/*-------------------------------------------------------------------------
*
* syslogger.c
*
* The system logger (syslogger) appeared in Postgres 8.0. It catches all
* stderr output from the postmaster, backends, and other subprocesses
* by redirecting to a pipe, and writes it to a set of logfiles.
* It's possible to have size and age limits for the logfile configured
* in postgresql.conf. If these limits are reached or passed, the
* current logfile is closed and a new one is created (rotated).
* The logfiles are stored in a subdirectory (configurable in
* postgresql.conf), using a user-selectable naming scheme.
*
* Author: Andreas Pflug <pgadmin@pse-consulting.de>
*
* Copyright (c) 2004-2018, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* src/backend/postmaster/syslogger.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/time.h>
#include "lib/stringinfo.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "nodes/pg_list.h"
#include "pgstat.h"
#include "pgtime.h"
#include "postmaster/fork_process.h"
#include "postmaster/postmaster.h"
#include "postmaster/syslogger.h"
#include "storage/dsm.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/pg_shmem.h"
#include "tcop/tcopprot.h"
#include "utils/guc.h"
#include "utils/ps_status.h"
#include "utils/timestamp.h"
/*
* We read() into a temp buffer twice as big as a chunk, so that any fragment
* left after processing can be moved down to the front and we'll still have
* room to read a full chunk.
*/
#define READ_BUF_SIZE (2 * PIPE_CHUNK_SIZE)
/*
* GUC parameters. Logging_collector cannot be changed after postmaster
* start, but the rest can change at SIGHUP.
*/
bool Logging_collector = false;
int Log_RotationAge = HOURS_PER_DAY * MINS_PER_HOUR;
int Log_RotationSize = 10 * 1024;
char *Log_directory = NULL;
char *Log_filename = NULL;
bool Log_truncate_on_rotation = false;
int Log_file_mode = S_IRUSR | S_IWUSR;
/*
* Globally visible state (used by elog.c)
*/
bool am_syslogger = false;
extern bool redirection_done;
/*
* Private state
*/
static pg_time_t next_rotation_time;
static bool pipe_eof_seen = false;
static bool rotation_disabled = false;
static FILE *syslogFile = NULL;
static FILE *csvlogFile = NULL;
NON_EXEC_STATIC pg_time_t first_syslogger_file_time = 0;
static char *last_file_name = NULL;
static char *last_csv_file_name = NULL;
/*
* Buffers for saving partial messages from different backends.
*
* Keep NBUFFER_LISTS lists of these, with the entry for a given source pid
* being in the list numbered (pid % NBUFFER_LISTS), so as to cut down on
* the number of entries we have to examine for any one incoming message.
* There must never be more than one entry for the same source pid.
*
* An inactive buffer is not removed from its list, just held for re-use.
* An inactive buffer has pid == 0 and undefined contents of data.
*/
typedef struct
{
int32 pid; /* PID of source process */
StringInfoData data; /* accumulated data, as a StringInfo */
} save_buffer;
#define NBUFFER_LISTS 256
static List *buffer_lists[NBUFFER_LISTS];
/* These must be exported for EXEC_BACKEND case ... annoying */
#ifndef WIN32
int syslogPipe[2] = {-1, -1};
#else
HANDLE syslogPipe[2] = {0, 0};
#endif
#ifdef WIN32
static HANDLE threadHandle = 0;
static CRITICAL_SECTION sysloggerSection;
#endif
/*
* Flags set by interrupt handlers for later service in the main loop.
*/
static volatile sig_atomic_t got_SIGHUP = false;
static volatile sig_atomic_t rotation_requested = false;
/* Local subroutines */
#ifdef EXEC_BACKEND
static pid_t syslogger_forkexec(void);
static void syslogger_parseArgs(int argc, char *argv[]);
#endif
NON_EXEC_STATIC void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn();
static void process_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
static void flush_pipe_input(char *logbuffer, int *bytes_in_logbuffer);
static FILE *logfile_open(const char *filename, const char *mode,
bool allow_errors);
#ifdef WIN32
static unsigned int __stdcall pipeThread(void *arg);
#endif
static void logfile_rotate(bool time_based_rotation, int size_rotation_for);
static char *logfile_getname(pg_time_t timestamp, const char *suffix);
static void set_next_rotation_time(void);
static void sigHupHandler(SIGNAL_ARGS);
static void sigUsr1Handler(SIGNAL_ARGS);
static void update_metainfo_datafile(void);
/*
* Main entry point for syslogger process
* argc/argv parameters are valid only in EXEC_BACKEND case.
*/
NON_EXEC_STATIC void
SysLoggerMain(int argc, char *argv[])
{
#ifndef WIN32
char logbuffer[READ_BUF_SIZE];
int bytes_in_logbuffer = 0;
#endif
char *currentLogDir;
char *currentLogFilename;
int currentLogRotationAge;
pg_time_t now;
now = MyStartTime;
#ifdef EXEC_BACKEND
syslogger_parseArgs(argc, argv);
#endif /* EXEC_BACKEND */
am_syslogger = true;
init_ps_display("logger", "", "", "");
/*
* If we restarted, our stderr is already redirected into our own input
* pipe. This is of course pretty useless, not to mention that it
* interferes with detecting pipe EOF. Point stderr to /dev/null. This
* assumes that all interesting messages generated in the syslogger will
* come through elog.c and will be sent to write_syslogger_file.
