evince/libdocument/ev-file-helpers.c

/*
 *  Copyright (C) 2002 Jorn Baayen
 *  Copyright © 2009 Christian Persch
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <config.h>

#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>

#include <glib.h>
#include <glib/gstdio.h>
#include <glib/gi18n-lib.h>

#include "ev-file-helpers.h"

static gchar *tmp_dir = NULL;

#ifndef O_BINARY
#define O_BINARY 0
#endif

/* On Windows, O_CLOEXEC does not exist */
#ifndef O_CLOEXEC
#define O_CLOEXEC 0
#endif

/*
 * ev_dir_ensure_exists:
 * @dir: the directory name
 * @mode: permissions to use when creating the directory
 * @error: a location to store a #GError
 *
 * Create @dir recursively with permissions @mode.
 *
 * Returns: %TRUE on success, or %FALSE on error with @error filled in
 */
static gboolean
_ev_dir_ensure_exists (const gchar *dir,
                       int          mode,
                       GError     **error)
{
        int errsv;
        char *display_name;

        g_return_val_if_fail (dir != NULL, FALSE);

        errno = 0;
	if (g_mkdir_with_parents (dir, mode) == 0)
		return TRUE;

        errsv = errno;
	if (errsv == EEXIST && g_file_test (dir, G_FILE_TEST_IS_DIR))
                return TRUE;

        display_name = g_filename_display_name (dir);
        g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv),
                     "Failed to create directory '%s': %s",
                     display_name, g_strerror (errsv));
        g_free (display_name);

	return FALSE;
}

/*
 * _ev_tmp_dir:
 * @error: a location to store a #GError
 *
 * Returns the tmp directory.
 *
 * Returns: the tmp directory, or %NULL with @error filled in if the
 *   directory could not be created
 */
static const char *
_ev_tmp_dir (GError **error)
{

        if (tmp_dir == NULL) {
                gchar *dirname;
                const gchar *prgname;

                prgname = g_get_prgname ();
                dirname = g_strdup_printf ("%s-%u", prgname ? prgname : "unknown", getpid ());
                tmp_dir = g_build_filename (g_get_tmp_dir (), dirname, NULL);
                g_free (dirname);
        }

        if (!_ev_dir_ensure_exists (tmp_dir, 0700, error))
                return NULL;

	return tmp_dir;
}

void
_ev_file_helpers_init (void)
{
}

void
_ev_file_helpers_shutdown (void)
{
	if (tmp_dir != NULL)
		g_rmdir (tmp_dir);

	g_clear_pointer (&tmp_dir, g_free);
}

/**
 * ev_mkstemp:
 * @tmpl: a template string; must contain 'XXXXXX', but not necessarily as a suffix
 * @file_name: a location to store the filename of the temp file
 * @error: a location to store a #GError
 *
 * Creates a temp file in the evince temp directory.
 *
 * Returns: a file descriptor to the newly created temp file name, or %-1
 *   on error with @error filled in
 */
int
ev_mkstemp (const char  *tmpl,
            char       **file_name,
            GError     **error)
{
        const char *tmp;
        char *name;
        int fd;

        if ((tmp = _ev_tmp_dir (error)) == NULL)
              return -1;

        name = g_build_filename (tmp, tmpl, NULL);
        fd = g_mkstemp_full (name, O_RDWR | O_BINARY | O_CLOEXEC, 0600);

        if (fd == -1) {
		int errsv = errno;

                g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv),
                             _("Failed to create a temporary file: %s"),
                             g_strerror (errsv));

                g_free (name);
                return -1;
        }

        if (file_name)
                *file_name = name;

        return fd;
}

static void
close_fd_cb (gpointer fdptr)
{
        int fd = GPOINTER_TO_INT (fdptr);

        close (fd);
}

/**
 * ev_mkstemp_file:
 * @tmpl: a template string; must contain 'XXXXXX', but not necessarily as a suffix
 * @error: a location to store a #GError
 *
 * Creates a temp #GFile in the evince temp directory. See ev_mkstemp() for more information.
 *
 * Returns: (transfer full): a newly allocated #GFile for the newly created temp file name, or %NULL
 *   on error with @error filled in
 */
GFile *
ev_mkstemp_file (const char        *tmpl,
                 GError           **error)
{
        char *file_name;
        int fd;
        GFile *file;

        fd = ev_mkstemp (tmpl, &file_name, error);
        if (fd == -1)
                return NULL;

        file = g_file_new_for_path (file_name);
        g_free (file_name);

        g_object_set_data_full (G_OBJECT (file), "ev-mkstemp-fd",
                                GINT_TO_POINTER (fd), (GDestroyNotify) close_fd_cb);

