This makes file_put_contents() work for:

<?php
    declare(encoding="latin1");
    $a = "1234å67890";
    file_put_contents( "/tmp/testuc.1", $a);
    file_put_contents( "/tmp/testuc.2", (string) $a);

    $context = stream_context_create();
    stream_context_set_params($context, array( "output_encoding" => "latin1" ) );
    file_put_contents( "/tmp/testuc.3", $a, FILE_TEXT, $context);
    file_put_contents( "/tmp/testuc.4", (string) $a, FILE_TEXT, $context);
?>

But it still throws a warning on ".3". It's a small design issue that I
didn't want to touch right now.

Author: Derick Rethans

ext/standard/file.c

@@ -662,7 +662,7 @@ PHP_FUNCTION(file_put_contents)
 				if (numchars < 0) {
 					php_error_docref(NULL TSRMLS_CC, E_WARNING, "Failed to write %d characters to %s", ustrlen, filename);
 					numchars = -1;
-				} else if (numchars != UBYTES(Z_USTRLEN_P(data))) {
+				} else if (numchars != ustrlen) {
 					int numchars = u_countChar32(Z_USTRVAL_P(data), numchars);
 
 					php_error_docref(NULL TSRMLS_CC, E_WARNING, "Only %d of %d characters written, possibly out of free disk space", numchars, ustrlen);

main/streams/streams.c

@@ -1140,7 +1140,7 @@ static size_t _php_stream_write_buffer(php_stream *stream, int buf_type, zstr bu
 		stream->ops->seek(stream, stream->position, SEEK_SET, &stream->position TSRMLS_CC);
 	}
 
-	if (stream->output_encoding) {
+	if (stream->output_encoding && buf_type == IS_UNICODE) {
 		char *dest;
 		int destlen;
 		UErrorCode status = U_ZERO_ERROR;
@@ -1150,7 +1150,9 @@ static size_t _php_stream_write_buffer(php_stream *stream, int buf_type, zstr bu
 		buflen = destlen;
 	} else {
 		/* Sloppy handling, make it a binary buffer */
-		buflen = UBYTES(buflen);
+		if (buf_type != IS_STRING) {
+			buflen = UBYTES(buflen);
+		}
 	}
 
 	while (buflen > 0) {