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349 lines
8.3 KiB
C
349 lines
8.3 KiB
C
/* GLIB - Library of useful routines for C programming
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* gmappedfile.c: Simplified wrapper around the mmap() function.
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*
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* Copyright 2005 Matthias Clasen
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "config.h"
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef HAVE_MMAP
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#include <sys/mman.h>
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#endif
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#include "glibconfig.h"
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#ifdef G_OS_WIN32
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#include <windows.h>
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#include <io.h>
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#define fstat(a,b) _fstati64(a,b)
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#define stat _stati64
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#endif
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#include "gconvert.h"
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#include "gerror.h"
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#include "gfileutils.h"
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#include "gmappedfile.h"
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#include "gmem.h"
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#include "gmessages.h"
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#include "gstdio.h"
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#include "gstrfuncs.h"
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#include "gatomic.h"
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#include "gbuffer.h"
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#include "glibintl.h"
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#include "galias.h"
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#ifndef _O_BINARY
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#define _O_BINARY 0
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#endif
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#ifndef MAP_FAILED
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#define MAP_FAILED ((void *) -1)
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#endif
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struct _GMappedFile
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{
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gchar *contents;
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gsize length;
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gpointer free_func;
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int ref_count;
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#ifdef G_OS_WIN32
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HANDLE mapping;
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#endif
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};
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/* Make sure the layout of GMappedFile is the same as GBuffer's */
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G_STATIC_ASSERT (G_STRUCT_OFFSET (GMappedFile, contents) ==
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G_STRUCT_OFFSET (GBuffer, data));
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G_STATIC_ASSERT (G_STRUCT_OFFSET (GMappedFile, length) ==
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G_STRUCT_OFFSET (GBuffer, size));
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G_STATIC_ASSERT (G_STRUCT_OFFSET (GMappedFile, ref_count) ==
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G_STRUCT_OFFSET (GBuffer, ref_count));
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G_STATIC_ASSERT (G_STRUCT_OFFSET (GMappedFile, free_func) ==
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G_STRUCT_OFFSET (GBuffer, free_func));
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static void
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g_mapped_file_destroy (GMappedFile *file)
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{
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if (file->length)
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{
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#ifdef HAVE_MMAP
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munmap (file->contents, file->length);
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#endif
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#ifdef G_OS_WIN32
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UnmapViewOfFile (file->contents);
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CloseHandle (file->mapping);
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#endif
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}
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g_slice_free (GMappedFile, file);
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}
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/**
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* g_mapped_file_new:
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* @filename: The path of the file to load, in the GLib filename encoding
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* @writable: whether the mapping should be writable
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* @error: return location for a #GError, or %NULL
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*
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* Maps a file into memory. On UNIX, this is using the mmap() function.
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*
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* If @writable is %TRUE, the mapped buffer may be modified, otherwise
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* it is an error to modify the mapped buffer. Modifications to the buffer
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* are not visible to other processes mapping the same file, and are not
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* written back to the file.
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*
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* Note that modifications of the underlying file might affect the contents
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* of the #GMappedFile. Therefore, mapping should only be used if the file
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* will not be modified, or if all modifications of the file are done
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* atomically (e.g. using g_file_set_contents()).
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*
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* Return value: a newly allocated #GMappedFile which must be unref'd
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* with g_mapped_file_unref(), or %NULL if the mapping failed.
