/*
 * This file Copyright (C) 2013-2014 Mnemosyne LLC
 *
 * It may be used under the GNU GPL versions 2 or 3
 * or any future license endorsed by Mnemosyne LLC.
 *
 * $Id$
 */

#if defined (HAVE_MKDTEMP) && (!defined (_XOPEN_SOURCE) || _XOPEN_SOURCE < 700)
 #undef _XOPEN_SOURCE
 #define _XOPEN_SOURCE 700
#elif (defined (HAVE_POSIX_FADVISE) || defined (HAVE_POSIX_FALLOCATE)) && (!defined (_XOPEN_SOURCE) || _XOPEN_SOURCE < 600)
 #undef _XOPEN_SOURCE
 #define _XOPEN_SOURCE 600
#endif

#if (defined (HAVE_FALLOCATE64) || defined (HAVE_CANONICALIZE_FILE_NAME)) && !defined (_GNU_SOURCE)
 #define _GNU_SOURCE
#endif

#if defined (__APPLE__) && !defined (_DARWIN_C_SOURCE)
 #define _DARWIN_C_SOURCE
#endif

#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h> /* O_LARGEFILE, posix_fadvise (), [posix_]fallocate () */
#include <libgen.h> /* basename (), dirname () */
#include <limits.h> /* PATH_MAX */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h> /* mmap (), munmap () */
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h> /* lseek (), write (), ftruncate (), pread (), pwrite (), pathconf (), etc */

#ifdef HAVE_XFS_XFS_H
 #include <xfs/xfs.h>
#endif

#include "transmission.h"
#include "error.h"
#include "file.h"
#include "log.h"
#include "platform.h"
#include "utils.h"

#ifndef O_LARGEFILE
 #define O_LARGEFILE 0
#endif
#ifndef O_BINARY
 #define O_BINARY 0
#endif
#ifndef O_SEQUENTIAL
 #define O_SEQUENTIAL 0
#endif
#ifndef O_CLOEXEC
 #define O_CLOEXEC 0
#endif

#ifndef PATH_MAX
 #define PATH_MAX 4096
#endif

/* don't use pread/pwrite on old versions of uClibc because they're buggy.
 * https://trac.transmissionbt.com/ticket/3826 */
#if defined (__UCLIBC__) && !TR_UCLIBC_CHECK_VERSION (0, 9, 28)
 #undef HAVE_PREAD
 #undef HAVE_PWRITE
#endif

#ifdef __APPLE__
 #ifndef HAVE_PREAD
  #define HAVE_PREAD
 #endif
 #ifndef HAVE_PWRITE
  #define HAVE_PWRITE
 #endif
 #ifndef HAVE_MKDTEMP
  #define HAVE_MKDTEMP
 #endif
#endif

static void
set_system_error (tr_error ** error,
                  int         code)
{
  if (error == NULL)
    return;

  tr_error_set_literal (error, code, tr_strerror (code));
}

static void
set_system_error_if_file_found (tr_error ** error,
                                int         code)
{
  if (code != ENOENT)
    set_system_error (error, code);
}

static void
stat_to_sys_path_info (const struct stat * sb,
                       tr_sys_path_info  * info)
{
  if (S_ISREG (sb->st_mode))
    info->type = TR_SYS_PATH_IS_FILE;
  else if (S_ISDIR (sb->st_mode))
    info->type = TR_SYS_PATH_IS_DIRECTORY;
  else
    info->type = TR_SYS_PATH_IS_OTHER;

  info->size = (uint64_t) sb->st_size;
  info->last_modified_at = sb->st_mtime;
}

static void
set_file_for_single_pass (tr_sys_file_t handle)
{
  /* Set hints about the lookahead buffer and caching. It's okay
     for these to fail silently, so don't let them affect errno */

  const int err = errno;

  if (handle == TR_BAD_SYS_FILE)
    return;

#ifdef HAVE_POSIX_FADVISE

  (void) posix_fadvise (handle, 0, 0, POSIX_FADV_SEQUENTIAL);

#endif

#ifdef __APPLE__

  (void) fcntl (handle, F_RDAHEAD, 1);
  (void) fcntl (handle, F_NOCACHE, 1);

