/*
 * Copyright (C) Sumit Bose 2009
 *
 * This program 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 3 of the License, or (at your option)
 * any later version.
 *
 * This program 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 General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include <libgen.h>
#include <limits.h>
#include <fcntl.h>
#include <sys/mman.h>




#include <libxml/tree.h>
#include <libxml/parser.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#include <libxml/relaxng.h>

#include <libxslt/xslt.h>
#include <libxslt/xsltInternals.h>
#include <libxslt/transform.h>
#include <libxslt/xsltutils.h>

#include "util.h"
#include "xml_helper.h"
#include "helpers.h"

#define BACKUP_PATH "/var/spool/poliproc"
#define ORIGINAL_BACKUP_EXTENSION "ipa_original_backup_DO_NOT_DELETE"

static int copy_file(const char *src_name, const char *dest_name) {
    int src_fd=-1;
    int dest_fd=-1;
    int ret=0;
    struct stat stat_buffer;
    void *src;
    void *dest;
    char *tmp_file_name=NULL;

    tmp_file_name=(char *) malloc(strlen(dest_name)+8);
    CHECK(tmp_file_name, NULL, ("malloc failed."), return -1);
    strcpy(tmp_file_name, dest_name);
    strcat(tmp_file_name, ".XXXXXX");

    if ( (ret=lstat(src_name, &stat_buffer)) == -1) {
        if (errno != ENOENT) {
            DEBUG(0,("stat on %s failed: %s\n",src_name, strerror(errno)));
            goto cleanup;
        }
        DEBUG(0,("stat on %s failed with ENOENT, I will create an empty copy.\n",src_name, strerror(errno)));

        dest_fd=open_temporary_file(tmp_file_name, "0600", "root", "root", NULL);
        CHECK(dest_fd, -1, ("Failed to open temporary file %s\n", tmp_file_name), goto cleanup);

        close(dest_fd);
        ret=rename(tmp_file_name, dest_name);
        CHECK(ret, -1, ("Cannot rename %s to %s: %s\n", tmp_file_name, dest_name, strerror(errno) ), goto cleanup);

        goto cleanup;
    } 

    ret=-1;
    src_fd = open(src_name, O_RDONLY);
    CHECK(src_fd, -1, ("Failed to open %s read-only.\n", src_name), goto cleanup);

    dest_fd=open_temporary_file(tmp_file_name, "0600", "root", "root", NULL);
    CHECK(dest_fd, -1, ("Failed to open temporary file %s\n", tmp_file_name), goto cleanup);

    ret=fstat(src_fd, &stat_buffer);
    CHECK(ret, -1, ("Failed to stat file %s: %s\n", src_name, strerror(errno)), goto cleanup);

    ret = lseek(dest_fd, stat_buffer.st_size - 1, SEEK_SET);
    CHECK(ret, -1, ("Lseek failed for file %s: %s\n", dest_name, strerror(errno)), goto cleanup);

    ret = write(dest_fd, "", 1);
    if ( ret != 1 ) {
        DEBUG(0, ("Failed to write one byte to %s: %s.\n", dest_name, strerror(errno)));
        goto cleanup;
    }
    
    src = mmap(NULL, stat_buffer.st_size, PROT_READ, MAP_SHARED, src_fd, 0);
    if ( src == MAP_FAILED ) {
        DEBUG(0, ("Mmap failed for file %s: %s.\n", src_name, strerror(errno)));
        goto cleanup;
    } 

    dest = mmap(NULL, stat_buffer.st_size, PROT_READ | PROT_WRITE, MAP_SHARED,
                dest_fd, 0);
    if ( src == MAP_FAILED ) {
        DEBUG(0, ("Mmap failed for file %s: %s.\n", src_name, strerror(errno)));
        munmap(src, stat_buffer.st_size);
        goto cleanup;
    }

    memcpy(dest, src, stat_buffer.st_size); 

    munmap(dest, stat_buffer.st_size);
    munmap(src, stat_buffer.st_size);

    close(dest_fd);
    close(src_fd);
    ret=rename(tmp_file_name, dest_name);
    CHECK(ret, -1, ("Cannot rename %s to %s: %s\n", tmp_file_name, dest_name, strerror(errno) ), goto cleanup);

cleanup:
    if (dest_fd != -1) close(dest_fd);
    if (src_fd != -1) close(src_fd);
    free(tmp_file_name);

    return ret;
}

static int check_dir_create(const char *name) {
    int ret;
    struct stat stat_buffer;

