C.2.3 Porting gawk to a New Operating System

If you want to port gawk to a new operating system, there are several steps:

1. Follow the guidelines in the previous section concerning coding style, submission of diffs, and so on.
2. Be prepared to sign the appropriate paperwork. In order for the FSF to distribute your code, you must either place your code in the public domain and submit a signed statement to that effect, or assign the copyright in your code to the FSF.
3. When doing a port, bear in mind that your code must coexist peacefully with the rest of gawk and the other ports. Avoid gratuitous changes to the system-independent parts of the code. If at all possible, avoid sprinkling ‘#ifdef’s just for your port throughout the code.

   If the changes needed for a particular system affect too much of the code, I probably will not accept them. In such a case, you can, of course, distribute your changes on your own, as long as you comply with the GPL (see section GNU General Public License).

4. A number of the files that come with gawk are maintained by other people. Thus, you should not change them unless it is for a very good reason; i.e., changes are not out of the question, but changes to these files are scrutinized extra carefully. The files are ‘dfa.c’, ‘dfa.h’, ‘getopt1.c’, ‘getopt.c’, ‘getopt.h’, ‘install-sh’, ‘mkinstalldirs’, ‘regcomp.c’, ‘regex.c’, ‘regexec.c’, ‘regexex.c’, ‘regex.h’, ‘regex_internal.c’, and ‘regex_internal.h’.
5. Be willing to continue to maintain the port. Non-Unix operating systems are supported by volunteers who maintain the code needed to compile and run gawk on their systems. If noone volunteers to maintain a port, it becomes unsupported and it may be necessary to remove it from the distribution.
6. Supply an appropriate ‘gawkmisc.???’ file. Each port has its own ‘gawkmisc.???’ that implements certain operating system specific functions. This is cleaner than a plethora of ‘#ifdef’s scattered throughout the code. The ‘gawkmisc.c’ in the main source directory includes the appropriate ‘gawkmisc.???’ file from each subdirectory. Be sure to update it as well.

   Each port’s ‘gawkmisc.???’ file has a suffix reminiscent of the machine or operating system for the port—for example, ‘pc/gawkmisc.pc’ and ‘vms/gawkmisc.vms’. The use of separate suffixes, instead of plain ‘gawkmisc.c’, makes it possible to move files from a port’s subdirectory into the main subdirectory, without accidentally destroying the real ‘gawkmisc.c’ file. (Currently, this is only an issue for the PC operating system ports.)

7. Supply a ‘Makefile’ as well as any other C source and header files that are necessary for your operating system. All your code should be in a separate subdirectory, with a name that is the same as, or reminiscent of, either your operating system or the computer system. If possible, try to structure things so that it is not necessary to move files out of the subdirectory into the main source directory. If that is not possible, then be sure to avoid using names for your files that duplicate the names of files in the main source directory.
8. Update the documentation. Please write a section (or sections) for this Web page describing the installation and compilation steps needed to compile and/or install gawk for your system.

Following these steps makes it much easier to integrate your changes into gawk and have them coexist happily with other operating systems’ code that is already there.

In the code that you supply and maintain, feel free to use a coding style and brace layout that suits your taste.