Function tar_open_for_write

src/bin/pg_basebackup/walmethods.c:630–785

}

static Walfile
tar_open_for_write(const char *pathname, const char *temp_suffix, size_t pad_to_size)
{
	char	   *tmppath;

	tar_clear_error();

	if (tar_data->fd < 0)
	{
		/*
		 * We open the tar file only when we first try to write to it.
		 */
		tar_data->fd = open(tar_data->tarfilename,
							O_WRONLY | O_CREAT | PG_BINARY,
							pg_file_create_mode);
		if (tar_data->fd < 0)
		{
			tar_data->lasterrno = errno;
			return NULL;
		}

#ifdef HAVE_LIBZ
		if (tar_data->compression)
		{
			tar_data->zp = (z_streamp) pg_malloc(sizeof(z_stream));
			tar_data->zp->zalloc = Z_NULL;
			tar_data->zp->zfree = Z_NULL;
			tar_data->zp->opaque = Z_NULL;
			tar_data->zp->next_out = tar_data->zlibOut;
			tar_data->zp->avail_out = ZLIB_OUT_SIZE;

			/*
			 * Initialize deflation library. Adding the magic value 16 to the
			 * default 15 for the windowBits parameter makes the output be
			 * gzip instead of zlib.
			 */
			if (deflateInit2(tar_data->zp, tar_data->compression, Z_DEFLATED, 15 + 16, 8, Z_DEFAULT_STRATEGY) != Z_OK)
			{
				pg_free(tar_data->zp);
				tar_data->zp = NULL;
				tar_set_error("could not initialize compression library");
				return NULL;
			}
		}
#endif

		/* There's no tar header itself, the file starts with regular files */
	}

	if (tar_data->currentfile != NULL)
	{
		tar_set_error("implementation error: tar files can't have more than one open file");
		return NULL;
	}

	tar_data->currentfile = pg_malloc0(sizeof(TarMethodFile));

	tmppath = tar_get_file_name(pathname, temp_suffix);