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atopacctd.c
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atopacctd.c
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/*
** The atopacctd daemon switches on the process accounting feature
** in the kernel and let the process accounting records be written to
** a file, called the source file. After process accounting is active,
** the atopacctd daemon transfers every process accounting record that
** is available in the source file to a shadow file.
** Client processes (like atop) can read the shadow file instead of
** the original process accounting source file.
**
** This approach has the following advantages:
**
** - The atopacctd daemon keeps the source file to a limited size
** by truncating it regularly.
**
** - The atopacct daemon takes care that a shadow file has a limited size.
** As soon as the current shadow file reaches its maximum size, the
** atopacctd daemon creates a subsequent shadow file. For this reason,
** the name of a shadow file contains a sequence number.
** Shadow files that are not used by client processes any more, are
** automatically removed by the atopacctd daemon.
**
** - When no client processes are active (any more), all shadow files
** will be deleted and no records will be transferred to shadow files
** any more. As soon as at least one client is activated again, the
** atopacctd daemon start writing shadow files again.
**
** The directory /run is used as the default top-directory. An
** alternative top-directory can be specified as command line argument
** (in that case, also modify /etc/atoprc to inform atop as a client).
** Below this top-directory the source file pacct_source is created and
** the subdirectory pacct_shadow.d as a 'container' for the shadow files.
** ----------------------------------------------------------------------
** Copyright (C) 2014 Gerlof Langeveld (gerlof.langeveld@atoptool.nl)
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License version 2 as
** published by the Free Software Foundation.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <syslog.h>
#include <string.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <errno.h>
#include <time.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/mman.h>
#include <sys/statvfs.h>
#include <sys/wait.h>
#include "atop.h"
#include "photoproc.h"
#include "acctproc.h"
#include "version.h"
#include "versdate.h"
#include "atopacctd.h"
#define RETRYCNT 10 // # retries to read account record
#define RETRYMS 25 // timeout (millisec) to read account record
#define NORECINTERVAL 3600 // no-record-available interval (seconds)
#define PACCTSEC 3 // timeout (sec) to retry switch on pacct
#define POLLSEC 1 // timeout (sec) when NETLINK fails
#define GCINTERVAL 60 // garbage collection interval (seconds)
/*
** Semaphore-handling
**
** Two semaphore groups are created:
**
** The private semaphore (group) specifies the number of atopacctd processes
** running (to be sure that only one daemon is active at the time).
**
** The public semaphore group contains two semaphores:
**
** 0: the number of processes using the process accounting shadow files,
** i.e. the number of (atop) clients. This semaphore starts at a high
** value and should be decremented by every (atop) client that starts
** using the shadow files and incremented again whenever that (atop)
** client terminates.
**
** 1: binary semphore that has to be claimed before using/modifying
** semaphore 0 in this group.
*/
static int semprv;
static int sempub;
#define SEMTOTAL 100
#define NUMCLIENTS (SEMTOTAL - semctl(sempub, 0, GETVAL, 0))
struct sembuf semlocknowait = {1, -1, SEM_UNDO|IPC_NOWAIT},
semunlock = {1, +1, SEM_UNDO};
static char atopacctdversion[] = ATOPVERS;
static char atopacctddate[] = ATOPDATE;
static unsigned long maxshadowrec = MAXSHADOWREC;
static char *pacctdir = PACCTDIR;
static char cleanup_and_go = 0;
/*
** function prototypes
*/
static int awaitprocterm(int, int, int, char *, int *,
unsigned long *, unsigned long *);
static int swonpacct(int, char *);
static int createshadow(long);
static int pass2shadow(int, char *, int);
static void gcshadows(unsigned long *, unsigned long);
static void setcurrent(long);
static int acctsize(struct acct *);
static void parent_cleanup(int);
static void child_cleanup(int);
int
main(int argc, char *argv[])
{
int i, nfd, afd, sfd;
int parentpid;
struct stat dirstat;
struct rlimit rlim;
FILE *pidf;
struct sembuf semincr = {0, +1, SEM_UNDO};
char shadowdir[128], shadowpath[128];
char accountpath[128];
unsigned long oldshadow = 0, curshadow = 0;
int shadowbusy = 0;
time_t gclast = time(0);
struct sigaction sigcleanup;
int liResult;
/*
** argument passed?
*/
if (argc == 2)
{
/*
** version number required (flag -v or -V)?
*/
if (*argv[1] == '-') // flag?
