/*-
 * Copyright (c) 1989, 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software developed by the Computer Systems
 * Engineering group at Lawrence Berkeley Laboratory under DARPA contract
 * BG 91-66 and contributed to Berkeley.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * @(#)kvm.c    8.2 (Berkeley) 2/13/94
 * $FreeBSD: src/lib/libkvm/kvm.c,v 1.12.2.3 2002/09/13 14:53:43 nectar Exp $
 */

#include <sys/user.h>   /* MUST BE FIRST */
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/linker.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/swap_pager.h>

#include <machine/vmparam.h>

#include <ctype.h>
#include <fcntl.h>
#include <limits.h>
#include <nlist.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>

#include "kvm.h"
#include "kvm_private.h"

/* from src/lib/libc/gen/nlist.c */
int __fdnlist           (int, struct nlist *);

static int
kvm_notrans(kvm_t *kd)
{
        return kvm_ishost(kd) || kvm_isvkernel(kd);
}

char *
kvm_geterr(kvm_t *kd)
{
        return (kd->errbuf);
}

/*
 * Report an error using printf style arguments.  "program" is kd->program
 * on hard errors, and 0 on soft errors, so that under sun error emulation,
 * only hard errors are printed out (otherwise, programs like gdb will
 * generate tons of error messages when trying to access bogus pointers).
 */
void
_kvm_err(kvm_t *kd, const char *program, const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        if (program != NULL) {
                (void)fprintf(stderr, "%s: ", program);
                (void)vfprintf(stderr, fmt, ap);
                (void)fputc('\n', stderr);
        } else
                (void)vsnprintf(kd->errbuf,
                    sizeof(kd->errbuf), fmt, ap);

        va_end(ap);
}

void
_kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...)
{
        va_list ap;
        int n;

        va_start(ap, fmt);
        if (program != NULL) {
                (void)fprintf(stderr, "%s: ", program);
                (void)vfprintf(stderr, fmt, ap);
                (void)fprintf(stderr, ": %s\n", strerror(errno));
        } else {
                char *cp = kd->errbuf;

                (void)vsnprintf(cp, sizeof(kd->errbuf), fmt, ap);
                n = strlen(cp);
                (void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s",
                    strerror(errno));
        }
        va_end(ap);
}

void *
_kvm_malloc(kvm_t *kd, size_t n)
{
        void *p;

        if ((p = calloc(n, sizeof(char))) == NULL)
                _kvm_err(kd, kd->program, "can't allocate %zd bytes: %s",
                         n, strerror(errno));
        return (p);
}

static int
is_proc_mem(const char *p)
{
        static char proc[] = "/proc/";
        static char mem[] = "/mem";
        if (strncmp(proc, p, sizeof(proc) - 1))
                return 0;
        p += sizeof(proc) - 1;
        for (; *p != '\0'; ++p)
                if (!isdigit(*p))
                        break;
        if (!isdigit(*(p - 1)))
                return 0;
        return !strncmp(p, mem, sizeof(mem) - 1);
}

static kvm_t *
_kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout)
{
        struct stat st;

        kd->vmfd = -1;
        kd->pmfd = -1;
        kd->nlfd = -1;
        kd->vmst = 0;
        kd->procbase = NULL;
        kd->procend = NULL;
        kd->argspc = 0;
        kd->argv = 0;
        kd->flags = 0;

        if (uf == NULL)
                uf = getbootfile();
        else if (strlen(uf) >= MAXPATHLEN) {
                _kvm_err(kd, kd->program, "exec file name too long");
                goto failed;
        }
        if (flag & ~O_RDWR) {
                _kvm_err(kd, kd->program, "bad flags arg");
                goto failed;
        }
        if (mf == NULL)
                mf = _PATH_MEM;

        if ((kd->pmfd = open(mf, flag, 0)) < 0) {
                _kvm_syserr(kd, kd->program, "%s", mf);
                goto failed;
        }
        if (fstat(kd->pmfd, &st) < 0) {
                _kvm_syserr(kd, kd->program, "%s", mf);
                goto failed;
        }
        if (fcntl(kd->pmfd, F_SETFD, FD_CLOEXEC) < 0) {
                _kvm_syserr(kd, kd->program, "%s", mf);
                goto failed;
        }
        if (S_ISCHR(st.st_mode)) {
                /*
                 * If this is a character special device, then check that
                 * it's /dev/mem.  If so, open kmem too.  (Maybe we should
                 * make it work for either /dev/mem or /dev/kmem -- in either
                 * case you're working with a live kernel.)
                 */
                if (strcmp(mf, _PATH_DEVNULL) == 0) {
                        kd->vmfd = open(_PATH_DEVNULL, O_RDONLY);
                } else {
                        if ((kd->vmfd = open(_PATH_KMEM, flag)) < 0) {
                                _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
                                goto failed;
                        }
                        if (fcntl(kd->vmfd, F_SETFD, FD_CLOEXEC) < 0) {
                                _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
                                goto failed;
                        }
                }
                kd->flags |= KVMF_HOST;
        } else {
                /*
                 * Crash dump or vkernel /proc/$pid/mem file:
                 * can't use kldsym, we are going to need ->nlfd
                 */
                if ((kd->nlfd = open(uf, O_RDONLY, 0)) < 0) {
                        _kvm_syserr(kd, kd->program, "%s", uf);
                        goto failed;
                }
                if (fcntl(kd->nlfd, F_SETFD, FD_CLOEXEC) < 0) {
                        _kvm_syserr(kd, kd->program, "%s", uf);
                        goto failed;
                }
                if(is_proc_mem(mf)) {
                        /*
                         * It's /proc/$pid/mem, so we rely on the host
                         * kernel to do address translation for us.
                         */
                        kd->vmfd = kd->pmfd;
                        kd->pmfd = -1;
                        kd->flags |= KVMF_VKERN;
                } else {
                        if (st.st_size <= 0) {
                                errno = EINVAL;
                                _kvm_syserr(kd, kd->program, "empty file");
                                goto failed;
                        }