*/
if (redirection_done)
{
int fd = open(DEVNULL, O_WRONLY, 0);
/*
* The closes might look redundant, but they are not: we want to be
* darn sure the pipe gets closed even if the open failed. We can
* survive running with stderr pointing nowhere, but we can't afford
* to have extra pipe input descriptors hanging around.
*
* As we're just trying to reset these to go to DEVNULL, there's not
* much point in checking for failure from the close/dup2 calls here,
* if they fail then presumably the file descriptors are closed and
* any writes will go into the bitbucket anyway.
*/
close(fileno(stdout));
close(fileno(stderr));
if (fd != -1)
{
(void) dup2(fd, fileno(stdout));
(void) dup2(fd, fileno(stderr));
close(fd);
}
}
/*
* Syslogger's own stderr can't be the syslogPipe, so set it back to text
* mode if we didn't just close it. (It was set to binary in
* SubPostmasterMain).
*/
#ifdef WIN32
else
_setmode(_fileno(stderr), _O_TEXT);
#endif
/*
* Also close our copy of the write end of the pipe. This is needed to
* ensure we can detect pipe EOF correctly. (But note that in the restart
* case, the postmaster already did this.)
*/
#ifndef WIN32
if (syslogPipe[1] >= 0)
close(syslogPipe[1]);
syslogPipe[1] = -1;
#else
if (syslogPipe[1])
CloseHandle(syslogPipe[1]);
syslogPipe[1] = 0;
#endif
/*
* Properly accept or ignore signals the postmaster might send us
*
* Note: we ignore all termination signals, and instead exit only when all
* upstream processes are gone, to ensure we don't miss any dying gasps of
* broken backends...
*/
pqsignal(SIGHUP, sigHupHandler); /* set flag to read config file */
pqsignal(SIGINT, SIG_IGN);
pqsignal(SIGTERM, SIG_IGN);
pqsignal(SIGQUIT, SIG_IGN);
pqsignal(SIGALRM, SIG_IGN);
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR1, sigUsr1Handler); /* request log rotation */
pqsignal(SIGUSR2, SIG_IGN);
/*
* Reset some signals that are accepted by postmaster but not here
*/
pqsignal(SIGCHLD, SIG_DFL);
pqsignal(SIGTTIN, SIG_DFL);
pqsignal(SIGTTOU, SIG_DFL);
pqsignal(SIGCONT, SIG_DFL);
pqsignal(SIGWINCH, SIG_DFL);
PG_SETMASK(&UnBlockSig);
#ifdef WIN32
/* Fire up separate data transfer thread */
InitializeCriticalSection(&sysloggerSection);
EnterCriticalSection(&sysloggerSection);
threadHandle = (HANDLE) _beginthreadex(NULL, 0, pipeThread, NULL, 0, NULL);
if (threadHandle == 0)
elog(FATAL, "could not create syslogger data transfer thread: %m");
#endif /* WIN32 */
/*
* Remember active logfiles' name(s). We recompute 'em from the reference
* time because passing down just the pg_time_t is a lot cheaper than
* passing a whole file path in the EXEC_BACKEND case.
*/
last_file_name = logfile_getname(first_syslogger_file_time, NULL);
if (csvlogFile != NULL)
last_csv_file_name = logfile_getname(first_syslogger_file_time, ".csv");
/* remember active logfile parameters */
currentLogDir = pstrdup(Log_directory);
currentLogFilename = pstrdup(Log_filename);
currentLogRotationAge = Log_RotationAge;
/* set next planned rotation time */
set_next_rotation_time();
update_metainfo_datafile();
/*
* Reset whereToSendOutput, as the postmaster will do (but hasn't yet, at
* the point where we forked). This prevents duplicate output of messages
* from syslogger itself.
*/
whereToSendOutput = DestNone;
/* main worker loop */
for (;;)
{
bool time_based_rotation = false;
int size_rotation_for = 0;
long cur_timeout;
int cur_flags;
#ifndef WIN32
int rc;
#endif
/* Clear any already-pending wakeups */
ResetLatch(MyLatch);
/*
* Process any requests or signals received recently.
*/
if (got_SIGHUP)
{
got_SIGHUP = false;
ProcessConfigFile(PGC_SIGHUP);
/*
* Check if the log directory or filename pattern changed in
* postgresql.conf. If so, force rotation to make sure we're
* writing the logfiles in the right place.
*/
if (strcmp(Log_directory, currentLogDir) != 0)
{
pfree(currentLogDir);
currentLogDir = pstrdup(Log_directory);
rotation_requested = true;
/*
* Also, create new directory if not present; ignore errors
*/
(void) MakePGDirectory(Log_directory);
}
if (strcmp(Log_filename, currentLogFilename) != 0)
{
pfree(currentLogFilename);
currentLogFilename = pstrdup(Log_filename);
rotation_requested = true;
}
/*
* Force a rotation if CSVLOG output was just turned on or off and
* we need to open or close csvlogFile accordingly.
*/
if (((Log_destination & LOG_DESTINATION_CSVLOG) != 0) !=
(csvlogFile != NULL))
rotation_requested = true;
/*
* If rotation time parameter changed, reset next rotation time,
* but don't immediately force a rotation.
*/
if (currentLogRotationAge != Log_RotationAge)
{
currentLogRotationAge = Log_RotationAge;
set_next_rotation_time();
}
/*
* If we had a rotation-disabling failure, re-enable rotation
* attempts after SIGHUP, and force one immediately.
