src/hb-blob.cc

/*
 * Copyright © 2009  Red Hat, Inc.
 * Copyright © 2018  Ebrahim Byagowi
 *
 *  This is part of HarfBuzz, a text shaping library.
 *
 * Permission is hereby granted, without written agreement and without
 * license or royalty fees, to use, copy, modify, and distribute this
 * software and its documentation for any purpose, provided that the
 * above copyright notice and the following two paragraphs appear in
 * all copies of this software.
 *
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 *
 * Red Hat Author(s): Behdad Esfahbod
 */

/* http://www.oracle.com/technetwork/articles/servers-storage-dev/standardheaderfiles-453865.html */
#ifndef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 200809L
#endif

#include "hb-private.hh"
#include "hb-debug.hh"
#include "hb-blob-private.hh"

#ifdef HAVE_SYS_MMAN_H
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif /* HAVE_UNISTD_H */
#include <sys/mman.h>
#endif /* HAVE_SYS_MMAN_H */

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>


/**
 * hb_blob_create: (skip)
 * @data: Pointer to blob data.
 * @length: Length of @data in bytes.
 * @mode: Memory mode for @data.
 * @user_data: Data parameter to pass to @destroy.
 * @destroy: Callback to call when @data is not needed anymore.
 *
 * Creates a new "blob" object wrapping @data.  The @mode parameter is used
 * to negotiate ownership and lifecycle of @data.
 *
 * Return value: New blob, or the empty blob if something failed or if @length is
 * zero.  Destroy with hb_blob_destroy().
 *
 * Since: 0.9.2
 **/
hb_blob_t *
hb_blob_create (const char        *data,
		unsigned int       length,
		hb_memory_mode_t   mode,
		void              *user_data,
		hb_destroy_func_t  destroy)
{
  hb_blob_t *blob;

  if (!length ||
      length >= 1u << 31 ||
      !(blob = hb_object_create<hb_blob_t> ())) {
    if (destroy)
      destroy (user_data);
    return hb_blob_get_empty ();
  }

  blob->data = data;
  blob->length = length;
  blob->mode = mode;

  blob->user_data = user_data;
  blob->destroy = destroy;

  if (blob->mode == HB_MEMORY_MODE_DUPLICATE) {
    blob->mode = HB_MEMORY_MODE_READONLY;
    if (!blob->try_make_writable ()) {
      hb_blob_destroy (blob);
      return hb_blob_get_empty ();
    }
  }

  return blob;
}

static void
_hb_blob_destroy (void *data)
{
  hb_blob_destroy ((hb_blob_t *) data);
}

/**
 * hb_blob_create_sub_blob:
 * @parent: Parent blob.
 * @offset: Start offset of sub-blob within @parent, in bytes.
 * @length: Length of sub-blob.
 *
 * Returns a blob that represents a range of bytes in @parent.  The new
 * blob is always created with %HB_MEMORY_MODE_READONLY, meaning that it
 * will never modify data in the parent blob.  The parent data is not
 * expected to be modified, and will result in undefined behavior if it
 * is.
 *
 * Makes @parent immutable.
 *
 * Return value: New blob, or the empty blob if something failed or if
 * @length is zero or @offset is beyond the end of @parent's data.  Destroy
 * with hb_blob_destroy().
 *
 * Since: 0.9.2
 **/
hb_blob_t *
hb_blob_create_sub_blob (hb_blob_t    *parent,
			 unsigned int  offset,
			 unsigned int  length)
{
  hb_blob_t *blob;

  if (!length || offset >= parent->length)
    return hb_blob_get_empty ();

  hb_blob_make_immutable (parent);

  blob = hb_blob_create (parent->data + offset,
			 MIN (length, parent->length - offset),
			 HB_MEMORY_MODE_READONLY,
			 hb_blob_reference (parent),
			 _hb_blob_destroy);

  return blob;
}

/**
 * hb_blob_copy_writable_or_fail:
 * @blob: A blob.
 *
 * Makes a writable copy of @blob.
 *
 * Return value: New blob, or nullptr if allocation failed.
 *
 * Since: 1.8.0
 **/
hb_blob_t *
hb_blob_copy_writable_or_fail (hb_blob_t *blob)
{
  blob = hb_blob_create (blob->data,
			 blob->length,
			 HB_MEMORY_MODE_DUPLICATE,
			 nullptr,
			 nullptr);

