1/*-------------------------------------------------------------------------
2 *
3 * syslogger.h
4 * Exports from postmaster/syslogger.c.
5 *
6 * Copyright (c) 2004-2019, PostgreSQL Global Development Group
7 *
8 * src/include/postmaster/syslogger.h
9 *
10 *-------------------------------------------------------------------------
11 */
12#ifndef _SYSLOGGER_H
13#define _SYSLOGGER_H
14
15#include <limits.h> /* for PIPE_BUF */
16
17
18/*
19 * Primitive protocol structure for writing to syslogger pipe(s). The idea
20 * here is to divide long messages into chunks that are not more than
21 * PIPE_BUF bytes long, which according to POSIX spec must be written into
22 * the pipe atomically. The pipe reader then uses the protocol headers to
23 * reassemble the parts of a message into a single string. The reader can
24 * also cope with non-protocol data coming down the pipe, though we cannot
25 * guarantee long strings won't get split apart.
26 *
27 * We use non-nul bytes in is_last to make the protocol a tiny bit
28 * more robust against finding a false double nul byte prologue. But
29 * we still might find it in the len and/or pid bytes unless we're careful.
30 */
31
32#ifdef PIPE_BUF
33/* Are there any systems with PIPE_BUF > 64K? Unlikely, but ... */
34#if PIPE_BUF > 65536
35#define PIPE_CHUNK_SIZE 65536
36#else
37#define PIPE_CHUNK_SIZE ((int) PIPE_BUF)
38#endif
39#else /* not defined */
40/* POSIX says the value of PIPE_BUF must be at least 512, so use that */
41#define PIPE_CHUNK_SIZE 512
42#endif
43
44typedef struct
45{
46 char nuls[2]; /* always \0\0 */
47 uint16 len; /* size of this chunk (counts data only) */
48 int32 pid; /* writer's pid */
49 char is_last; /* last chunk of message? 't' or 'f' ('T' or
50 * 'F' for CSV case) */
51 char data[FLEXIBLE_ARRAY_MEMBER]; /* data payload starts here */
52} PipeProtoHeader;
53
54typedef union
55{
56 PipeProtoHeader proto;
57 char filler[PIPE_CHUNK_SIZE];
58} PipeProtoChunk;
59
60#define PIPE_HEADER_SIZE offsetof(PipeProtoHeader, data)
61#define PIPE_MAX_PAYLOAD ((int) (PIPE_CHUNK_SIZE - PIPE_HEADER_SIZE))
62
63
64/* GUC options */
65extern bool Logging_collector;
66extern int Log_RotationAge;
67extern int Log_RotationSize;
68extern PGDLLIMPORT char *Log_directory;
69extern PGDLLIMPORT char *Log_filename;
70extern bool Log_truncate_on_rotation;
71extern int Log_file_mode;
72
73extern bool am_syslogger;
74
75#ifndef WIN32
76extern int syslogPipe[2];
77#else
78extern HANDLE syslogPipe[2];
79#endif
80
81
82extern int SysLogger_Start(void);
83
84extern void write_syslogger_file(const char *buffer, int count, int dest);
85
86#ifdef EXEC_BACKEND
87extern void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn();
88#endif
89
90extern bool CheckLogrotateSignal(void);
91extern void RemoveLogrotateSignalFiles(void);
92
93/*
94 * Name of files saving meta-data information about the log
95 * files currently in use by the syslogger
96 */
97#define LOG_METAINFO_DATAFILE "current_logfiles"
98#define LOG_METAINFO_DATAFILE_TMP LOG_METAINFO_DATAFILE ".tmp"
99
100#endif /* _SYSLOGGER_H */
101