PostgreSQL Source Code  git master
syslogger.h
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1 /*-------------------------------------------------------------------------
2  *
3  * syslogger.h
4  * Exports from postmaster/syslogger.c.
5  *
6  * Copyright (c) 2004-2021, 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 
44 typedef 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  bits8 flags; /* bitmask of PIPE_PROTO_* */
50  char data[FLEXIBLE_ARRAY_MEMBER]; /* data payload starts here */
52 
53 typedef union
54 {
56  char filler[PIPE_CHUNK_SIZE];
58 
59 #define PIPE_HEADER_SIZE offsetof(PipeProtoHeader, data)
60 #define PIPE_MAX_PAYLOAD ((int) (PIPE_CHUNK_SIZE - PIPE_HEADER_SIZE))
61 
62 /* flag bits for PipeProtoHeader->flags */
63 #define PIPE_PROTO_IS_LAST 0x01 /* last chunk of message? */
64 /* log destinations */
65 #define PIPE_PROTO_DEST_STDERR 0x10
66 #define PIPE_PROTO_DEST_CSVLOG 0x20
67 
68 /* GUC options */
69 extern bool Logging_collector;
70 extern int Log_RotationAge;
71 extern int Log_RotationSize;
72 extern PGDLLIMPORT char *Log_directory;
73 extern PGDLLIMPORT char *Log_filename;
74 extern bool Log_truncate_on_rotation;
75 extern int Log_file_mode;
76 
77 #ifndef WIN32
78 extern int syslogPipe[2];
79 #else
80 extern HANDLE syslogPipe[2];
81 #endif
82 
83 
84 extern int SysLogger_Start(void);
85 
86 extern void write_syslogger_file(const char *buffer, int count, int dest);
87 
88 #ifdef EXEC_BACKEND
89 extern void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn();
90 #endif
91 
92 extern bool CheckLogrotateSignal(void);
93 extern void RemoveLogrotateSignalFiles(void);
94 
95 /*
96  * Name of files saving meta-data information about the log
97  * files currently in use by the syslogger
98  */
99 #define LOG_METAINFO_DATAFILE "current_logfiles"
100 #define LOG_METAINFO_DATAFILE_TMP LOG_METAINFO_DATAFILE ".tmp"
101 
102 #endif /* _SYSLOGGER_H */
NON_EXEC_STATIC void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn()
Definition: syslogger.c:157
#define pg_attribute_noreturn()
Definition: c.h:179
int Log_file_mode
Definition: syslogger.c:77
void write_syslogger_file(const char *buffer, int count, int dest)
Definition: syslogger.c:1088
#define FLEXIBLE_ARRAY_MEMBER
Definition: c.h:350
#define PGDLLIMPORT
Definition: c.h:1317
signed int int32
Definition: c.h:429
PipeProtoHeader proto
Definition: syslogger.h:55
bool Log_truncate_on_rotation
Definition: syslogger.c:76
bool Logging_collector
Definition: syslogger.c:71
unsigned short uint16
Definition: c.h:440
int Log_RotationSize
Definition: syslogger.c:73
int syslogPipe[2]
Definition: syslogger.c:115
PGDLLIMPORT char * Log_filename
Definition: syslogger.c:75
bool CheckLogrotateSignal(void)
Definition: syslogger.c:1546
#define PIPE_CHUNK_SIZE
Definition: syslogger.h:41
uint8 bits8
Definition: c.h:448
PGDLLIMPORT char * Log_directory
Definition: syslogger.c:74
void RemoveLogrotateSignalFiles(void)
Definition: syslogger.c:1560
int Log_RotationAge
Definition: syslogger.c:72
int SysLogger_Start(void)
Definition: syslogger.c:541