*/
if (rotation_disabled)
{
rotation_disabled = false;
rotation_requested = true;
}
/*
* Force rewriting last log filename when reloading configuration.
* Even if rotation_requested is false, log_destination may have
* been changed and we don't want to wait the next file rotation.
*/
update_metainfo_datafile();
}
if (Log_RotationAge > 0 && !rotation_disabled)
{
/* Do a logfile rotation if it's time */
now = (pg_time_t) time(NULL);
if (now >= next_rotation_time)
rotation_requested = time_based_rotation = true;
}
if (!rotation_requested && Log_RotationSize > 0 && !rotation_disabled)
{
/* Do a rotation if file is too big */
if (ftell(syslogFile) >= Log_RotationSize * 1024L)
{
rotation_requested = true;
size_rotation_for |= LOG_DESTINATION_STDERR;
}
if (csvlogFile != NULL &&
ftell(csvlogFile) >= Log_RotationSize * 1024L)
{
rotation_requested = true;
size_rotation_for |= LOG_DESTINATION_CSVLOG;
}
}
if (rotation_requested)
{
/*
* Force rotation when both values are zero. It means the request
* was sent by pg_rotate_logfile.
*/
if (!time_based_rotation && size_rotation_for == 0)
size_rotation_for = LOG_DESTINATION_STDERR | LOG_DESTINATION_CSVLOG;
logfile_rotate(time_based_rotation, size_rotation_for);
}
/*
* Calculate time till next time-based rotation, so that we don't
* sleep longer than that. We assume the value of "now" obtained
* above is still close enough. Note we can't make this calculation
* until after calling logfile_rotate(), since it will advance
* next_rotation_time.
*
* Also note that we need to beware of overflow in calculation of the
* timeout: with large settings of Log_RotationAge, next_rotation_time
* could be more than INT_MAX msec in the future. In that case we'll
* wait no more than INT_MAX msec, and try again.
*/
if (Log_RotationAge > 0 && !rotation_disabled)
{
pg_time_t delay;
delay = next_rotation_time - now;
if (delay > 0)
{
if (delay > INT_MAX / 1000)
delay = INT_MAX / 1000;
cur_timeout = delay * 1000L; /* msec */
}
else
cur_timeout = 0;
cur_flags = WL_TIMEOUT;
}
else
{
cur_timeout = -1L;
cur_flags = 0;
}
/*
* Sleep until there's something to do
*/
#ifndef WIN32
rc = WaitLatchOrSocket(MyLatch,
WL_LATCH_SET | WL_SOCKET_READABLE | cur_flags,
syslogPipe[0],
cur_timeout,
WAIT_EVENT_SYSLOGGER_MAIN);
if (rc & WL_SOCKET_READABLE)
{
int bytesRead;
bytesRead = read(syslogPipe[0],
logbuffer + bytes_in_logbuffer,
sizeof(logbuffer) - bytes_in_logbuffer);
if (bytesRead < 0)
{
if (errno != EINTR)
ereport(LOG,
(errcode_for_socket_access(),
errmsg("could not read from logger pipe: %m")));
}
else if (bytesRead > 0)
{
bytes_in_logbuffer += bytesRead;
process_pipe_input(logbuffer, &bytes_in_logbuffer);
continue;
}
else
{
/*
* Zero bytes read when select() is saying read-ready means
* EOF on the pipe: that is, there are no longer any processes
* with the pipe write end open. Therefore, the postmaster
* and all backends are shut down, and we are done.
*/
pipe_eof_seen = true;
/* if there's any data left then force it out now */
flush_pipe_input(logbuffer, &bytes_in_logbuffer);
}
}
#else /* WIN32 */
/*
* On Windows we leave it to a separate thread to transfer data and
* detect pipe EOF. The main thread just wakes up to handle SIGHUP
* and rotation conditions.
*
* Server code isn't generally thread-safe, so we ensure that only one
* of the threads is active at a time by entering the critical section
* whenever we're not sleeping.
*/
LeaveCriticalSection(&sysloggerSection);
(void) WaitLatch(MyLatch,
WL_LATCH_SET | cur_flags,
cur_timeout,
WAIT_EVENT_SYSLOGGER_MAIN);
EnterCriticalSection(&sysloggerSection);
#endif /* WIN32 */
if (pipe_eof_seen)
{
/*
* seeing this message on the real stderr is annoying - so we make
* it DEBUG1 to suppress in normal use.
*/
ereport(DEBUG1,
(errmsg("logger shutting down")));
/*
* Normal exit from the syslogger is here. Note that we
* deliberately do not close syslogFile before exiting; this is to
* allow for the possibility of elog messages being generated
* inside proc_exit. Regular exit() will take care of flushing
* and closing stdio channels.
*/
proc_exit(0);
}
}
}
/*
* Postmaster subroutine to start a syslogger subprocess.
*/
int
SysLogger_Start(void)
{
pid_t sysloggerPid;
char *filename;
if (!Logging_collector)
return 0;
/*
* If first time through, create the pipe which will receive stderr
* output.
*
* If the syslogger crashes and needs to be restarted, we continue to use
* the same pipe (indeed must do so, since extant backends will be writing
* into that pipe).
*
* This means the postmaster must continue to hold the read end of the
* pipe open, so we can pass it down to the reincarnated syslogger. This
* is a bit klugy but we have little choice.
