| /* GLIB - Library of useful routines for C programming |
| * gmappedfile.c: Simplified wrapper around the mmap() function. |
| * |
| * Copyright 2005 Matthias Clasen |
| * |
| * SPDX-License-Identifier: LGPL-2.1-or-later |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * This library 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 |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with this library; if not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include "config.h" |
| |
| #include <errno.h> |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| #include <fcntl.h> |
| #ifdef HAVE_MMAP |
| #include <sys/mman.h> |
| #endif |
| |
| #include "glibconfig.h" |
| |
| #ifdef G_OS_UNIX |
| #include <unistd.h> |
| #endif |
| |
| #ifdef G_OS_WIN32 |
| #include <windows.h> |
| #include <io.h> |
| |
| #undef fstat |
| #define fstat(a,b) _fstati64(a,b) |
| #undef stat |
| #define stat _stati64 |
| |
| #ifndef S_ISREG |
| #define S_ISREG(m) (((m) & _S_IFMT) == _S_IFREG) |
| #endif |
| |
| #endif |
| |
| #ifndef O_CLOEXEC |
| #define O_CLOEXEC 0 |
| #endif |
| |
| #include "gconvert.h" |
| #include "gerror.h" |
| #include "gfileutils.h" |
| #include "gmappedfile.h" |
| #include "gmem.h" |
| #include "gmessages.h" |
| #include "gstdio.h" |
| #include "gstrfuncs.h" |
| #include "gatomic.h" |
| |
| #include "glibintl.h" |
| |
| |
| #ifndef _O_BINARY |
| #define _O_BINARY 0 |
| #endif |
| |
| #ifndef MAP_FAILED |
| #define MAP_FAILED ((void *) -1) |
| #endif |
| |
| /** |
| * GMappedFile: |
| * |
| * The #GMappedFile represents a file mapping created with |
| * g_mapped_file_new(). It has only private members and should |
| * not be accessed directly. |
| */ |
| |
| struct _GMappedFile |
| { |
| gchar *contents; |
| gsize length; |
| gpointer free_func; |
| int ref_count; |
| #ifdef G_OS_WIN32 |
| HANDLE mapping; |
| #endif |
| }; |
| |
| static void |
| g_mapped_file_destroy (GMappedFile *file) |
| { |
| if (file->length) |
| { |
| #ifdef HAVE_MMAP |
| munmap (file->contents, file->length); |
| #endif |
| #ifdef G_OS_WIN32 |
| UnmapViewOfFile (file->contents); |
| CloseHandle (file->mapping); |
| #endif |
| } |
| |
| g_slice_free (GMappedFile, file); |
| } |
| |
| static GMappedFile* |
| mapped_file_new_from_fd (int fd, |
| gboolean writable, |
| const gchar *filename, |
| GError **error) |
| { |
| GMappedFile *file; |
| struct stat st; |
| |
| file = g_slice_new0 (GMappedFile); |
| file->ref_count = 1; |
| file->free_func = g_mapped_file_destroy; |
| |
| if (fstat (fd, &st) == -1) |
| { |
| int save_errno = errno; |
| gchar *display_filename = filename ? g_filename_display_name (filename) : NULL; |
| |
| g_set_error (error, |
| G_FILE_ERROR, |
| g_file_error_from_errno (save_errno), |
| _("Failed to get attributes of file ā%s%s%s%sā: fstat() failed: %s"), |
| display_filename ? display_filename : "fd", |
| display_filename ? "' " : "", |
| display_filename ? display_filename : "", |
| display_filename ? "'" : "", |
| g_strerror (save_errno)); |
| g_free (display_filename); |
| goto out; |
| } |
| |
| /* mmap() on size 0 will fail with EINVAL, so we avoid calling mmap() |
| * in that case -- but only if we have a regular file; we still want |
| * attempts to mmap a character device to fail, for example. |
| */ |
| if (st.st_size == 0 && S_ISREG (st.st_mode)) |
| { |
| file->length = 0; |
| file->contents = NULL; |
| return file; |
| } |
| |
| file->contents = MAP_FAILED; |
| |
| #ifdef HAVE_MMAP |
| if (sizeof (st.st_size) > sizeof (gsize) && st.st_size > (off_t) G_MAXSIZE) |
| { |
| errno = EINVAL; |
| } |
| else |
| { |
| file->length = (gsize) st.st_size; |
| file->contents = (gchar *) mmap (NULL, file->length, |
| writable ? PROT_READ|PROT_WRITE : PROT_READ, |