#endif

  errno = err;
}

#ifndef HAVE_MKDIRP

static bool
create_path (const char  * path_in,
             int           permissions,
             tr_error   ** error)
{
  char * p;
  char * pp;
  bool done;
  int tmperr;
  int rv;
  struct stat sb;
  char * path;

  /* make a temporary copy of path */
  path = tr_strdup (path_in);

  /* walk past the root */
  p = path;
  while (*p == TR_PATH_DELIMITER)
    ++p;

  pp = p;
  done = false;
  while ((p = strchr (pp, TR_PATH_DELIMITER)) || (p = strchr (pp, '\0')))
    {
      if (!*p)
        done = true;
      else
        *p = '\0';

      tmperr = errno;
      rv = stat (path, &sb);
      errno = tmperr;
      if (rv)
        {
          tr_error * my_error = NULL;

          /* Folder doesn't exist yet */
          if (!tr_sys_dir_create (path, 0, permissions, &my_error))
            {
              tr_logAddError (_ ("Couldn't create \"%1$s\": %2$s"), path, my_error->message);
              tr_free (path);
              tr_error_propagate (error, &my_error);
              return false;
            }
        }
      else if ((sb.st_mode & S_IFMT) != S_IFDIR)
        {
          /* Node exists but isn't a folder */
          char * const buf = tr_strdup_printf (_ ("File \"%s\" is in the way"), path);
          tr_logAddError (_ ("Couldn't create \"%1$s\": %2$s"), path_in, buf);
          tr_free (buf);
          tr_free (path);
          set_system_error (error, ENOTDIR);
          return false;
        }

      if (done)
        break;

      *p = TR_PATH_DELIMITER;
      p++;
      pp = p;
    }

  tr_free (path);
  return true;
}

#endif

bool
tr_sys_path_exists (const char  * path,
                    tr_error   ** error)
{
  bool ret;

  assert (path != NULL);

  ret = access (path, F_OK) != -1;

  if (!ret)
    set_system_error_if_file_found (error, errno);

  return ret;
}

bool
tr_sys_path_get_info (const char        * path,
                      int                 flags,
                      tr_sys_path_info  * info,
                      tr_error         ** error)
{
  bool ret;
  struct stat sb;

  assert (path != NULL);
  assert (info != NULL);

  if ((flags & TR_SYS_PATH_NO_FOLLOW) == 0)
    ret = stat (path, &sb) != -1;
  else
    ret = lstat (path, &sb) != -1;

  if (ret)
    stat_to_sys_path_info (&sb, info);
  else
    set_system_error (error, errno);

  return ret;
}

bool
tr_sys_path_is_same (const char  * path1,
                     const char  * path2,
                     tr_error   ** error)
{
  bool ret = false;
  struct stat sb1, sb2;

  assert (path1 != NULL);
  assert (path2 != NULL);

  if (stat (path1, &sb1) != -1 && stat (path2, &sb2) != -1)
    ret = sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino;
  else
    set_system_error_if_file_found (error, errno);

  return ret;
}

char *
tr_sys_path_resolve (const char  * path,
                     tr_error   ** error)
{
  char * ret = NULL;
  char * tmp = NULL;

  assert (path != NULL);

#if defined (HAVE_CANONICALIZE_FILE_NAME)

  ret = canonicalize_file_name (path);

#endif

#if defined (_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200809L

  /* Better safe than sorry: realpath () officially supports NULL as destination
     starting off POSIX.1-2008. */

  if (ret == NULL)
    ret = realpath (path, NULL);

#endif

  if (ret == NULL)
    {
      tmp = tr_new (char, PATH_MAX);
      ret = realpath (path, tmp);
      if (ret != NULL)
        ret = tr_strdup (ret);
    }

  if (ret == NULL)
    set_system_error (error, errno);

  tr_free (tmp);

  return ret;
}

char *
tr_sys_path_basename (const char  * path,
                      tr_error   ** error)
{
  char * ret = NULL;
  char * tmp;

  assert (path != NULL);

  tmp = tr_strdup (path);
  ret = basename (tmp);
  if (ret != NULL)
    ret = tr_strdup (ret);
  else
    set_system_error (error, errno);

  tr_free (tmp);