*/
#ifndef WIN32
if (syslogPipe[0] < 0)
{
if (pipe(syslogPipe) < 0)
ereport(FATAL,
(errcode_for_socket_access(),
(errmsg("could not create pipe for syslog: %m"))));
}
#else
if (!syslogPipe[0])
{
SECURITY_ATTRIBUTES sa;
memset(&sa, 0, sizeof(SECURITY_ATTRIBUTES));
sa.nLength = sizeof(SECURITY_ATTRIBUTES);
sa.bInheritHandle = TRUE;
if (!CreatePipe(&syslogPipe[0], &syslogPipe[1], &sa, 32768))
ereport(FATAL,
(errcode_for_file_access(),
(errmsg("could not create pipe for syslog: %m"))));
}
#endif
/*
* Create log directory if not present; ignore errors
*/
(void) MakePGDirectory(Log_directory);
/*
* The initial logfile is created right in the postmaster, to verify that
* the Log_directory is writable. We save the reference time so that the
* syslogger child process can recompute this file name.
*
* It might look a bit strange to re-do this during a syslogger restart,
* but we must do so since the postmaster closed syslogFile after the
* previous fork (and remembering that old file wouldn't be right anyway).
* Note we always append here, we won't overwrite any existing file. This
* is consistent with the normal rules, because by definition this is not
* a time-based rotation.
*/
first_syslogger_file_time = time(NULL);
filename = logfile_getname(first_syslogger_file_time, NULL);
syslogFile = logfile_open(filename, "a", false);
pfree(filename);
/*
* Likewise for the initial CSV log file, if that's enabled. (Note that
* we open syslogFile even when only CSV output is nominally enabled,
* since some code paths will write to syslogFile anyway.)
*/
if (Log_destination & LOG_DESTINATION_CSVLOG)
{
filename = logfile_getname(first_syslogger_file_time, ".csv");
csvlogFile = logfile_open(filename, "a", false);
pfree(filename);
}
#ifdef EXEC_BACKEND
switch ((sysloggerPid = syslogger_forkexec()))
#else
switch ((sysloggerPid = fork_process()))
#endif
{
case -1:
ereport(LOG,
(errmsg("could not fork system logger: %m")));
return 0;
#ifndef EXEC_BACKEND
case 0:
/* in postmaster child ... */
InitPostmasterChild();
/* Close the postmaster's sockets */
ClosePostmasterPorts(true);
/* Drop our connection to postmaster's shared memory, as well */
dsm_detach_all();
PGSharedMemoryDetach();
/* do the work */
SysLoggerMain(0, NULL);
break;
#endif
default:
/* success, in postmaster */
/* now we redirect stderr, if not done already */
if (!redirection_done)
{
#ifdef WIN32
int fd;
#endif
/*
* Leave a breadcrumb trail when redirecting, in case the user
* forgets that redirection is active and looks only at the
* original stderr target file.
*/
ereport(LOG,
(errmsg("redirecting log output to logging collector process"),
errhint("Future log output will appear in directory \"%s\".",
Log_directory)));
#ifndef WIN32
fflush(stdout);
if (dup2(syslogPipe[1], fileno(stdout)) < 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not redirect stdout: %m")));
fflush(stderr);
if (dup2(syslogPipe[1], fileno(stderr)) < 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not redirect stderr: %m")));
/* Now we are done with the write end of the pipe. */
close(syslogPipe[1]);
syslogPipe[1] = -1;
#else
/*
* open the pipe in binary mode and make sure stderr is binary
* after it's been dup'ed into, to avoid disturbing the pipe
* chunking protocol.
*/
fflush(stderr);
fd = _open_osfhandle((intptr_t) syslogPipe[1],
_O_APPEND | _O_BINARY);
if (dup2(fd, _fileno(stderr)) < 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not redirect stderr: %m")));
close(fd);
_setmode(_fileno(stderr), _O_BINARY);
/*
* Now we are done with the write end of the pipe.
* CloseHandle() must not be called because the preceding
* close() closes the underlying handle.
*/
syslogPipe[1] = 0;
#endif
redirection_done = true;
}
/* postmaster will never write the file(s); close 'em */
fclose(syslogFile);
syslogFile = NULL;
if (csvlogFile != NULL)
{
fclose(csvlogFile);
csvlogFile = NULL;
}
return (int) sysloggerPid;
}
/* we should never reach here */
return 0;
}
#ifdef EXEC_BACKEND
/*
* syslogger_forkexec() -
*
* Format up the arglist for, then fork and exec, a syslogger process
*/
static pid_t
syslogger_forkexec(void)
{
char *av[10];
int ac = 0;
char filenobuf[32];
char csvfilenobuf[32];
av[ac++] = "postgres";
av[ac++] = "--forklog";
av[ac++] = NULL; /* filled in by postmaster_forkexec */
/* static variables (those not passed by write_backend_variables) */
#ifndef WIN32
if (syslogFile != NULL)
snprintf(filenobuf, sizeof(filenobuf), "%d",
fileno(syslogFile));
else
strcpy(filenobuf, "-1");
#else /* WIN32 */
if (syslogFile != NULL)
snprintf(filenobuf, sizeof(filenobuf), "%ld",
(long) _get_osfhandle(_fileno(syslogFile)));
else
strcpy(filenobuf, "0");
#endif /* WIN32 */
av[ac++] = filenobuf;
#ifndef WIN32
if (csvlogFile != NULL)
snprintf(csvfilenobuf, sizeof(csvfilenobuf), "%d",
fileno(csvlogFile));
else
strcpy(csvfilenobuf, "-1");
#else /* WIN32 */
if (csvlogFile != NULL)
snprintf(csvfilenobuf, sizeof(csvfilenobuf), "%ld",
(long) _get_osfhandle(_fileno(csvlogFile)));
else
strcpy(csvfilenobuf, "0");
#endif /* WIN32 */
av[ac++] = csvfilenobuf;
av[ac] = NULL;
Assert(ac < lengthof(av));
return postmaster_forkexec(ac, av);
}
/*
* syslogger_parseArgs() -
*
* Extract data from the arglist for exec'ed syslogger process
*/
static void
syslogger_parseArgs(int argc, char *argv[])
{
int fd;
Assert(argc == 5);
argv += 3;
/*
* Re-open the error output files that were opened by SysLogger_Start().