| MAP_PRIVATE, fd, 0); |
| } |
| #endif |
| #ifdef G_OS_WIN32 |
| file->length = st.st_size; |
| file->mapping = CreateFileMapping ((HANDLE) _get_osfhandle (fd), NULL, |
| writable ? PAGE_WRITECOPY : PAGE_READONLY, |
| 0, 0, |
| NULL); |
| if (file->mapping != NULL) |
| { |
| file->contents = MapViewOfFile (file->mapping, |
| writable ? FILE_MAP_COPY : FILE_MAP_READ, |
| 0, 0, |
| 0); |
| if (file->contents == NULL) |
| { |
| file->contents = MAP_FAILED; |
| CloseHandle (file->mapping); |
| file->mapping = NULL; |
| } |
| } |
| #endif |
| |
| |
| if (file->contents == MAP_FAILED) |
| { |
| int save_errno = errno; |
| gchar *display_filename = filename ? g_filename_display_name (filename) : NULL; |
| |
| g_set_error (error, |
| G_FILE_ERROR, |
| g_file_error_from_errno (save_errno), |
| _("Failed to map %s%s%s%s: mmap() failed: %s"), |
| display_filename ? display_filename : "fd", |
| display_filename ? "' " : "", |
| display_filename ? display_filename : "", |
| display_filename ? "'" : "", |
| g_strerror (save_errno)); |
| g_free (display_filename); |
| goto out; |
| } |
| |
| return file; |
| |
| out: |
| g_slice_free (GMappedFile, file); |
| |
| return NULL; |
| } |
| |
| /** |
| * g_mapped_file_new: |
| * @filename: (type filename): The path of the file to load, in the GLib |
| * filename encoding |
| * @writable: whether the mapping should be writable |
| * @error: return location for a #GError, or %NULL |
| * |
| * Maps a file into memory. On UNIX, this is using the mmap() function. |
| * |
| * If @writable is %TRUE, the mapped buffer may be modified, otherwise |
| * it is an error to modify the mapped buffer. Modifications to the buffer |
| * are not visible to other processes mapping the same file, and are not |
| * written back to the file. |
| * |
| * Note that modifications of the underlying file might affect the contents |
| * of the #GMappedFile. Therefore, mapping should only be used if the file |
| * will not be modified, or if all modifications of the file are done |
| * atomically (e.g. using g_file_set_contents()). |
| * |
| * If @filename is the name of an empty, regular file, the function |
| * will successfully return an empty #GMappedFile. In other cases of |
| * size 0 (e.g. device files such as /dev/null), @error will be set |
| * to the #GFileError value %G_FILE_ERROR_INVAL. |
| * |
| * Returns: a newly allocated #GMappedFile which must be unref'd |
| * with g_mapped_file_unref(), or %NULL if the mapping failed. |
| * |
| * Since: 2.8 |
| */ |
| GMappedFile * |
| g_mapped_file_new (const gchar *filename, |
| gboolean writable, |
| GError **error) |
| { |
| GMappedFile *file; |
| int fd; |
| |
| g_return_val_if_fail (filename != NULL, NULL); |
| g_return_val_if_fail (!error || *error == NULL, NULL); |
| |
| fd = g_open (filename, (writable ? O_RDWR : O_RDONLY) | _O_BINARY | O_CLOEXEC, 0); |
| if (fd == -1) |
| { |
| int save_errno = errno; |
| gchar *display_filename = g_filename_display_name (filename); |
| |
| g_set_error (error, |
| G_FILE_ERROR, |
| g_file_error_from_errno (save_errno), |
| _("Failed to open file ā%sā: open() failed: %s"), |
| display_filename, |
| g_strerror (save_errno)); |
| g_free (display_filename); |
| return NULL; |
| } |
| |
| file = mapped_file_new_from_fd (fd, writable, filename, error); |
| |
| close (fd); |
| |
| return file; |
| } |
| |
| |
| /** |
| * g_mapped_file_new_from_fd: |
| * @fd: The file descriptor of the file to load |
| * @writable: whether the mapping should be writable |
| * @error: return location for a #GError, or %NULL |
| * |
| * Maps a file into memory. On UNIX, this is using the mmap() function. |
| * |
| * If @writable is %TRUE, the mapped buffer may be modified, otherwise |
