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, 3 insertions, 2 deletions

diff --git a/ext/standard/exec.c b/ext/standard/exec.c
index b79eb37c04..da8b5712cf 100644
--- a/ext/standard/exec.c
+++ b/ext/standard/exec.c
@@ -178,8 +178,9 @@ PHPAPI int php_exec(int type, char *cmd, zval *array, zval *return_value)
 			RETVAL_EMPTY_STRING();
 		}
 	} else {
-		while((bufl = php_stream_read(stream, buf, EXEC_INPUT_BUF)) > 0) {
-			PHPWRITE(buf, bufl);
+		ssize_t read;
+		while ((read = php_stream_read(stream, buf, EXEC_INPUT_BUF)) > 0) {
+			PHPWRITE(buf, read);
 		}
 	}