        return file;
}

/**
 * ev_mkdtemp:
 * @tmpl: a template string; must end in 'XXXXXX'
 * @error: a location to store a #GError
 *
 * Creates a temp directory in the evince temp directory.
 *
 * Returns: a newly allocated string with the temp directory name, or %NULL
 *   on error with @error filled in
 */
gchar *
ev_mkdtemp (const char        *tmpl,
            GError           **error)
{
        const char *tmp;
        char *name;

        if ((tmp = _ev_tmp_dir (error)) == NULL)
              return NULL;

        name = g_build_filename (tmp, tmpl, NULL);
        if (g_mkdtemp (name) == NULL) {
		int errsv = errno;

                g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv),
                             _("Failed to create a temporary directory: %s"),
                             g_strerror (errsv));

                g_free (name);
                return NULL;
        }

        return name;
}

/* Remove a local temp file created by evince */
void
ev_tmp_filename_unlink (const gchar *filename)
{
	if (!filename)
		return;

	if (!tmp_dir)
		return;

	if (g_str_has_prefix (filename, tmp_dir)) {
		g_unlink (filename);
	}
}

void
ev_tmp_file_unlink (GFile *file)
{
	gboolean res;
	GError  *error = NULL;

	if (!file)
		return;

	res = g_file_delete (file, NULL, &error);
	if (!res) {
		char *uri;

		uri = g_file_get_uri (file);
		g_warning ("Unable to delete temp file %s: %s\n", uri, error->message);
		g_free (uri);
		g_error_free (error);
	}
}

void
ev_tmp_uri_unlink (const gchar *uri)
{
	GFile *file;

	if (!uri)
		return;

	file = g_file_new_for_uri (uri);
	if (!g_file_is_native (file)) {
		g_warning ("Attempting to delete non native uri: %s\n", uri);
		g_object_unref (file);
		return;
	}

	ev_tmp_file_unlink (file);
	g_object_unref (file);
}

gboolean
ev_file_is_temp (GFile *file)
{
	gchar   *path;
	gboolean retval;

	if (!g_file_is_native (file))
		return FALSE;

	path = g_file_get_path (file);
	if (!path)
		return FALSE;

	retval = g_str_has_prefix (path, g_get_tmp_dir ());
	g_free (path);

	return retval;
}

/**
 * ev_xfer_uri_simple:
 * @from: the source URI
 * @to: the target URI
 * @error: a #GError location to store an error, or %NULL
 *
 * Performs a g_file_copy() from @from to @to.
 *
 * Returns: %TRUE on success, or %FALSE on error with @error filled in
 */
gboolean
ev_xfer_uri_simple (const char *from,
		    const char *to,
		    GError     **error)
{
	GFile *source_file;
	GFile *target_file;
	gboolean result;

	if (!from)
		return TRUE;

        g_return_val_if_fail (to != NULL, TRUE);

	source_file = g_file_new_for_uri (from);
	target_file = g_file_new_for_uri (to);

	result = g_file_copy (source_file, target_file,
			      G_FILE_COPY_TARGET_DEFAULT_PERMS |
			      G_FILE_COPY_OVERWRITE,
			      NULL, NULL, NULL, error);

	g_object_unref (target_file);
	g_object_unref (source_file);

	return result;
}

/**
 * ev_file_copy_metadata:
 * @from: the source URI
 * @to: the target URI
 * @error: a #GError location to store an error, or %NULL
 *
 * Performs a g_file_copy_attributes() with %G_FILE_COPY_ALL_METADATA
 * from @from to @to.
 *
 * Returns: %TRUE if the attributes were copied successfully, %FALSE otherwise.
 *
 * Since: 3.4
 */
gboolean
ev_file_copy_metadata (const char *from,
                       const char *to,
                       GError     **error)
{
        GFile *source_file;
        GFile *target_file;
        gboolean result;

        g_return_val_if_fail (from != NULL, FALSE);
        g_return_val_if_fail (to != NULL, FALSE);

        source_file = g_file_new_for_uri (from);
        target_file = g_file_new_for_uri (to);

        result = g_file_copy_attributes (source_file, target_file,
                                         G_FILE_COPY_ALL_METADATA |
                                         G_FILE_COPY_TARGET_DEFAULT_PERMS,
                                         NULL, error);

        g_object_unref (target_file);
        g_object_unref (source_file);

        return result;
}

static gchar *
get_mime_type_from_uri (const gchar *uri, GError **error)
{
	GFile       *file;
	GFileInfo   *file_info;
	const gchar *content_type;
        gchar       *mime_type = NULL;

	file = g_file_new_for_uri (uri);
	file_info = g_file_query_info (file,
				       G_FILE_ATTRIBUTE_STANDARD_CONTENT_TYPE,
				       0, NULL, error);
	g_object_unref (file);

	if (file_info == NULL)
		return NULL;