{
if ( *(argv[1]+1) == 'v' || *(argv[1]+1) == 'V')
{
printf("%s <gerlof.langeveld@atoptool.nl>\n",
getstrvers());
return 0;
}
else
{
fprintf(stderr,
"Usage: atopacctd [-v|topdirectory]\n"
"Default topdirectory: %s\n", PACCTDIR);
exit(1);
}
}
/*
** if first argument is not a flag, it should be the name
** of an alternative top directory (to be validated later on)
*/
pacctdir = argv[1];
}
else
{
if (argc != 1)
{
fprintf(stderr,
"Usage: atopacctd [-v|topdirectory]\n"
"Default topdirectory: %s\n", PACCTDIR);
exit(1);
}
}
/*
** verify if we are running with the right privileges
*/
if (geteuid() != 0)
{
fprintf(stderr, "Root privileges are needed!\n");
exit(1);
}
/*
** verify that the top directory is not world-writable
** and owned by root
*/
if ( stat(pacctdir, &dirstat) == -1 )
{
perror(pacctdir);
fprintf(stderr, "Usage: atopacctd [-v|topdirectory]\n"
"Default topdirectory: %s\n", PACCTDIR);
exit(2);
}
if (! S_ISDIR(dirstat.st_mode) )
{
fprintf(stderr, "atopacctd: %s is not a directory\n", pacctdir);
exit(2);
}
if (dirstat.st_uid != 0)
{
fprintf(stderr,
"atopacctd: directory %s must be owned by root\n",
pacctdir);
exit(2);
}
if (dirstat.st_mode & (S_IWGRP|S_IWOTH))
{
fprintf(stderr,
"atopacctd: directory %s may not be writable "
"for group/others\n", pacctdir);
exit(2);
}
/*
** create the semaphore groups and initialize the semaphores;
** if the private semaphore already exists, verify if another
** atopacctd daemon is already running
*/
if ( (semprv = semget(PACCTPRVKEY, 0, 0)) >= 0) // exists?
{
if ( semctl(semprv, 0, GETVAL, 0) > 0)
{
fprintf(stderr, "atopacctd is already running!\n");
exit(3);
}
}
else
{
if ( (semprv = semget(PACCTPRVKEY, 1,
0600|IPC_CREAT|IPC_EXCL)) >= 0)
{
(void) semctl(semprv, 0, SETVAL, 0);
}
else
{
perror("cannot create private semaphore");
exit(3);
}
}
// create new semaphore group
//
if ( (sempub = semget(PACCTPUBKEY, 0, 0)) != -1) // existing?