  if (unlikely (blob == hb_blob_get_empty ()))
    blob = nullptr;

  return blob;
}

/**
 * hb_blob_get_empty:
 *
 * Returns the singleton empty blob.
 *
 * See TODO:link object types for more information.
 *
 * Return value: (transfer full): the empty blob.
 *
 * Since: 0.9.2
 **/
hb_blob_t *
hb_blob_get_empty (void)
{
  static const hb_blob_t _hb_blob_nil = {
    HB_OBJECT_HEADER_STATIC,

    true, /* immutable */

    nullptr, /* data */
    0, /* length */
    HB_MEMORY_MODE_READONLY, /* mode */

    nullptr, /* user_data */
    nullptr  /* destroy */
  };

  return const_cast<hb_blob_t *> (&_hb_blob_nil);
}

/**
 * hb_blob_reference: (skip)
 * @blob: a blob.
 *
 * Increases the reference count on @blob.
 *
 * See TODO:link object types for more information.
 *
 * Return value: @blob.
 *
 * Since: 0.9.2
 **/
hb_blob_t *
hb_blob_reference (hb_blob_t *blob)
{
  return hb_object_reference (blob);
}

/**
 * hb_blob_destroy: (skip)
 * @blob: a blob.
 *
 * Decreases the reference count on @blob, and if it reaches zero, destroys
 * @blob, freeing all memory, possibly calling the destroy-callback the blob
 * was created for if it has not been called already.
 *
 * See TODO:link object types for more information.
 *
 * Since: 0.9.2
 **/
void
hb_blob_destroy (hb_blob_t *blob)
{
  if (!hb_object_destroy (blob)) return;

  blob->fini_shallow ();

  free (blob);
}

/**
 * hb_blob_set_user_data: (skip)
 * @blob: a blob.
 * @key: key for data to set.
 * @data: data to set.
 * @destroy: callback to call when @data is not needed anymore.
 * @replace: whether to replace an existing data with the same key.
 *
 * Return value:
 *
 * Since: 0.9.2
 **/
hb_bool_t
hb_blob_set_user_data (hb_blob_t          *blob,
		       hb_user_data_key_t *key,
		       void *              data,
		       hb_destroy_func_t   destroy,
		       hb_bool_t           replace)
{
  return hb_object_set_user_data (blob, key, data, destroy, replace);
}

/**
 * hb_blob_get_user_data: (skip)
 * @blob: a blob.
 * @key: key for data to get.
 *
 *
 *
 * Return value: (transfer none):
 *
 * Since: 0.9.2
 **/
void *
hb_blob_get_user_data (hb_blob_t          *blob,
		       hb_user_data_key_t *key)
{
  return hb_object_get_user_data (blob, key);
}


/**
 * hb_blob_make_immutable:
 * @blob: a blob.
 *
 *
 *
 * Since: 0.9.2
 **/
void
hb_blob_make_immutable (hb_blob_t *blob)
{
  if (hb_object_is_inert (blob))
    return;

  blob->immutable = true;
}

/**
 * hb_blob_is_immutable:
 * @blob: a blob.
 *
 *
 *
 * Return value: TODO
 *
 * Since: 0.9.2
 **/
hb_bool_t
hb_blob_is_immutable (hb_blob_t *blob)
{
  return blob->immutable;
}


/**
 * hb_blob_get_length:
 * @blob: a blob.
 *
 *
 *
 * Return value: the length of blob data in bytes.
 *
 * Since: 0.9.2
 **/
unsigned int
hb_blob_get_length (hb_blob_t *blob)
{
  return blob->length;
}

