pg_backup_db.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

			appendBinaryPQExpBuffer(AH->pgCopyBuf, qry, (eos - qry));
			return eos;
		}

		/*
		 * fprintf(stderr, "Found cr at %d, prev char was %c, next was %c\n",
		 * loc, qry[loc-1], qry[loc+1]);
		 */

		/* Count the number of preceding slashes */
		sPos = loc;
		while (sPos > 0 && qry[sPos - 1] == '\\')
			sPos--;

		sPos = loc - sPos;

		/*
		 * If an odd number of preceding slashes, then \n was escaped so set
		 * the next search pos, and loop (if any left).
		 */
		if ((sPos & 1) == 1)
		{
			/* fprintf(stderr, "cr was escaped\n"); */
			pos = loc + 1;
			if (pos >= (eos - qry))
			{
				appendBinaryPQExpBuffer(AH->pgCopyBuf, qry, (eos - qry));
				return eos;
			}
		}
		else
			break;
	}

	/* We found an unquoted newline */
	qry[loc] = '\0';
	appendPQExpBuffer(AH->pgCopyBuf, "%s\n", qry);
	isEnd = (strcmp(AH->pgCopyBuf->data, "\\.\n") == 0);

	/*
	 * Note that we drop the data on the floor if libpq has failed to
	 * enter COPY mode; this allows us to behave reasonably when trying
	 * to continue after an error in a COPY command.
	 */
	if (AH->pgCopyIn && PQputline(AH->connection, AH->pgCopyBuf->data) != 0)
		die_horribly(AH, modulename, "error returned by PQputline: %s",
					 PQerrorMessage(AH->connection));

	resetPQExpBuffer(AH->pgCopyBuf);

	/*
	 * fprintf(stderr, "Buffer is '%s'\n", AH->pgCopyBuf->data);
	 */

	if (isEnd)
	{
		if (AH->pgCopyIn && PQendcopy(AH->connection) != 0)
			die_horribly(AH, modulename, "error returned by PQendcopy: %s",
						 PQerrorMessage(AH->connection));

		AH->pgCopyIn = false;
	}

	return qry + loc + 1;
}

/*
 * Used by ExecuteSqlCommandBuf to send one buffered line of SQL
 * (not data for the copy command).
 */
static char *
_sendSQLLine(ArchiveHandle *AH, char *qry, char *eos)
{
	/*
	 * The following is a mini state machine to assess the end of an SQL
	 * statement. It really only needs to parse good SQL, or at least that's
	 * the theory... End-of-statement is assumed to be an unquoted,
	 * un-commented semi-colon that's not within any parentheses.
	 *
	 * Note: the input can be split into bufferloads at arbitrary boundaries.
	 * Therefore all state must be kept in AH->sqlparse, not in local
	 * variables of this routine.  We assume that AH->sqlparse was filled with
	 * zeroes when created.
	 */
	for (; qry < eos; qry++)
	{
		switch (AH->sqlparse.state)
		{
			case SQL_SCAN:		/* Default state == 0, set in _allocAH */
				if (*qry == ';' && AH->sqlparse.braceDepth == 0)
				{
					/*
					 * We've found the end of a statement. Send it and reset
					 * the buffer.
					 */
					appendPQExpBufferChar(AH->sqlBuf, ';');		/* inessential */
					ExecuteSqlCommand(AH, AH->sqlBuf,
									  "could not execute query");
					resetPQExpBuffer(AH->sqlBuf);
					AH->sqlparse.lastChar = '\0';

					/*
					 * Remove any following newlines - so that embedded COPY
					 * commands don't get a starting newline.
					 */
					qry++;
					while (qry < eos && *qry == '\n')
						qry++;