  return ret;
}

char *
tr_sys_path_dirname (const char  * path,
                     tr_error   ** error)
{
  char * ret = NULL;
  char * tmp;

  assert (path != NULL);

  tmp = tr_strdup (path);
  ret = dirname (tmp);
  if (ret != NULL)
    ret = tr_strdup (ret);
  else
    set_system_error (error, errno);

  tr_free (tmp);

  return ret;
}

bool
tr_sys_path_rename (const char  * src_path,
                    const char  * dst_path,
                    tr_error   ** error)
{
  bool ret;

  assert (src_path != NULL);
  assert (dst_path != NULL);

  ret = rename (src_path, dst_path) != -1;

  if (!ret)
    set_system_error (error, errno);

  return ret;
}

bool
tr_sys_path_remove (const char  * path,
                    tr_error   ** error)
{
  bool ret;

  assert (path != NULL);

  ret = remove (path) != -1;

  if (!ret)
    set_system_error (error, errno);

  return ret;
}

tr_sys_file_t
tr_sys_file_get_std (tr_std_sys_file_t    std_file,
                     tr_error          ** error)
{
  tr_sys_file_t ret = TR_BAD_SYS_FILE;

  switch (std_file)
    {
    case TR_STD_SYS_FILE_IN:
      ret = STDIN_FILENO;
      break;
    case TR_STD_SYS_FILE_OUT:
      ret = STDOUT_FILENO;
      break;
    case TR_STD_SYS_FILE_ERR:
      ret = STDERR_FILENO;
      break;
    default:
      assert (0 && "Unknown standard file");
      set_system_error (error, EINVAL);
    }

  return ret;
}

tr_sys_file_t
tr_sys_file_open (const char  * path,
                  int           flags,
                  int           permissions,
                  tr_error   ** error)
{
  tr_sys_file_t ret;
  int native_flags = 0;

  assert (path != NULL);
  assert ((flags & (TR_SYS_FILE_READ | TR_SYS_FILE_WRITE)) != 0);

  if ((flags & (TR_SYS_FILE_READ | TR_SYS_FILE_WRITE)) == (TR_SYS_FILE_READ | TR_SYS_FILE_WRITE))
    native_flags |= O_RDWR;
  else if (flags & TR_SYS_FILE_READ)
    native_flags |= O_RDONLY;
  else if (flags & TR_SYS_FILE_WRITE)
    native_flags |= O_WRONLY;

  native_flags |=
    (flags & TR_SYS_FILE_CREATE ? O_CREAT : 0) |
    (flags & TR_SYS_FILE_CREATE_NEW ? O_CREAT | O_EXCL : 0) |
    (flags & TR_SYS_FILE_APPEND ? O_APPEND : 0) |
    (flags & TR_SYS_FILE_TRUNCATE ? O_TRUNC : 0) |
    (flags & TR_SYS_FILE_SEQUENTIAL ? O_SEQUENTIAL : 0) |
    O_BINARY | O_LARGEFILE | O_CLOEXEC;

  ret = open (path, native_flags, permissions);

  if (ret != TR_BAD_SYS_FILE)
    {
      if (flags & TR_SYS_FILE_SEQUENTIAL)
        set_file_for_single_pass (ret);
    }
  else
    {
      set_system_error (error, errno);
    }

  return ret;
}

tr_sys_file_t
tr_sys_file_open_temp (char      * path_template,
                       tr_error ** error)
{
  tr_sys_file_t ret;

  assert (path_template != NULL);

  ret = mkstemp (path_template);

  if (ret == TR_BAD_SYS_FILE)
    set_system_error (error, errno);

  set_file_for_single_pass (ret);

  return ret;
}

bool
tr_sys_file_close (tr_sys_file_t    handle,
                   tr_error      ** error)
{
  bool ret;

  assert (handle != TR_BAD_SYS_FILE);

  ret = close (handle) != -1;

  if (!ret)
    set_system_error (error, errno);

  return ret;
}

bool
tr_sys_file_get_info (tr_sys_file_t       handle,
                      tr_sys_path_info  * info,
                      tr_error         ** error)
{
  bool ret;
  struct stat sb;

  assert (handle != TR_BAD_SYS_FILE);
  assert (info != NULL);

  ret = fstat (handle, &sb) != -1;

  if (ret)
    stat_to_sys_path_info (&sb, info);
  else
    set_system_error (error, errno);

  return ret;
}

bool
tr_sys_file_seek (tr_sys_file_t       handle,
                  int64_t             offset,
                  tr_seek_origin_t    origin,
                  uint64_t          * new_offset,
                  tr_error         ** error)
{
  bool ret = false;
  off_t my_new_offset;

