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/// inotify cron table manipulator main file

/**

 * \file ict-main.cpp

 *

 * inotify cron system

 *

 * Copyright (C) 2006, 2007, 2008 Lukas Jelinek, <lukas@aiken.cz>

 *

 * This program is free software; you can use it, redistribute

 * it and/or modify it under the terms of the GNU General Public

 * License, version 2 (see LICENSE-GPL).

 *  

 */

#include <argp.h>

#include <pwd.h>

#include <string>

#include <stdio.h>

#include <unistd.h>

#include <sys/stat.h>

#include <sys/wait.h>

#include <sys/inotify.h>

#include <fcntl.h>

#include <stdlib.h>

#include <limits.h>

#include <cstring>

#include "inotify-cxx.h"

#include "appargs.h"

#include "incron.h"

#include "incrontab.h"

#include "incroncfg.h"

/// Alternative editor

#define INCRON_ALT_EDITOR "/etc/alternatives/editor"

/// Default (hard-wired) editor

#define INCRON_DEFAULT_EDITOR "vim"

/// incrontab version string

#define INCRONTAB_VERSION INCRONTAB_NAME " " INCRON_VERSION

/// incrontab description string

#define INCRONTAB_DESCRIPTION "incrontab - inotify cron table manipulator\n" \

                              "(c) Lukas Jelinek, 2006, 2007, 208"

/// incrontab help string

#define INCRONTAB_HELP INCRONTAB_DESCRIPTION "\n\n" \

          "usage: incrontab [<options>] <operation>\n" \

          "       incrontab [<options>] <FILE-TO-IMPORT>\n\n" \

          "<operation> may be one of the following:\n" \

          "  -?, --about                  gives short information about program\n" \

          "  -h, --help                   prints this help text\n" \

          "  -l, --list                   lists user table\n" \

          "  -r, --remove                 removes user table\n" \

          "  -e, --edit                   provides editting user table\n" \

          "  -t, --types                  list supported event types\n" \

          "  -d, --reload                 request incrond to reload user table\n" \

          "  -V, --version                prints program version\n\n" \

          "\n" \

          "These options may be used:\n" \

          "  -u <USER>, --user=<USER>     overrides current user (requires root privileges)\n" \

          "  -f <FILE>, --config=<FILE>   overrides default configuration file  (requires root privileges)\n\n" \

          "For reporting bugs please use http://bts.aiken.cz\n"

/// Copies a file to an user table.

/**

 * \param[in] rPath path to file

 * \param[in] rUser user name

 * \return true = success, false = failure

 */

bool copy_from_file(const std::string& rPath, const std::string& rUser)

{

  fprintf(stderr, "copying table from file '%s'\n", rPath.c_str());

  IncronTab tab;

  std::string s(rPath);

  if (s == "-")

    s = "/dev/stdin";

  if (!tab.Load(s)) {

    fprintf(stderr, "cannot load table from file '%s'\n", rPath.c_str());

    return false;

  }

  std::string out(IncronTab::GetUserTablePath(rUser));

  if (!tab.Save(out)) {

    fprintf(stderr, "cannot create table for user '%s'\n", rUser.c_str());

    return false;

  }

  return true;

}

/// Removes an user table.

/**

 * \param[in] rUser user name

 * \return true = success, false = failure

 */

bool remove_table(const std::string& rUser)

{

  fprintf(stderr, "removing table for user '%s'\n", rUser.c_str());

  std::string tp(IncronTab::GetUserTablePath(rUser));

  if (unlink(tp.c_str()) != 0) {

    if (errno == ENOENT) {

      fprintf(stderr, "table for user '%s' does not exist\n", rUser.c_str());

      return true;

    }

    else {

      fprintf(stderr, "cannot remove table for user '%s': %s\n", rUser.c_str(), strerror(errno));

      return false;

    }

  }

  fprintf(stderr, "table for user '%s' successfully removed\n", rUser.c_str());  

  return true;

}

/// Lists an user table.

