text: /*-------------------------------------------------------------------------
   *
   * syslogger.h
   *	  Exports from postmaster/syslogger.c.
   *
   * Copyright (c) 2004-2016, PostgreSQL Global Development Group
   *
   * src/include/postmaster/syslogger.h
   *
   *-------------------------------------------------------------------------
   */
  #ifndef _SYSLOGGER_H
  #define _SYSLOGGER_H
  
  #include <limits.h>				/* for PIPE_BUF */
  
  
  /*
   * Primitive protocol structure for writing to syslogger pipe(s).  The idea
   * here is to divide long messages into chunks that are not more than
   * PIPE_BUF bytes long, which according to POSIX spec must be written into
   * the pipe atomically.  The pipe reader then uses the protocol headers to
   * reassemble the parts of a message into a single string.  The reader can
   * also cope with non-protocol data coming down the pipe, though we cannot
   * guarantee long strings won't get split apart.
   *
   * We use non-nul bytes in is_last to make the protocol a tiny bit
   * more robust against finding a false double nul byte prologue. But
   * we still might find it in the len and/or pid bytes unless we're careful.
   */
  
  #ifdef PIPE_BUF
  /* Are there any systems with PIPE_BUF > 64K?  Unlikely, but ... */
  #if PIPE_BUF > 65536
  #define PIPE_CHUNK_SIZE  65536
  #else
  #define PIPE_CHUNK_SIZE  ((int) PIPE_BUF)
  #endif
  #else							/* not defined */
  /* POSIX says the value of PIPE_BUF must be at least 512, so use that */
  #define PIPE_CHUNK_SIZE  512
  #endif
  
  typedef struct
  {
  	char		nuls[2];		/* always \0\0 */
  	uint16		len;			/* size of this chunk (counts data only) */
  	int32		pid;			/* writer's pid */
  	char		is_last;		/* last chunk of message? 't' or 'f' ('T' or
  								 * 'F' for CSV case) */
  	char		data[FLEXIBLE_ARRAY_MEMBER];	/* data payload starts here */
  } PipeProtoHeader;
  
  typedef union
  {
  	PipeProtoHeader proto;
  	char		filler[PIPE_CHUNK_SIZE];
  } PipeProtoChunk;
  
  #define PIPE_HEADER_SIZE  offsetof(PipeProtoHeader, data)
  #define PIPE_MAX_PAYLOAD  ((int) (PIPE_CHUNK_SIZE - PIPE_HEADER_SIZE))
  
  
  /* GUC options */
  extern bool Logging_collector;
  extern int	Log_RotationAge;
  extern int	Log_RotationSize;
  extern PGDLLIMPORT char *Log_directory;
  extern PGDLLIMPORT char *Log_filename;
  extern bool Log_truncate_on_rotation;
  extern int	Log_file_mode;
  
  extern bool am_syslogger;
  
  #ifndef WIN32
  extern int	syslogPipe[2];
  #else
  extern HANDLE syslogPipe[2];
  #endif
  
  
  extern int	SysLogger_Start(void);
  
  extern void write_syslogger_file(const char *buffer, int count, int dest);
  
  #ifdef EXEC_BACKEND
  extern void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn();
  #endif
  
  #endif   /* _SYSLOGGER_H */
  