ef_last_error

ef_expand_file(3)          Library Functions Manual          ef_expand_file(3)



NAME
       ef_expand_file, del_ExpandFile, ef_last_error, ef_list_expansions,
       new_ExpandFile - expand filenames containing ~user/$envvar and wildcard
       expressions

SYNOPSIS
       #include <libtecla.h>

       ExpandFile *new_ExpandFile(void);

       ExpandFile *del_ExpandFile(ExpandFile *ef);

       FileExpansion *ef_expand_file(ExpandFile *ef,
                                     const char *path,
                                     int pathlen);

       int ef_list_expansions(FileExpansion *result, FILE *fp,
                              int term_width);

       const char *ef_last_error(ExpandFile *ef);


DESCRIPTION
       The ef_expand_file() function is part of the tecla library (see the
       libtecla(3) man page). It expands a specified filename, converting
       ~user/ and ~/ expressions at the start of the filename to the
       corresponding home directories, replacing $envvar with the value of the
       corresponding environment variable, and then, if there are any
       wildcards, matching these against existing filenames. Backslashes in
       the input filename are interpreted as escaping any special meanings of
       the characters that follow them.  Only backslahes that are themselves
       preceded by backslashes are preserved in the expanded filename.

       In the presence of wildcards, the returned list of filenames only
       includes the names of existing files which match the wildcards.
       Otherwise, the original filename is returned after expansion of tilde
       and dollar expressions, and the result is not checked against existing
       files. This mimics the file-globbing behavior of the unix tcsh shell.

       The supported wildcards and their meanings are:
         *        -  Match any sequence of zero or more characters.
         ?        -  Match any single character.
         [chars]  -  Match any single character that appears in
                     'chars'.  If 'chars' contains an expression of
                     the form a-b, then any character between a and
                     b, including a and b, matches. The '-'
                     character looses its special meaning as a
                     range specifier when it appears at the start
                     of the sequence of characters. The ']'
                     character also looses its significance as the
                     terminator of the range expression if it
                     appears immediately after the opening '[', at
                     which point it is treated one of the
                     characters of the range. If you want both '-'
                     and ']' to be part of the range, the '-'
                     should come first and the ']' second.

         [^chars] -  The same as [chars] except that it matches any
                     single character that doesn't appear in
                     'chars'.

       Note that wildcards never match the initial dot in filenames that start
       with '.'. The initial '.' must be explicitly specified in the filename.
       This again mimics the globbing behavior of most unix shells, and its
       rational is based in the fact that in unix, files with names that start
       with '.' are usually hidden configuration files, which are not listed
       by default by the ls command.

       The following is a complete example of how to use the file expansion
       function.

         #include <stdio.h>
         #include <libtecla.h>

         int main(int argc, char *argv[])
         {
           ExpandFile *ef;      /* The expansion resource object */
           char *filename;      /* The filename being expanded */
           FileExpansion *expn; /* The results of the expansion */
           int i;

           ef = new_ExpandFile();
           if(!ef)
             return 1;

           for(arg = *(argv++); arg; arg = *(argv++)) {
             if((expn = ef_expand_file(ef, arg, -1)) == NULL) {
               fprintf(stderr, "Error expanding %s (%s).\n", arg,
                                ef_last_error(ef));
             } else {
               printf("%s matches the following files:\n", arg);
               for(i=0; i<expn->nfile; i++)
                 printf(" %s\n", expn->files[i]);
             }
           }

           ef = del_ExpandFile(ef);
           return 0;
         }

       Descriptions of the functions used above are as follows:

         ExpandFile *new_ExpandFile(void)

       This function creates the resources used by the ef_expand_file()
       function. In particular, it maintains the memory that is used to record
       the array of matching filenames that is returned by ef_expand_file().
       This array is expanded as needed, so there is no built in limit to the
       number of files that can be matched.

         ExpandFile *del_ExpandFile(ExpandFile *ef)

       This function deletes the resources that were returned by a previous
       call to new_ExpandFile(). It always returns NULL (ie a deleted object).
       It does nothing if the ef argument is NULL.

       A container of the following type is returned by ef_expand_file().

         typedef struct {
           int exists;   /* True if the files in files[] exist */
           int nfile;    /* The number of files in files[] */
           char **files; /* An array of 'nfile' filenames. */
         } FileExpansion;

         FileExpansion *ef_expand_file(ExpandFile *ef,
                                       const char *path,
                                       int pathlen)

       The ef_expand_file() function performs filename expansion, as
       documented at the start of this section. Its first argument is a
       resource object returned by new_ExpandFile(). A pointer to the start of
       the filename to be matched is passed via the path argument. This must
       be a normal NUL terminated string, but unless a length of -1 is passed
       in pathlen, only the first pathlen characters will be used in the
       filename expansion.  If the length is specified as -1, the whole of the
       string will be expanded.

       The function returns a pointer to a container who's contents are the
       results of the expansion. If there were no wildcards in the filename,
       the nfile member will be 1, and the exists member should be queried if
       it is important to know if the expanded file currently exists or not.
       If there were wildcards, then the contained files[] array will contain
       the names of the nfile existing files that matched the wildcarded
       filename, and the exists member will have the value 1. Note that the
       returned container belongs to the specified ef object, and its contents
       will change on each call, so if you need to retain the results of more
       than one call to ef_expand_file(), you should either make a private
       copy of the returned results, or create multiple file-expansion
       resource objects via multiple calls to new_ExpandFile().

       On error, NULL is returned, and an explanation of the error can be
       determined by calling ef_last_error(ef).

         const char *ef_last_error(ExpandFile *ef)

       This function returns the message which describes the error that
       occurred on the last call to ef_expand_file(), for the given
       (ExpandFile *ef) resource object.

         int ef_list_expansions(FileExpansion *result, FILE *fp,
                                int terminal_width);

       The ef_list_expansions() function provides a convenient way to list the
       filename expansions returned by ef_expand_file(). Like the unix ls
       command, it arranges the filenames into equal width columns, each
       column having the width of the largest file. The number of columns used
       is thus determined by the length of the longest filename, and the
       specified terminal width. Beware that filenames that are longer than
       the specified terminal width are printed without being truncated, so
       output longer than the specified terminal width can occur. The list is
       written to the stdio stream specified by the fp argument.


THREAD SAFETY
       In multi-threaded programs, you should use the libtecla_r.a version of
       the library. This uses POSIX reentrant functions where available (hence
       the _r suffix), and disables features that rely on non-reentrant system
       functions. Currently there are no features disabled in this module.

       Using the libtecla_r.a version of the library, it is safe to use the
       facilities of this module in multiple threads, provided that each
       thread uses a separately allocated ExpandFile object. In other words,
       if two threads want to do file expansion, they should each call
       new_ExpandFile() to allocate their own file-expansion objects.


FILES
       libtecla.a    -    The tecla library
       libtecla.h    -    The tecla header file.


SEE ALSO
       libtecla(3), gl_get_line(3), cpl_complete_word(3),
       pca_lookup_file(3)


AUTHOR
       Martin Shepherd  (mcs@astro.caltech.edu)




                                                             ef_expand_file(3)