/**

 * \param[in] rUser user name

 * \return true = success, false = failure

 */

bool list_table(const std::string& rUser)

{

  std::string tp(IncronTab::GetUserTablePath(rUser));

  FILE* f = fopen(tp.c_str(), "r");

  if (f == NULL) {

    if (errno == ENOENT) {

      fprintf(stderr, "no table for %s\n", rUser.c_str());

      return true;

    }

    else {

      fprintf(stderr, "cannot read table for '%s': %s\n", rUser.c_str(), strerror(errno));

      return false;

    }

  }

  char s[1024];

  while (fgets(s, 1024, f) != NULL) {

    fputs(s, stdout);

  }

  fclose(f);

  return true;

}

/// Allows to edit an user table.

/**

 * \param[in] rUser user name

 * \return true = success, false = failure

 *

 * \attention This function is very complex and may contain

 *            various bugs including security ones. Please keep

 *            it in mind..

 */

bool edit_table(const std::string& rUser)

{

  std::string tp(IncronTab::GetUserTablePath(rUser));

  struct passwd* ppwd = getpwnam(rUser.c_str());

  if (ppwd == NULL) {

    fprintf(stderr, "cannot find user '%s': %s\n", rUser.c_str(), strerror(errno));

    return false;

  }

  uid_t uid = ppwd->pw_uid;

  uid_t gid = ppwd->pw_gid;

  char s[NAME_MAX];

  strcpy(s, "/tmp/incron.table-XXXXXX");

  uid_t iu = geteuid();

  uid_t ig = getegid();

  if (setegid(gid) != 0 || seteuid(uid) != 0) {

    fprintf(stderr, "cannot change effective UID/GID for user '%s': %s\n", rUser.c_str(), strerror(errno));

    return false;

  }

  int fd = mkstemp(s);

  if (fd == -1) {

    fprintf(stderr, "cannot create temporary file: %s\n", strerror(errno));

    return false;

  }

  bool ok = false;

  FILE* out = NULL;

  FILE* in = NULL;

  time_t mt = (time_t) 0;

  const char* e = NULL;

  std::string ed;

  if (setegid(ig) != 0 || seteuid(iu) != 0) {

    fprintf(stderr, "cannot change effective UID/GID: %s\n", strerror(errno));

    close(fd);

    goto end;

  }

  out = fdopen(fd, "w");

  if (out == NULL) {

    fprintf(stderr, "cannot write to temporary file: %s\n", strerror(errno));

    close(fd);

    goto end;

  }

  in = fopen(tp.c_str(), "r");

  if (in == NULL) {

    if (errno == ENOENT) {

      in = fopen("/dev/null", "r");

      if (in == NULL) {

        fprintf(stderr, "cannot get empty table for '%s': %s\n", rUser.c_str(), strerror(errno));

        fclose(out);

        goto end;

      }

    }

    else {

      fprintf(stderr, "cannot read old table for '%s': %s\n", rUser.c_str(), strerror(errno));

      fclose(out);

      goto end;

    }

  }

  char buf[1024];

  while (fgets(buf, 1024, in) != NULL) {

    fputs(buf, out);

  }

  fclose(in);

  fclose(out);

  struct stat st;

  if (stat(s, &st) != 0) {

    fprintf(stderr, "cannot stat temporary file: %s\n", strerror(errno));

    goto end;

  }

  mt = st.st_mtime; // save modification time for detecting its change

  // Editor selecting algorithm:

  // 1. Check EDITOR environment variable

  // 2. Check VISUAL environment variable

  // 3. Try to get from configuration

  // 4. Check presence of /etc/alternatives/editor

  // 5. Use hard-wired editor

  e = getenv("EDITOR");

  if (e == NULL) {

    e = getenv("VISUAL");

    if (e == NULL) {

      if (!IncronCfg::GetValue("editor", ed))

        throw InotifyException("configuration is corrupted", EINVAL);

      if (!ed.empty()) {

        e = ed.c_str();

      }

      else {

        if (access(INCRON_ALT_EDITOR, X_OK) == 0)

          e = INCRON_ALT_EDITOR;

        else

          e = INCRON_DEFAULT_EDITOR;