	content_type = g_file_info_get_content_type (file_info);
	if (content_type != NULL) {
                mime_type = g_content_type_get_mime_type (content_type);
        }
        if (mime_type == NULL) {
                g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                                     _("Unknown MIME Type"));
        }

	g_object_unref (file_info);
	return mime_type;
}

static gchar *
get_mime_type_from_data (const gchar *uri, GError **error)
{
	GFile            *file;
	GFileInputStream *input_stream;
	gssize            size_read;
	guchar            buffer[1024];
	gboolean          retval;
	gchar            *content_type;
        gchar            *mime_type = NULL;

	file = g_file_new_for_uri (uri);

	input_stream = g_file_read (file, NULL, error);
	if (!input_stream) {
		g_object_unref (file);
		return NULL;
	}

	size_read = g_input_stream_read (G_INPUT_STREAM (input_stream),
					 buffer, sizeof (buffer), NULL, error);
	if (size_read == -1) {
		g_object_unref (input_stream);
		g_object_unref (file);
		return NULL;
	}

	retval = g_input_stream_close (G_INPUT_STREAM (input_stream), NULL, error);

	g_object_unref (input_stream);
	g_object_unref (file);
	if (!retval)
		return NULL;

	content_type = g_content_type_guess (NULL, /* no filename */
					     buffer, size_read,
					     NULL);
        if (content_type == NULL) {
                g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                                     _("Unknown MIME Type"));
                return NULL;
        }

#ifdef G_OS_WIN32
       /* On Windows, the implementation of g_content_type_guess() is
        * sometimes too limited, so we do use get_mime_type_from_uri()
        * as a fallback */
       if (strcmp (content_type, "*") == 0) {
               g_free (content_type);
               return get_mime_type_from_uri (uri, error);
       }
#endif /* G_OS_WIN32 */

        mime_type = g_content_type_get_mime_type (content_type);
        g_free (content_type);

        if (mime_type == NULL) {
                g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                                     _("Unknown MIME Type"));
        }

	return mime_type;
}

/**
 * ev_file_get_mime_type:
 * @uri: the URI
 * @fast: whether to use fast MIME type detection
 * @error: a #GError location to store an error, or %NULL
 *
 * Returns: a newly allocated string with the MIME type of the file at
 *   @uri, or %NULL on error or if the MIME type could not be determined
 */
gchar *
ev_file_get_mime_type (const gchar *uri,
		       gboolean     fast,
		       GError     **error)
{
	return fast ? get_mime_type_from_uri (uri, error) : get_mime_type_from_data (uri, error);
}

/**
 * ev_file_get_mime_type_from_fd:
 * @fd: an file descriptor (must be seekable)
 * @error: a #GError location to store an error, or %NULL
 *
 * Returns: a newly allocated string with the MIME type of the file referred to
 *   by @fd, or %NULL on error or if the MIME type could not be determined
 */
gchar *
ev_file_get_mime_type_from_fd (int      fd,
                               GError **error)
{
        guchar buffer[4096];
        ssize_t r;
        off_t pos;
        char *content_type, *mime_type;

        g_return_val_if_fail (fd != -1, NULL);

        pos = lseek (fd, 0, SEEK_CUR);
        if (pos == (off_t)-1) {
                int errsv = errno;
                g_set_error (error, G_IO_ERROR,
                             g_io_error_from_errno (errsv),
                             "Failed to get MIME type: %s",
                             g_strerror (errsv));
                return NULL;
        }

        do {
                r = read (fd, buffer, sizeof (buffer));
        } while (r == -1 && errno == EINTR);

        if (r == -1) {
                int errsv = errno;
                g_set_error (error, G_IO_ERROR,
                             g_io_error_from_errno (errsv),
                             "Failed to get MIME type: %s",
                             g_strerror (errsv));

                (void) lseek (fd, pos, SEEK_SET);
                return NULL;
        }

        if (lseek (fd, pos, SEEK_SET) == (off_t)-1) {
                int errsv = errno;
                g_set_error (error, G_IO_ERROR,
                             g_io_error_from_errno (errsv),
                             "Failed to get MIME type: %s",
                             g_strerror (errsv));
                return NULL;
        }

        content_type = g_content_type_guess (NULL, /* no filename */
                                             buffer, r,
                                             NULL);
        if (content_type == NULL) {
                g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                                     _("Unknown MIME Type"));
                return NULL;
        }

        mime_type = g_content_type_get_mime_type (content_type);
        g_free (content_type);

        if (mime_type == NULL) {
                g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                                     _("Unknown MIME Type"));
                return NULL;
        }

        return mime_type;
}

/* Compressed files support */

static const char *compressor_cmds[] = {
  NULL,
  "bzip2",
  "gzip",
  "xz"
};

