;
         }
@@ -905,9 +959,12 @@ Tcl_AttemptSetObjLength(objPtr, length)
     } else {
 	/* Changing length of pure unicode string */
 	size_t uallocated = STRING_UALLOC(length);
+	if (length > STRING_MAXCHARS) {
+	    return 0;
+	}
+
 	if (uallocated > stringPtr->uallocated) {
-	    stringPtr = (String *) attemptckrealloc((char*) stringPtr,
-		    STRING_SIZE(uallocated));
+	    stringPtr = stringAttemptRealloc(stringPtr, length);
 	    if (stringPtr == NULL) {
 	        return 0;
 	    }
@@ -959,6 +1016,21 @@ Tcl_SetUnicodeObj(objPtr, unicode, numChars)
     SetUnicodeObj(objPtr, unicode, numChars);
 }
 
+static int
+UnicodeLength(
+    const Tcl_UniChar *unicode)
+{
+    int numChars = 0;
+
+    if (unicode) {
+	while (numChars >= 0 && unicode[numChars] != 0) {
+	    numChars++;
+	}
+    }
+    stringCheckLimits(numChars);
+    return numChars;
+}
+
 static void
 SetUnicodeObj(objPtr, unicode, numChars)
     Tcl_Obj *objPtr;		/* The object to set the string of. */
@@ -971,16 +1043,14 @@ SetUnicodeObj(objPtr, unicode, numChars)
     size_t uallocated;
 
     if (numChars < 0) {
-	numChars = 0;
-	if (unicode) {
-	    while (unicode[numChars] != 0) { numChars++; }
-	}
+	numChars = UnicodeLength(unicode);
     }
 
     /*
      * Allocate enough space for the String structure + Unicode string.
      */
 	
+    stringCheckLimits(numChars);
     uallocated = STRING_UALLOC(numChars);
     stringPtr = (String *) ckalloc(STRING_SIZE(uallocated));
 
@@ -1215,14 +1285,11 @@ AppendUnicodeToUnicodeRep(objPtr, unicode, appendNumChars)
     CONST Tcl_UniChar *unicode; /* String to append. */
     int appendNumChars;	        /* Number of chars of "unicode" to append. */
 {
-    String *stringPtr, *tmpString;
+    String *stringPtr;
     size_t numChars;
 
     if (appendNumChars < 0) {
-	appendNumChars = 0;
-	if (unicode) {
-	    while (unicode[appendNumChars] != 0) { appendNumChars++; }
-	}
+	appendNumChars = UnicodeLength(unicode);
     }
     if (appendNumChars == 0) {
 	return;
@@ -1240,6 +1307,7 @@ AppendUnicodeToUnicodeRep(objPtr, unicode, appendNumChars)
      */
 
     numChars = stringPtr->numChars + appendNumChars;
+    stringCheckLimits(numChars);
 
     if (STRING_UALLOC(numChars) >= stringPtr->uallocated) {
 	/*
@@ -1253,18 +1321,8 @@ AppendUnicodeToUnicodeRep(objPtr, unicode, appendNumChars)
 	    offset = unicode - stringPtr->unicode;
 	}
 
-     	stringPtr->uallocated = STRING_UALLOC(2 * numChars);
-	tmpString = (String *) attemptckrealloc((char *)stringPtr,
-		STRING_SIZE(stringPtr->uallocated));
-	if (tmpString == NULL) {
-	    stringPtr->uallocated =
-	        STRING_UALLOC(numChars + appendNumChars) 
-		+ TCL_GROWTH_MIN_ALLOC;
-	    tmpString = (String *) ckrealloc((char *)stringPtr,
-		    STRING_SIZE(stringPtr->uallocated));
-	}
-	stringPtr = tmpString;
-	SET_STRING(objPtr, stringPtr);
+	GrowUnicodeBuffer(objPtr, numChars);
+	stringPtr = GET_STRING(objPtr);
 
