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, 4 insertions, 7 deletions

diff --git a/ext/zlib/zlib_fopen_wrapper.c b/ext/zlib/zlib_fopen_wrapper.c
index d600f09a65..514773f2b0 100644
--- a/ext/zlib/zlib_fopen_wrapper.c
+++ b/ext/zlib/zlib_fopen_wrapper.c
@@ -30,7 +30,7 @@ struct php_gz_stream_data_t	{
 	php_stream *stream;
 };
 
-static size_t php_gziop_read(php_stream *stream, char *buf, size_t count)
+static ssize_t php_gziop_read(php_stream *stream, char *buf, size_t count)
 {
 	struct php_gz_stream_data_t *self = (struct php_gz_stream_data_t *) stream->abstract;
 	int read;
@@ -42,18 +42,15 @@ static size_t php_gziop_read(php_stream *stream, char *buf, size_t count)
 		stream->eof = 1;
 	}
 
-	return (size_t)((read < 0) ? 0 : read);
+	return read;
 }
 
-static size_t php_gziop_write(php_stream *stream, const char *buf, size_t count)
+static ssize_t php_gziop_write(php_stream *stream, const char *buf, size_t count)
 {
 	struct php_gz_stream_data_t *self = (struct php_gz_stream_data_t *) stream->abstract;
-	int wrote;
 
 	/* XXX this needs to be looped for the case count > UINT_MAX */
-	wrote = gzwrite(self->gz_file, (char *) buf, count);
-
-	return (size_t)((wrote < 0) ? 0 : wrote);
+	return gzwrite(self->gz_file, (char *) buf, count);
 }
 
 static int php_gziop_seek(php_stream *stream, zend_off_t offset, int whence, zend_off_t *newoffs)