/* Copyright (c) 2003, Roger Dingledine

 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.

 * Copyright (c) 2007-2018, The Tor Project, Inc. */

/* See LICENSE for licensing information */

/**

 * \file path.c

 *

 * \brief Manipulate strings that contain filesystem paths.

 **/

#include "lib/fs/path.h"

#include "lib/malloc/malloc.h"

#include "lib/log/log.h"

#include "lib/log/util_bug.h"

#include "lib/string/printf.h"

#include "lib/string/util_string.h"

#include "lib/string/compat_ctype.h"

#include "lib/fs/userdb.h"

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#include <errno.h>

#include <string.h>

/** Removes enclosing quotes from <b>path</b> and unescapes quotes between the

 * enclosing quotes. Backslashes are not unescaped. Return the unquoted

 * <b>path</b> on success or 0 if <b>path</b> is not quoted correctly. */

char *

get_unquoted_path(const char *path)

{

  size_t len = strlen(path);

  if (len == 0) {

    return tor_strdup("");

  }

  int has_start_quote = (path[0] == '\"');

  int has_end_quote = (len > 0 && path[len-1] == '\"');

  if (has_start_quote != has_end_quote || (len == 1 && has_start_quote)) {

    return NULL;

  }

  char *unquoted_path = tor_malloc(len - has_start_quote - has_end_quote + 1);

  char *s = unquoted_path;

  size_t i;

  for (i = has_start_quote; i < len - has_end_quote; i++) {

    if (path[i] == '\"' && (i > 0 && path[i-1] == '\\')) {

      *(s-1) = path[i];

    } else if (path[i] != '\"') {

      *s++ = path[i];

    } else {  /* unescaped quote */

      tor_free(unquoted_path);

      return NULL;

    }

  }

  *s = '\0';

  return unquoted_path;

}

/** Expand any homedir prefix on <b>filename</b>; return a newly allocated

 * string. */

char *

expand_filename(const char *filename)

{

  tor_assert(filename);

#ifdef _WIN32

  /* Might consider using GetFullPathName() as described here:

   * http://etutorials.org/Programming/secure+programming/

   *     Chapter+3.+Input+Validation/3.7+Validating+Filenames+and+Paths/

   */

  return tor_strdup(filename);

#else /* !(defined(_WIN32)) */

  if (*filename == '~') {

    char *home, *result=NULL;

    const char *rest;

    if (filename[1] == '/' || filename[1] == '\0') {

      home = getenv("HOME");

      if (!home) {

        log_warn(LD_CONFIG, "Couldn't find $HOME environment variable while "

                 "expanding \"%s\"; defaulting to \"\".", filename);

        home = tor_strdup("");

      } else {

        home = tor_strdup(home);

      }

      rest = strlen(filename)>=2?(filename+2):"";

    } else {

#ifdef HAVE_PWD_H

      char *username, *slash;

      slash = strchr(filename, '/');

      if (slash)

        username = tor_strndup(filename+1,slash-filename-1);

      else

        username = tor_strdup(filename+1);

      if (!(home = get_user_homedir(username))) {

        log_warn(LD_CONFIG,"Couldn't get homedir for \"%s\"",username);

        tor_free(username);

        return NULL;

      }

      tor_free(username);

      rest = slash ? (slash+1) : "";

#else /* !(defined(HAVE_PWD_H)) */

      log_warn(LD_CONFIG, "Couldn't expand homedir on system without pwd.h");

      return tor_strdup(filename);

#endif /* defined(HAVE_PWD_H) */

    }

    tor_assert(home);

    /* Remove trailing slash. */

    if (strlen(home)>1 && !strcmpend(home,PATH_SEPARATOR)) {

      home[strlen(home)-1] = '\0';

    }

    tor_asprintf(&result,"%s"PATH_SEPARATOR"%s",home,rest);

    tor_free(home);

    return result;

  } else {

    return tor_strdup(filename);

  }

#endif /* defined(_WIN32) */

}

/** Return true iff <b>filename</b> is a relative path. */

int

path_is_relative(const char *filename)

{

  if (filename && filename[0] == '/')

    return 0;

#ifdef _WIN32

  else if (filename && filename[0] == '\\')

    return 0;

  else if (filename && strlen(filename)>3 && TOR_ISALPHA(filename[0]) &&

           filename[1] == ':' && filename[2] == '\\')

    return 0;

#endif /* defined(_WIN32) */

  else

    return 1;

}

/** Clean up <b>name</b> so that we can use it in a call to "stat".  On Unix,

 * we do nothing.  On Windows, we remove a trailing slash, unless the path is

 * the root of a disk. */

void

clean_fname_for_stat(char *name)

{

#ifdef _WIN32

  size_t len = strlen(name);

  if (!len)

    return;

  if (name[len-1]=='\\' || name[len-1]=='/') {

    if (len == 1 || (len==3 && name[1]==':'))

      return;

    name[len-1]='\0';

  }

#else /* !(defined(_WIN32)) */

  (void)name;

#endif /* defined(_WIN32) */

}

/** Modify <b>fname</b> to contain the name of its parent directory.  Doesn't

 * actually examine the filesystem; does a purely syntactic modification.

