/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (c) 1993 Paul Kranenburg
 * All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Paul Kranenburg.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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/wait.h>

#include <machine/elf.h>

#include <arpa/inet.h>

#include <dlfcn.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <gelf.h>
#include <libelf.h>
#include <rtld_paths.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/*
 * 32-bit ELF data structures can only be used if the system header[s] declare
 * them.  There is no official macro for determining whether they are declared,
 * so check for the existence of one of the 32-macros defined in elf(5).
 */
#ifdef ELF32_R_TYPE
#define ELF32_SUPPORTED
#endif

#define LDD_SETENV(name, value, overwrite) do {         \
        setenv("LD_" name, value, overwrite);           \
        setenv("LD_32_" name, value, overwrite);        \
} while (0)

#define LDD_UNSETENV(name) do {         \
        unsetenv("LD_" name);           \
        unsetenv("LD_32_" name);        \
} while (0)

static int      is_executable(const char *fname, int fd, int *is_shlib,
                    int *type);
static void     usage(void);

#define TYPE_UNKNOWN    0
#define TYPE_ELF        1       /* Architecture default */
#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
#define TYPE_ELF32      2       /* Explicit 32 bits on architectures >32 bits */

#define _PATH_LDD32     "/usr/bin/ldd32"

static int
execldd32(char *file, char *fmt1, char *fmt2, int aflag)
{
        char *argv[9];
        int i, rval, status;

        LDD_UNSETENV("TRACE_LOADED_OBJECTS");
        rval = 0;
        i = 0;
        argv[i++] = strdup(_PATH_LDD32);
        if (aflag)
                argv[i++] = strdup("-a");
        if (fmt1 != NULL) {
                argv[i++] = strdup("-f");
                argv[i++] = strdup(fmt1);
        }
        if (fmt2 != NULL) {
                argv[i++] = strdup("-f");
                argv[i++] = strdup(fmt2);
        }
        argv[i++] = strdup(file);
        argv[i++] = NULL;

        switch (fork()) {
        case -1:
                err(1, "fork");
                break;
        case 0:
                execv(_PATH_LDD32, argv);
                warn("%s", _PATH_LDD32);
                _exit(127);
                break;
        default:
                if (wait(&status) < 0)
                        rval = 1;
                else if (WIFSIGNALED(status))
                        rval = 1;
                else if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
                        rval = 1;
                break;
        }
        while (i--)
                free(argv[i]);
        LDD_SETENV("TRACE_LOADED_OBJECTS", "yes", 1);
        return (rval);
}
#endif

int
main(int argc, char *argv[])
{
        char *fmt1, *fmt2;
        const char *rtld;
        int aflag, c, fd, rval, status, is_shlib, rv, type;

        aflag = 0;
        fmt1 = fmt2 = NULL;

        while ((c = getopt(argc, argv, "af:")) != -1) {
                switch (c) {
                case 'a':
                        aflag++;
                        break;
                case 'f':
                        if (fmt1 != NULL) {
                                if (fmt2 != NULL)
                                        errx(1, "too many formats");
                                fmt2 = optarg;
                        } else
                                fmt1 = optarg;
                        break;
                default:
                        usage();
                        /* NOTREACHED */
                }
        }
        argc -= optind;
        argv += optind;

        if (argc <= 0) {
                usage();
                /* NOTREACHED */
        }

        rval = 0;
        for (; argc > 0; argc--, argv++) {
                if ((fd = open(*argv, O_RDONLY | O_VERIFY, 0)) < 0) {
                        warn("%s", *argv);
                        rval |= 1;
                        continue;
                }
                rv = is_executable(*argv, fd, &is_shlib, &type);
                close(fd);
                if (rv == 0) {
                        rval |= 1;
                        continue;
                }

                switch (type) {
                case TYPE_ELF:
                        break;
#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
                case TYPE_ELF32:
                        rval |= execldd32(*argv, fmt1, fmt2, aflag);
                        continue;
#endif
                case TYPE_UNKNOWN:
                default:
                        /*
                         * This shouldn't happen unless is_executable()
                         * is broken.
                         */
                        errx(EDOOFUS, "unknown executable type");
                }

                /* ld.so magic */
                LDD_SETENV("TRACE_LOADED_OBJECTS", "yes", 1);
                if (fmt1 != NULL)
                        LDD_SETENV("TRACE_LOADED_OBJECTS_FMT1", fmt1, 1);
                if (fmt2 != NULL)
                        LDD_SETENV("TRACE_LOADED_OBJECTS_FMT2", fmt2, 1);