                        /*
                         * This is a crash dump.
                         * Initialize the virtual address translation machinery,
                         * but first setup the namelist fd.
                         */
                        if (_kvm_initvtop(kd) < 0)
                                goto failed;
                }
        }
        return (kd);
failed:
        /*
         * Copy out the error if doing sane error semantics.
         */
        if (errout != NULL)
                strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
        (void)kvm_close(kd);
        return (0);
}

kvm_t *
kvm_openfiles(const char *uf, const char *mf, const char *sf __unused, int flag,
              char *errout)
{
        kvm_t *kd;

        if ((kd = malloc(sizeof(*kd))) == NULL) {
                (void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
                return (0);
        }
        memset(kd, 0, sizeof(*kd));
        kd->program = 0;
        return (_kvm_open(kd, uf, mf, flag, errout));
}

kvm_t *
kvm_open(const char *uf, const char *mf, const char *sf __unused, int flag,
         const char *errstr)
{
        kvm_t *kd;

        if ((kd = malloc(sizeof(*kd))) == NULL) {
                if (errstr != NULL)
                        (void)fprintf(stderr, "%s: %s\n",
                                      errstr, strerror(errno));
                return (0);
        }
        memset(kd, 0, sizeof(*kd));
        kd->program = errstr;
        return (_kvm_open(kd, uf, mf, flag, NULL));
}

int
kvm_close(kvm_t *kd)
{
        int error = 0;

        if (kd->pmfd >= 0)
                error |= close(kd->pmfd);
        if (kd->vmfd >= 0)
                error |= close(kd->vmfd);
        if (kd->nlfd >= 0)
                error |= close(kd->nlfd);
        if (kd->vmst)
                _kvm_freevtop(kd);
        if (kd->procbase != NULL)
                free(kd->procbase);
        if (kd->argv != 0)
                free((void *)kd->argv);
        free((void *)kd);

        return (error);
}

int
kvm_nlist(kvm_t *kd, struct nlist *nl)
{
        struct nlist *p;
        int nvalid;
        struct kld_sym_lookup lookup;
        int error;

        /*
         * If we can't use the kld symbol lookup, revert to the
         * slow library call.
         */
        if (!kvm_ishost(kd))
                return (__fdnlist(kd->nlfd, nl));

        /*
         * We can use the kld lookup syscall.  Go through each nlist entry
         * and look it up with a kldsym(2) syscall.
         */
        nvalid = 0;
        for (p = nl; p->n_name && p->n_name[0]; ++p) {
                lookup.version = sizeof(lookup);
                lookup.symname = p->n_name;
                lookup.symvalue = 0;
                lookup.symsize = 0;

                if (lookup.symname[0] == '_')
                        lookup.symname++;

                if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
                        p->n_type = N_TEXT;
                        p->n_other = 0;
                        p->n_desc = 0;
                        p->n_value = lookup.symvalue;
                        ++nvalid;
                        /* lookup.symsize */
                }
        }
        /*
         * Return the number of entries that weren't found. If they exist,
         * also fill internal error buffer.
         */
        error = ((p - nl) - nvalid);
        if (error)
                _kvm_syserr(kd, kd->program, "kvm_nlist");
        return (error);
}

ssize_t
kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len)
{
        int cc;
        void *cp;

        if (kvm_notrans(kd)) {
                /*
                 * We're using /dev/kmem.  Just read straight from the
                 * device and let the active kernel do the address translation.
                 */
                errno = 0;
                if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
                        _kvm_err(kd, 0, "invalid address (%lx)", kva);
                        return (-1);
                }

