5.1.2. struct proc Structure

This structure contains all the information about a process. It is defined in /usr/src/sys/sys/proc.h:

/*
 * Description of a process.
 *
 * This structure contains the information needed to manage a thread of
 * control, known in UN*X as a process; it has references to substructures
 * containing descriptions of things that the process uses, but may share
 * with related processes.  The process structure and the substructures
 * are always addressable except for those marked "(PROC ONLY)" below,
 * which might be addressable only on a processor on which the process
 * is running.
 */
struct  proc {
        struct  proc *p_forw;           /* Doubly-linked run/sleep queue. */
        struct  proc *p_back;
        struct  proc *p_next;           /* Linked list of active procs */
        struct  proc **p_prev;          /*    and zombies. */

        /* substructures: */
        struct  pcred *p_cred;          /* Process owner's identity. */
        struct  filedesc *p_fd;         /* Ptr to open files structure. */
        struct  pstats *p_stats;        /* Accounting/statistics (PROC ONLY). */        struct  plimit *p_limit;        /* Process limits. */
        struct  vmspace *p_vmspace;     /* Address space. */
        struct  sigacts *p_sigacts;     /* Signal actions, state (PROC ONLY). */

#define p_ucred         p_cred->pc_ucred
#define p_rlimit        p_limit->pl_rlimit

        int     p_flag;                 /* P_* flags. */
        char    p_stat;                 /* S* process status. */
        char    p_pad1[3];

        pid_t   p_pid;                  /* Process identifier. */
        struct  proc *p_hash;    /* Hashed based on p_pid for kill+exit+... */
        struct  proc *p_pgrpnxt; /* Pointer to next process in process group. */
        struct  proc *p_pptr;    /* Pointer to process structure of parent. */
        struct  proc *p_osptr;   /* Pointer to older sibling processes. */

/* The following fields are all zeroed upon creation in fork. */
#define p_startzero     p_ysptr
        struct  proc *p_ysptr;   /* Pointer to younger siblings. */
        struct  proc *p_cptr;    /* Pointer to youngest living child. */
        pid_t   p_oppid;         /* Save parent pid during ptrace. XXX */
        int     p_dupfd;         /* Sideways return value from fdopen. XXX */

        /* scheduling */
        u_int   p_estcpu;        /* Time averaged value of p_cpticks. */
        int     p_cpticks;       /* Ticks of cpu time. */
        fixpt_t p_pctcpu;        /* %cpu for this process during p_swtime */
        void    *p_wchan;        /* Sleep address. */
        char    *p_wmesg;        /* Reason for sleep. */
        u_int   p_swtime;        /* Time swapped in or out. */
        u_int   p_slptime;       /* Time since last blocked. */

        struct  itimerval p_realtimer;  /* Alarm timer. */
        struct  timeval p_rtime;        /* Real time. */
        u_quad_t p_uticks;              /* Statclock hits in user mode. */
        u_quad_t p_sticks;              /* Statclock hits in system mode. */
        u_quad_t p_iticks;              /* Statclock hits processing intr. */

        int     p_traceflag;            /* Kernel trace points. */
        struct  vnode *p_tracep;        /* Trace to vnode. */

        int     p_siglist;              /* Signals arrived but not delivered. */

        struct  vnode *p_textvp;        /* Vnode of executable. */

        char    p_lock;                 /* Process lock (prevent swap) count. */
        char    p_pad2[3];              /* alignment */

/* End area that is zeroed on creation. */
#define p_endzero       p_startcopy

/* The following fields are all copied upon creation in fork. */
#define p_startcopy     p_sigmask

        sigset_t p_sigmask;     /* Current signal mask. */
        sigset_t p_sigignore;   /* Signals being ignored. */
        sigset_t p_sigcatch;    /* Signals being caught by user. */

        u_char  p_priority;     /* Process priority. */
        u_char  p_usrpri;       /* User-priority based on p_cpu and p_nice. */
        char    p_nice;         /* Process "nice" value. */
        char    p_comm[MAXCOMLEN+1];

        struct  pgrp *p_pgrp;   /* Pointer to process group. */

        struct  sysentvec *p_sysent; /* System call dispatch information. */

        struct  rtprio p_rtprio;        /* Realtime priority. */
/* End area that is copied on creation. */
#define p_endcopy       p_addr
        struct  user *p_addr;   /* Kernel virtual addr of u-area (PROC ONLY). */
        struct  mdproc p_md;    /* Any machine-dependent fields. */

        u_short p_xstat;        /* Exit status for wait; also stop signal. */
        u_short p_acflag;       /* Accounting flags. */
        struct  rusage *p_ru;   /* Exit information. XXX */
};