(void) semctl(sempub, 0, IPC_RMID, 0);
if ( (sempub = semget(PACCTPUBKEY, 2, 0666|IPC_CREAT|IPC_EXCL)) >= 0)
{
(void) semctl(sempub, 0, SETVAL, SEMTOTAL);
(void) semctl(sempub, 1, SETVAL, 1);
}
else
{
perror("cannot create public semaphore");
exit(3);
}
/*
** daemonize this process
** i.e. be sure that the daemon is no session leader (any more)
** and get rid of a possible bad context that might have been
** inherited from ancestors
*/
parentpid = getpid(); // to be killed when initialized
/*
** prepare cleanup signal handler
*/
memset(&sigcleanup, 0, sizeof sigcleanup);
sigemptyset(&sigcleanup.sa_mask);
sigcleanup.sa_handler = parent_cleanup;
(void) sigaction(SIGTERM, &sigcleanup, (struct sigaction *)0);
if ( fork() ) // implicitly switch to background
{
/*
** parent after forking first child:
** wait for signal 15 from child before terminating
** because systemd expects parent to terminate whenever
** service is up and running
*/
pause(); // wait for signal from child
exit(0); // finish parent
}
setsid(); // become session leader to lose ctty
if ( fork() ) // finish parent; continue in child
exit(0); // --> no session leader, no ctty
sigcleanup.sa_handler = child_cleanup;
(void) sigaction(SIGTERM, &sigcleanup, (struct sigaction *)0);
getrlimit(RLIMIT_NOFILE, &rlim);
for (i=0; i < rlim.rlim_cur; i++) // close all files, but
{
if (i != 2) // do not close stderr
close(i);
}
umask(022);
liResult = chdir("/tmp"); // go to a safe place
if(liResult != 0)
{
char lcMessage[64];
snprintf(lcMessage, sizeof(lcMessage) - 1,
"%s:%d - Error %d changing to tmp dir\n",
__FILE__, __LINE__, errno );
fprintf(stderr, "%s", lcMessage);
}
/*
** increase semaphore to define that atopacctd is running
*/
if ( semop(semprv, &semincr, 1) == -1)
{
perror("cannot increment private semaphore");
kill(parentpid, SIGTERM);
exit(4);
}
/*
** create source accounting file to which the kernel can write
** its records
*/
snprintf(accountpath, sizeof accountpath, "%s/%s", pacctdir, PACCTORIG);
(void) unlink(accountpath); // in case atopacctd previously killed
if ( (afd = creat(accountpath, 0600)) == -1)
{
perror(accountpath);
kill(parentpid, SIGTERM);
exit(5);
}
(void) close(afd);
/*
** open the accounting file for read
*/
if ( (afd = open(accountpath, O_RDONLY)) == -1)
{
perror(accountpath);
kill(parentpid, SIGTERM);
exit(5);
}
/*
** create directory to store the shadow files
** when atopacctd was previously killed, rename the
** old directory to a unique name
*/
snprintf(shadowdir, sizeof shadowdir, "%s/%s", pacctdir, PACCTSHADOWD);
if ( stat(shadowdir, &dirstat) == 0 ) // already exists?
{
if (S_ISDIR(dirstat.st_mode)) // and is directory?
{
// define new name to save directory
char newshadow[256];
snprintf(newshadow, sizeof newshadow, "%s-old-%d",
shadowdir, getpid());
if ( rename(shadowdir, newshadow) == -1)
{
perror("could not rename old shadow directory");
exit(5);
}
}
}
if ( mkdir(shadowdir, 0755) == -1)
{
perror(shadowdir);
kill(parentpid, SIGTERM);
exit(5);
}
sfd = createshadow(curshadow);
setcurrent(curshadow);
/*
** open syslog interface
*/
openlog("atopacctd", LOG_PID, LOG_DAEMON);
syslog(LOG_INFO, "%s <gerlof.langeveld@atoptool.nl>", getstrvers());
/*
** raise priority (be sure the nice value becomes -20,
** independent of the current nice value)
** this may fail without notice for non-privileged processes
*/
liResult = nice(-39);
/*
** connect to NETLINK socket of kernel to be triggered
** when processes have finished
*/
if ( (nfd = netlink_open()) == -1)
{
(void) unlink(accountpath);
kill(parentpid, SIGTERM);
exit(5);
}
/*
** switch on accounting - inital
*/
if ( swonpacct(afd, accountpath) == -1)
{
(void) unlink(accountpath);
kill(parentpid, SIGTERM);
exit(6);
}
syslog(LOG_INFO, "accounting to %s", accountpath);
/*
** signal handling
*/
(void) signal(SIGHUP, SIG_IGN);
(void) sigaction(SIGINT, &sigcleanup, (struct sigaction *)0);
(void) sigaction(SIGQUIT, &sigcleanup, (struct sigaction *)0);
(void) sigaction(SIGTERM, &sigcleanup, (struct sigaction *)0);
/*
** create PID file
*/
if ( (pidf = fopen(PIDFILE, "w")) )
{
fprintf(pidf, "%d\n", getpid());
fclose(pidf);
}
/*
** terminate parent: service initialized
*/
kill(parentpid, SIGTERM);
/*
** main loop
*/
while (! cleanup_and_go)
{
int state;
time_t curtime;
/*
** await termination of (at least) one process and
** copy the process accounting record(s)
*/
state = awaitprocterm(nfd, afd, sfd, accountpath,
&shadowbusy, &oldshadow, &curshadow);
if (state == -1) // irrecoverable error?