					/* We've finished one line, so exit */
					return qry;
				}
				else if (*qry == '\'')
				{
					if (AH->sqlparse.lastChar == 'E')
						AH->sqlparse.state = SQL_IN_E_QUOTE;
					else
						AH->sqlparse.state = SQL_IN_SINGLE_QUOTE;
					AH->sqlparse.backSlash = false;
				}
				else if (*qry == '"')
				{
					AH->sqlparse.state = SQL_IN_DOUBLE_QUOTE;
				}

				/*
				 * Look for dollar-quotes. We make the assumption that
				 * $-quotes will not have an ident character just before them
				 * in pg_dump output.  XXX is this good enough?
				 */
				else if (*qry == '$' && !_isIdentChar(AH->sqlparse.lastChar))
				{
					AH->sqlparse.state = SQL_IN_DOLLAR_TAG;
					/* initialize separate buffer with possible tag */
					if (AH->sqlparse.tagBuf == NULL)
						AH->sqlparse.tagBuf = createPQExpBuffer();
					else
						resetPQExpBuffer(AH->sqlparse.tagBuf);
					appendPQExpBufferChar(AH->sqlparse.tagBuf, *qry);
				}
				else if (*qry == '-' && AH->sqlparse.lastChar == '-')
					AH->sqlparse.state = SQL_IN_SQL_COMMENT;
				else if (*qry == '*' && AH->sqlparse.lastChar == '/')
					AH->sqlparse.state = SQL_IN_EXT_COMMENT;
				else if (*qry == '(')
					AH->sqlparse.braceDepth++;
				else if (*qry == ')')
					AH->sqlparse.braceDepth--;
				break;

			case SQL_IN_SQL_COMMENT:
				if (*qry == '\n')
					AH->sqlparse.state = SQL_SCAN;
				break;

			case SQL_IN_EXT_COMMENT:

				/*
				 * This isn't fully correct, because we don't account for
				 * nested slash-stars, but pg_dump never emits such.
				 */
				if (AH->sqlparse.lastChar == '*' && *qry == '/')
					AH->sqlparse.state = SQL_SCAN;
				break;

			case SQL_IN_SINGLE_QUOTE:
				/* We needn't handle '' specially */
				if (*qry == '\'' && !AH->sqlparse.backSlash)
					AH->sqlparse.state = SQL_SCAN;
				else if (*qry == '\\')
					AH->sqlparse.backSlash = !AH->sqlparse.backSlash;
				else
					AH->sqlparse.backSlash = false;
				break;

			case SQL_IN_E_QUOTE:

				/*
				 * Eventually we will need to handle '' specially, because
				 * after E'...''... we should still be in E_QUOTE state.
				 *
				 * XXX problem: how do we tell whether the dump was made by a
				 * version that thinks backslashes aren't special in non-E
				 * literals??
				 */
				if (*qry == '\'' && !AH->sqlparse.backSlash)
					AH->sqlparse.state = SQL_SCAN;
				else if (*qry == '\\')
					AH->sqlparse.backSlash = !AH->sqlparse.backSlash;
				else
					AH->sqlparse.backSlash = false;
				break;

			case SQL_IN_DOUBLE_QUOTE:
				/* We needn't handle "" specially */
				if (*qry == '"')
					AH->sqlparse.state = SQL_SCAN;
				break;

			case SQL_IN_DOLLAR_TAG:
				if (*qry == '$')
				{
					/* Do not add the closing $ to tagBuf */
					AH->sqlparse.state = SQL_IN_DOLLAR_QUOTE;
					AH->sqlparse.minTagEndPos = AH->sqlBuf->len + AH->sqlparse.tagBuf->len + 1;
				}
				else if (_isDQChar(*qry, (AH->sqlparse.tagBuf->len == 1)))
				{
					/* Valid, so add to tag */
					appendPQExpBufferChar(AH->sqlparse.tagBuf, *qry);
				}
				else
				{
					/*
					 * Ooops, we're not really in a dollar-tag.  Valid tag
					 * chars do not include the various chars we look for in
					 * this state machine, so it's safe to just jump from this
					 * state back to SCAN.	We have to back up the qry pointer
					 * so that the current character gets rescanned in SCAN
					 * state; and then "continue" so that the bottom-of-loop
					 * actions aren't done yet.
					 */
					AH->sqlparse.state = SQL_SCAN;
					qry--;
					continue;
				}
				break;

			case SQL_IN_DOLLAR_QUOTE:

