Function sendFile

src/backend/replication/basebackup.c:1775–2028

* Given the member, write the TAR header & send the file. * * If 'missing_ok' is true, will not throw an error if the file is not found. * * If dboid is anything other than InvalidOid then any checksum failures detected * will get reported to the stats collector. * * Returns true if the file was successfully sent, false if 'missing_ok', * and the file did not exist. */

 * and the file did not exist.
 */
static bool
sendFile(const char *readfilename, const char *tarfilename,
		 struct stat *statbuf, bool missing_ok, Oid dboid,
		 backup_manifest_info *manifest, const char *spcoid)
{
	int			fd;
	BlockNumber blkno = 0;
	bool		block_retry = false;
	char		buf[TAR_SEND_SIZE];
	uint16		checksum;
	int			checksum_failures = 0;
	off_t		cnt;
	int			i;
	pgoff_t		len = 0;
	char	   *page;
	size_t		pad;
	PageHeader	phdr;
	int			segmentno = 0;
	char	   *segmentpath;
	bool		verify_checksum = false;
	pg_checksum_context checksum_ctx;

	if (pg_checksum_init(&checksum_ctx, manifest->checksum_type) < 0)
		elog(ERROR, "could not initialize checksum of file \"%s\"",
			 readfilename);

	fd = OpenTransientFile(readfilename, O_RDONLY | PG_BINARY);
	if (fd < 0)
	{
		if (errno == ENOENT && missing_ok)
			return false;
		ereport(ERROR,
				(errcode_for_file_access(),
				 errmsg("could not open file \"%s\": %m", readfilename)));
	}

	_tarWriteHeader(tarfilename, NULL, statbuf, false);

	if (!noverify_checksums && DataChecksumsEnabled())
	{
		char	   *filename;

		/*
		 * Get the filename (excluding path).  As last_dir_separator()
		 * includes the last directory separator, we chop that off by
		 * incrementing the pointer.
		 */
		filename = last_dir_separator(readfilename) + 1;

		if (is_checksummed_file(readfilename, filename))
		{
			verify_checksum = true;

			/*
			 * Cut off at the segment boundary (".") to get the segment number
			 * in order to mix it into the checksum.
			 */
			segmentpath = strstr(filename, ".");