break;
/*
** garbage collection (i.e. removal of shadow files that
** are not in use any more) is needed in case:
**
** - shadow files are currently maintained because
** at least one atop is running, and
** - shadow files have not been removed for GCINTERVAL
** seconds, or
** - the system clock has been modified (lowered)
*/
if ( shadowbusy &&
(time(&curtime) > gclast + GCINTERVAL ||
curtime < gclast ) )
{
gcshadows(&oldshadow, curshadow);
gclast = time(0);
}
}
/*
** cleanup and terminate
*/
(void) acct((char *) 0); // disable process accounting
(void) unlink(accountpath); // remove source file
for (; oldshadow <= curshadow; oldshadow++) // remove shadow files
{
/*
** assemble path name of shadow file (starting by oldest)
*/
snprintf(shadowpath, sizeof shadowpath, PACCTSHADOWF,
pacctdir, PACCTSHADOWD, oldshadow);
(void) unlink(shadowpath);
}
snprintf(shadowpath, sizeof shadowpath, "%s/%s/%s",
pacctdir, PACCTSHADOWD, PACCTSHADOWC);
(void) unlink(shadowpath); // remove file 'current'
(void) rmdir(shadowdir); // remove shadow.d directory
if (cleanup_and_go)
{
syslog(LOG_NOTICE, "Terminated by signal %d\n", cleanup_and_go);
if (cleanup_and_go == SIGTERM)
return 0;
else
return cleanup_and_go + 128;
}
else
{
syslog(LOG_NOTICE, "Terminated!\n");
return 13;
}
}
/*
** wait for at least one process termination and copy process accounting
** record(s) from the source process accounting file to the current
** shadow accounting file
**
** return code: 0 - no process accounting record read
** 1 - at least one process accounting record read
** -1 - irrecoverable failure
*/
static int
awaitprocterm(int nfd, int afd, int sfd, char *accountpath,
int *shadowbusyp, unsigned long *oldshadowp, unsigned long *curshadowp)
{
static int arecsize, netlinkactive = 1;
static unsigned long long atotsize, stotsize, maxshadowsz;
static time_t reclast;
struct timespec retrytimer = {0, RETRYMS/2*1000000};
int retrycount = RETRYCNT;
int asz, rv, ssz;
char abuf[16000];
int partsz, remsz;
/*
** neutral state:
**
** wait for info from NETLINK indicating that at least
** one process has finished; the real contents of the
** NETLINK message is ignored, it is only used as trigger
** that something can be read from the process accounting file
**
** unfortunately it is not possible to use inotify() on the
** source file as a trigger that a new accounting record
** has been written (does not work if the kernel itself
** writes to the file)
**
** when the NETLINK interface fails due to kernel bug 190711,
** we switch to polling mode:
** wait for timer and verify if process accounting
** records are available (repeatedly); ugly but the only
** thing we can do if we can't use NETLINK
*/
if (netlinkactive)
{
rv = netlink_recv(nfd, 0);
if (rv == 0) // EOF?
{
syslog(LOG_ERR, "unexpected EOF on NETLINK\n");
perror("unexpected EOF on NETLINK\n");
return -1;
}
if (rv < 0) // failure?