    if( (ret=stat(name, &stat_buffer)) == -1) {
        DEBUG(0, ("Directory %s does not exist, creating it.\n", name, strerror(errno)));
        ret=mkdir(name, 0600);
        CHECK(ret, -1, ("mkdir %s failed: %s\n", name, strerror(errno)), return -1);
    } else if (!S_ISDIR(stat_buffer.st_mode)) {
        DEBUG(0,("%s is not a regular file!\n",name));
        return -1;
    } 

    return 0;
}

static int safe_config_file(const char *name, const char *app_name) {
    int ret;
    struct stat stat_buffer;
    char backup_dir[PATH_MAX];
    char backup_file[PATH_MAX];
    char original_backup[PATH_MAX];
    char *buffer=NULL;
    char *base_name=NULL;

    if ( (ret=lstat(name, &stat_buffer)) == -1) {
        if (errno != ENOENT) {
            DEBUG(0,("stat on %s failed: %s\n",name, strerror(errno)));
            goto cleanup;
        }
        DEBUG(0,("stat on %s failed with ENOENT, I will create an empty backup file.\n",name, strerror(errno)));
    } else {
        if (!S_ISREG(stat_buffer.st_mode)) {
            DEBUG(0,("%s is not a regular file!\n",name));
            ret=-1;
            goto cleanup;
        }
    } 

    ret=check_dir_create(BACKUP_PATH);
    CHECK(ret, -1, ("Failed to create main backup directory %s.\n", BACKUP_PATH), goto cleanup);

    ret=snprintf(backup_dir, PATH_MAX, "%s/%s", BACKUP_PATH, app_name);
    ret=snprintf(original_backup, PATH_MAX, "%s/%s.%s",backup_dir,base_name,ORIGINAL_BACKUP_EXTENSION);
    if (ret<0) {
        DEBUG(0,("snprintf failed.\n"));
        ret=-1;
        goto cleanup;
    }
    ret=check_dir_create(backup_dir);
    CHECK(ret, -1, ("Failed to create backup directory %s for application %s.\n", backup_dir, app_name), goto cleanup);

    buffer=strdup(name);
    base_name=basename(buffer);
    ret=snprintf(original_backup, PATH_MAX, "%s/%s.%s",backup_dir,base_name,ORIGINAL_BACKUP_EXTENSION);
    if (ret<0) {
        DEBUG(0,("snprintf failed.\n"));
        ret=-1;
        goto cleanup;
    }

    if ( (ret=lstat(original_backup, &stat_buffer)) == -1) {
        DEBUG(0, ("There is no original backup file, I will assume that %s is the original file.\n", name));
        ret=copy_file(name, original_backup);
    } else {
        DEBUG(3, ("Original backup file exists, I will create an ordinary backup file\n", name));
        ret=snprintf(backup_file, PATH_MAX, "%s/%s.%d",backup_dir,base_name,time(NULL));
        if (ret<0) {
            DEBUG(0,("snprintf failed.\n"));
            ret=-1;
            goto cleanup;
        }
        ret=copy_file(name, backup_file);
    }


cleanup:
    free(buffer);
    return ret;
}


char *get_output_handler_parameter(xmlNode *node, const char *name, const char *default_value, const int required) {
    char *value;

    DEBUG(3,("Search for attribute '%s'.\n",name));
    value = (char *) xmlGetProp(node, (xmlChar *) name);
    if (required == 1) {
        CHECK_NULL_FATAL(value, ("Cannot find required attribute '%s' for output handler.\n", name));
        DEBUG(3,("Found required attribute '%s' with value '%s'.\n",name, value));
    } else if (required == 0 ) {
        if (value == NULL) {
            DEBUG(3,("Optional attribute '%s' not found, using default '%s'.\n",name, default_value));
            if (default_value != NULL ) value=strdup(default_value);
        } else {
            DEBUG(3,("Found optional attribute '%s' with value '%s'.\n",name, value));
        }
    } else {
        DEBUG(0,("I am not allowed to be here, aborting ...\n"));
        exit(-1);
    }

    return value;
}

int output_handler_file(xmlNode *node, const xmlDocPtr doc, const char *xslt_file_name) {
    char *name=NULL;
    char *owner=NULL;
    char *group=NULL;
    char *permission=NULL;
    char *param_name=NULL;
    char *param_value=NULL;
    char *app_name=NULL;
    struct stat stat_buffer;
    char *dir_name=NULL;
    char *tmp_file_name=NULL;
    char *buffer=NULL;
    int ret=0;
    int fd;
    xsltStylesheetPtr parsed_stylesheet = NULL;
    xmlDocPtr res=NULL;

    name=get_output_handler_parameter(node, "name", NULL, 1);
   
