/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2010 The FreeBSD Foundation
 *
 * This software was developed by Rui Paulo under sponsorship from the
 * FreeBSD Foundation.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/user.h>

#include <assert.h>
#include <err.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <machine/elf.h>

#include <libelf.h>
#include <libproc.h>
#include <libprocstat.h>
#include <libutil.h>

#include "rtld_db.h"

static int _librtld_db_debug = 0;
#define DPRINTF(...) do {                               \
        if (_librtld_db_debug) {                        \
                fprintf(stderr, "librtld_db: DEBUG: "); \
                fprintf(stderr, __VA_ARGS__);           \
        }                                               \
} while (0)

void
rd_delete(rd_agent_t *rdap)
{

        if (rdap->rda_procstat != NULL)
                procstat_close(rdap->rda_procstat);
        free(rdap);
}

const char *
rd_errstr(rd_err_e rderr)
{

        switch (rderr) {
        case RD_ERR:
                return "generic error";
        case RD_OK:
                return "no error";
        case RD_NOCAPAB:
                return "capability not supported";
        case RD_DBERR:
                return "database error";
        case RD_NOBASE:
                return "NOBASE";
        case RD_NOMAPS:
                return "NOMAPS";
        default:
                return "unknown error";
        }
}

rd_err_e
rd_event_addr(rd_agent_t *rdap, rd_event_e event, rd_notify_t *notify)
{
        rd_err_e ret;

        DPRINTF("%s rdap %p event %d notify %p\n", __func__, rdap, event,
            notify);

        ret = RD_OK;
        switch (event) {
        case RD_NONE:
                break;
        case RD_PREINIT:
                notify->type = RD_NOTIFY_BPT;
                notify->u.bptaddr = rdap->rda_preinit_addr;
                break;
        case RD_POSTINIT:
                notify->type = RD_NOTIFY_BPT;
                notify->u.bptaddr = rdap->rda_postinit_addr;
                break;
        case RD_DLACTIVITY:
                notify->type = RD_NOTIFY_BPT;
                notify->u.bptaddr = rdap->rda_dlactivity_addr;
                break;
        default:
                ret = RD_ERR;
                break;
        }
        return (ret);
}

rd_err_e
rd_event_enable(rd_agent_t *rdap __unused, int onoff)
{
        DPRINTF("%s onoff %d\n", __func__, onoff);

        return (RD_OK);
}

rd_err_e
rd_event_getmsg(rd_agent_t *rdap __unused, rd_event_msg_t *msg)
{
        DPRINTF("%s\n", __func__);

        msg->type = RD_POSTINIT;
        msg->u.state = RD_CONSISTENT;

        return (RD_OK);
}

rd_err_e
rd_init(int version)
{
        char *debug = NULL;

        if (version == RD_VERSION) {
                debug = getenv("LIBRTLD_DB_DEBUG");
                _librtld_db_debug = debug ? atoi(debug) : 0;
                return (RD_OK);
        } else
                return (RD_NOCAPAB);
}

rd_err_e
rd_loadobj_iter(rd_agent_t *rdap, rl_iter_f *cb, void *clnt_data)
{
        struct kinfo_vmentry *kves, *kve;
        const char *path;
        uint64_t fileid;
        rd_loadobj_t rdl;
        rd_err_e ret;
        uintptr_t base;
        uint32_t offset;
        int cnt, i;

        DPRINTF("%s\n", __func__);

        if ((kves = kinfo_getvmmap(proc_getpid(rdap->rda_php), &cnt)) == NULL) {
                warn("ERROR: kinfo_getvmmap() failed");
                return (RD_ERR);
        }

        base = 0;
        fileid = 0;
        path = NULL;
        ret = RD_OK;
        for (i = 0; i < cnt; i++) {
                kve = &kves[i];
                /*
                 * Cache the base offset of the file mapping.  The kve_offset
                 * field gives the file offset of a particular mapping into the
                 * file, but we want the mapping offset relative to the base
                 * mapping.
                 */
                if (kve->kve_type == KVME_TYPE_VNODE) {
                        if (kve->kve_vn_fileid != fileid) {
                                base = kve->kve_start;
                                fileid = kve->kve_vn_fileid;
                        }
                        path = kve->kve_path;
                        offset = kve->kve_start - base;
                } else {
                        path = NULL;
                        offset = 0;
                }
                memset(&rdl, 0, sizeof(rdl));
                /*
                 * Map the kinfo_vmentry struct to the rd_loadobj structure.
                 */
                rdl.rdl_saddr = kve->kve_start;
                rdl.rdl_eaddr = kve->kve_end;
                rdl.rdl_offset = offset;
                if (kve->kve_protection & KVME_PROT_READ)
                        rdl.rdl_prot |= RD_RDL_R;
                if (kve->kve_protection & KVME_PROT_WRITE)
                        rdl.rdl_prot |= RD_RDL_W;
                if (kve->kve_protection & KVME_PROT_EXEC)
                        rdl.rdl_prot |= RD_RDL_X;
                if (path != NULL)
                        strlcpy(rdl.rdl_path, path, sizeof(rdl.rdl_path));
                if ((*cb)(&rdl, clnt_data) != 0) {
                        ret = RD_ERR;
                        break;
                }
        }
        free(kves);
        return (ret);
}

void
rd_log(const int onoff)
{
        DPRINTF("%s\n", __func__);