{
switch (-rv)
{
// acceptable errors that might indicate that
// processes have terminated
case EINTR:
case ENOMEM:
case ENOBUFS:
break;
default:
syslog(LOG_ERR,
"unexpected error on NETLINK: %s\n",
strerror(-rv));
fprintf(stderr,
"unexpected error on NETLINK: %s\n",
strerror(-rv));
if (-rv == EINVAL)
{
syslog(LOG_ERR,
"(see ATOP README about kernel bug 190711)\n");
fprintf(stderr,
"(see ATOP README about kernel bug 190711)\n");
}
syslog(LOG_ERR,
"switching to polling mode\n");
fprintf(stderr,
"switching to polling mode\n");
netlinkactive = 0; // polling mode wanted
return 0;
}
}
/*
** get rid of all other waiting finished processes via netlink
** before handling the process accounting record(s)
*/
while ( netlink_recv(nfd, MSG_DONTWAIT) > 0 );
}
else // POLLING MODE
{
sleep(POLLSEC);
retrycount = 1;
}
/*
** read new process accounting record(s)
** such record(s) may not immediately be available (timing matter),
** so some retries might be necessary
*/
while ((asz = read(afd, abuf, sizeof abuf)) == 0 && --retrycount)
{
nanosleep(&retrytimer, (struct timespec *)0);
retrytimer.tv_nsec = RETRYMS*1000000;
}
switch (asz)
{
case 0: // EOF (no records available)?
if (time(0) > reclast + NORECINTERVAL && reclast)
{
syslog(LOG_WARNING, "reactivate process accounting\n");
if (truncate(accountpath, 0) != -1)
{
lseek(afd, 0, SEEK_SET);
atotsize = swonpacct(afd, accountpath);
}
reclast = time(0);
}
return 0; // wait for NETLINK again
case -1: // failure?
syslog(LOG_ERR, "%s - unexpected read error: %s\n",
accountpath, strerror(errno));
return -1;
}
reclast = time(0);
/*
** only once: determine the size of an accounting
** record and calculate the maximum size for each
** shadow file
*/
if (!arecsize)
{
arecsize = acctsize((struct acct *)abuf);
if (arecsize)
{
maxshadowsz = maxshadowrec * arecsize;
}
else
{
syslog(LOG_ERR,
"cannot determine size of account record\n");
return -1;
}
}
/*
** truncate process accounting file regularly
*/
atotsize += asz; // maintain current size
if (atotsize >= MAXORIGSZ)
{
if (truncate(accountpath, 0) != -1)
{
lseek(afd, 0, SEEK_SET);
atotsize = 0;
}
}
/*
** determine if any client is using the shadow
** accounting files; if not, verify if clients
** have been using the shadow files till now and
** cleanup has to be performed
*/
if (semop(sempub, &semlocknowait, 1) == 0) // lock succeeded?
{
if (NUMCLIENTS == 0)
{
/*
** did last client just disappear?
*/
if (*shadowbusyp)
{
/*
** remove all shadow files
*/
gcshadows(oldshadowp, (*curshadowp)+1);
*oldshadowp = 0;
*curshadowp = 0;
stotsize = 0;
/*
** create new file with sequence 0
*/
(void) close(sfd);
sfd = createshadow(*curshadowp);
setcurrent(*curshadowp);
*shadowbusyp = 0;
}
(void) semop(sempub, &semunlock, 1);
return 1;
}
(void) semop(sempub, &semunlock, 1);
}
*shadowbusyp = 1;
/*
** transfer process accounting data to shadow file
** but take care to fill a shadow file exactly
** to its maximum and not more...
*/
if (stotsize + asz <= maxshadowsz) // would fit?
{
/*
** pass all data
*/
if ( (ssz = pass2shadow(sfd, abuf, asz)) > 0)
stotsize += ssz;
remsz = 0;
partsz = 0;
}
else
{
/*
** calculate the remainder that has to
** be written to the next shadow file
*/
partsz = maxshadowsz - stotsize;
remsz = asz - partsz;
/*
** transfer first part of the data to current
** shadow file
*/
if ( (ssz = pass2shadow(sfd, abuf, partsz)) > 0)
stotsize += ssz;
}
/*
** verify if current shadow file has reached its
** maximum size; if so, switch to next sequence number
** and write remaining data (if any)
*/
if (stotsize >= maxshadowsz)
{
close(sfd);
sfd = createshadow(++(*curshadowp));
setcurrent(*curshadowp);
stotsize = 0;
/*
** transfer remaining part of the data
*/
if (remsz)
{
if ( (ssz = pass2shadow(sfd, abuf+partsz, remsz)) > 0)
stotsize += ssz;
}
}
return 1;
}
/*
** create first shadow file with requested sequence number
*/
static int
createshadow(long seq)
{
int sfd;
char shadowpath[128];
snprintf(shadowpath, sizeof shadowpath, PACCTSHADOWF,
pacctdir, PACCTSHADOWD, seq);
/*
** open the shadow file for write
*/
if ( (sfd = creat(shadowpath, 0644)) == -1)
{
perror(shadowpath);
exit(5);
}
return sfd;
}
/*
** transfer process accounting data to shadow file
*/
static int
pass2shadow(int sfd, char *sbuf, int ssz)
{
static unsigned long long nrskipped;
struct statvfs statvfs;
/*
** check if the filesystem is not filled for more than 95%
*/
if ( fstatvfs(sfd, &statvfs) != -1)
{
if (statvfs.f_blocks == 0 ||
statvfs.f_bfree * 100 / statvfs.f_blocks < 5 )
{
if (nrskipped == 0) // first skip?