  TR_STATIC_ASSERT (TR_SEEK_SET == SEEK_SET, "values should match");
  TR_STATIC_ASSERT (TR_SEEK_CUR == SEEK_CUR, "values should match");
  TR_STATIC_ASSERT (TR_SEEK_END == SEEK_END, "values should match");

  TR_STATIC_ASSERT (sizeof (*new_offset) >= sizeof (my_new_offset), "");

  assert (handle != TR_BAD_SYS_FILE);
  assert (origin == TR_SEEK_SET || origin == TR_SEEK_CUR || origin == TR_SEEK_END);

  my_new_offset = lseek (handle, offset, origin);

  if (my_new_offset != -1)
    {
      if (new_offset != NULL)
        *new_offset = my_new_offset;
      ret = true;
    }
  else
    {
      set_system_error (error, errno);
    }

  return ret;
}

bool
tr_sys_file_read (tr_sys_file_t    handle,
                  void           * buffer,
                  uint64_t         size,
                  uint64_t       * bytes_read,
                  tr_error      ** error)
{
  bool ret = false;
  ssize_t my_bytes_read;

  TR_STATIC_ASSERT (sizeof (*bytes_read) >= sizeof (my_bytes_read), "");

  assert (handle != TR_BAD_SYS_FILE);
  assert (buffer != NULL || size == 0);

  my_bytes_read = read (handle, buffer, size);

  if (my_bytes_read != -1)
    {
      if (bytes_read != NULL)
        *bytes_read = my_bytes_read;
      ret = true;
    }
  else
    {
      set_system_error (error, errno);
    }

  return ret;
}

bool
tr_sys_file_read_at (tr_sys_file_t    handle,
                     void           * buffer,
                     uint64_t         size,
                     uint64_t         offset,
                     uint64_t       * bytes_read,
                     tr_error      ** error)
{
  bool ret = false;
  ssize_t my_bytes_read;

  TR_STATIC_ASSERT (sizeof (*bytes_read) >= sizeof (my_bytes_read), "");

  assert (handle != TR_BAD_SYS_FILE);
  assert (buffer != NULL || size == 0);
  /* seek requires signed offset, so it should be in mod range */
  assert (offset < UINT64_MAX / 2);

#ifdef HAVE_PREAD

  my_bytes_read = pread (handle, buffer, size, offset);

#else

  if (lseek (handle, offset, SEEK_SET) != -1)
    my_bytes_read = read (handle, buffer, size);
  else
    my_bytes_read = -1;

#endif

  if (my_bytes_read != -1)
    {
      if (bytes_read != NULL)
        *bytes_read = my_bytes_read;
      ret = true;
    }
  else
    {
      set_system_error (error, errno);
    }

  return ret;
}

bool
tr_sys_file_write (tr_sys_file_t    handle,
                   const void     * buffer,
                   uint64_t         size,
                   uint64_t       * bytes_written,
                   tr_error      ** error)
{
  bool ret = false;
  ssize_t my_bytes_written;

  TR_STATIC_ASSERT (sizeof (*bytes_written) >= sizeof (my_bytes_written), "");

  assert (handle != TR_BAD_SYS_FILE);
  assert (buffer != NULL || size == 0);

  my_bytes_written = write (handle, buffer, size);

  if (my_bytes_written != -1)
    {
      if (bytes_written != NULL)
        *bytes_written = my_bytes_written;
      ret = true;
    }
  else
    {
      set_system_error (error, errno);
    }

  return ret;
}

bool
tr_sys_file_write_at (tr_sys_file_t    handle,
                      const void     * buffer,
                      uint64_t         size,
                      uint64_t         offset,
                      uint64_t       * bytes_written,
                      tr_error      ** error)
{
  bool ret = false;
  ssize_t my_bytes_written;