/**
 * hb_blob_get_data:
 * @blob: a blob.
 * @length: (out):
 *
 *
 *
 * Returns: (transfer none) (array length=length):
 *
 * Since: 0.9.2
 **/
const char *
hb_blob_get_data (hb_blob_t *blob, unsigned int *length)
{
  if (length)
    *length = blob->length;

  return blob->data;
}

/**
 * hb_blob_get_data_writable:
 * @blob: a blob.
 * @length: (out): output length of the writable data.
 *
 * Tries to make blob data writable (possibly copying it) and
 * return pointer to data.
 *
 * Fails if blob has been made immutable, or if memory allocation
 * fails.
 *
 * Returns: (transfer none) (array length=length): Writable blob data,
 * or %NULL if failed.
 *
 * Since: 0.9.2
 **/
char *
hb_blob_get_data_writable (hb_blob_t *blob, unsigned int *length)
{
  if (!blob->try_make_writable ()) {
    if (length)
      *length = 0;

    return nullptr;
  }

  if (length)
    *length = blob->length;

  return const_cast<char *> (blob->data);
}


bool
hb_blob_t::try_make_writable_inplace_unix (void)
{
#if defined(HAVE_SYS_MMAN_H) && defined(HAVE_MPROTECT)
  uintptr_t pagesize = -1, mask, length;
  const char *addr;

#if defined(HAVE_SYSCONF) && defined(_SC_PAGE_SIZE)
  pagesize = (uintptr_t) sysconf (_SC_PAGE_SIZE);
#elif defined(HAVE_SYSCONF) && defined(_SC_PAGESIZE)
  pagesize = (uintptr_t) sysconf (_SC_PAGESIZE);
#elif defined(HAVE_GETPAGESIZE)
  pagesize = (uintptr_t) getpagesize ();
#endif

  if ((uintptr_t) -1L == pagesize) {
    DEBUG_MSG_FUNC (BLOB, this, "failed to get pagesize: %s", strerror (errno));
    return false;
  }
  DEBUG_MSG_FUNC (BLOB, this, "pagesize is %lu", (unsigned long) pagesize);

  mask = ~(pagesize-1);
  addr = (const char *) (((uintptr_t) this->data) & mask);
  length = (const char *) (((uintptr_t) this->data + this->length + pagesize-1) & mask)  - addr;
  DEBUG_MSG_FUNC (BLOB, this,
		  "calling mprotect on [%p..%p] (%lu bytes)",
		  addr, addr+length, (unsigned long) length);
  if (-1 == mprotect ((void *) addr, length, PROT_READ | PROT_WRITE)) {
    DEBUG_MSG_FUNC (BLOB, this, "mprotect failed: %s", strerror (errno));
    return false;
  }

  this->mode = HB_MEMORY_MODE_WRITABLE;

  DEBUG_MSG_FUNC (BLOB, this,
		  "successfully made [%p..%p] (%lu bytes) writable\n",
		  addr, addr+length, (unsigned long) length);
  return true;
#else
  return false;
#endif
}

bool
hb_blob_t::try_make_writable_inplace (void)
{
  DEBUG_MSG_FUNC (BLOB, this, "making writable inplace\n");

  if (this->try_make_writable_inplace_unix ())
    return true;

  DEBUG_MSG_FUNC (BLOB, this, "making writable -> FAILED\n");

  /* Failed to make writable inplace, mark that */
  this->mode = HB_MEMORY_MODE_READONLY;
  return false;
}

bool
hb_blob_t::try_make_writable (void)
{
  if (this->immutable)
    return false;

  if (this->mode == HB_MEMORY_MODE_WRITABLE)
    return true;

  if (this->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE && this->try_make_writable_inplace ())
    return true;

  if (this->mode == HB_MEMORY_MODE_WRITABLE)
    return true;


  DEBUG_MSG_FUNC (BLOB, this, "current data is -> %p\n", this->data);

  char *new_data;

  new_data = (char *) malloc (this->length);
  if (unlikely (!new_data))
    return false;

  DEBUG_MSG_FUNC (BLOB, this, "dupped successfully -> %p\n", this->data);

  memcpy (new_data, this->data, this->length);
  this->destroy_user_data ();
  this->mode = HB_MEMORY_MODE_WRITABLE;
  this->data = new_data;
  this->user_data = new_data;
  this->destroy = free;

  return true;
}

/*
 * Mmap
 */

#ifdef HAVE_MMAP
# include <sys/types.h>
# include <sys/stat.h>
# include <fcntl.h>
#endif

