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Implement GOutputStream::writev_fn() for GLocalFileOutputStream on UNIX

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This commit is contained in:
Sebastian Dröge 2018-09-13 21:07:39 +03:00
parent 89da9eb6c0
commit c39264d35b
1 changed files with 95 additions and 0 deletions
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95
gio/glocalfileoutputstream.c
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@ -38,6 +38,7 @@
#ifdef G_OS_UNIX
#include <unistd.h>
#include "gfiledescriptorbased.h"
#include <sys/uio.h>
#endif
#include "glib-private.h"
@ -93,6 +94,14 @@ static gssize g_local_file_output_stream_write (GOutputStream *s
gsize count,
GCancellable *cancellable,
GError **error);
#ifdef G_OS_UNIX
static gboolean g_local_file_output_stream_writev (GOutputStream *stream,
const GOutputVector *vectors,
gsize n_vectors,
gsize *bytes_written,
GCancellable *cancellable,
GError **error);
#endif
static gboolean g_local_file_output_stream_close (GOutputStream *stream,
GCancellable *cancellable,
GError **error);
@ -142,6 +151,9 @@ g_local_file_output_stream_class_init (GLocalFileOutputStreamClass *klass)
gobject_class->finalize = g_local_file_output_stream_finalize;
stream_class->write_fn = g_local_file_output_stream_write;
#ifdef G_OS_UNIX
stream_class->writev_fn = g_local_file_output_stream_writev;
#endif
stream_class->close_fn = g_local_file_output_stream_close;
file_stream_class->query_info = g_local_file_output_stream_query_info;
file_stream_class->get_etag = g_local_file_output_stream_get_etag;
@ -203,6 +215,89 @@ g_local_file_output_stream_write (GOutputStream *stream,
return res;
}
/* On Windows there is no equivalent API for files. The closest API to that is
* WriteFileGather() but it is useless in general: it requires, among other
* things, that each chunk is the size of a whole page and in memory aligned
* to a page. We can't possibly guarantee that in GLib.
*/
#ifdef G_OS_UNIX
/* Macro to check if struct iovec and GOutputVector have the same ABI */
#define G_OUTPUT_VECTOR_IS_IOVEC (sizeof (struct iovec) == sizeof (GOutputVector) && \
sizeof ((struct iovec *) 0)->iov_base == sizeof ((GOutputVector *) 0)->buffer && \
G_STRUCT_OFFSET (struct iovec, iov_base) == G_STRUCT_OFFSET (GOutputVector, buffer) && \
sizeof ((struct iovec *) 0)->iov_len == sizeof((GOutputVector *) 0)->size && \
G_STRUCT_OFFSET (struct iovec, iov_len) == G_STRUCT_OFFSET (GOutputVector, size))
static gboolean
g_local_file_output_stream_writev (GOutputStream *stream,
const GOutputVector *vectors,
gsize n_vectors,
gsize *bytes_written,
GCancellable *cancellable,
GError **error)
{
GLocalFileOutputStream *file;
gssize res;
struct iovec *iov;
if (bytes_written)
*bytes_written = 0;
/* Clamp to G_MAXINT as writev() takes an integer for the number of vectors.
* We handle this like a short write in this case
*/
if (n_vectors > G_MAXINT)
n_vectors = G_MAXINT;
file = G_LOCAL_FILE_OUTPUT_STREAM (stream);
if (G_OUTPUT_VECTOR_IS_IOVEC)
{
/* ABI is compatible */
iov = (struct iovec *) vectors;
}
else
{
gsize i;
/* ABI is incompatible */
iov = g_newa (struct iovec, n_vectors);
for (i = 0; i < n_vectors; i++)
{
iov[i].iov_base = (void *)vectors[i].buffer;
iov[i].iov_len = vectors[i].size;
}
}
while (1)
{
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return FALSE;
res = writev (file->priv->fd, iov, n_vectors);
if (res == -1)
{
int errsv = errno;
if (errsv == EINTR)
continue;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (errsv),
_("Error writing to file: %s"),
g_strerror (errsv));
}
else if (bytes_written)
{
*bytes_written = res;
}
break;
}
return res != -1;
}
#endif
void
_g_local_file_output_stream_set_do_close (GLocalFileOutputStream *out,
gboolean do_close)