  TR_STATIC_ASSERT (sizeof (*bytes_written) >= sizeof (my_bytes_written), "");

  assert (handle != TR_BAD_SYS_FILE);
  assert (buffer != NULL || size == 0);
  /* seek requires signed offset, so it should be in mod range */
  assert (offset < UINT64_MAX / 2);

#ifdef HAVE_PWRITE

  my_bytes_written = pwrite (handle, buffer, size, offset);

#else

  if (lseek (handle, offset, SEEK_SET) != -1)
    my_bytes_written = write (handle, buffer, size);
  else
    my_bytes_written = -1;

#endif

  if (my_bytes_written != -1)
    {
      if (bytes_written != NULL)
        *bytes_written = my_bytes_written;
      ret = true;
    }
  else
    {
      set_system_error (error, errno);
    }

  return ret;
}

bool
tr_sys_file_flush (tr_sys_file_t    handle,
                   tr_error      ** error)
{
  bool ret;

  assert (handle != TR_BAD_SYS_FILE);

  ret = fsync (handle) != -1;

  if (!ret)
    set_system_error (error, errno);

  return ret;
}

bool
tr_sys_file_truncate (tr_sys_file_t    handle,
                      uint64_t         size,
                      tr_error      ** error)
{
  bool ret;

  assert (handle != TR_BAD_SYS_FILE);

  ret = ftruncate (handle, size) != -1;

  if (!ret)
    set_system_error (error, errno);

  return ret;
}

bool
tr_sys_file_prefetch (tr_sys_file_t    handle,
                      uint64_t         offset,
                      uint64_t         size,
                      tr_error      ** error)
{
  bool ret = false;

#if defined (HAVE_POSIX_FADVISE)

  int code;

  assert (handle != TR_BAD_SYS_FILE);
  assert (size > 0);

  code = posix_fadvise (handle, offset, size, POSIX_FADV_WILLNEED);

  if (code == 0)
    ret = true;
  else
    set_system_error (error, code);

#elif defined (__APPLE__)

  struct radvisory radv;

  assert (handle != TR_BAD_SYS_FILE);
  assert (size > 0);

  radv.ra_offset = offset;
  radv.ra_count = size;

  ret = fcntl (handle, F_RDADVISE, &radv) != -1;

  if (!ret)
    set_system_error (error, errno);

#endif

  return ret;
}

bool
tr_sys_file_preallocate (tr_sys_file_t    handle,
                         uint64_t         size,
                         int              flags,
                         tr_error      ** error)
{
  bool ret = false;

  assert (handle != TR_BAD_SYS_FILE);

  errno = 0;

#ifdef HAVE_FALLOCATE64

  /* fallocate64 is always preferred, so try it first */
  ret = fallocate64 (handle, 0, 0, size) != -1;

  if (ret || errno == ENOSPC)
    goto out;

#endif

  if ((flags & TR_SYS_FILE_PREALLOC_SPARSE) == 0)
    {
      int code = errno;

#ifdef HAVE_XFS_XFS_H

      if (platform_test_xfs_fd (handle))
        {
          xfs_flock64_t fl;

          fl.l_whence = 0;
          fl.l_start = 0;
          fl.l_len = size;

          ret = xfsctl (NULL, handle, XFS_IOC_RESVSP64, &fl) != -1;

          if (ret)
            ret = ftruncate (handle, size) != -1;

          code = errno;

          if (ret || code == ENOSPC)
            goto non_sparse_out;
        }

#endif

#ifdef __APPLE__

      {
        fstore_t fst;

        fst.fst_flags = F_ALLOCATEALL;
        fst.fst_posmode = F_PEOFPOSMODE;
        fst.fst_offset = 0;
        fst.fst_length = size;
        fst.fst_bytesalloc = 0;

        ret = fcntl (handle, F_PREALLOCATE, &fst) != -1;

        if (ret)
          ret = ftruncate (handle, size) != -1;

        code = errno;

        if (ret || code == ENOSPC)
          goto non_sparse_out;
      }

#endif

#ifdef HAVE_POSIX_FALLOCATE

      code = posix_fallocate (handle, 0, size);
      ret = code == 0;