      }

    }

  }

  // this block is explicite due to gotos' usage simplification

  {

    pid_t pid = fork();

    if (pid == 0) {

      if (setgid(gid) != 0 || setuid(uid) != 0) {

        fprintf(stderr, "cannot set user '%s': %s\n", rUser.c_str(), strerror(errno));

        goto end;

      }    

      execlp(e, e, s, (const char*) NULL);

      _exit(1);

    }

    else if (pid > 0) {

      int status;

      if (wait(&status) != pid) {

        perror("error while waiting for editor");

        goto end;

      }

      if (!(WIFEXITED(status)) || WEXITSTATUS(status) != 0) {

        perror("editor finished with error");

        goto end;

      }

    }

    else {

      perror("cannot start editor");

      goto end;

    }

  }

  if (stat(s, &st) != 0) {

    fprintf(stderr, "cannot stat temporary file: %s\n", strerror(errno));

    goto end;

  }

  if (st.st_mtime == mt) {

    fprintf(stderr, "table unchanged\n");

    ok = true;

    goto end;

  }

  {

    IncronTab ict;

    if (ict.Load(s) && ict.Save(tp)) {

      if (chmod(tp.c_str(), S_IRUSR | S_IWUSR) != 0) {

        fprintf(stderr, "cannot change mode of temporary file: %s\n", strerror(errno));

      }

    }

    else {

      fprintf(stderr, "cannot move temporary table: %s\n", strerror(errno));

      goto end;

    }

  }

  ok = true;

  fprintf(stderr, "table updated\n");

end:  

  unlink(s);

  return ok;

}

/// Prints the list of all available inotify event types.

void list_types()

{

  printf( "IN_ACCESS,IN_MODIFY,IN_ATTRIB,IN_CLOSE_WRITE,"\

          "IN_CLOSE_NOWRITE,IN_OPEN,IN_MOVED_FROM,IN_MOVED_TO,"\

          "IN_CREATE,IN_DELETE,IN_DELETE_SELF,IN_CLOSE,IN_MOVE,"\

          "IN_ONESHOT,IN_ALL_EVENTS");

#ifdef IN_DONT_FOLLOW

  printf(",IN_DONT_FOLLOW");

#endif // IN_DONT_FOLLOW

#ifdef IN_ONLYDIR

  printf(",IN_ONLYDIR");

#endif // IN_ONLYDIR

#ifdef IN_MOVE_SELF

  printf(",IN_MOVE_SELF");

#endif // IN_MOVE_SELF

  printf("\n");

}

/// Reloads an user table.

/**

 * \param[in] rUser user name

 * \return true = success, false = otherwise

 */

bool reload_table(const std::string& rUser)

{

  fprintf(stderr, "requesting table reload for user '%s'...\n", rUser.c_str());

  std::string tp(IncronTab::GetUserTablePath(rUser));

  int fd = open(tp.c_str(), O_WRONLY | O_APPEND);

  if (fd == -1) {

    if (errno == ENOENT) {

      fprintf(stderr, "no table for '%s'\n", rUser.c_str());

      return true;

    }

    else {

      fprintf(stderr, "cannot access table for '%s': %s\n", rUser.c_str(), strerror(errno));

      return false;

    }

  }

  close(fd);

  fprintf(stderr, "request done\n");

  return true;

}

int main(int argc, char** argv)

{

  AppArgs::Init();

  if (!(  AppArgs::AddOption("about",   '?', AAT_NO_VALUE, false)

      &&  AppArgs::AddOption("help",    'h', AAT_NO_VALUE, false)

      &&  AppArgs::AddOption("list",    'l', AAT_NO_VALUE, false)

      &&  AppArgs::AddOption("remove",  'r', AAT_NO_VALUE, false)

      &&  AppArgs::AddOption("edit",    'e', AAT_NO_VALUE, false)

      &&  AppArgs::AddOption("types",   't', AAT_NO_VALUE, false)

      &&  AppArgs::AddOption("reload",  'd', AAT_NO_VALUE, false)

      &&  AppArgs::AddOption("user",    'u', AAT_MANDATORY_VALUE, false)

      &&  AppArgs::AddOption("config",  'f', AAT_MANDATORY_VALUE, false)

      &&  AppArgs::AddOption("version", 'V', AAT_NO_VALUE, false)))