 	/* Relocate unicode if needed; see above. */
 	if (offset >= 0) {
@@ -1312,10 +1370,7 @@ AppendUnicodeToUtfRep(objPtr, unicode, numChars)
     CONST char *bytes;
     
     if (numChars < 0) {
-	numChars = 0;
-	if (unicode) {
-	    while (unicode[numChars] != 0) { numChars++; }
-	}
+	numChars = UnicodeLength(unicode);
     }
     if (numChars == 0) {
 	return;
@@ -1408,10 +1463,10 @@ AppendUtfToUtfRep(objPtr, bytes, numBytes)
      */
 
     oldLength = objPtr->length;
-    if (numBytes > INT_MAX - oldLength) {
+    newLength = numBytes + oldLength;
+    if (newLength < 0) {
 	Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
     }
-    newLength = numBytes + oldLength;
 
     stringPtr = GET_STRING(objPtr);
     if (newLength > (int) stringPtr->allocated) {
@@ -1677,28 +1732,11 @@ FillUnicodeRep(objPtr)
     }
     stringPtr->hasUnicode = (stringPtr->numChars > 0);
 
+    stringCheckLimits(stringPtr->numChars);
     uallocated = STRING_UALLOC(stringPtr->numChars);
     if (uallocated > stringPtr->uallocated) {
-    
-	/*
-	 * If not enough space has been allocated for the unicode rep,
-	 * reallocate the internal rep object.
-	 */
-
-	/*
-	 * There isn't currently enough space in the Unicode
-	 * representation so allocate additional space.  If the current
-	 * Unicode representation isn't empty (i.e. it looks like we've
-	 * done some appends) then overallocate the space so
-	 * that we won't have to do as much reallocation in the future.
-	 */
-
-	if (stringPtr->uallocated > 0) {
-	    uallocated *= 2;
-	}
-	stringPtr = (String *) ckrealloc((char*) stringPtr,
-		STRING_SIZE(uallocated));
-	stringPtr->uallocated = uallocated;
+	GrowUnicodeBuffer(objPtr, stringPtr->numChars);
+	stringPtr = GET_STRING(objPtr);
     }
 
     /*
@@ -1750,8 +1788,8 @@ DupStringInternalRep(srcPtr, copyPtr)
      */
     
     if (srcStringPtr->hasUnicode == 0) {
-    	copyStringPtr = (String *) ckalloc(STRING_SIZE(STRING_UALLOC(0)));
-	copyStringPtr->uallocated = STRING_UALLOC(0);
+    	copyStringPtr = (String *) ckalloc(sizeof(String));
+	copyStringPtr->uallocated = 0;
     } else {
 	copyStringPtr = (String *) ckalloc(
 	    STRING_SIZE(srcStringPtr->uallocated));
@@ -1823,9 +1861,9 @@ SetStringFromAny(interp, objPtr)
 	 * Allocate enough space for the basic String structure.
 	 */
 
-	stringPtr = (String *) ckalloc(STRING_SIZE(STRING_UALLOC(0)));
+	stringPtr = (String *) ckalloc(sizeof(String));
 	stringPtr->numChars = -1;
-	stringPtr->uallocated = STRING_UALLOC(0);
+	stringPtr->uallocated = 0;
 	stringPtr->hasUnicode = 0;
 
 	if (objPtr->bytes != NULL) {
@@ -1889,17 +1927,26 @@ UpdateStringOfString(objPtr)
 	 * amount of space the UTF string needs.
 	 */
 
+	if (stringPtr->numChars <= INT_MAX/TCL_UTF_MAX
+		&& stringPtr->allocated >= stringPtr->numChars * TCL_UTF_MAX) {
+	    goto copyBytes;
+	}
+
 	size = 0;
 	for (i = 0; i < stringPtr->numChars; i++) {
 	    size += Tcl_UniCharToUtf((int) unicode[i], dummy);
 	}
+	if (size < 0) {
+	    Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
+	}
 	
 	dst = (char *) ckalloc((unsigned) (size + 1));
 	objPtr->bytes = dst;
 	objPtr->length = size;
 	stringPtr->allocated = size;
 
-	for (i = 0; i < stringPtr->numChars; i++) {
+    copyBytes:
+	for (i = 0; i < stringPtr->numChars && size >= 0; i++) {
 	    dst += Tcl_UniCharToUtf(unicode[i], dst);
 	}
 	*dst = '\0';