Report errors from stream read and write operations

The php_stream_read() and php_stream_write() functions now return
an ssize_t value, with negative results indicating failure. Functions
like fread() and fwrite() will return false in that case.

As a special case, EWOULDBLOCK and EAGAIN on non-blocking streams
should not be regarded as error conditions, and be reported as
successful zero-length reads/writes instead. The handling of EINTR
remains unclear and is internally inconsistent (e.g. some code-paths
will automatically retry on EINTR, while some won't).

I'm landing this now to make sure the stream wrapper ops API changes
make it into 7.4 -- however, if the user-facing changes turn out to
be problematic we have the option of clamping negative returns to
zero in php_stream_read() and php_stream_write() to restore the
old behavior in a relatively non-intrusive manner.

1 files changed, 18 insertions, 11 deletions

diff --git a/main/streams/userspace.c b/main/streams/userspace.c
index bdd9b1b48e..de3e8591e6 100644
--- a/main/streams/userspace.c
+++ b/main/streams/userspace.c
@@ -588,14 +588,14 @@ PHP_FUNCTION(stream_wrapper_restore)
 }
 /* }}} */
 
-static size_t php_userstreamop_write(php_stream *stream, const char *buf, size_t count)
+static ssize_t php_userstreamop_write(php_stream *stream, const char *buf, size_t count)
 {
 	zval func_name;
 	zval retval;
 	int call_result;
 	php_userstream_data_t *us = (php_userstream_data_t *)stream->abstract;
 	zval args[1];
-	size_t didwrite = 0;
+	ssize_t didwrite;
 
 	assert(us != NULL);
 
@@ -612,18 +612,21 @@ static size_t php_userstreamop_write(php_stream *stream, const char *buf, size_t
 	zval_ptr_dtor(&args[0]);
 	zval_ptr_dtor(&func_name);
 
-	didwrite = 0;
-
 	if (EG(exception)) {
-		return 0;
+		return -1;
 	}
 
 	if (call_result == SUCCESS && Z_TYPE(retval) != IS_UNDEF) {
-		convert_to_long(&retval);
-		didwrite = Z_LVAL(retval);
-	} else if (call_result == FAILURE) {
+		if (Z_TYPE(retval) == IS_FALSE) {
+			didwrite = -1;
+		} else {
+			convert_to_long(&retval);
+			didwrite = Z_LVAL(retval);
+		}
+	} else {
 		php_error_docref(NULL, E_WARNING, "%s::" USERSTREAM_WRITE " is not implemented!",
 				us->wrapper->classname);
+		didwrite = -1;
 	}
 
 	/* don't allow strange buffer overruns due to bogus return */
@@ -639,7 +642,7 @@ static size_t php_userstreamop_write(php_stream *stream, const char *buf, size_t
 	return didwrite;
 }
 
-static size_t php_userstreamop_read(php_stream *stream, char *buf, size_t count)
+static ssize_t php_userstreamop_read(php_stream *stream, char *buf, size_t count)
 {
 	zval func_name;
 	zval retval;
@@ -669,6 +672,10 @@ static size_t php_userstreamop_read(php_stream *stream, char *buf, size_t count)
 	}
 
 	if (call_result == SUCCESS && Z_TYPE(retval) != IS_UNDEF) {
+		if (Z_TYPE(retval) == IS_FALSE) {
+			return -1;
+		}
+
 		if (!try_convert_to_string(&retval)) {
 			return -1;
 		}
@@ -1401,7 +1408,7 @@ static int user_wrapper_stat_url(php_stream_wrapper *wrapper, const char *url, i
 
 }
 
-static size_t php_userstreamop_readdir(php_stream *stream, char *buf, size_t count)
+static ssize_t php_userstreamop_readdir(php_stream *stream, char *buf, size_t count)
 {
 	zval func_name;
 	zval retval;
@@ -1412,7 +1419,7 @@ static size_t php_userstreamop_readdir(php_stream *stream, char *buf, size_t cou
 
 	/* avoid problems if someone mis-uses the stream */
 	if (count != sizeof(php_stream_dirent))
-		return 0;
+		return -1;
 
 	ZVAL_STRINGL(&func_name, USERSTREAM_DIR_READ, sizeof(USERSTREAM_DIR_READ)-1);