Backport of bytearray append machinery to support bug fixes in ReadBytes.

3 files changed, 98 insertions, 13 deletions

diff --git a/generic/tclBinary.c b/generic/tclBinary.c
index dbb296b..68289f2 100644
--- a/generic/tclBinary.c
+++ b/generic/tclBinary.c
@@ -549,6 +549,98 @@ UpdateStringOfByteArray(
 /*
  *----------------------------------------------------------------------
  *
+ * TclAppendBytesToByteArray --
+ *
+ *	This function appends an array of bytes to a byte array object. Note
+ *	that the object *must* be unshared, and the array of bytes *must not*
+ *	refer to the object being appended to.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Allocates enough memory for an array of bytes of the requested total
+ *	size, or possibly larger. [Bug 2992970]
+ *
+ *----------------------------------------------------------------------
+ */
+
+#define TCL_MIN_GROWTH 1024
+void
+TclAppendBytesToByteArray(
+    Tcl_Obj *objPtr,
+    const unsigned char *bytes,
+    int len)
+{
+    ByteArray *byteArrayPtr;
+    int needed;
+
+    if (Tcl_IsShared(objPtr)) {
+	Tcl_Panic("%s called with shared object","TclAppendBytesToByteArray");
+    }
+    if (len < 0) {
+	Tcl_Panic("%s must be called with definite number of bytes to append",
+		"TclAppendBytesToByteArray");
+    }
+    if (len == 0) {
+	/* Append zero bytes is a no-op. */
+	return;
+    }
+    if (objPtr->typePtr != &tclByteArrayType) {
+	SetByteArrayFromAny(NULL, objPtr);
+    }
+    byteArrayPtr = GET_BYTEARRAY(objPtr);
+
+    if (len > INT_MAX - byteArrayPtr->used) {
+	Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
+    }
+
+    needed = byteArrayPtr->used + len;
+    /*
+     * If we need to, resize the allocated space in the byte array.
+     */
+
+    if (needed > byteArrayPtr->allocated) {
+	ByteArray *ptr = NULL;
+	int attempt;
+
+	if (needed <= INT_MAX/2) {
+	    /* Try to allocate double the total space that is needed. */
+	    attempt = 2 * needed;
+	    ptr = (ByteArray *) attemptckrealloc((void *) byteArrayPtr,
+		    BYTEARRAY_SIZE(attempt));
+	}
+	if (ptr == NULL) {
+	    /* Try to allocate double the increment that is needed (plus). */
+	    unsigned int limit = INT_MAX - needed;
+	    unsigned int extra = len + TCL_MIN_GROWTH;
+	    int growth = (int) ((extra > limit) ? limit : extra);
+
+	    attempt = needed + growth;
+	    ptr = (ByteArray *) attemptckrealloc((void *) byteArrayPtr,
+		    BYTEARRAY_SIZE(attempt));
+	}
+	if (ptr == NULL) {
+	    /* Last chance: Try to allocate exactly what is needed. */
+	    attempt = needed;
+	    ptr = (ByteArray *) ckrealloc((void *)byteArrayPtr,
+		    BYTEARRAY_SIZE(attempt));
+	}
+	byteArrayPtr = ptr;
+	byteArrayPtr->allocated = attempt;
+	SET_BYTEARRAY(objPtr, byteArrayPtr);
+    }
+
+    if (bytes) {
+	memcpy(byteArrayPtr->bytes + byteArrayPtr->used, bytes, len);
+    }
+    byteArrayPtr->used += len;
+    TclInvalidateStringRep(objPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * Tcl_BinaryObjCmd --
  *
  *	This procedure implements the "binary" Tcl command.
diff --git a/generic/tclIO.c b/generic/tclIO.c
index f1d8909..c1b7ee9 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -5586,20 +5586,8 @@ ReadBytes(
 	toRead = srcLen;
     }
 
+    TclAppendBytesToByteArray(objPtr, NULL, toRead);
     dst = (char *) Tcl_GetByteArrayFromObj(objPtr, &length);
-    if (toRead > length - offset - 1) {
-	/*
-	 * Double the existing size of the object or make enough room to hold
-	 * all the characters we may get from the source buffer, whichever is
-	 * larger.
-	 */
-
-	length = offset * 2;
-	if (offset < toRead) {
-	    length = offset + toRead + 1;
-	}
-	dst = (char *) Tcl_SetByteArrayLength(objPtr, length);
-    }
     dst += offset;
 
     if (statePtr->flags & INPUT_NEED_NL) {
@@ -5607,6 +5595,7 @@ ReadBytes(
 	if ((srcLen == 0) || (*src != '\n')) {
 	    *dst = '\r';
 	    *offsetPtr += 1;
+	    Tcl_SetByteArrayLength(objPtr, *offsetPtr);
 	    return 1;
 	}
 	*dst++ = '\n';
@@ -5619,11 +5608,13 @@ ReadBytes(
     dstWrote = toRead;
     if (TranslateInputEOL(statePtr, dst, src, &dstWrote, &srcRead) != 0) {
 	if (dstWrote == 0) {
+	    Tcl_SetByteArrayLength(objPtr, *offsetPtr);
 	    return -1;
 	}
     }
     bufPtr->nextRemoved += srcRead;
     *offsetPtr += dstWrote;
+    Tcl_SetByteArrayLength(objPtr, *offsetPtr);
     return dstWrote;
 }
 
diff --git a/generic/tclInt.h b/generic/tclInt.h
index dc28b97..64d39a0 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -2477,6 +2477,8 @@ MODULE_SCOPE char	tclEmptyString;
  *----------------------------------------------------------------
  */
 
+MODULE_SCOPE void	TclAppendBytesToByteArray(Tcl_Obj *objPtr,
+			    const unsigned char *bytes, int len);
 MODULE_SCOPE void       TclAdvanceContinuations(int* line, int** next, int loc);
 MODULE_SCOPE void       TclAdvanceLines(int *line, const char *start,
 			    const char *end);