usr/src/usr.bin/gcore/gcore.c

/*-
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * %sccs.include.redist.c%
 */

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1992, 1993\n\
        The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)gcore.c     8.1 (Berkeley) %G%";
#endif /* not lint */

/*
 * Originally written by Eric Cooper in Fall 1981.
 * Inspired by a version 6 program by Len Levin, 1978.
 * Several pieces of code lifted from Bill Joy's 4BSD ps.
 * Most recently, hacked beyond recognition for 4.4BSD by Steven McCanne,
 * Lawrence Berkeley Laboratory.
 *
 * Portions of this software were developed by the Computer Systems
 * Engineering group at Lawrence Berkeley Laboratory under DARPA
 * contract BG 91-66 and contributed to Berkeley.
 */
#include <sys/param.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/user.h>
#include <sys/sysctl.h>

#include <machine/vmparam.h>

#include <a.out.h>
#include <fcntl.h>
#include <kvm.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "extern.h"

void    core __P((int, int, struct kinfo_proc *));
void    datadump __P((int, int, struct proc *, u_long, int));
void    usage __P((void));
void    userdump __P((int, struct proc *, u_long, int));

kvm_t *kd;
/* XXX undocumented routine, should be in kvm.h? */
ssize_t kvm_uread __P((kvm_t *, struct proc *, u_long, char *, size_t));

static int data_offset;

int
main(argc, argv)
        int argc;
        char *argv[];
{
        register struct proc *p;
        struct kinfo_proc *ki;
        struct exec exec;
        int ch, cnt, efd, fd, pid, sflag, uid;
        char *corefile, errbuf[_POSIX2_LINE_MAX], fname[MAXPATHLEN + 1];

        sflag = 0;
        corefile = NULL;
        while ((ch = getopt(argc, argv, "c:s")) != EOF) {
                switch (ch) {
                case 'c':
                        corefile = optarg;
                        break;
                case 's':
                        sflag = 1;
                        break;
                default:
                        usage();
                        break;
                }
        }
        argv += optind;
        argc -= optind;

        if (argc != 2)
                usage();

        kd = kvm_openfiles(0, 0, 0, O_RDONLY, errbuf);
        if (kd == NULL)
                err(1, "%s", errbuf);

        uid = getuid();
        pid = atoi(argv[1]);

        ki = kvm_getprocs(kd, KERN_PROC_PID, pid, &cnt);
        if (ki == NULL || cnt != 1)
                err(1, "%d: not found", pid);

        p = &ki->kp_proc;
        if (ki->kp_eproc.e_pcred.p_ruid != uid && uid != 0)
                err(1, "%d: not owner", pid);

        if (p->p_stat == SZOMB)
                err(1, "%d: zombie", pid);

        if (p->p_flag & SWEXIT)
                err(0, "process exiting");
        if (p->p_flag & SSYS)           /* Swapper or pagedaemon. */
                err(1, "%d: system process");

        if (corefile == NULL) {
                (void)snprintf(fname, sizeof(fname), "core.%d", pid);
                corefile = fname;
        }
        fd = open(corefile, O_RDWR|O_CREAT|O_TRUNC, DEFFILEMODE);
        if (fd < 0)
                err(1, "%s: %s\n", corefile, strerror(errno));

        efd = open(argv[0], O_RDONLY, 0);
        if (efd < 0)
                err(1, "%s: %s\n", argv[0], strerror(errno));

        cnt = read(efd, &exec, sizeof(exec));
        if (cnt != sizeof(exec))
                err(1, "%s exec header: %s",
                    argv[0], cnt > 0 ? strerror(EIO) : strerror(errno));

        data_offset = N_DATOFF(exec);

        if (sflag && kill(pid, SIGSTOP) < 0)
                err(0, "%d: stop signal: %s", pid, strerror(errno));

        core(efd, fd, ki);

        if (sflag && kill(pid, SIGCONT) < 0)
                err(0, "%d: continue signal: %s", pid, strerror(errno));
        (void)close(fd);

        exit(0);
}

/*
 * core --
 *      Build the core file.
 */
void
core(efd, fd, ki)
        int efd;
        int fd;
        struct kinfo_proc *ki;
{
        union {
                struct user user;
                char ubytes[ctob(UPAGES)];
        } uarea;
        struct proc *p = &ki->kp_proc;
        int tsize = ki->kp_eproc.e_vm.vm_tsize;
        int dsize = ki->kp_eproc.e_vm.vm_dsize;
        int ssize = ki->kp_eproc.e_vm.vm_ssize;
        int cnt;

