/*
 * Delete Printer helper for Samba and CUPS
 * 
 * Compile with gcc -Wall deleteprinter.c -o deleteprinter and set as your
 * deleteprinter command in smb.conf.
 */
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <errno.h>
#include <string.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#define CONFFILE "/etc/samba/smb.conf"

int main( int argc, char *argv[] )
{
        pid_t pid = 0;
        FILE *smbconf = NULL;
        FILE *newconf = NULL;
        char *printer;
        char *sharename;
        int found = 0;

        /* Syslog support */
        openlog( "deleteprinter", LOG_PID, LOG_LPR );
        
        /*
          Args are:
          - printer /share/ name
        */
        if ( argc != 2 ) {
                syslog( LOG_ERR, "Expected 1 argument, found %d", argc - 1 );
                exit( 1 );
        } else {
                syslog( LOG_INFO, "deleteprinter '%s'",
                        argv[1] );
        }

        sharename = strdup( argv[1] );
        

        /* Try and find the printer in smb.conf. We need this for two
         * reasons: firstly, to delete any per-share info this printer holds,
         * and secondly to get the actual printer name.
         */
        if (( newconf = fopen( CONFFILE ".new", "w" )) == NULL ) {
                syslog( LOG_ERR, "Can't create %s.new (%m)", CONFFILE );
                exit( 1 );
        }

        if (( smbconf = fopen( CONFFILE, "r" )) != NULL ) {
                char *line = NULL;
                size_t linelen, dummy;
                while(( linelen = getline( &line, &dummy, smbconf )) != -1 ) {
                        /* skip comments and blanks */
                        size_t looking_at = strspn( line, " \t\r\n" );

                        if ( linelen == looking_at ||
                             line[ looking_at ] == '#' ||
                             line[ looking_at ] == ';' ) {
                                fprintf( newconf, "%s", line );
                                continue;
                        }

                        if ( line[looking_at] == '[' ) {
                                if ( !found && !strncmp( &line[looking_at + 1], sharename, strlen( sharename ))) {
                                        syslog( LOG_INFO, "found an entry for %s in %s", sharename, CONFFILE );
                                        found = 1;
                                        continue;
                                } else if ( found ) {
                                        /* end of definition */
                                        found = 0;
                                } else {
                                        /* ignore this share */
                                }
                        }

                        if ( !found ) {
                                fprintf( newconf, "%s", line ); /* XXX */
                        }

                        if ( found && !strncmp( &line[looking_at], "printer name", strlen( "printer name" ))) {
                                looking_at += strlen( "printer name" );
                                looking_at += strspn( &line[looking_at], " \t=");
                                printer = strdup( &line[looking_at] );
                                if ( strlen( printer )) {
                                        /* trailing newline */
                                        printer[ strlen( printer ) - 1 ] = '\0';
                                }
                                if ( strlen( printer )) {
                                        /* */
                                } else {
                                        syslog( LOG_ERR, "printer name for %s not specified!", sharename );
                                        exit( 1 );
                                }
                        }
                }
                fclose( smbconf );
                fclose( newconf );
        } else {
                syslog( LOG_ERR, "failed to open %s: %m", CONFFILE );
                exit( 1 );
        }

        /* default printer name */
        if ( printer == NULL ) {
                printer = strdup( sharename );
        }

        syslog( LOG_INFO, "deleting printer %s", printer );
        
        pid = fork();
        if ( pid == -1 ) {
                syslog( LOG_ERR, "error forking: %m" );
                exit( 1 );
        }
        
        if ( !pid ) {
                /* Child */
                execl( "/usr/sbin/lpadmin", "lpadmin", "-x", printer, NULL );
                syslog( LOG_ERR, "exec error running lpadmin: %m" );
                exit( 1 );
        } else {
                int status;
                waitpid( pid, &status, 0 );
                /* Bail on error */
                if ( status != 0 ) {
                        syslog( LOG_ERR, "lpadmin exited with status %d", status );
                        exit( 1 );
                }
        }
        
        /* Finally, fix smb.conf */
        rename( CONFFILE, CONFFILE ".old" );
        rename( CONFFILE ".new", CONFFILE );
        
        /* unnecessary, but tidy */
        free( sharename );
        free( printer );

        return 0;
}