#endif

non_sparse_out:
      errno = code;
    }

out:
  if (!ret)
    set_system_error (error, errno);

  return ret;
}

void *
tr_sys_file_map_for_reading (tr_sys_file_t    handle,
                             uint64_t         offset,
                             uint64_t         size,
                             tr_error      ** error)
{
  void * ret;

  assert (handle != TR_BAD_SYS_FILE);
  assert (size > 0);

  ret = mmap (NULL, size, PROT_READ, MAP_SHARED, handle, offset);

  if (ret == MAP_FAILED)
    {
      set_system_error (error, errno);
      ret = NULL;
    }

  return ret;
}

bool
tr_sys_file_unmap (const void  * address,
                   uint64_t      size,
                   tr_error   ** error)
{
  bool ret;

  assert (address != NULL);
  assert (size > 0);

  ret = munmap ((void *) address, size) != -1;

  if (!ret)
    set_system_error (error, errno);

  return ret;
}

char *
tr_sys_dir_get_current (tr_error ** error)
{
  char * ret;

  ret = getcwd (NULL, 0);

  if (ret == NULL && (errno == EINVAL || errno == ERANGE))
    {
      size_t size = PATH_MAX;
      char * tmp = NULL;

      do
        {
          tmp = tr_renew (char, tmp, size);
          if (tmp == NULL)
            break;
          ret = getcwd (tmp, size);
          size += 2048;
        }
      while (ret == NULL && errno == ERANGE);

      if (ret == NULL)
        {
          const int err = errno;
          tr_free (tmp);
          errno = err;
        }
    }

  if (ret == NULL)
    set_system_error (error, errno);

  return ret;
}

bool
tr_sys_dir_create (const char  * path,
                   int           flags,
                   int           permissions,
                   tr_error   ** error)
{
  bool ret;
  tr_error * my_error = NULL;

  assert (path != NULL);

  if ((flags & TR_SYS_DIR_CREATE_PARENTS) != 0)
#ifdef HAVE_MKDIRP
    ret = mkdirp (path, permissions) != -1;
#else
    ret = create_path (path, permissions, &my_error);
#endif
  else
    ret = mkdir (path, permissions) != -1;

  if (!ret && errno == EEXIST)
    {
      struct stat sb;

      if (stat (path, &sb) != -1 && S_ISDIR (sb.st_mode))
        {
          tr_error_clear (&my_error);
          ret = true;
        }
      else
        {
          errno = EEXIST;
        }
    }

  if (!ret)
    {
      if (my_error != NULL)
        tr_error_propagate (error, &my_error);
      else
        set_system_error (error, errno);
    }

  return ret;
}

bool
tr_sys_dir_create_temp (char      * path_template,
                        tr_error ** error)
{
  bool ret;

  assert (path_template != NULL);

#ifdef HAVE_MKDTEMP

  ret = mkdtemp (path_template) != NULL;

#else

  ret = mktemp (path_template) != NULL && mkdir (path_template, 0700) != -1;

#endif

  if (!ret)
    set_system_error (error, errno);

  return ret;
}

tr_sys_dir_t
tr_sys_dir_open (const char  * path,
                 tr_error   ** error)
{
  tr_sys_dir_t ret;

#ifndef __clang__
  /* Clang gives "static_assert expression is not an integral constant expression" error */
  TR_STATIC_ASSERT (TR_BAD_SYS_DIR == NULL, "values should match");
#endif

  assert (path != NULL);

  ret = opendir (path);

  if (ret == TR_BAD_SYS_DIR)
    set_system_error (error, errno);

  return ret;
}

const char *
tr_sys_dir_read_name (tr_sys_dir_t    handle,
                      tr_error     ** error)
{
  const char * ret = NULL;
  struct dirent * entry;

  assert (handle != TR_BAD_SYS_DIR);

  errno = 0;
  entry = readdir (handle);

  if (entry != NULL)
    ret = entry->d_name;
  else if (errno != 0)
    set_system_error (error, errno);

  return ret;
}

bool
tr_sys_dir_close (tr_sys_dir_t    handle,
                  tr_error     ** error)
{
  bool ret;

  assert (handle != TR_BAD_SYS_DIR);

  ret = closedir (handle) != -1;

  if (!ret)
    set_system_error (error, errno);

  return ret;
}