Adds new options to c99
- -G: shared libraries
- -B: dynamic executables
- -R: setting rpath
To quote from the standard:
−B mode : If mode is dynamic, produce a dynamically linked executable file. If the −B option is present with −c, −E, or −G, the result is unspecified.
For shared libraries:
−G : Create a shared library or create object files suitable for inclusion in such a shared library. Compilations shall be performed in a manner suitable for the creation of shared libraries (for example, by producing position-independent code).
If −c is also specified, create object files suitable for inclusion in a shared library.
If −c is not specified, create a shared library. In this case the application shall ensure that the file named by the −o outfile option-argument includes an element named so or an implementation-defined element denoting a shared library, where elements in the last component of outfile are separated by
<period>characters, for example libx.so.1; if no −o option is included in the options or the file named by the −o outfile option does not contain an element named so or an implementation-defined element denoting a shared library, the result is unspecified. If a pathname operand or −l option-argument names a shared library and that shared library defines an object used by the library being created, it shall become a dependency of the created shared library.If the −G option is present with −B or −E, the result is unspecified.
For the rpath:
−R directory : If the object file format supports it, specify a directory to be searched for shared libraries when an executable file or shared library being created by c99 is subsequently executed, or loaded using dlopen(). If directory contains any
<colon>or<dollar-sign>characters, the behavior is unspecified. If an implementation provides a means for setting a default load time search location or locations, the −R option shall take precedence.The directory named by directory shall not be searched by a process performing dynamic loading if either of the following are true:
- The real and effective user IDs of that process are different and the directory has write permission for a user ID outside the set of the effective user ID of that process and any implementation-specific user IDs used for directories containing system libraries.
- The real and effective group IDs of that process are different and the directory has write permission for group IDs other than the effective group ID of that process.
Directories named in −R options shall be searched in the order specified, before the default system library locations are searched.
If a directory specified by a −R option contains files with names starting with any of the strings
"libc.","libl.","libpthread.","libm.","librt.","libxnet.", or"liby.", the result is unspecified.If the −R option is present with −c or −E, the result is unspecified.
And finally:
Multiple instances of the −D, −I, −L, −l, −R, and −U options can be specified.