                /*
                 * Try to pre-fault the user memory to reduce instances of
                 * races within the kernel.  XXX workaround for kernel bug
                 * where kernel does a sanity check, but user faults during
                 * the copy can block and race against another kernel entity
                 * unmapping the memory in question.
                 */
                bzero(buf, len);
                cc = read(kd->vmfd, buf, len);
                if (cc < 0) {
                        _kvm_syserr(kd, 0, "kvm_read");
                        return (-1);
                } else if (cc < (ssize_t)len)
                        _kvm_err(kd, kd->program, "short read");
                return (cc);
        } else {
                cp = buf;
                while (len > 0) {
                        off_t pa;

                        cc = _kvm_kvatop(kd, kva, &pa);
                        if (cc == 0)
                                return (-1);
                        if (cc > (ssize_t)len)
                                cc = len;
                        errno = 0;
                        if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
                                _kvm_syserr(kd, 0, _PATH_MEM);
                                break;
                        }
                        bzero(cp, cc);
                        cc = read(kd->pmfd, cp, cc);
                        if (cc < 0) {
                                _kvm_syserr(kd, kd->program, "kvm_read");
                                break;
                        }
                        /*
                         * If kvm_kvatop returns a bogus value or our core
                         * file is truncated, we might wind up seeking beyond
                         * the end of the core file in which case the read will
                         * return 0 (EOF).
                         */
                        if (cc == 0)
                                break;
                        cp = (char *)cp + cc;
                        kva += cc;
                        len -= cc;
                }
                return ((char *)cp - (char *)buf);
        }
        /* NOTREACHED */
}

char *
kvm_readstr(kvm_t *kd, u_long kva, char *buf, size_t *lenp)
{
        size_t len, cc, pos;
        char ch;
        int asize = -1;

        if (buf == NULL) {
                asize = len = 16;
                buf = malloc(len);
                if (buf == NULL) {
                        _kvm_syserr(kd, kd->program, "kvm_readstr");
                        return NULL;
                }
        } else {
                len = *lenp;
        }

        if (kvm_notrans(kd)) {
                /*
                 * We're using /dev/kmem.  Just read straight from the
                 * device and let the active kernel do the address translation.
                 */
                errno = 0;
                if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
                        _kvm_err(kd, 0, "invalid address (%lx)", kva);
                        return NULL;
                }

                for (pos = 0, ch = -1; ch != 0; pos++) {
                        cc = read(kd->vmfd, &ch, 1);
                        if ((ssize_t)cc < 0) {
                                _kvm_syserr(kd, 0, "kvm_readstr");
                                return NULL;
                        } else if (cc < 1)
                                _kvm_err(kd, kd->program, "short read");
                        if (asize > 0 && asize == (ssize_t)pos) {
                                buf = realloc(buf, asize *= 2);
                                if (buf == NULL) {
                                        _kvm_syserr(kd, kd->program, "kvm_readstr");
                                        return NULL;
                                }
                                len = asize;
                        }
                        if (pos < len)
                                buf[pos] = ch;
                }

                if (lenp != NULL)
                        *lenp = pos;
                if (pos > len)
                        return NULL;
                else
                        return buf;
        } else {
                size_t left = 0;
                for (pos = 0, ch = -1; ch != 0; pos++, left--, kva++) {
                        if (left == 0) {
                                off_t pa;

                                left = _kvm_kvatop(kd, kva, &pa);
                                if (left == 0)
                                        return NULL;
                                errno = 0;
                                if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
                                        _kvm_syserr(kd, 0, _PATH_MEM);
                                        return NULL;
                                }
                        }
                        cc = read(kd->pmfd, &ch, 1);
                        if ((ssize_t)cc < 0) {
                                _kvm_syserr(kd, 0, "kvm_readstr");
                                return NULL;
                        } else if (cc < 1)
                                _kvm_err(kd, kd->program, "short read");
                        if (asize > 0 && asize == (ssize_t)pos) {
                                buf = realloc(buf, asize *= 2);
                                if (buf == NULL) {
                                        _kvm_syserr(kd, kd->program, "kvm_readstr");
                                        return NULL;
                                }
                                len = asize;
                        }
                        if (pos < len)
                                buf[pos] = ch;
                }

                if (lenp != NULL)
                        *lenp = pos;
                if (pos > len)
                        return NULL;
                else
                        return buf;
        }
        /* NOTREACHED */
}

ssize_t
kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len)
{
        int cc;

        if (kvm_notrans(kd)) {
                /*
                 * Just like kvm_read, only we write.
                 */
                errno = 0;
                if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
                        _kvm_err(kd, 0, "invalid address (%lx)", kva);
                        return (-1);
                }
                cc = write(kd->vmfd, buf, len);
                if (cc < 0) {
                        _kvm_syserr(kd, 0, "kvm_write");
                        return (-1);
                } else if (cc < (ssize_t)len)
                        _kvm_err(kd, kd->program, "short write");
                return (cc);
        } else {
                _kvm_err(kd, kd->program,
                    "kvm_write not implemented for dead kernels");
                return (-1);
        }
        /* NOTREACHED */
}