*
* We expect this will always succeed, which is too optimistic, but if it
* fails there's not a lot we can do to report the problem anyway. As
* coded, we'll just crash on a null pointer dereference after failure...
*/
#ifndef WIN32
fd = atoi(*argv++);
if (fd != -1)
{
syslogFile = fdopen(fd, "a");
setvbuf(syslogFile, NULL, PG_IOLBF, 0);
}
fd = atoi(*argv++);
if (fd != -1)
{
csvlogFile = fdopen(fd, "a");
setvbuf(csvlogFile, NULL, PG_IOLBF, 0);
}
#else /* WIN32 */
fd = atoi(*argv++);
if (fd != 0)
{
fd = _open_osfhandle(fd, _O_APPEND | _O_TEXT);
if (fd > 0)
{
syslogFile = fdopen(fd, "a");
setvbuf(syslogFile, NULL, PG_IOLBF, 0);
}
}
fd = atoi(*argv++);
if (fd != 0)
{
fd = _open_osfhandle(fd, _O_APPEND | _O_TEXT);
if (fd > 0)
{
csvlogFile = fdopen(fd, "a");
setvbuf(csvlogFile, NULL, PG_IOLBF, 0);
}
}
#endif /* WIN32 */
}
#endif /* EXEC_BACKEND */
/* --------------------------------
* pipe protocol handling
* --------------------------------
*/
/*
* Process data received through the syslogger pipe.
*
* This routine interprets the log pipe protocol which sends log messages as
* (hopefully atomic) chunks - such chunks are detected and reassembled here.
*
* The protocol has a header that starts with two nul bytes, then has a 16 bit
* length, the pid of the sending process, and a flag to indicate if it is
* the last chunk in a message. Incomplete chunks are saved until we read some
* more, and non-final chunks are accumulated until we get the final chunk.
*
* All of this is to avoid 2 problems:
* . partial messages being written to logfiles (messes rotation), and
* . messages from different backends being interleaved (messages garbled).
*
* Any non-protocol messages are written out directly. These should only come
* from non-PostgreSQL sources, however (e.g. third party libraries writing to
* stderr).
*
* logbuffer is the data input buffer, and *bytes_in_logbuffer is the number
* of bytes present. On exit, any not-yet-eaten data is left-justified in
* logbuffer, and *bytes_in_logbuffer is updated.
*/
static void
process_pipe_input(char *logbuffer, int *bytes_in_logbuffer)
{
char *cursor = logbuffer;
int count = *bytes_in_logbuffer;
int dest = LOG_DESTINATION_STDERR;
/* While we have enough for a header, process data... */
while (count >= (int) (offsetof(PipeProtoHeader, data) + 1))
{
PipeProtoHeader p;
int chunklen;
/* Do we have a valid header? */
memcpy(&p, cursor, offsetof(PipeProtoHeader, data));
if (p.nuls[0] == '\0' && p.nuls[1] == '\0' &&
p.len > 0 && p.len <= PIPE_MAX_PAYLOAD &&
p.pid != 0 &&
(p.is_last == 't' || p.is_last == 'f' ||
p.is_last == 'T' || p.is_last == 'F'))
{
List *buffer_list;
ListCell *cell;
save_buffer *existing_slot = NULL,
*free_slot = NULL;
StringInfo str;
chunklen = PIPE_HEADER_SIZE + p.len;
/* Fall out of loop if we don't have the whole chunk yet */
if (count < chunklen)
break;
dest = (p.is_last == 'T' || p.is_last == 'F') ?
LOG_DESTINATION_CSVLOG : LOG_DESTINATION_STDERR;
/* Locate any existing buffer for this source pid */
buffer_list = buffer_lists[p.pid % NBUFFER_LISTS];
foreach(cell, buffer_list)
{
save_buffer *buf = (save_buffer *) lfirst(cell);
if (buf->pid == p.pid)
{
existing_slot = buf;
break;
}
if (buf->pid == 0 && free_slot == NULL)
free_slot = buf;
}
if (p.is_last == 'f' || p.is_last == 'F')
{
/*
* Save a complete non-final chunk in a per-pid buffer
*/
if (existing_slot != NULL)
{
/* Add chunk to data from preceding chunks */
str = &(existing_slot->data);
appendBinaryStringInfo(str,
cursor + PIPE_HEADER_SIZE,
p.len);
}
else
{
/* First chunk of message, save in a new buffer */
if (free_slot == NULL)
{
/*
* Need a free slot, but there isn't one in the list,
* so create a new one and extend the list with it.
