[[ Bug 23055 ]] Reset EOF marker when seeking in a file on macOS

Ian Macphail · Ian Macphail · commit 5b7aec5d36ad · 2021-01-08T13:48:53.000Z
This patch fixes an issue where if a previous read from a filehandle has
resulted in an END-OF-FILE then subsequent reads would always fail with
EOF result even after seeking to another location within the file. This
is fixed by resetting the error state of the filehandle before seeking.
diff --git a/engine/src/dskmac.cpp b/engine/src/dskmac.cpp
@@ -1601,6 +1601,11 @@ class MCStdioFileHandle: public MCSystemFileHandle
 	virtual bool Seek(int64_t offset, int p_dir)
 	{
         // TODO Add MCSystemFileHandle::SetStream(char *newptr) ?
+		if (m_is_eof)
+		{
+			clearerr(m_stream);
+			m_is_eof = false;
+		}
 		return fseeko(m_stream, offset, p_dir < 0 ? SEEK_END : (p_dir > 0 ? SEEK_SET : SEEK_CUR)) == 0;
 	}
 	

Original file line number	Diff line number	Diff line change
`@@ -1601,6 +1601,11 @@ class MCStdioFileHandle: public MCSystemFileHandle`
`1601`	`1601`	`virtual bool Seek(int64_t offset, int p_dir)`
`1602`	`1602`	`{`
`1603`	`1603`	`// TODO Add MCSystemFileHandle::SetStream(char *newptr) ?`
	`1604`	`+ if (m_is_eof)`
	`1605`	`+ {`
	`1606`	`+ clearerr(m_stream);`
	`1607`	`+ m_is_eof = false;`
	`1608`	`+ }`
`1604`	`1609`	`return fseeko(m_stream, offset, p_dir < 0 ? SEEK_END : (p_dir > 0 ? SEEK_SET : SEEK_CUR)) == 0;`
`1605`	`1610`	`}`
`1606`	`1611`