        /* Read in user struct */
        cnt = kvm_read(kd, (u_long)p->p_addr, &uarea, sizeof(uarea));
        if (cnt != sizeof(uarea))
                err(1, "read user structure: %s",
                    cnt > 0 ? strerror(EIO) : strerror(errno));

        /*
         * Fill in the eproc vm parameters, since these are garbage unless
         * the kernel is dumping core or something.
         */
        uarea.user.u_kproc = *ki;

        /* Dump user area */
        cnt = write(fd, &uarea, sizeof(uarea));
        if (cnt != sizeof(uarea))
                err(1, "write user structure: %s",
                    cnt > 0 ? strerror(EIO) : strerror(errno));

        /* Dump data segment */
        datadump(efd, fd, p, USRTEXT + ctob(tsize), dsize);

        /* Dump stack segment */
        userdump(fd, p, USRSTACK - ctob(ssize), ssize);

        /* Dump machine dependent portions of the core. */
        md_core(kd, fd, ki);
}

void
datadump(efd, fd, p, addr, npage)
        register int efd;
        register int fd;
        struct proc *p;
        register u_long addr;
        register int npage;
{
        register int cc, delta;
        char buffer[NBPG];

        delta = data_offset - addr;
        while (--npage >= 0) {
                cc = kvm_uread(kd, p, addr, buffer, NBPG);
                if (cc != NBPG) {
                        /* Try to read the page from the executable. */
                        if (lseek(efd, (off_t)addr + delta, SEEK_SET) == -1)
                                err(1, "seek executable: %s", strerror(errno));
                        cc = read(efd, buffer, sizeof(buffer));
                        if (cc != sizeof(buffer))
                                if (cc < 0)
                                        err(1, "read executable: %s",
                                            strerror(errno));
                                else    /* Assume untouched bss page. */
                                        bzero(buffer, sizeof(buffer));
                }
                cc = write(fd, buffer, NBPG);
                if (cc != NBPG)
                        err(1, "write data segment: %s",
                            cc > 0 ? strerror(EIO) : strerror(errno));
                addr += NBPG;
        }
}

void
userdump(fd, p, addr, npage)
        register int fd;
        struct proc *p;
        register u_long addr;
        register int npage;
{
        register int cc;
        char buffer[NBPG];

        while (--npage >= 0) {
                cc = kvm_uread(kd, p, addr, buffer, NBPG);
                if (cc != NBPG)
                        /* Could be an untouched fill-with-zero page. */
                        bzero(buffer, NBPG);
                cc = write(fd, buffer, NBPG);
                if (cc != NBPG)
                        err(1, "write stack segment: %s",
                            cc > 0 ? strerror(EIO) : strerror(errno));
                addr += NBPG;
        }
}

void
usage()
{
        (void)fprintf(stderr, "usage: gcore [-s] [-c core] executable pid\n");
        exit(1);
}

#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif

void
#if __STDC__
err(int fatal, const char *fmt, ...)
#else
err(fatal, fmt, va_alist)
        int fatal;
        char *fmt;
        va_dcl
#endif
{
        va_list ap;
#if __STDC__
        va_start(ap, fmt);
#else
        va_start(ap);
#endif
        (void)fprintf(stderr, "gcore: ");
        (void)vfprintf(stderr, fmt, ap);
        va_end(ap);
        (void)fprintf(stderr, "\n");
        exit(1);
        /* NOTREACHED */
}