    buffer=strdup(name);
    CHECK_NULL_RETURN(buffer ,("strdup failed\n"));
    dir_name=dirname(buffer); 
    if( (ret=stat(dir_name, &stat_buffer)) == -1) {
        DEBUG(0,("stat on %s failed: %s\n",dir_name, strerror(errno)));
        goto cleanup;
    }
    if(!S_ISDIR(stat_buffer.st_mode)) {
        DEBUG(0,("%s is not a directory!\n",dir_name));
        ret=-1;
        goto cleanup;
    } 

    if( (ret=lstat(name, &stat_buffer)) == -1) {
        if ( errno != ENOENT ) {
            DEBUG(0,("stat on %s failed: %s\n",name, strerror(errno)));
            goto cleanup;
        }
        DEBUG(0,("stat on %s failed with ENOENT, this is ok\n",name, strerror(errno)));
    } else {
        if(!S_ISREG(stat_buffer.st_mode)) {
            DEBUG(0,("%s is not a regular file!\n",name));
            ret=-1;
            goto cleanup;
        }
    } 
     
    owner=get_output_handler_parameter(node, "owner", "root", 0);
    group=get_output_handler_parameter(node, "group", "root", 0);
   
    permission=get_output_handler_parameter(node, "permission", "0400", 0);
    param_name=get_output_handler_parameter(node, "param_name", NULL, 0);
    param_value=get_output_handler_parameter(node, "param_value", NULL, 0);

    /* TODO: create backup copy */
    app_name = find_by_xpath(doc, "//def:metadata/def:app", FIND_VALUE);
    CHECK(app_name, NULL, ("Cannot find the name of the application in policy file.\n"), goto failed);
    DEBUG(3, ("Found application name: %s\n", app_name));
    ret=safe_config_file(name, app_name);
    CHECK(ret, -1, ("Failed to safe config file %s of application %s.\n", name, app_name), goto cleanup);

    tmp_file_name=(char *) malloc(strlen(name)+8);
    CHECK_NULL_RETURN(tmp_file_name,("malloc failed."));
    strcpy(tmp_file_name, name);
    strcat(tmp_file_name, ".XXXXXX");
    fd=open_temporary_file(tmp_file_name, permission, owner, group, NULL);
    CHECK(fd, -1, ("Failed to open temporary file.\n"), goto failed);
 
    parsed_stylesheet = xsltParseStylesheetFile((xmlChar *) xslt_file_name);
    CHECK_NULL_FATAL(parsed_stylesheet, ("Cannot parse stylesheet!\n"));

    res = xsltApplyStylesheet(parsed_stylesheet, doc, NULL);
    CHECK_NULL_FATAL(res, ("Cannot apply stylesheet!\n"));
    ret = xsltSaveResultToFd(fd, res, parsed_stylesheet);
    if (ret == -1) {
        DEBUG(0, ("Cannot save result!\n"));
        close(fd);
        goto cleanup;
    }

    close(fd);
    ret=rename(tmp_file_name, name);
    CHECK(ret, -1, ("Cannot rename %s to %s: %s\n", tmp_file_name, name, strerror(errno) ), goto cleanup);

cleanup:
    xmlFreeDoc(res);
    xsltFreeStylesheet(parsed_stylesheet);

    free(buffer);
    free(tmp_file_name);

    free(name);
    free(owner);
    free(group);
    free(permission);
    free(param_name);
    free(param_value);
    free(app_name);
    return ret;

failed:
    free(buffer);
    free(tmp_file_name);

    free(name);
    free(owner);
    free(group);
    free(permission);
    free(param_name);
    free(param_value);
    free(app_name);
    return -1;
}

int output_handler_exec_with_args(xmlNode *node, const xmlDocPtr doc, const char *xslt_file_name) {
    char *command;
    char *arguments;
    char *user;
    char *group;
    char *param_name;
    char *param_value;
    int ret;
    struct stat stat_buffer;
    xsltStylesheetPtr parsed_stylesheet = NULL;
    xmlDocPtr res;
    xmlChar *result_string;
    int result_length;
    char *cur;
    char *end_of_line;
    
    command=get_output_handler_parameter(node, "command", NULL, 1);

    if( (ret=stat(command, &stat_buffer)) == -1) {
        DEBUG(0,("stat on %s failed: %s\n",command, strerror(errno)));
        free(command);
        return -1;
    }


    arguments=get_output_handler_parameter(node, "arguments", NULL, 0);

    user=get_output_handler_parameter(node, "user", "nobody", 0);
    group=get_output_handler_parameter(node, "group", "nobody", 0);