				/*
				 * If we are at a $, see whether what precedes it matches
				 * tagBuf.	(Remember that the trailing $ of the tag was not
				 * added to tagBuf.)  However, don't compare until we have
				 * enough data to be a possible match --- this is needed to
				 * avoid false match on '$a$a$...'
				 */
				if (*qry == '$' &&
					AH->sqlBuf->len >= AH->sqlparse.minTagEndPos &&
					strcmp(AH->sqlparse.tagBuf->data,
						   AH->sqlBuf->data + AH->sqlBuf->len - AH->sqlparse.tagBuf->len) == 0)
					AH->sqlparse.state = SQL_SCAN;
				break;
		}

		appendPQExpBufferChar(AH->sqlBuf, *qry);
		AH->sqlparse.lastChar = *qry;
	}

	/*
	 * If we get here, we've processed entire bufferload with no complete SQL
	 * stmt
	 */
	return eos;
}


/* Convenience function to send one or more queries. Monitors result to handle COPY statements */
int
ExecuteSqlCommandBuf(ArchiveHandle *AH, void *qryv, size_t bufLen)
{
	char	   *qry = (char *) qryv;
	char	   *eos = qry + bufLen;

	/*
	 * fprintf(stderr, "\n\n*****\n Buffer:\n\n%s\n*******************\n\n",
	 * qry);
	 */

	/* Could switch between command and COPY IN mode at each line */
	while (qry < eos)
	{
		/*
		 * If libpq is in CopyIn mode *or* if the archive structure shows we
		 * are sending COPY data, treat the data as COPY data.  The pgCopyIn
		 * check is only needed for backwards compatibility with ancient
		 * archive files that might just issue a COPY command without marking
		 * it properly.  Note that in an archive entry that has a copyStmt,
		 * all data up to the end of the entry will go to _sendCopyLine, and
		 * therefore will be dropped if libpq has failed to enter COPY mode.
		 * Also, if a "\." data terminator is found, anything remaining in the
		 * archive entry will be dropped.
		 */
		if (AH->pgCopyIn || AH->writingCopyData)
			qry = _sendCopyLine(AH, qry, eos);
		else
			qry = _sendSQLLine(AH, qry, eos);
	}

	return 1;
}

void
StartTransaction(ArchiveHandle *AH)
{
	PQExpBuffer qry = createPQExpBuffer();

	appendPQExpBuffer(qry, "BEGIN");

	ExecuteSqlCommand(AH, qry, "could not start database transaction");

	destroyPQExpBuffer(qry);
}

void
CommitTransaction(ArchiveHandle *AH)
{
	PQExpBuffer qry = createPQExpBuffer();

	appendPQExpBuffer(qry, "COMMIT");

	ExecuteSqlCommand(AH, qry, "could not commit database transaction");

	destroyPQExpBuffer(qry);
}

static bool
_isIdentChar(unsigned char c)
{
	if ((c >= 'a' && c <= 'z')
		|| (c >= 'A' && c <= 'Z')
		|| (c >= '0' && c <= '9')
		|| (c == '_')
		|| (c == '$')
		|| (c >= (unsigned char) '\200')		/* no need to check <= \377 */
		)
		return true;
	else
		return false;
}

static bool
_isDQChar(unsigned char c, bool atStart)
{
	if ((c >= 'a' && c <= 'z')
		|| (c >= 'A' && c <= 'Z')
		|| (c == '_')
		|| (!atStart && c >= '0' && c <= '9')
		|| (c >= (unsigned char) '\200')		/* no need to check <= \377 */
		)
		return true;
	else
		return false;
}