(kpathsea.info)Calling sequence

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5.2 Calling sequence
====================

The typical way to use Kpathsea in your program goes something like
this:

  1. Call `kpathsea_new' to create a new library instance. This variable
     must be passed as the first argument to all the following library
     functions.  The rest of this manual will be using `kpse' as a
     placeholder for the name of this variable.

  2. Call `kpathsea_set_program_name' with `argv[0]' as the second
     argument; the third argument is a string or `NULL'.  The third
     argument is used by Kpathsea as the program name for the
     `.PROGRAM' feature of config files (Note: Config files).  If the
     third argument is `NULL', the value of the second argument is
     used.  This function must be called before any other use of the
     Kpathsea library.

     `kpathsea_set_program_name' always sets the variables
     `kpse->invocation_name' and `kpse->invocation_short_name'.  These
     variables are used in the error message macros defined in
     `kpathsea/lib.h'.  It sets the variable `kpse->program_name' to
     the program name it uses.

     It also initializes debugging options based on the environment
     variable `KPATHSEA_DEBUG' (if that is set).

     Finally, it sets the environment variables `SELFAUTOLOC',
     `SELFAUTODIR' and `SELFAUTOPARENT' to the location, parent and
     grandparent directory of the executable, removing `.' and `..' path
     elements and resolving symbolic links.  These are used in the
     default configuration file to allow people to invoke TeX from
     anywhere.  You can use `kpsewhich --expand-var=\$SELFAUTOLOC',
     etc., to see the values.

  3. Set debugging options. Note: Debugging.  If your program doesn't
     have a debugging option already, you can define one and set
     `kpse->debug' to the number that the user supplies (as in Dviljk
     and Web2c), or you can just omit this altogether (people can
     always set `KPATHSEA_DEBUG').  If you do have runtime debugging
     already, you need to merge Kpathsea's options with yours (as in
     Dvipsk and Xdvik).

  4. If your program has its own configuration files that can define
     search paths, you should assign those paths to the `client_path'
     member in the appropriate element of the `kpse->format_info'
     array.  (This array is indexed by file type; see `tex-file.h'.)
     See `resident.c' in Dvipsk for an example.

  5. Call `kpathsea_init_prog' (see `proginit.c'). It's useful for the
     DVI drivers, at least, but for other programs it may be simpler to
     extract the parts of it that actually apply.  This does not
     initialize any paths, it just looks for (and sets) certain
     environment variables and other random information.  (A search
     path is always initialized at the first call to find a file of
     that type; this eliminates much useless work, e.g., initializing
     the BibTeX search paths in a DVI driver.)

  6. The routine to actually find a file of type FORMAT is
     `kpathsea_find_file'.  You can call `kpathsea_find_file' after
     doing only the first and second of the initialization steps
     above--Kpathsea automatically reads the `texmf.cnf' generic config
     files, looks for environment variables, and does expansions at the
     first lookup.

  7. To find PK and/or GF bitmap fonts, the routine is
     `kpathsea_find_glyph', defined in `tex-glyph.h'. This returns a
     structure in addition to the resultant filename, because fonts can
     be found in so many ways. See the documentation in the source.

  8. To actually open a file, not just return a filename, call
     `kpathsea_open_file'.  This function takes the name to look up and
     a Kpathsea file format as arguments, and returns the usual `FILE
     *'.  It always assumes the file must exist, and thus will search
     the disk if necessary (unless the search path specified `!!',
     etc.).  In other words, if you are looking up a VF or some other
     file that need not exist, don't use this.

  9. To close the kpathsea library instance you are using, call
     `kpathsea_finish'.  This function closes any open log files and
     frees the memory used by the instance.


   Kpathsea also provides many utility routines. Some are generic: hash
tables, memory allocation, string concatenation and copying, string
lists, reading input lines of arbitrary length, etc. Others are
filename-related: default path, tilde, and variable expansion, `stat'
calls, etc. (Perhaps someday I'll move the former to a separate
library.)

   The `c-*.h' header files can also help your program adapt to many
different systems.  You will almost certainly want to use Autoconf for
configuring your software if you use Kpathsea; I strongly recommend
using Autoconf regardless.  It is available from
`ftp://prep.ai.mit.edu/pub/gnu/'.