*/
free_slot = palloc(sizeof(save_buffer));
buffer_list = lappend(buffer_list, free_slot);
buffer_lists[p.pid % NBUFFER_LISTS] = buffer_list;
}
free_slot->pid = p.pid;
str = &(free_slot->data);
initStringInfo(str);
appendBinaryStringInfo(str,
cursor + PIPE_HEADER_SIZE,
p.len);
}
}
else
{
/*
* Final chunk --- add it to anything saved for that pid, and
* either way write the whole thing out.
*/
if (existing_slot != NULL)
{
str = &(existing_slot->data);
appendBinaryStringInfo(str,
cursor + PIPE_HEADER_SIZE,
p.len);
write_syslogger_file(str->data, str->len, dest);
/* Mark the buffer unused, and reclaim string storage */
existing_slot->pid = 0;
pfree(str->data);
}
else
{
/* The whole message was one chunk, evidently. */
write_syslogger_file(cursor + PIPE_HEADER_SIZE, p.len,
dest);
}
}
/* Finished processing this chunk */
cursor += chunklen;
count -= chunklen;
}
else
{
/* Process non-protocol data */
/*
* Look for the start of a protocol header. If found, dump data
* up to there and repeat the loop. Otherwise, dump it all and
* fall out of the loop. (Note: we want to dump it all if at all
* possible, so as to avoid dividing non-protocol messages across
* logfiles. We expect that in many scenarios, a non-protocol
* message will arrive all in one read(), and we want to respect
* the read() boundary if possible.)
*/
for (chunklen = 1; chunklen < count; chunklen++)
{
if (cursor[chunklen] == '\0')
break;
}
/* fall back on the stderr log as the destination */
write_syslogger_file(cursor, chunklen, LOG_DESTINATION_STDERR);
cursor += chunklen;
count -= chunklen;
}
}
/* We don't have a full chunk, so left-align what remains in the buffer */
if (count > 0 && cursor != logbuffer)
memmove(logbuffer, cursor, count);
*bytes_in_logbuffer = count;
}
/*
* Force out any buffered data
*
* This is currently used only at syslogger shutdown, but could perhaps be
* useful at other times, so it is careful to leave things in a clean state.
*/
static void
flush_pipe_input(char *logbuffer, int *bytes_in_logbuffer)
{
int i;
/* Dump any incomplete protocol messages */
for (i = 0; i < NBUFFER_LISTS; i++)
{
List *list = buffer_lists[i];
ListCell *cell;
foreach(cell, list)
{
save_buffer *buf = (save_buffer *) lfirst(cell);
if (buf->pid != 0)
{
StringInfo str = &(buf->data);
write_syslogger_file(str->data, str->len,
LOG_DESTINATION_STDERR);
/* Mark the buffer unused, and reclaim string storage */
buf->pid = 0;
pfree(str->data);
}
}
}
/*
* Force out any remaining pipe data as-is; we don't bother trying to
* remove any protocol headers that may exist in it.
*/
if (*bytes_in_logbuffer > 0)
write_syslogger_file(logbuffer, *bytes_in_logbuffer,
LOG_DESTINATION_STDERR);
*bytes_in_logbuffer = 0;
}
/* --------------------------------
* logfile routines
* --------------------------------
*/
/*
* Write text to the currently open logfile
*
* This is exported so that elog.c can call it when am_syslogger is true.
* This allows the syslogger process to record elog messages of its own,
* even though its stderr does not point at the syslog pipe.
*/
void
write_syslogger_file(const char *buffer, int count, int destination)
{
int rc;
FILE *logfile;
/*
* If we're told to write to csvlogFile, but it's not open, dump the data
* to syslogFile (which is always open) instead. This can happen if CSV
* output is enabled after postmaster start and we've been unable to open
* csvlogFile. There are also race conditions during a parameter change
* whereby backends might send us CSV output before we open csvlogFile or
* after we close it. Writing CSV-formatted output to the regular log
* file isn't great, but it beats dropping log output on the floor.
*
* Think not to improve this by trying to open csvlogFile on-the-fly. Any
* failure in that would lead to recursion.
*/
logfile = (destination == LOG_DESTINATION_CSVLOG &&
csvlogFile != NULL) ? csvlogFile : syslogFile;
rc = fwrite(buffer, 1, count, logfile);
/*
* Try to report any failure. We mustn't use ereport because it would
* just recurse right back here, but write_stderr is OK: it will write
* either to the postmaster's original stderr, or to /dev/null, but never
* to our input pipe which would result in a different sort of looping.
*/
if (rc != count)
write_stderr("could not write to log file: %s\n", strerror(errno));
}
#ifdef WIN32
/*
* Worker thread to transfer data from the pipe to the current logfile.
*
* We need this because on Windows, WaitforMultipleObjects does not work on
* unnamed pipes: it always reports "signaled", so the blocking ReadFile won't
* allow for SIGHUP; and select is for sockets only.
*/
static unsigned int __stdcall
pipeThread(void *arg)
{
char logbuffer[READ_BUF_SIZE];
int bytes_in_logbuffer = 0;
for (;;)
{
DWORD bytesRead;
BOOL result;
result = ReadFile(syslogPipe[0],
logbuffer + bytes_in_logbuffer,
sizeof(logbuffer) - bytes_in_logbuffer,
&bytesRead, 0);
/*
* Enter critical section before doing anything that might touch
* global state shared by the main thread. Anything that uses
* palloc()/pfree() in particular are not safe outside the critical
* section.