  {

    fprintf(stderr, "error while initializing application");

    return 1;

  }

  AppArgs::Parse(argc, argv);

  if (AppArgs::ExistsOption("help")) {

    fprintf(stderr, "%s\n", INCRONTAB_HELP);

    return 0;

  }

  if (AppArgs::ExistsOption("about")) {

    fprintf(stderr, "%s\n", INCRONTAB_DESCRIPTION);

    return 0;

  }

  if (AppArgs::ExistsOption("version")) {

    fprintf(stderr, "%s\n", INCRONTAB_VERSION);

    return 0;

  }

  bool oper = AppArgs::ExistsOption("list")

          ||  AppArgs::ExistsOption("remove")

          ||  AppArgs::ExistsOption("edit")

          ||  AppArgs::ExistsOption("types")

          ||  AppArgs::ExistsOption("reload");

  size_t vals = AppArgs::GetValueCount();          

  if (!oper && vals == 0) {

    fprintf(stderr, "invalid arguments - specify operation or source file\n");

    return 1;

  }

  if (oper && vals > 0) {

    fprintf(stderr, "invalid arguments - operation and source file cannot be combined\n");

    return 1;

  }

  uid_t uid = getuid();

  std::string user;

  bool chuser = AppArgs::GetOption("user", user);

  if (uid != 0 && chuser) {

    fprintf(stderr, "cannot override user to '%s': insufficient privileges\n", user.c_str());

    return 1;

  }

  struct passwd pwd;

  if (!chuser) {

    struct passwd* ppwd = getpwuid(uid);

    if (ppwd == NULL) {

      fprintf(stderr, "cannot determine current user\n");

      return 1;

    }

    memcpy(&pwd, ppwd, sizeof(pwd));

    user = pwd.pw_name;

  }

  else if (getpwnam(user.c_str()) == NULL) {

    fprintf(stderr, "user '%s' not found\n", user.c_str());

    return 1;

  }

  else if ( setenv("LOGNAME",   pwd.pw_name,   1) != 0

        ||  setenv("USER",      pwd.pw_name,   1) != 0

        ||  setenv("USERNAME",  pwd.pw_name,   1) != 0

        ||  setenv("HOME",      pwd.pw_dir,    1) != 0

        ||  setenv("SHELL",     pwd.pw_shell,  1) != 0)

  {

    perror("cannot set environment variables");

    return 1;

  }

  try {

    IncronCfg::Init();

    std::string cfg(INCRON_CONFIG);

    if (AppArgs::GetOption("config", cfg)) {

      if (uid != 0) {

        fprintf(stderr, "insufficient privileges to use custom configuration (will use default)\n");

      }

      else if (euidaccess(cfg.c_str(), R_OK) != 0) {

        perror("cannot read configuration file (will use default)");

      }

    }

    IncronCfg::Load(cfg);

    if (!IncronTab::CheckUser(user)) {

      fprintf(stderr, "user '%s' is not allowed to use incron\n", user.c_str());

      return 1;

    }

    if (!oper) {

      std::string file;

      if (!AppArgs::GetValue(0, file)

          || !copy_from_file(file, user))

      {

        return 1;

      }

    }

    else {

      if (AppArgs::ExistsOption("list")) {

        if (!list_table(user))

          return 1;

      }

      else if (AppArgs::ExistsOption("remove")) {

        if (!remove_table(user))

          return 1;

      }

      else if (AppArgs::ExistsOption("edit")) {

        if (!edit_table(user))

          return 1;

      }

      else if (AppArgs::ExistsOption("types")) {

        list_types();

      }

      else if (AppArgs::ExistsOption("reload")) {

        if (!reload_table(user))

          return 1;

      }

      else {

        fprintf(stderr, "invalid usage\n");

        return 1;

      }

    }

    return 0;    

  } catch (InotifyException e) {

    fprintf(stderr, "*** unhandled exception occurred ***\n");

    fprintf(stderr, "%s\n", e.GetMessage().c_str());

    fprintf(stderr, "error: (%i) %s\n", e.GetErrorNumber(), strerror(e.GetErrorNumber()));

    return 1;

  }

}