.\"	$OpenBSD: acct.5,v 1.27 2024/02/25 00:07:14 deraadt Exp $
.\"	$NetBSD: acct.5,v 1.4 1995/10/22 01:40:10 ghudson Exp $
.\"
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.\"     @(#)acct.5	8.1 (Berkeley) 6/5/93
.\"
.Dd $Mdocdate: February 25 2024 $
.Dt ACCT 5
.Os
.Sh NAME
.Nm acct
.Nd execution accounting file
.Sh SYNOPSIS
.In sys/acct.h
.Sh DESCRIPTION
The kernel maintains the following
.Fa acct
information structure for all
processes.
If a process terminates or misbehaves in specific ways,
and accounting is enabled, the kernel calls the
.Xr acct 2
function call to prepare and append the record
to the accounting file.
.Bd -literal
/*
 * Accounting structures; these use a comp_t type which is a 3 bits base 8
 * exponent, 13 bit fraction floating point number.  Units are 1/AHZ
 * seconds.
 */
typedef u_int16_t comp_t;

struct acct {
	char	  ac_comm[24];	/* command name, incl NUL */
	comp_t	  ac_utime;	/* user time */
	comp_t	  ac_stime;	/* system time */
	comp_t	  ac_etime;	/* elapsed time */
	comp_t	  ac_io;	/* count of IO blocks */
	time_t	  ac_btime;	/* starting time */
	uid_t	  ac_uid;	/* user id */
	gid_t	  ac_gid;	/* group id */
	u_int32_t ac_mem;	/* average memory usage */
	dev_t	  ac_tty;	/* controlling tty, or -1 */
	pid_t	  ac_pid;	/* process id */

	u_int32_t ac_flag;	/* accounting flags */
#define	AFORK	0x00000001	/* fork'd but not exec'd */
#define	AMAP	0x00000004	/* killed by syscall or stack mapping violation */
#define	ACORE	0x00000008	/* dumped core */
#define	AXSIG	0x00000010	/* killed by a signal */
#define	APLEDGE	0x00000020	/* killed due to pledge violation */
#define	ATRAP	0x00000040	/* memory access violation */
#define	AUNVEIL	0x00000080	/* unveil access violation */
#define APINSYS 0x00000200      /* killed by syscall pin violation */
#define ABTCFI  0x00000400      /* BT CFI violation */
};

/*
 * 1/AHZ is the granularity of the data encoded in the comp_t fields.
 * This is not necessarily equal to hz.
 */
#define	AHZ	64

#ifdef _KERNEL
int	acct_process(struct proc *p);
int	acct_shutdown(void);
#endif
.Ed
.Pp
If a terminated or misbehaving process was created by an
.Xr execve 2 ,
the name of the executed file (at most ten characters of it)
is saved in the field
.Fa ac_comm
and its status is saved by setting one or more of the following flags in
.Fa ac_flag :
.Bl -tag -width "AUNVEIL"
.It Dv AFORK
A new process was created via
.Xr fork 2
that was not followed by a call to
.Xr execve 2 .
.It Dv AMAP
The process terminated abnormally due to a system call or stack mapping
violation.
.It Dv ACORE
The process terminated abnormally due to a signal and dumped
.Xr core 5 .
.It Dv AXSIG
The process was killed by a
.Xr signal 3 .
.It Dv APLEDGE
The process was killed due to a
.Xr pledge 2
violation.
.It Dv ATRAP
The process was killed due to a memory access violation
detected by a processor trap.
.It Dv AUNVEIL
The process attempted a file access that was prevented by
.Xr unveil 2
restrictions.
Note that this does not cause the process to terminate.
.It Dv APINSYS
The command tried to execute a system call from the wrong
system call instruction, see
.Xr pinsyscalls 2 .
.It Dv ABTCFI
The command executed an indirect branch to a location that did not
start with a
.Ql BTI
instruction, and terminated with signal
.Dv SIGILL ,
.Va code
.Dv ILL_BTCFI .
.El
.Sh SEE ALSO
.Xr lastcomm 1 ,
.Xr acct 2 ,
.Xr execve 2 ,
.Xr pledge 2 ,
.Xr unveil 2 ,
.Xr signal 3 ,
.Xr core 5 ,
.Xr accton 8 ,
.Xr sa 8
.Sh HISTORY
An
.Nm
file format first appeared in
.At v7 .