*/
EnterCriticalSection(&sysloggerSection);
if (!result)
{
DWORD error = GetLastError();
if (error == ERROR_HANDLE_EOF ||
error == ERROR_BROKEN_PIPE)
break;
_dosmaperr(error);
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not read from logger pipe: %m")));
}
else if (bytesRead > 0)
{
bytes_in_logbuffer += bytesRead;
process_pipe_input(logbuffer, &bytes_in_logbuffer);
}
/*
* If we've filled the current logfile, nudge the main thread to do a
* log rotation.
*/
if (Log_RotationSize > 0)
{
if (ftell(syslogFile) >= Log_RotationSize * 1024L ||
(csvlogFile != NULL && ftell(csvlogFile) >= Log_RotationSize * 1024L))
SetLatch(MyLatch);
}
LeaveCriticalSection(&sysloggerSection);
}
/* We exit the above loop only upon detecting pipe EOF */
pipe_eof_seen = true;
/* if there's any data left then force it out now */
flush_pipe_input(logbuffer, &bytes_in_logbuffer);
/* set the latch to waken the main thread, which will quit */
SetLatch(MyLatch);
LeaveCriticalSection(&sysloggerSection);
_endthread();
return 0;
}
#endif /* WIN32 */
/*
* Open a new logfile with proper permissions and buffering options.
*
* If allow_errors is true, we just log any open failure and return NULL
* (with errno still correct for the fopen failure).
* Otherwise, errors are treated as fatal.
*/
static FILE *
logfile_open(const char *filename, const char *mode, bool allow_errors)
{
FILE *fh;
mode_t oumask;
/*
* Note we do not let Log_file_mode disable IWUSR, since we certainly want
* to be able to write the files ourselves.
*/
oumask = umask((mode_t) ((~(Log_file_mode | S_IWUSR)) & (S_IRWXU | S_IRWXG | S_IRWXO)));
fh = fopen(filename, mode);
umask(oumask);
if (fh)
{
setvbuf(fh, NULL, PG_IOLBF, 0);
#ifdef WIN32
/* use CRLF line endings on Windows */
_setmode(_fileno(fh), _O_TEXT);
#endif
}
else
{
int save_errno = errno;
ereport(allow_errors ? LOG : FATAL,
(errcode_for_file_access(),
errmsg("could not open log file \"%s\": %m",
filename)));
errno = save_errno;
}
return fh;
}
/*
* perform logfile rotation
*/
static void
logfile_rotate(bool time_based_rotation, int size_rotation_for)
{
char *filename;
char *csvfilename = NULL;
pg_time_t fntime;
FILE *fh;
rotation_requested = false;
/*
* When doing a time-based rotation, invent the new logfile name based on
* the planned rotation time, not current time, to avoid "slippage" in the
* file name when we don't do the rotation immediately.
*/
if (time_based_rotation)
fntime = next_rotation_time;
else
fntime = time(NULL);
filename = logfile_getname(fntime, NULL);
if (Log_destination & LOG_DESTINATION_CSVLOG)
csvfilename = logfile_getname(fntime, ".csv");
/*
* Decide whether to overwrite or append. We can overwrite if (a)
* Log_truncate_on_rotation is set, (b) the rotation was triggered by
* elapsed time and not something else, and (c) the computed file name is
* different from what we were previously logging into.
*
* Note: last_file_name should never be NULL here, but if it is, append.
*/
if (time_based_rotation || (size_rotation_for & LOG_DESTINATION_STDERR))
{
if (Log_truncate_on_rotation && time_based_rotation &&
last_file_name != NULL &&
strcmp(filename, last_file_name) != 0)
fh = logfile_open(filename, "w", true);
else
fh = logfile_open(filename, "a", true);
if (!fh)
{
/*
* ENFILE/EMFILE are not too surprising on a busy system; just
* keep using the old file till we manage to get a new one.
* Otherwise, assume something's wrong with Log_directory and stop
* trying to create files.
*/
if (errno != ENFILE && errno != EMFILE)
{
ereport(LOG,
(errmsg("disabling automatic rotation (use SIGHUP to re-enable)")));
rotation_disabled = true;
}
if (filename)
pfree(filename);
if (csvfilename)
pfree(csvfilename);
return;
}
fclose(syslogFile);
syslogFile = fh;
/* instead of pfree'ing filename, remember it for next time */
if (last_file_name != NULL)
pfree(last_file_name);
last_file_name = filename;
filename = NULL;
}
/*
* Same as above, but for csv file. Note that if LOG_DESTINATION_CSVLOG
* was just turned on, we might have to open csvlogFile here though it was
* not open before. In such a case we'll append not overwrite (since
* last_csv_file_name will be NULL); that is consistent with the normal
* rules since it's not a time-based rotation.
*/
if ((Log_destination & LOG_DESTINATION_CSVLOG) &&
(csvlogFile == NULL ||
time_based_rotation || (size_rotation_for & LOG_DESTINATION_CSVLOG)))
{
if (Log_truncate_on_rotation && time_based_rotation &&
last_csv_file_name != NULL &&
strcmp(csvfilename, last_csv_file_name) != 0)
fh = logfile_open(csvfilename, "w", true);
else
fh = logfile_open(csvfilename, "a", true);
if (!fh)
{
/*
* ENFILE/EMFILE are not too surprising on a busy system; just
* keep using the old file till we manage to get a new one.
