diff options
| -rw-r--r-- | ChangeLog | 3 | ||||
| -rw-r--r-- | generic/tclStringObj.c | 95 |
2 files changed, 54 insertions, 44 deletions
@@ -6,6 +6,9 @@ 2009-02-17 Don Porter <dgp@users.sourceforge.net> + * generic/tclStringObj.c: Factor out common GrowUnicodeBuffer() + and solve overflow and growth algorithm fallbacks in it. + * generic/tclStringObj.c: Factor out common GrowStringBuffer(). * generic/tclStringObj.c: Convert Tcl_AppendStringsToObj into diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c index ad8ec05..d79a565 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 1.111 2009/02/17 17:17:32 dgp Exp $ */ + * RCS: @(#) $Id: tclStringObj.c,v 1.112 2009/02/17 21:05:41 dgp Exp $ */ #include "tclInt.h" #include "tommath.h" @@ -62,6 +62,7 @@ static void ExtendUnicodeRepWithString(Tcl_Obj *objPtr, static void FillUnicodeRep(Tcl_Obj *objPtr); static void FreeStringInternalRep(Tcl_Obj *objPtr); static void GrowStringBuffer(Tcl_Obj *objPtr, int needed, int flag); +static void GrowUnicodeBuffer(Tcl_Obj *objPtr, int needed); static int SetStringFromAny(Tcl_Interp *interp, Tcl_Obj *objPtr); static void SetUnicodeObj(Tcl_Obj *objPtr, const Tcl_UniChar *unicode, int numChars); @@ -227,6 +228,47 @@ GrowStringBuffer( } } } + +static void +GrowUnicodeBuffer( + Tcl_Obj *objPtr, + int needed) +{ + /* Pre-conditions: + * objPtr->typePtr == &tclStringType + * needed > stringPtr->maxChars + */ + String *ptr = NULL, *stringPtr = GET_STRING(objPtr); + int attempt; + + if (stringPtr->maxChars > 0) { + /* Subsequent appends - apply the growth algorithm. */ + attempt = 2 * needed; + if (attempt >= 0) { + ptr = stringAttemptRealloc(stringPtr, STRING_UALLOC(attempt)); + } + if (ptr == NULL) { + /* + * Take care computing the amount of modest growth to avoid + * overflow into invalid argument values for attempt. + */ + unsigned int limit = INT_MAX - needed; + unsigned int extra = needed - stringPtr->numChars + + TCL_GROWTH_MIN_ALLOC; + int growth = (int) ((extra > limit) ? limit : extra); + attempt = needed + growth; + ptr = stringAttemptRealloc(stringPtr, STRING_UALLOC(attempt)); + } + } + if (ptr == NULL) { + /* First allocation - just big enough; or last chance fallback. */ + attempt = needed; + ptr = stringRealloc(stringPtr, STRING_UALLOC(attempt)); + } + stringPtr = ptr; + stringPtr->maxChars = attempt; + SET_STRING(objPtr, stringPtr); +} /* *---------------------------------------------------------------------- @@ -1340,7 +1382,7 @@ AppendUnicodeToUnicodeRep( const Tcl_UniChar *unicode, /* String to append. */ int appendNumChars) /* Number of chars of "unicode" to append. */ { - String *stringPtr, *tmpString; + String *stringPtr; int numChars; if (appendNumChars < 0) { @@ -1366,7 +1408,7 @@ AppendUnicodeToUnicodeRep( Tcl_Panic("max length for a Tcl value (%d chars) exceeded", INT_MAX); } - if (numChars >= stringPtr->maxChars) { + if (numChars > stringPtr->maxChars) { /* * Protect against case where unicode points into the existing * stringPtr->unicode array. Force it to follow any relocations @@ -1378,17 +1420,8 @@ AppendUnicodeToUnicodeRep( offset = unicode - stringPtr->unicode; } - /* TODO: overflow check */ - stringPtr->maxChars = 2 * numChars; - tmpString = stringAttemptRealloc(stringPtr, - STRING_UALLOC(2 * numChars)); - if (tmpString == NULL) { - stringPtr->maxChars = numChars + appendNumChars - + TCL_GROWTH_MIN_ALLOC/sizeof(Tcl_UniChar); - tmpString = stringRealloc(stringPtr, STRING_UALLOC(stringPtr->maxChars)); - } - stringPtr = tmpString; - SET_STRING(objPtr, stringPtr); + GrowUnicodeBuffer(objPtr, numChars); + stringPtr = GET_STRING(objPtr); /* Relocate unicode if needed; see above. */ if (offset >= 0) { @@ -2630,30 +2663,8 @@ ExtendUnicodeRepWithString( } if (needed > stringPtr->maxChars) { - /* - * 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. - */ - int growChars = needed; - - if (stringPtr->maxChars > 0) { - if (growChars <= INT_MAX/2) { - growChars *= 2; - } else { - growChars = INT_MAX; - } - } - /* TODO: proper fallback */ - stringPtr = stringRealloc(stringPtr, STRING_UALLOC(growChars)); - stringPtr->maxChars = growChars; - - SET_STRING(objPtr, stringPtr); + GrowUnicodeBuffer(objPtr, needed); + stringPtr = GET_STRING(objPtr); } stringPtr->hasUnicode = 1; @@ -2826,14 +2837,10 @@ ExtendStringRepWithUnicode( return 0; } - if (objPtr->bytes == tclEmptyStringRep) { - objPtr->bytes = NULL; - } else if (objPtr->bytes) { - size = objPtr->length; - } else { + if (objPtr->bytes == NULL) { objPtr->length = 0; } - origLength = objPtr->length; + size = origLength = objPtr->length; /* Quick cheap check in case we have more than enough room. */ if (numChars <= (INT_MAX - size)/TCL_UTF_MAX |