 *

 * The parent of the root director is considered to be iteself.

 *

 * Path separators are the forward slash (/) everywhere and additionally

 * the backslash (\) on Win32.

 *

 * Cuts off any number of trailing path separators but otherwise ignores

 * them for purposes of finding the parent directory.

 *

 * Returns 0 if a parent directory was successfully found, -1 otherwise (fname

 * did not have any path separators or only had them at the end).

 * */

int

get_parent_directory(char *fname)

{

  char *cp;

  int at_end = 1;

  tor_assert(fname);

#ifdef _WIN32

  /* If we start with, say, c:, then don't consider that the start of the path

   */

  if (fname[0] && fname[1] == ':') {

    fname += 2;

  }

#endif /* defined(_WIN32) */

  /* Now we want to remove all path-separators at the end of the string,

   * and to remove the end of the string starting with the path separator

   * before the last non-path-separator.  In perl, this would be

   *   s#[/]*$##; s#/[^/]*$##;

   * on a unixy platform.

   */

  cp = fname + strlen(fname);

  at_end = 1;

  while (--cp >= fname) {

    int is_sep = (*cp == '/'

#ifdef _WIN32

                  || *cp == '\\'

#endif

                  );

    if (is_sep) {

      if (cp == fname) {

        /* This is the first separator in the file name; don't remove it! */

        cp[1] = '\0';

        return 0;

      }

      *cp = '\0';

      if (! at_end)

        return 0;

    } else {

      at_end = 0;

    }

  }

  return -1;

}

#ifndef _WIN32

/** Return a newly allocated string containing the output of getcwd(). Return

 * NULL on failure. (We can't just use getcwd() into a PATH_MAX buffer, since

 * Hurd hasn't got a PATH_MAX.)

 */

static char *

alloc_getcwd(void)

{

#ifdef HAVE_GET_CURRENT_DIR_NAME

  /* Glibc makes this nice and simple for us. */

  char *cwd = get_current_dir_name();

  char *result = NULL;

  if (cwd) {

    /* We make a copy here, in case tor_malloc() is not malloc(). */

    result = tor_strdup(cwd);

    raw_free(cwd); // alias for free to avoid tripping check-spaces.

  }

  return result;

#else /* !(defined(HAVE_GET_CURRENT_DIR_NAME)) */

  size_t size = 1024;

  char *buf = NULL;

  char *ptr = NULL;

  while (ptr == NULL) {

    buf = tor_realloc(buf, size);

    ptr = getcwd(buf, size);

    if (ptr == NULL && errno != ERANGE) {

      tor_free(buf);

      return NULL;

    }

    size *= 2;

  }

  return buf;

#endif /* defined(HAVE_GET_CURRENT_DIR_NAME) */

}

#endif /* !defined(_WIN32) */

/** Expand possibly relative path <b>fname</b> to an absolute path.

 * Return a newly allocated string, possibly equal to <b>fname</b>. */

char *

make_path_absolute(char *fname)

{

#ifdef _WIN32

  char *absfname_malloced = _fullpath(NULL, fname, 1);

  /* We don't want to assume that tor_free can free a string allocated

   * with malloc.  On failure, return fname (it's better than nothing). */

  char *absfname = tor_strdup(absfname_malloced ? absfname_malloced : fname);

  if (absfname_malloced) raw_free(absfname_malloced);

  return absfname;

#else /* !(defined(_WIN32)) */

  char *absfname = NULL, *path = NULL;

  tor_assert(fname);

  if (fname[0] == '/') {

    absfname = tor_strdup(fname);

  } else {

    path = alloc_getcwd();

    if (path) {

      tor_asprintf(&absfname, "%s/%s", path, fname);

      tor_free(path);

    } else {

      /* LCOV_EXCL_START Can't make getcwd fail. */

      /* If getcwd failed, the best we can do here is keep using the

       * relative path.  (Perhaps / isn't readable by this UID/GID.) */

      log_warn(LD_GENERAL, "Unable to find current working directory: %s",

               strerror(errno));

      absfname = tor_strdup(fname);

      /* LCOV_EXCL_STOP */

    }

  }

  return absfname;

#endif /* defined(_WIN32) */

}