#define N_ARGS      4
#define BUFFER_SIZE 1024

static void
compression_child_setup_cb (gpointer fd_ptr)
{
#ifdef _WIN32
        /* On Windows, processes are not inherited by default */
        (void)fd_ptr;
#else
        int fd = GPOINTER_TO_INT (fd_ptr);
        int flags;

        flags = fcntl (fd, F_GETFD);
        if (flags >= 0 && (flags & FD_CLOEXEC)) {
                flags &= ~FD_CLOEXEC;
                fcntl (fd, F_SETFD, flags);
        }
#endif
}

static gchar *
compression_run (const gchar       *uri,
		 EvCompressionType  type,
		 gboolean           compress,
		 GError           **error)
{
	gchar *argv[N_ARGS];
	gchar *uri_dst = NULL;
	gchar *filename, *filename_dst = NULL;
	gchar *cmd;
	gint   fd, pout;
	GError *err = NULL;

	if (type == EV_COMPRESSION_NONE)
		return NULL;

	cmd = g_find_program_in_path (compressor_cmds[type]);
	if (!cmd) {
		/* FIXME: better error codes! */
		/* FIXME: i18n later */
		g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
			     "Failed to find the \"%s\" command in the search path.",
                             compressor_cmds[type]);
		return NULL;
	}

	filename = g_filename_from_uri (uri, NULL, error);
	if (!filename) {
		g_free (cmd);
		return NULL;
	}

        fd = ev_mkstemp ("comp.XXXXXX", &filename_dst, error);
	if (fd == -1) {
		g_free (cmd);
		g_free (filename);

		return NULL;
	}

	argv[0] = cmd;
	argv[1] = compress ? (char *) "-c" : (char *) "-cd";
	argv[2] = filename;
	argv[3] = NULL;

	if (g_spawn_async_with_pipes (NULL, argv, NULL,
				      G_SPAWN_STDERR_TO_DEV_NULL,
                                      compression_child_setup_cb, GINT_TO_POINTER (fd),
                                      NULL,
				      NULL, &pout, NULL, &err)) {
		GIOChannel *in, *out;
		gchar buf[BUFFER_SIZE];
		GIOStatus read_st, write_st;
		gsize bytes_read, bytes_written;

		in = g_io_channel_unix_new (pout);
		g_io_channel_set_encoding (in, NULL, NULL);
		out = g_io_channel_unix_new (fd);
		g_io_channel_set_encoding (out, NULL, NULL);

		do {
			read_st = g_io_channel_read_chars (in, buf,
							   BUFFER_SIZE,
							   &bytes_read,
							   error);
			if (read_st == G_IO_STATUS_NORMAL) {
				write_st = g_io_channel_write_chars (out, buf,
								     bytes_read,
								     &bytes_written,
								     error);
				if (write_st == G_IO_STATUS_ERROR)
					break;
			} else if (read_st == G_IO_STATUS_ERROR) {
				break;
			}
		} while (bytes_read > 0);

		g_io_channel_unref (in);
		g_io_channel_unref (out);
	}

	close (fd);

	if (err) {
		g_propagate_error (error, err);
	} else {
		uri_dst = g_filename_to_uri (filename_dst, NULL, error);
	}

	g_free (cmd);
	g_free (filename);
	g_free (filename_dst);

	return uri_dst;
}

/**
 * ev_file_uncompress:
 * @uri: a file URI
 * @type: the compression type
 * @error: a #GError location to store an error, or %NULL
 *
 * Uncompresses the file at @uri.
 *
 * If @type is %EV_COMPRESSION_NONE, it does nothing and returns %NULL.
 *
 * Otherwise, it returns the filename of a
 * temporary file containing the decompressed data from the file at @uri.
 * On error it returns %NULL and fills in @error.
 *
 * It is the caller's responsibility to unlink the temp file after use.
 *
 * Returns: a newly allocated string URI, or %NULL on error
 */
gchar *
ev_file_uncompress (const gchar       *uri,
		    EvCompressionType  type,
		    GError           **error)
{
	g_return_val_if_fail (uri != NULL, NULL);

	return compression_run (uri, type, FALSE, error);
}

/**
 * ev_file_compress:
 * @uri: a file URI
 * @type: the compression type
 * @error: a #GError location to store an error, or %NULL
 *
 * Compresses the file at @uri.

 * If @type is %EV_COMPRESSION_NONE, it does nothing and returns %NULL.
 *
 * Otherwise, it returns the filename of a
 * temporary file containing the compressed data from the file at @uri.
 *
 * On error it returns %NULL and fills in @error.
 *
 * It is the caller's responsibility to unlink the temp file after use.
 *
 * Returns: a newly allocated string URI, or %NULL on error
 */
gchar *
ev_file_compress (const gchar       *uri,
		  EvCompressionType  type,
		  GError           **error)
{
	g_return_val_if_fail (uri != NULL, NULL);

	return compression_run (uri, type, TRUE, error);
}