{
syslog(LOG_WARNING,
"Filesystem > 95%% full; "
"pacct writing skipped\n");
}
nrskipped++;
return 0;
}
}
/*
** there is enough space in the filesystem (again)
** verify if writing has been suspended due to lack of space (if so,
** write a log message)
*/
if (nrskipped)
{
syslog(LOG_WARNING, "Pacct writing continued (%llu skipped)\n",
nrskipped);
nrskipped = 0;
}
/*
** transfer process accounting record(s) to shadow file
*/
if ( write(sfd, sbuf, ssz) == -1 )
{
syslog(LOG_ERR, "Unexpected write error to shadow file: %s\n",
strerror(errno));
exit(7);
}
return ssz;
}
/*
** switch on the process accounting mechanism
** first parameter: file descriptor of open accounting file
** second parameter: name of accounting file
** return value: -1 in case of permanent failure,
** otherwise number of bytes read from accounting file
*/
static int
swonpacct(int afd, char *accountpath)
{
int n, acctokay = 0;
char abuf[4096];
/*
** due to kernel bug 190271 (process accounting sometimes
** does not work), we verify if process accounting really
** works after switching it on. If not, we keep retrying
** for a while.
*/
while (! acctokay)
{
int maxcnt = 40;
/*
** switch on process accounting
*/
if ( acct(accountpath) == -1)
{
perror("cannot switch on process accounting");
return -1;
}
/*
** try if process accounting works by spawning a
** child process that immediately finishes (should
** result in a process accounting record)
*/
if ( fork() == 0 )
exit(0);
(void) wait((int *)0); // wait for child to finish
while ( (n = read(afd, abuf, sizeof abuf)) <= 0 && --maxcnt)
usleep(50000);
if (n > 0) // process accounting works
{
acctokay = 1;
}
else
{
syslog(LOG_ERR,
"Retrying to switch on process accounting\n");
syslog(LOG_ERR,
"(see ATOP README about kernel bug 190271)\n");
acct((char *)0); // switch off process accounting
sleep(PACCTSEC); // wait a while before retrying
}
}
return n;
}
/*
** remove old shadow files not being in use any more
**
** When a reading process (atop) opens a shadow file,
** it places a read lock on the first byte of that file.
** More then one read lock is allowed on that first byte
** (in case of more atop incarnations).
** If at least one read lock exists, a write lock (to be
** tried here) will fail which means that the file is still
** in use by at least one reader.
*/
static void
gcshadows(unsigned long *oldshadowp, unsigned long curshadow)
{
struct flock flock;
int tmpsfd;
char shadowpath[128];
/*
** fill flock structure: write lock on first byte
*/
flock.l_type = F_WRLCK;
flock.l_whence = SEEK_SET;
flock.l_start = 0;
flock.l_len = 1;
for (; *oldshadowp < curshadow; (*oldshadowp)++)
{
/*
** assemble path name of shadow file (starting by oldest)
*/
snprintf(shadowpath, sizeof shadowpath, PACCTSHADOWF,
pacctdir, PACCTSHADOWD, *oldshadowp);
/*
** try to open oldest existing file for write
** and verify if it is in use