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, 5 insertions, 5 deletions

diff --git a/ext/zip/zip_stream.c b/ext/zip/zip_stream.c
index f24a91ff85..bce62f5614 100644
--- a/ext/zip/zip_stream.c
+++ b/ext/zip/zip_stream.c
@@ -45,7 +45,7 @@ struct php_zip_stream_data_t {
 
 
 /* {{{ php_zip_ops_read */
-static size_t php_zip_ops_read(php_stream *stream, char *buf, size_t count)
+static ssize_t php_zip_ops_read(php_stream *stream, char *buf, size_t count)
 {
 	ssize_t n = 0;
 	STREAM_DATA_FROM_STREAM();
@@ -65,7 +65,7 @@ static size_t php_zip_ops_read(php_stream *stream, char *buf, size_t count)
 			php_error_docref(NULL, E_WARNING, "Zip stream error: %s", zip_error_strerror(err));
 			zip_error_fini(err);
 #endif
-			return 0;
+			return -1;
 		}
 		/* cast count to signed value to avoid possibly negative n
 		 * being cast to unsigned value */
@@ -75,15 +75,15 @@ static size_t php_zip_ops_read(php_stream *stream, char *buf, size_t count)
 			self->cursor += n;
 		}
 	}
-	return (n < 1 ? 0 : (size_t)n);
+	return n;
 }
 /* }}} */
 
 /* {{{ php_zip_ops_write */
-static size_t php_zip_ops_write(php_stream *stream, const char *buf, size_t count)
+static ssize_t php_zip_ops_write(php_stream *stream, const char *buf, size_t count)
 {
 	if (!stream) {
-		return 0;
+		return -1;
 	}
 
 	return count;