Fix use of XMaxTransChars in stead of TCL_UTF_MAX in some places. This should prevent possible buffer overflow when TCL_UTF_MAX=6

Micro-optimizations in tkEntry and ttkEntry

3 files changed, 7 insertions, 5 deletions

diff --git a/generic/tkEntry.c b/generic/tkEntry.c
index 5681e47..a66cf18 100644
--- a/generic/tkEntry.c
+++ b/generic/tkEntry.c
@@ -1927,7 +1927,7 @@ EntryComputeGeometry(
 
     if (entryPtr->showChar != NULL) {
 	Tcl_UniChar ch;
-	char buf[TCL_UTF_MAX];
+	char buf[4];
 	int size;
 
 	/*
@@ -1945,7 +1945,8 @@ EntryComputeGeometry(
 	entryPtr->displayString = p;
 
 	for (i = entryPtr->numChars; --i >= 0; ) {
-	    p += Tcl_UniCharToUtf(ch, p);
+	    memcpy(p, buf, size);
+	    p += size;
 	}
 	*p = '\0';
     }
diff --git a/generic/tkSelect.c b/generic/tkSelect.c
index ab9018a..74b3964 100644
--- a/generic/tkSelect.c
+++ b/generic/tkSelect.c
@@ -26,7 +26,7 @@ typedef struct {
     int charOffset;		/* The offset of the next char to retrieve. */
     int byteOffset;		/* The expected byte offset of the next
 				 * chunk. */
-    char buffer[TCL_UTF_MAX];	/* A buffer to hold part of a UTF character
+    char buffer[4];		/* A buffer to hold part of a UTF character
 				 * that is split across chunks. */
     char command[1];		/* Command to invoke. Actual space is
 				 * allocated as large as necessary. This must
diff --git a/generic/ttk/ttkEntry.c b/generic/ttk/ttkEntry.c
index f395649..d80e1fd 100644
--- a/generic/ttk/ttkEntry.c
+++ b/generic/ttk/ttkEntry.c
@@ -283,14 +283,15 @@ static char *EntryDisplayString(const char *showChar, int numChars)
     char *displayString, *p;
     int size;
     Tcl_UniChar ch;
-    char buf[TCL_UTF_MAX];
+    char buf[4];
 
     Tcl_UtfToUniChar(showChar, &ch);
     size = Tcl_UniCharToUtf(ch, buf);
     p = displayString = ckalloc(numChars * size + 1);
 
     while (numChars--) {
-	p += Tcl_UniCharToUtf(ch, p);
+	memcpy(p, buf, size);
+	p += size;
     }
     *p = '\0';