Here is a rough translation, I'm sorry to tell that I have a hard time parsing the original in the context of OSS too.
IV. The reproduction of the code of the software or the translation of the shape of the code is not subject to the author's authorization when the reproduction or translation in the sense of 1° and 2° of article L. 122-6 is essential to get the information necessary to the interoperability of an independently created software with other softwares provided the following conditions are met:
1) those actions are fulfilled by the person with the right to use one copy of the software or on his behalf by someone empowered to this end;
2) the informations needed for interoperability have not been easily and quickly available to the people mentioned at 1° above;
3) and those actions are limited to the part of the original software needed to this interoperabilty
The information obtained this way [disassembly] shall not be:
1) Neither used for any other purpose than interoperability of the independently created software
2) Neither communicated to thirds parties unless that is necessary for the interoperability of the independently created software
3) Neither used for development, production or sale of a software whose expression is substantially similar or for any other act infringing the author's copyright
IV. The reproduction of the code of the software or the translation of the shape of the code is not subject to the author's authorization when the reproduction or translation in the sense of 1° and 2° of article L. 122-6 is essential to get the information necessary to the interoperability of an independently created software with other softwares provided the following conditions are met:
1) those actions are fulfilled by the person with the right to use one copy of the software or on his behalf by someone empowered to this end;
2) the informations needed for interoperability have not been easily and quickly available to the people mentioned at 1° above;
3) and those actions are limited to the part of the original software needed to this interoperabilty
The information obtained this way [disassembly] shall not be:
1) Neither used for any other purpose than interoperability of the independently created software
2) Neither communicated to thirds parties unless that is necessary for the interoperability of the independently created software
3) Neither used for development, production or sale of a software whose expression is substantially similar or for any other act infringing the author's copyright