file_expand.c

#include <stdio.h>
#include <string.h>
#include <alloca.h>
#include <pwd.h>
#include "cinterf.h"

#define TRUE 1
/* 
 * Expands the initial ~ of a Unix filename and returns the absolute 
 * file name.  Otherwise it returns the file name unchanged.
 */

DllExport int call_conv expand_file()
{
   unsigned char *file_name;
   unsigned char *expanded_file_name;

   int tlen, lose;
   struct passwd *pw;
   register unsigned char *new_dir, *p, *user_name;

   file_name = (unsigned char *)ptoc_string(1);

   /* If file_name is absolute, flush ...// and detect /./ and /../.
      If no /./ or /../ we can return right away. */

   if (file_name[0] == '/')
   {
        p = file_name; lose = 0;
        while (*p)
        {
            if (p[0] == '/' && p[1] == '/')
                file_name = p + 1;
            if (p[0] == '/' && p[1] == '~')
                file_name = p + 1, lose = 1;
            if (p[0] == '/' && p[1] == '.'
                && (p[2] == '/' || p[2] == 0
                    || (p[2] == '.' && (p[3] == '/' || p[3] == 0))))
                lose = 1;
            p++;
        }
        if (!lose)
        {
            ctop_string(2, file_name);
            return TRUE;
        }
   }

   /* Now determine directory to start with and put it in new_dir */

   new_dir = 0;

   if (file_name[0] == '~' && file_name[1] == '/')      /* prefix  ~/ */
   {
        if (!(new_dir = (unsigned char *) getenv("HOME")))
            new_dir = (unsigned char *) "";
        file_name++;
   }
   else         /* prefix  ~username/ */
   {
        for (p = file_name; *p && (*p != '/'); p++);
             user_name = (unsigned char *) alloca(p - file_name + 1);
        bcopy ((char *) file_name, user_name, p - file_name);
        user_name[p - file_name] = 0;

        pw = (struct passwd *) getpwnam(user_name + 1);
        if (!pw)
        {
            fprintf(stderr, "++Error: \"%s\" is not a registered user\n", user_name + 1);
            ctop_string(2, file_name); /* return the input file name unchanged */
            return TRUE;
        }
 
        file_name = p;
        new_dir = (unsigned char *) pw -> pw_dir;
   }

   /* Now concatenate the directory and name to new space in the stack frame */

   tlen = (new_dir ? strlen(new_dir) + 1 : 0) + strlen(file_name) + 1;
   expanded_file_name = (unsigned char *) alloca(tlen);
   if (new_dir) strcpy(expanded_file_name, new_dir);
   strcat(expanded_file_name, file_name);


   /* Make sure you insert the newly created symbol into the symbol table. */

   ctop_string(2, (unsigned char *) string_find(expanded_file_name, 1));

   return TRUE;
}

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