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### 3.21 Running Protoize

The program `protoize` is an optional part of GCC. You can use it to add prototypes to a program, thus converting the program to ISO C in one respect. The companion program `unprotoize` does the reverse: it removes argument types from any prototypes that are found.

When you run these programs, you must specify a set of source files as command line arguments. The conversion programs start out by compiling these files to see what functions they define. The information gathered about a file foo is saved in a file named `foo.X`.

After scanning comes actual conversion. The specified files are all eligible to be converted; any files they include (whether sources or just headers) are eligible as well.

But not all the eligible files are converted. By default, `protoize` and `unprotoize` convert only source and header files in the current directory. You can specify additional directories whose files should be converted with the `-d directory` option. You can also specify particular files to exclude with the `-x file` option. A file is converted if it is eligible, its directory name matches one of the specified directory names, and its name within the directory has not been excluded.

Basic conversion with `protoize` consists of rewriting most function definitions and function declarations to specify the types of the arguments. The only ones not rewritten are those for varargs functions.

`protoize` optionally inserts prototype declarations at the beginning of the source file, to make them available for any calls that precede the function's definition. Or it can insert prototype declarations with block scope in the blocks where undeclared functions are called.

Basic conversion with `unprotoize` consists of rewriting most function declarations to remove any argument types, and rewriting function definitions to the old-style pre-ISO form.

Both conversion programs print a warning for any function declaration or definition that they can't convert. You can suppress these warnings with `-q`.

The output from `protoize` or `unprotoize` replaces the original source file. The original file is renamed to a name ending with ‘`.save`’ (for DOS, the saved filename ends in ‘`.sav`’ without the original ‘`.c`’ suffix). If the ‘`.save`’ (‘`.sav`’ for DOS) file already exists, then the source file is simply discarded.

`protoize` and `unprotoize` both depend on GCC itself to scan the program and collect information about the functions it uses. So neither of these programs will work until GCC is installed.

Here is a table of the options you can use with `protoize` and `unprotoize`. Each option works with both programs unless otherwise stated.

`-B` directory
  Look for the file `SYSCALLS.c.X` in directory, instead of the usual directory (normally `/usr/local/lib`). This file contains prototype information about standard system functions. This option applies only to `protoize`.
`-c` compilation-options
  Use compilation-options as the options when running `gcc` to produce the ‘`.X`’ files. The special option `-aux-info` is always passed in addition, to tell `gcc` to write a ‘`.X`’ file.

  Note that the compilation options must be given as a single argument to `protoize` or `unprotoize`. If you want to specify several `gcc` options, you must quote the entire set of compilation options to make them a single word in the shell.

  There are certain `gcc` arguments that you cannot use, because they would produce the wrong kind of output. These include `-g`, `-O`, `-c`, `-S`, and `-o` If you include these in the compilation-options, they are ignored.

`-C`
  Rename files to end in ‘`.C`’ (‘`.cc`’ for DOS-based file systems) instead of ‘`.c`’. This is convenient if you are converting a C program to C++. This option applies only to `protoize`.
`-g`
  Add explicit global declarations. This means inserting explicit declarations at the beginning of each source file for each function that is called in the file and was not declared. These declarations precede the first function definition that contains a call to an undeclared function. This option applies only to `protoize`.
`-i` string
  Indent old-style parameter declarations with the string string. This option applies only to `protoize`.

  `unprotoize` converts prototyped function definitions to old-style function definitions, where the arguments are declared between the argument list and the initial ‘`{`’. By default, `unprotoize` uses five spaces as the indentation. If you want to indent with just one space instead, use `-i " "`.

`-k`
  Keep the ‘`.X`’ files. Normally, they are deleted after conversion is finished.
`-l`
  Add explicit local declarations. `protoize` with `-l` inserts a prototype declaration for each function in each block which calls the function without any declaration. This option applies only to `protoize`.
`-n`
  Make no real changes. This mode just prints information about the conversions that would have been done without `-n`.
`-N`
  Make no ‘`.save`’ files. The original files are simply deleted. Use this option with caution.
`-p` program
  Use the program program as the compiler. Normally, the name `gcc` is used.
`-q`
  Work quietly. Most warnings are suppressed.
`-v`
  Print the version number, just like `-v` for `gcc`.

If you need special compiler options to compile one of your program's source files, then you should generate that file's ‘`.X`’ file specially, by running `gcc` on that source file with the appropriate options and the option `-aux-info`. Then run `protoize` on the entire set of files. `protoize` will use the existing ‘`.X`’ file because it is newer than the source file. For example:

         gcc -Dfoo=bar file1.c -aux-info file1.X
         protoize *.c

You need to include the special files along with the rest in the `protoize` command, even though their ‘`.X`’ files already exist, because otherwise they won't get converted.

See Protoize Caveats, for more information on how to use `protoize` successfully.