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*
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* Since: 2.8
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*/
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GMappedFile *
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g_mapped_file_new (const gchar *filename,
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gboolean writable,
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GError **error)
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{
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GMappedFile *file;
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int fd;
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struct stat st;
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g_return_val_if_fail (filename != NULL, NULL);
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g_return_val_if_fail (!error || *error == NULL, NULL);
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fd = g_open (filename, (writable ? O_RDWR : O_RDONLY) | _O_BINARY, 0);
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if (fd == -1)
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{
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int save_errno = errno;
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gchar *display_filename = g_filename_display_name (filename);
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g_set_error (error,
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G_FILE_ERROR,
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g_file_error_from_errno (save_errno),
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_("Failed to open file '%s': open() failed: %s"),
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display_filename,
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g_strerror (save_errno));
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g_free (display_filename);
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return NULL;
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}
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file = g_slice_new0 (GMappedFile);
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file->ref_count = 1;
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file->free_func = g_mapped_file_destroy;
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if (fstat (fd, &st) == -1)
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{
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int save_errno = errno;
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gchar *display_filename = g_filename_display_name (filename);
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g_set_error (error,
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G_FILE_ERROR,
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g_file_error_from_errno (save_errno),
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_("Failed to get attributes of file '%s': fstat() failed: %s"),
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display_filename,
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g_strerror (save_errno));
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g_free (display_filename);
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goto out;
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}
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if (st.st_size == 0)
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{
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file->length = 0;
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file->contents = NULL;
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close (fd);
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return file;
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}
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file->contents = MAP_FAILED;
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#ifdef HAVE_MMAP
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if (st.st_size > G_MAXSIZE)
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{
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errno = EINVAL;
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}
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else
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{
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file->length = (gsize) st.st_size;
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file->contents = (gchar *) mmap (NULL, file->length,
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writable ? PROT_READ|PROT_WRITE : PROT_READ,
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MAP_PRIVATE, fd, 0);
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}
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#endif
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#ifdef G_OS_WIN32
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file->length = st.st_size;
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file->mapping = CreateFileMapping ((HANDLE) _get_osfhandle (fd), NULL,
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writable ? PAGE_WRITECOPY : PAGE_READONLY,
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0, 0,
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NULL);
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if (file->mapping != NULL)
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{
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file->contents = MapViewOfFile (file->mapping,
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writable ? FILE_MAP_COPY : FILE_MAP_READ,
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0, 0,
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0);
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if (file->contents == NULL)
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{
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file->contents = MAP_FAILED;
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CloseHandle (file->mapping);
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file->mapping = NULL;
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}
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}
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#endif
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if (file->contents == MAP_FAILED)
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{
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int save_errno = errno;
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gchar *display_filename = g_filename_display_name (filename);
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g_set_error (error,
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G_FILE_ERROR,
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g_file_error_from_errno (save_errno),
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_("Failed to map file '%s': mmap() failed: %s"),
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display_filename,
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g_strerror (save_errno));
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g_free (display_filename);
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goto out;
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}
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close (fd);
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return file;
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out:
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close (fd);
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g_slice_free (GMappedFile, file);
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return NULL;
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}
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/**
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* g_mapped_file_get_length:
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* @file: a #GMappedFile
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*
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* Returns the length of the contents of a #GMappedFile.
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*
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* Returns: the length of the contents of @file.
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*
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* Since: 2.8
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*/
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gsize
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g_mapped_file_get_length (GMappedFile *file)
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{
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g_return_val_if_fail (file != NULL, 0);
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return file->length;
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}
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/**
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* g_mapped_file_get_contents:
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* @file: a #GMappedFile
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*
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* Returns the contents of a #GMappedFile.
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*
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* Note that the contents may not be zero-terminated,
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* even if the #GMappedFile is backed by a text file.
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*
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* If the file is empty then %NULL is returned.
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*
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* Returns: the contents of @file, or %NULL.
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*
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* Since: 2.8
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*/
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gchar *
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g_mapped_file_get_contents (GMappedFile *file)
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{
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g_return_val_if_fail (file != NULL, NULL);
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return file->contents;
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}
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/**
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* g_mapped_file_free:
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* @file: a #GMappedFile
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*
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* This call existed before #GMappedFile had refcounting and is currently
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* exactly the same as g_mapped_file_unref().
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*
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* Since: 2.8
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* Deprecated:2.22: Use g_mapped_file_unref() instead.
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*/
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void
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g_mapped_file_free (GMappedFile *file)
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{
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g_mapped_file_unref (file);
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}
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/**
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* g_mapped_file_ref:
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* @file: a #GMappedFile
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*
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* Increments the reference count of @file by one. It is safe to call
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* this function from any thread.
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*
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* Return value: the passed in #GMappedFile.
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*
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* Since: 2.22
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**/
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GMappedFile *
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g_mapped_file_ref (GMappedFile *file)
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{
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g_return_val_if_fail (file != NULL, NULL);
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g_return_val_if_fail (file->ref_count > 0, file);
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g_atomic_int_inc (&file->ref_count);
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return file;
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}
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/**
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* g_mapped_file_unref:
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* @file: a #GMappedFile
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*
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* Decrements the reference count of @file by one. If the reference count
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* drops to 0, unmaps the buffer of @file and frees it.
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*
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* It is safe to call this function from any thread.
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*
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* Since 2.22
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**/
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void
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g_mapped_file_unref (GMappedFile *file)
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{
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g_return_if_fail (file != NULL);
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g_return_if_fail (file->ref_count > 0);
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if (g_atomic_int_dec_and_test (&file->ref_count))
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g_mapped_file_destroy (file);
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}
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#define __G_MAPPED_FILE_C__
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#include "galiasdef.c"
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