/*
 * Add Printer helper for Samba and CUPS
 * 
 * Compile with gcc -Wall addprinter.c -o addprinter and set as your
 * addprinter command in smb.conf. It expects to find a file mapping
 * Samba-friendly port names to CUPS-friendly port names in the location
 * marked by PORTSFILE, below. The map file is just
 * PORTNAME[whitespace]CUPSNAME, one port per line.
 */
#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 PORTSFILE "/etc/samba/ports-map"
#define CONFFILE "/etc/samba/smb.conf"
#define SPOOL_PATH "/var/spool/samba"

int main( int argc, char *argv[] )
{
        pid_t pid = 0;
        char *line = NULL;
        size_t linelen, dummy = 0;
        FILE *ports = NULL;
        char *port = NULL;
        FILE *smbconf = NULL;
        int idx = 0;
        char *printer;
        char *sharename;
        char *portarg;

        /* Syslog support */
        openlog( "addprinter", LOG_PID, LOG_LPR );

        /* The manual page claims 6 arguments!
           Args are:
           - printer name
           - share name
           - port name
           - driver name
           - location
           - comment
           - host requesting printer addition
        */
        if ( argc != 8 ) {
                syslog( LOG_ERR, "Expected 7 arguments, found %d", argc - 1 );
                exit( 1 );
        } else {
                syslog( LOG_INFO, "addprinter '%s' '%s' '%s' '%s' '%s' '%s' '%s'",
                        argv[1], argv[2], argv[3], argv[4], argv[5], argv[6],
                        argv[7] );
        }

        /* these are to make the code more readable :) */
        printer = strdup( argv[1] );
        sharename = strdup( argv[2] );
        portarg = strdup( argv[3] );

        /* Next, find the correct translation for the port */
        if (( ports = fopen( PORTSFILE, "r" )) == NULL ) {
                syslog( LOG_ERR, "Failed to open ports file" );
                exit( 1 );
        }

        while(( linelen = getline( &line, &dummy, ports )) != -1 ) {
                if ( strncmp( line, portarg, strlen( portarg )) == 0 ) {
                        /* Yay, match */
                        if ( linelen > strlen( portarg ) && !isblank( line[strlen(portarg)])) {
                                /* Boo, it's not (i.e. it's a substring match) */
                                continue;
                        } else {
                                idx = strlen( portarg );

                                /* Nuke trailing newline */
                                if ( line[strlen( line ) - 1] == '\n' ) {
                                        line[ strlen( line ) - 1 ] = '\0';
                                }

                                while( idx < linelen && isblank( line[ idx ])) {
                                        idx++;
                                }
                                if ( idx == linelen ) {
                                        continue;
                                }
                                port = strdup( &line[idx] );
                        }
                }
        }
  
        if ( line )
                free( line );

        /* clean up printer name, because otherwise lpadmin will barf. Might
         * be necessary to further restrict the printer name? We should also
         * probably check that the printer doesn't already exist. */
        for ( idx = 0; idx < strlen( printer ); idx++ ) {
                if ( isblank( printer[idx] ))
                        printer[idx] = '_';
        }

        if ( !port ) {
                syslog( LOG_ERR, "No port found matching %s", portarg );
                exit( 1 );
        } else {
                syslog( LOG_INFO, "Setting up %s on %s\n", printer, port );
        }

        pid = fork();
        if ( pid == -1 ) {
                syslog( LOG_ERR, "error forking: %m" );
                exit( 1 );
        }

        if ( !pid ) {
                /* Child */
                execl( "/usr/sbin/lpadmin", "lpadmin", "-p", printer, "-o", "raw",
                       "-v", port, "-E", NULL );
                syslog( LOG_ERR, "exec error running lpadmin: %m" );
                exit( 1 ); /* notreached */
        } else {
                int status;
                waitpid( pid, &status, 0 );
                /* Bail on error */
                if ( status != 0 ) {
                        syslog( LOG_INFO, "lpadmin exited with status %d", status );
                        exit( 1 );
                }
        }

        free( port );

        /* Add the new printer to smb.conf */
        if (( smbconf = fopen( CONFFILE, "a" )) != NULL ) {
                fprintf( smbconf, "\n" );
                fprintf( smbconf, "[%s]\n", sharename );
                fprintf( smbconf, ";; automatically added printer definition\n" );
                fprintf( smbconf, "printer name = %s\n", printer );
                fprintf( smbconf, "printable = yes\n" );
                fprintf( smbconf, "path = %s\n", SPOOL_PATH );
                fclose( smbconf );
        } else {
                syslog( LOG_ERR, "failed to open %s: %m", CONFFILE );
                exit( 1 );
        }

        /* If this isn't printed out, Samba will not reload shares */
        fprintf( stdout, "%s\n", portarg );

        /* unnecessary, but tidy */
        free( printer );
        free( sharename );
        free( portarg );

        return 0;
}