| * it is an error to modify the mapped buffer. Modifications to the buffer |
| * are not visible to other processes mapping the same file, and are not |
| * written back to the file. |
| * |
| * Note that modifications of the underlying file might affect the contents |
| * of the #GMappedFile. Therefore, mapping should only be used if the file |
| * will not be modified, or if all modifications of the file are done |
| * atomically (e.g. using g_file_set_contents()). |
| * |
| * Returns: a newly allocated #GMappedFile which must be unref'd |
| * with g_mapped_file_unref(), or %NULL if the mapping failed. |
| * |
| * Since: 2.32 |
| */ |
| GMappedFile * |
| g_mapped_file_new_from_fd (gint fd, |
| gboolean writable, |
| GError **error) |
| { |
| return mapped_file_new_from_fd (fd, writable, NULL, error); |
| } |
| |
| /** |
| * g_mapped_file_get_length: |
| * @file: a #GMappedFile |
| * |
| * Returns the length of the contents of a #GMappedFile. |
| * |
| * Returns: the length of the contents of @file. |
| * |
| * Since: 2.8 |
| */ |
| gsize |
| g_mapped_file_get_length (GMappedFile *file) |
| { |
| g_return_val_if_fail (file != NULL, 0); |
| |
| return file->length; |
| } |
| |
| /** |
| * g_mapped_file_get_contents: |
| * @file: a #GMappedFile |
| * |
| * Returns the contents of a #GMappedFile. |
| * |
| * Note that the contents may not be zero-terminated, |
| * even if the #GMappedFile is backed by a text file. |
| * |
| * If the file is empty then %NULL is returned. |
| * |
| * Returns: the contents of @file, or %NULL. |
| * |
| * Since: 2.8 |
| */ |
| gchar * |
| g_mapped_file_get_contents (GMappedFile *file) |
| { |
| g_return_val_if_fail (file != NULL, NULL); |
| |
| return file->contents; |
| } |
| |
| /** |
| * g_mapped_file_free: |
| * @file: a #GMappedFile |
| * |
| * This call existed before #GMappedFile had refcounting and is currently |
| * exactly the same as g_mapped_file_unref(). |
| * |
| * Since: 2.8 |
| * Deprecated:2.22: Use g_mapped_file_unref() instead. |
| */ |
| void |
| g_mapped_file_free (GMappedFile *file) |
| { |
| g_mapped_file_unref (file); |
| } |
| |
| /** |
| * g_mapped_file_ref: |
| * @file: a #GMappedFile |
| * |
| * Increments the reference count of @file by one. It is safe to call |
| * this function from any thread. |
| * |
| * Returns: the passed in #GMappedFile. |
| * |
| * Since: 2.22 |
| **/ |
| GMappedFile * |
| g_mapped_file_ref (GMappedFile *file) |
| { |
| g_return_val_if_fail (file != NULL, NULL); |
| |
| g_atomic_int_inc (&file->ref_count); |
| |
| return file; |
| } |
| |
| /** |
| * g_mapped_file_unref: |
| * @file: a #GMappedFile |
| * |
| * Decrements the reference count of @file by one. If the reference count |
| * drops to 0, unmaps the buffer of @file and frees it. |
| * |
| * It is safe to call this function from any thread. |
| * |
| * Since 2.22 |
| **/ |
| void |
| g_mapped_file_unref (GMappedFile *file) |
| { |
| g_return_if_fail (file != NULL); |
| |
| if (g_atomic_int_dec_and_test (&file->ref_count)) |
| g_mapped_file_destroy (file); |
| } |
| |
| /** |
| * g_mapped_file_get_bytes: |
| * @file: a #GMappedFile |
| * |
| * Creates a new #GBytes which references the data mapped from @file. |
| * The mapped contents of the file must not be modified after creating this |
| * bytes object, because a #GBytes should be immutable. |
| * |
| * Returns: (transfer full): A newly allocated #GBytes referencing data |
| * from @file |
| * |
| * Since: 2.34 |
| **/ |
| GBytes * |
| g_mapped_file_get_bytes (GMappedFile *file) |
| { |
| g_return_val_if_fail (file != NULL, NULL); |
| |
| return g_bytes_new_with_free_func (file->contents, |
| file->length, |
| (GDestroyNotify) g_mapped_file_unref, |
| g_mapped_file_ref (file)); |
| } |