/***********************************************************************
 *  File: modinstall.c
 *  Author: Juan Carlos Luciani (jluciani@novell.com)
 * 
 *  Abstract: Implements a utility to install or un-install the
 *  pam_pwcapture module.
 * 
 *  Copyright (C) 2004 Novell, Inc.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 ***********************************************************************/

#include "stdio.h"
#include "errno.h"
#include <unistd.h>
#include <getopt.h>

typedef int BOOL;
#define TRUE 1
#define FALSE 0


// Usage string
char usage[] = "\nmodinstall: usage: [-i InstallPamConfigFilePath] [-u UninstallPamConfigFilePath]\n";

// Our PAM Configuration Line
char pamConfigLine[] = "auth       required\tpam_pwcapture.so\n";


/* ************************************************************************
 * InstallModule()
 *
 * Installs the pam_pwcapture file in the specified file.
 *
 * ************************************************************************/
void
InstallModule(char *pFilePath)
{
   FILE *fp;
   FILE *fpTemp;
   fpos_t currLinePosition;
   char currLine[512];
   BOOL authLineFound = FALSE;
   BOOL insertedOurLine = FALSE;

   // Open temporary file
   if ((fpTemp = tmpfile()) != NULL)
   {
      // Open the PAM config file for reading
      if ((fp = fopen(pFilePath, "r")) != NULL)
      {
         // Copy the PAM config file onto the temp file
         while (fgets(currLine, 512, fp) != NULL)
            if (fputs(currLine, fpTemp) < 0)
               fprintf(stderr, "Error writing line to temp file\n");

         // Close the PAM Config file and reopen it for writing
         fclose(fp);
         if ((fp = fopen(pFilePath, "w")) != NULL)
         {
            // Reset the file position on the temp file to the beginning
            if (fseek(fpTemp, 0, SEEK_SET) == 0)
            {
               // Now move the lines from the temp file onto the clean
               // PAM config file looking for a place to insert our own
               // line.
               while (fgets(currLine, 512, fpTemp) != NULL)
               {
                  // Check if we are dealing with a line configuring an authentication service
                  if (strlen(currLine) > 4
                      && tolower(currLine[0]) == 'a'
                      && tolower(currLine[1]) == 'u'
                      && tolower(currLine[2]) == 't'
                      && tolower(currLine[3]) == 'h')
                  {
                     authLineFound = TRUE;
                  }
                  else
                  {
                     // This line is not configuring an authentication service, check if we
                     // now need to add a line for our module.
                     if (authLineFound && insertedOurLine == FALSE)
                     {
                        // Do not add our line if the line is commented out
                        if (strlen(currLine) > 1
                            && currLine[0] != '#')
                        {
                           // Ok, now insert our line into the configuration.
                           if (fputs(pamConfigLine, fp) < 0)
                              fprintf(stderr, "Error writing line to PAM Config file\n");
                           insertedOurLine = TRUE;
                        }
                     }
                  }

                  if (fputs(currLine, fp) < 0)
                     fprintf(stderr, "Error writing line to PAM Config file\n");
               }
            }
            else
            {
               fprintf(stderr, "Error resetting position in temp file\n");
            }

            // Close the PAM Config file
            fclose(fp);
         }
         else
         {
            fprintf(stderr, "Error reopening PAM Config file\n");
         }
      }
      else
      {
         fprintf(stderr, "Error opening PAM Config file for reading\n");
      }

      // Close the temporary file
      fclose(fpTemp);
   }
   else
   {
      fprintf(stderr, "Unable to open temporary file\n");
   }
}


/* ************************************************************************
 * UninstallModule()
 *
 * Uninstalls the pam_pwcapture file from the specified file.
 *
 * ************************************************************************/
void
UninstallModule(char *pFilePath)
{
   FILE *fp;
   FILE *fpTemp;
   char currLine[512];

   // Open temporary file
   if ((fpTemp = tmpfile()) != NULL)
   {
      // Open the PAM config file for reading
      if ((fp = fopen(pFilePath, "r")) != NULL)
      {
         // Copy the PAM config file onto the temp file
         while (fgets(currLine, 512, fp) != NULL)
            if (fputs(currLine, fpTemp) < 0)
               fprintf(stderr, "Error writing line to temp file\n");

         // Close the PAM Config file and reopen it for writing
         fclose(fp);
         if ((fp = fopen(pFilePath, "w")) != NULL)
         {
            // Reset the file position on the temp file to the beginning
            if (fseek(fpTemp, 0, SEEK_SET) == 0)
            {
               // Now move the lines from the temp file onto the clean
               // PAM config file looking for our own line.
               while (fgets(currLine, 512, fpTemp) != NULL)
               {
                  // Write lines other than our own back to the PAM Config file
                  if (strcmp(currLine, pamConfigLine) != 0)
                  {
                     if (fputs(currLine, fp) < 0)
                        fprintf(stderr, "Error writing line to PAM Config file\n");
                  }
               }
            }
            else
            {
               fprintf(stderr, "Error resetting position in temp file\n");
            }

            // Close the PAM Config file
            fclose(fp);
         }
         else
         {
            fprintf(stderr, "Error reopening PAM Config file\n");
         }
      }
      else
      {
         fprintf(stderr, "Error opening PAM Config file for reading\n");
      }

      // Close the temporary file
      fclose(fpTemp);
   }
   else
   {
      fprintf(stderr, "Unable to open temporary file\n");
   }
}


/* ************************************************************************
 * main()
 *
 * Entry point for console application.
 *
 * ************************************************************************/
int main(int argc, char* argv[])
{
   int         option;
   int         optionsSpecified = 0;
   BOOL        doneScanning = FALSE;
   BOOL        invalidUsage = FALSE;
   char        *pInstallFile = NULL;
   char        *pUninstallFile = NULL;

   // Scan options
   while (!doneScanning)
   {
      opterr = 0;
      option = getopt(argc, argv, "i:u:?");

      // Proceed based on the result
      switch (option)
      {
         case 'i':
            // Install option, check the argument.
            if (optarg != NULL)
            {
               // Record location of argument
               pInstallFile = optarg;
               optionsSpecified ++;
            }
            else
            {
               // No install file path specified
               doneScanning = TRUE;
               invalidUsage = TRUE;
            }
            break;

         case 'u':
            // Uninstall option, check the argument.
            if (optarg != NULL)
            {
               // Record location of argument
               pUninstallFile = optarg;
               optionsSpecified ++;
            }
            else
            {
               // No uninstall file path specified
               doneScanning = TRUE;
               invalidUsage = TRUE;
            }
            break;

         case '?':
            // Invalid option detected
            doneScanning = TRUE;
            invalidUsage = TRUE;
            break;

         default:
            // Done scanning
            doneScanning = TRUE;
            break;
      }
   }

   // Do some sanity checking
   if (!invalidUsage
       && optionsSpecified)
   {
      // Check if we need to install the module
      if (pInstallFile)
      {
         InstallModule(pInstallFile);
      }

      // Check if we need to uninstall the module
      if (pUninstallFile)
      {
         UninstallModule(pUninstallFile);
      }
   }
   else
   {
      // Invalid option detected, print usage message.
      printf(usage, argv[0]);
   }

   return 0;
}