#if defined(_WIN32) || defined(__CYGWIN__)
# include <windows.h>
#endif

#ifndef _O_BINARY
# define _O_BINARY 0
#endif

#ifndef MAP_NORESERVE
# define MAP_NORESERVE 0
#endif

struct hb_mapped_file_t
{
  char *contents;
  unsigned long length;
#if defined(_WIN32) || defined(__CYGWIN__)
  HANDLE mapping;
#endif
};

static void
_hb_mapped_file_destroy (hb_mapped_file_t *file)
{
#ifdef HAVE_MMAP
  munmap (file->contents, file->length);
#elif defined(_WIN32) || defined(__CYGWIN__)
  UnmapViewOfFile (file->contents);
  CloseHandle (file->mapping);
#else
  free (file->contents);
#endif

  free (file);
}

/**
 * hb_blob_create_from_file:
 * @file_name: font filename.
 *
 * Returns: A hb_blob_t pointer with the content of the file
 *
 * Since: 1.7.7
 **/
hb_blob_t *
hb_blob_create_from_file (const char *file_name)
{
  // Adopted from glib's gmappedfile.c with Matthias Clasen and
  // Allison Lortie permission but changed a lot to suit our need.
  bool writable = false;
  hb_memory_mode_t mm = HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE;
  hb_mapped_file_t *file = (hb_mapped_file_t *) calloc (1, sizeof (hb_mapped_file_t));
  if (unlikely (!file)) return hb_blob_get_empty ();

#ifdef HAVE_MMAP
  int fd = open (file_name, (writable ? O_RDWR : O_RDONLY) | _O_BINARY, 0);
# define CLOSE close
  if (unlikely (fd == -1)) goto fail_without_close;

  struct stat st;
  if (unlikely (fstat (fd, &st) == -1)) goto fail;

  // See https://github.com/GNOME/glib/blob/f9faac7/glib/gmappedfile.c#L139-L142
  if (unlikely (st.st_size == 0 && S_ISREG (st.st_mode))) goto fail;

  file->length = (unsigned long) st.st_size;
  file->contents = (char *) mmap (nullptr, file->length,
				  writable ? PROT_READ|PROT_WRITE : PROT_READ,
				  MAP_PRIVATE | MAP_NORESERVE, fd, 0);

  if (unlikely (file->contents == MAP_FAILED)) goto fail;

#elif defined(_WIN32) || defined(__CYGWIN__)
  HANDLE fd = CreateFile (file_name,
			  writable ? GENERIC_READ|GENERIC_WRITE : GENERIC_READ,
			  FILE_SHARE_READ, nullptr, OPEN_EXISTING,
			  FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, nullptr);
# define CLOSE CloseHandle

  if (unlikely (fd == INVALID_HANDLE_VALUE)) goto fail_without_close;

  file->length = (unsigned long) GetFileSize (fd, nullptr);
  file->mapping = CreateFileMapping (fd, nullptr,
				     writable ? PAGE_WRITECOPY : PAGE_READONLY,
				     0, 0, nullptr);
  if (unlikely (file->mapping == nullptr)) goto fail;

  file->contents = (char *) MapViewOfFile (file->mapping,
					   writable ? FILE_MAP_COPY : FILE_MAP_READ,
					   0, 0, 0);
  if (unlikely (file->contents == nullptr)) goto fail;

#else
  mm = HB_MEMORY_MODE_WRITABLE;

  FILE *fd = fopen (file_name, "rb");
# define CLOSE fclose
  if (unlikely (!fd)) goto fail_without_close;

  fseek (fd, 0, SEEK_END);
  file->length = ftell (fd);
  rewind (fd);
  file->contents = (char *) malloc (file->length);
  if (unlikely (!file->contents)) goto fail;

  if (unlikely (fread (file->contents, 1, file->length, fd) != file->length))
    goto fail;

#endif

  CLOSE (fd);
  return hb_blob_create (file->contents, file->length, mm, (void *) file,
			 (hb_destroy_func_t) _hb_mapped_file_destroy);

fail:
  CLOSE (fd);
#undef CLOSE
fail_without_close:
  free (file);
  return hb_blob_get_empty ();
}