    param_name=get_output_handler_parameter(node, "param_name", NULL, 0);
    param_value=get_output_handler_parameter(node, "param_value", NULL, 0);

    parsed_stylesheet = xsltParseStylesheetFile((xmlChar *) xslt_file_name);
    CHECK_NULL_FATAL(parsed_stylesheet, ("Cannot parse stylesheet!\n"));

    res = xsltApplyStylesheet(parsed_stylesheet, doc, NULL);
    CHECK_NULL_FATAL(res, ("Cannot apply stylesheet!\n"));
    ret = xsltSaveResultToString(&result_string, &result_length, res, parsed_stylesheet);
    if (ret == -1) {
        DEBUG(0, ("Cannot save result!\n"));
        exit(1);
    }
    xmlFreeDoc(res);
    xsltFreeStylesheet(parsed_stylesheet);
    xsltCleanupGlobals();

    cur=(char *)result_string;
    while ( (end_of_line = strchr(cur, '\n'))!=NULL ) {
        *end_of_line='\0';
        DEBUG(3,("found argument to %s: |%s|\n",command, cur));
        ret=exec_command(command, user, group, arguments, cur);
        DEBUG(3,("exec_command retrun value: %d\n",ret));
        cur=end_of_line+1;
    };

    free(result_string);

    free(command);
    free(arguments);
    free(user);
    free(group);
    free(param_name);
    free(param_value);
    return 0;
}

int find_output_handler(const char *policy_file_name, const char *xslt_file_name) {
    int i;
    xmlXPathContextPtr xpath_context=NULL;
    xmlXPathObjectPtr xpath_obj=NULL;
    xmlDocPtr xslt_doc=NULL;
    xmlDocPtr doc=NULL;

    doc = xmlParseFile(policy_file_name);
    CHECK(doc, NULL, ("Cannot parse file %s!\n", policy_file_name), goto failed);

    xslt_doc = xmlParseFile(xslt_file_name);
    CHECK(xslt_doc, NULL, ("Cannot parse file %s!\n", xslt_file_name), goto failed);

    xpath_context = xmlXPathNewContext(xslt_doc);
    CHECK(xpath_context, NULL, ("Error: unable to create new XPath context\n"), goto failed);

    if (xmlXPathRegisterNs(xpath_context, XSLT_METADATA_NAMESPACE_PREFIX, XSLT_METADATA_NAMESPACE) != 0) {
        DEBUG(0,
              ("Error: unable to register NS with prefix=\"%s\" and href=\"%s\"\n",
               XSLT_METADATA_NAMESPACE_PREFIX, XSLT_METADATA_NAMESPACE));
        goto failed;
    }

    xpath_obj = xmlXPathEvalExpression(XPATH_OUTPUT_HANDLER, xpath_context);
    if (xpath_obj == NULL) {
        DEBUG(0,
              ("Error: unable to evaluate xpath expression \"%s\"\n",
               XPATH_OUTPUT_HANDLER));
        goto failed;
    }

    if (xmlXPathNodeSetIsEmpty(xpath_obj->nodesetval)) {
        DEBUG(0, ("Nothing found for %s\n", XPATH_OUTPUT_HANDLER));
        goto failed;
    } 

    for (i=0; i<xmlXPathNodeSetGetLength(xpath_obj->nodesetval); i++) {
        DEBUG(3, ("found output_handler: %s\n",(char *) xpath_obj->nodesetval->nodeTab[i]->name));
        /*print_all_attributes(xpath_obj->nodesetval->nodeTab[i]);*/
        if ( xmlStrEqual(xpath_obj->nodesetval->nodeTab[i]->name, (xmlChar *) "file" )) {
            output_handler_file(xpath_obj->nodesetval->nodeTab[i], doc, xslt_file_name);
        } else if ( xmlStrEqual(xpath_obj->nodesetval->nodeTab[i]->name, (xmlChar *) "exec_with_args" )) {
            output_handler_exec_with_args(xpath_obj->nodesetval->nodeTab[i], doc, xslt_file_name);
        } else {
            DEBUG(0, ("Unknow outout handler '%s'.\n", xpath_obj->nodesetval->nodeTab[i]->name));
            goto failed;
        }
    }


    xmlXPathFreeObject(xpath_obj);
    xmlXPathFreeContext(xpath_context);
    xmlFreeDoc(xslt_doc);
    xmlFreeDoc(doc);
    xmlCleanupParser();
    return 0;

failed:
    xmlXPathFreeObject(xpath_obj);
    xmlXPathFreeContext(xpath_context);
    xmlFreeDoc(xslt_doc);
    xmlFreeDoc(doc);
    xmlCleanupParser();
    return -1;
}