* Otherwise, assume something's wrong with Log_directory and stop
* trying to create files.
*/
if (errno != ENFILE && errno != EMFILE)
{
ereport(LOG,
(errmsg("disabling automatic rotation (use SIGHUP to re-enable)")));
rotation_disabled = true;
}
if (filename)
pfree(filename);
if (csvfilename)
pfree(csvfilename);
return;
}
if (csvlogFile != NULL)
fclose(csvlogFile);
csvlogFile = fh;
/* instead of pfree'ing filename, remember it for next time */
if (last_csv_file_name != NULL)
pfree(last_csv_file_name);
last_csv_file_name = csvfilename;
csvfilename = NULL;
}
else if (!(Log_destination & LOG_DESTINATION_CSVLOG) &&
csvlogFile != NULL)
{
/* CSVLOG was just turned off, so close the old file */
fclose(csvlogFile);
csvlogFile = NULL;
if (last_csv_file_name != NULL)
pfree(last_csv_file_name);
last_csv_file_name = NULL;
}
if (filename)
pfree(filename);
if (csvfilename)
pfree(csvfilename);
update_metainfo_datafile();
set_next_rotation_time();
}
/*
* construct logfile name using timestamp information
*
* If suffix isn't NULL, append it to the name, replacing any ".log"
* that may be in the pattern.
*
* Result is palloc'd.
*/
static char *
logfile_getname(pg_time_t timestamp, const char *suffix)
{
char *filename;
int len;
filename = palloc(MAXPGPATH);
snprintf(filename, MAXPGPATH, "%s/", Log_directory);
len = strlen(filename);
/* treat Log_filename as a strftime pattern */
pg_strftime(filename + len, MAXPGPATH - len, Log_filename,
pg_localtime(×tamp, log_timezone));
if (suffix != NULL)
{
len = strlen(filename);
if (len > 4 && (strcmp(filename + (len - 4), ".log") == 0))
len -= 4;
strlcpy(filename + len, suffix, MAXPGPATH - len);
}
return filename;
}
/*
* Determine the next planned rotation time, and store in next_rotation_time.
*/
static void
set_next_rotation_time(void)
{
pg_time_t now;
struct pg_tm *tm;
int rotinterval;
/* nothing to do if time-based rotation is disabled */
if (Log_RotationAge <= 0)
return;
/*
* The requirements here are to choose the next time > now that is a
* "multiple" of the log rotation interval. "Multiple" can be interpreted
* fairly loosely. In this version we align to log_timezone rather than
* GMT.
*/
rotinterval = Log_RotationAge * SECS_PER_MINUTE; /* convert to seconds */
now = (pg_time_t) time(NULL);
tm = pg_localtime(&now, log_timezone);
now += tm->tm_gmtoff;
now -= now % rotinterval;
now += rotinterval;
now -= tm->tm_gmtoff;
next_rotation_time = now;
}
/*
* Store the name of the file(s) where the log collector, when enabled, writes
* log messages. Useful for finding the name(s) of the current log file(s)
* when there is time-based logfile rotation. Filenames are stored in a
* temporary file and which is renamed into the final destination for
* atomicity.
*/
static void
update_metainfo_datafile(void)
{
FILE *fh;
if (!(Log_destination & LOG_DESTINATION_STDERR) &&
!(Log_destination & LOG_DESTINATION_CSVLOG))
{
if (unlink(LOG_METAINFO_DATAFILE) < 0 && errno != ENOENT)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m",
LOG_METAINFO_DATAFILE)));
return;
}
if ((fh = logfile_open(LOG_METAINFO_DATAFILE_TMP, "w", true)) == NULL)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m",
LOG_METAINFO_DATAFILE_TMP)));
return;
}
if (last_file_name && (Log_destination & LOG_DESTINATION_STDERR))
{
if (fprintf(fh, "stderr %s\n", last_file_name) < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write file \"%s\": %m",
LOG_METAINFO_DATAFILE_TMP)));
fclose(fh);
return;
}
}
if (last_csv_file_name && (Log_destination & LOG_DESTINATION_CSVLOG))
{
if (fprintf(fh, "csvlog %s\n", last_csv_file_name) < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write file \"%s\": %m",
LOG_METAINFO_DATAFILE_TMP)));
fclose(fh);
return;
}
}
fclose(fh);
if (rename(LOG_METAINFO_DATAFILE_TMP, LOG_METAINFO_DATAFILE) != 0)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not rename file \"%s\" to \"%s\": %m",
LOG_METAINFO_DATAFILE_TMP, LOG_METAINFO_DATAFILE)));
}
/* --------------------------------
* signal handler routines
* --------------------------------
*/
/* SIGHUP: set flag to reload config file */
static void
sigHupHandler(SIGNAL_ARGS)
{
int save_errno = errno;
got_SIGHUP = true;
SetLatch(MyLatch);
errno = save_errno;
}
/* SIGUSR1: set flag to rotate logfile */
static void
sigUsr1Handler(SIGNAL_ARGS)
{
int save_errno = errno;
rotation_requested = true;
SetLatch(MyLatch);
errno = save_errno;
}