        (void)onoff;
}

rd_agent_t *
rd_new(struct proc_handle *php)
{
        rd_agent_t *rdap;

        rdap = malloc(sizeof(*rdap));
        if (rdap == NULL)
                return (NULL);

        memset(rdap, 0, sizeof(rd_agent_t));
        rdap->rda_php = php;
        rdap->rda_procstat = procstat_open_sysctl();

        if (rd_reset(rdap) != RD_OK) {
                rd_delete(rdap);
                rdap = NULL;
        }
        return (rdap);
}

rd_err_e
rd_objpad_enable(rd_agent_t *rdap, size_t padsize)
{
        DPRINTF("%s\n", __func__);

        (void)rdap;
        (void)padsize;

        return (RD_ERR);
}

rd_err_e
rd_plt_resolution(rd_agent_t *rdap, uintptr_t pc, struct proc *proc,
    uintptr_t plt_base, rd_plt_info_t *rpi)
{
        DPRINTF("%s\n", __func__);

        (void)rdap;
        (void)pc;
        (void)proc;
        (void)plt_base;
        (void)rpi;

        return (RD_ERR);
}

static int
rtld_syms(rd_agent_t *rdap, const char *rtldpath, u_long base)
{
        GElf_Shdr shdr;
        GElf_Sym sym;
        Elf *e;
        Elf_Data *data;
        Elf_Scn *scn;
        const char *symname;
        Elf64_Word strscnidx;
        int fd, i, ret;

        ret = 1;
        e = NULL;

        fd = open(rtldpath, O_RDONLY);
        if (fd < 0)
                goto err;

        if (elf_version(EV_CURRENT) == EV_NONE)
                goto err;
        e = elf_begin(fd, ELF_C_READ, NULL);
        if (e == NULL)
                goto err;

        scn = NULL;
        while ((scn = elf_nextscn(e, scn)) != NULL) {
                gelf_getshdr(scn, &shdr);
                if (shdr.sh_type == SHT_DYNSYM)
                        break;
        }
        if (scn == NULL)
                goto err;

        strscnidx = shdr.sh_link;
        data = elf_getdata(scn, NULL);
        if (data == NULL)
                goto err;

        for (i = 0; gelf_getsym(data, i, &sym) != NULL; i++) {
                if (GELF_ST_TYPE(sym.st_info) != STT_FUNC ||
                    GELF_ST_BIND(sym.st_info) != STB_GLOBAL)
                        continue;
                symname = elf_strptr(e, strscnidx, sym.st_name);
                if (symname == NULL)
                        continue;

                if (strcmp(symname, "r_debug_state") == 0) {
                        rdap->rda_preinit_addr = sym.st_value + base;
                        rdap->rda_dlactivity_addr = sym.st_value + base;
                } else if (strcmp(symname, "_r_debug_postinit") == 0) {
                        rdap->rda_postinit_addr = sym.st_value + base;
                }
        }

        if (rdap->rda_preinit_addr != 0 &&
            rdap->rda_postinit_addr != 0 &&
            rdap->rda_dlactivity_addr != 0)
                ret = 0;

err:
        if (e != NULL)
                (void)elf_end(e);
        if (fd >= 0)
                (void)close(fd);
        return (ret);
}

rd_err_e
rd_reset(rd_agent_t *rdap)
{
        struct kinfo_proc *kp;
        struct kinfo_vmentry *kve;
        Elf_Auxinfo *auxv;
        const char *rtldpath;
        u_long base;
        rd_err_e rderr;
        int count, i;

        kp = NULL;
        auxv = NULL;
        kve = NULL;
        rderr = RD_ERR;

        kp = procstat_getprocs(rdap->rda_procstat, KERN_PROC_PID,
            proc_getpid(rdap->rda_php), &count);
        if (kp == NULL)
                return (RD_ERR);
        assert(count == 1);

        auxv = procstat_getauxv(rdap->rda_procstat, kp, &count);
        if (auxv == NULL)
                goto err;

        base = 0;
        for (i = 0; i < count; i++) {
                if (auxv[i].a_type == AT_BASE) {
                        base = auxv[i].a_un.a_val;
                        break;
                }
        }
        if (i == count)
                goto err;

        rtldpath = NULL;
        kve = procstat_getvmmap(rdap->rda_procstat, kp, &count);
        if (kve == NULL)
                goto err;
        for (i = 0; i < count; i++) {
                if (kve[i].kve_start == base) {
                        rtldpath = kve[i].kve_path;
                        break;
                }
        }
        if (i == count)
                goto err;

        if (rtld_syms(rdap, rtldpath, base) != 0)
                goto err;

        rderr = RD_OK;

err:
        if (kve != NULL)
                procstat_freevmmap(rdap->rda_procstat, kve);
        if (auxv != NULL)
                procstat_freeauxv(rdap->rda_procstat, auxv);
        if (kp != NULL)
                procstat_freeprocs(rdap->rda_procstat, kp);
        return (rderr);
}