                LDD_SETENV("TRACE_LOADED_OBJECTS_PROGNAME", *argv, 1);
                if (aflag)
                        LDD_SETENV("TRACE_LOADED_OBJECTS_ALL", "1", 1);
                else if (fmt1 == NULL && fmt2 == NULL)
                        /* Default formats */
                        printf("%s:\n", *argv);
                fflush(stdout);

                switch (fork()) {
                case -1:
                        err(1, "fork");
                        break;
                default:
                        if (wait(&status) < 0) {
                                warn("wait");
                                rval |= 1;
                        } else if (WIFSIGNALED(status)) {
                                fprintf(stderr, "%s: signal %d\n", *argv,
                                    WTERMSIG(status));
                                rval |= 1;
                        } else if (WIFEXITED(status) &&
                            WEXITSTATUS(status) != 0) {
                                fprintf(stderr, "%s: exit status %d\n", *argv,
                                    WEXITSTATUS(status));
                                rval |= 1;
                        }
                        break;
                case 0:
                        rtld = _PATH_RTLD;
#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
                        if (type == TYPE_ELF32)
                                rtld = __PATH_RTLD("32");
#endif
                        if (is_shlib == 0) {
                                execl(rtld, rtld, "--",
                                    *argv, (char *)NULL);
                                warn("%s", *argv);
                        } else if (fmt1 == NULL && fmt2 == NULL && !aflag) {
                                dlopen(*argv, RTLD_TRACE);
                                warnx("%s: %s", *argv, dlerror());
                        } else {
                                execl(rtld, rtld, "-d", "--",
                                    *argv, (char *)NULL);
                        }
                        _exit(1);
                }
        }

        return (rval);
}

static void
usage(void)
{

        fprintf(stderr,
            "usage: ldd [-a] [-f format [-f format]] program ...\n");
        exit(1);
}

static bool
has_freebsd_abi_tag(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset,
    size_t len)
{
        Elf_Data dst, src;
        const Elf_Note *note;
        char *buf;
        const char *name;
        void *copy;
        size_t namesz, descsz;
        bool has_abi_tag;

        buf = elf_rawfile(elf, NULL);
        if (buf == NULL) {
                warnx("%s: %s", fname, elf_errmsg(0));
                return (false);
        }

        memset(&src, 0, sizeof(src));
        src.d_buf = buf + offset;
        src.d_size = len;
        src.d_type = ELF_T_NOTE;
        src.d_version = EV_CURRENT;

        memset(&dst, 0, sizeof(dst));
        dst.d_buf = copy = malloc(len);
        dst.d_size = len;
        dst.d_type = ELF_T_NOTE;
        dst.d_version = EV_CURRENT;

        if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
                warnx("%s: failed to parse notes: %s", fname, elf_errmsg(0));
                free(copy);
                return (false);
        }

        buf = copy;
        has_abi_tag = false;
        for (;;) {
                if (len < sizeof(*note))
                        break;

                note = (const void *)buf;
                buf += sizeof(*note);
                len -= sizeof(*note);

                namesz = roundup2(note->n_namesz, sizeof(uint32_t));
                descsz = roundup2(note->n_descsz, sizeof(uint32_t));
                if (len < namesz + descsz)
                        break;

                name = buf;
                if (note->n_namesz == sizeof(ELF_NOTE_FREEBSD) &&
                    strncmp(name, ELF_NOTE_FREEBSD, note->n_namesz) == 0 &&
                    note->n_type == NT_FREEBSD_ABI_TAG &&
                    note->n_descsz == sizeof(uint32_t)) {
                        has_abi_tag = true;
                        break;
                }

                buf += namesz + descsz;
                len -= namesz + descsz;
        }

        free(copy);
        return (has_abi_tag);
}

static bool
is_pie(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset, size_t len)
{
        Elf_Data dst, src;
        char *buf;
        void *copy;
        const GElf_Dyn *dyn;
        size_t dynsize;
        u_int count, i;
        bool pie;

        buf = elf_rawfile(elf, NULL);
        if (buf == NULL) {
                warnx("%s: %s", fname, elf_errmsg(0));
                return (false);
        }

        dynsize = gelf_fsize(elf, ELF_T_DYN, 1, EV_CURRENT);
        if (dynsize == 0) {
                warnx("%s: %s", fname, elf_errmsg(0));
                return (false);
        }
        count = len / dynsize;

        memset(&src, 0, sizeof(src));
        src.d_buf = buf + offset;
        src.d_size = len;
        src.d_type = ELF_T_DYN;
        src.d_version = EV_CURRENT;

        memset(&dst, 0, sizeof(dst));
        dst.d_buf = copy = malloc(count * sizeof(*dyn));
        dst.d_size = count * sizeof(*dyn);
        dst.d_type = ELF_T_DYN;
        dst.d_version = EV_CURRENT;

        if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
                warnx("%s: failed to parse .dynamic: %s", fname, elf_errmsg(0));
                free(copy);
                return (false);
        }

        dyn = copy;
        pie = false;
        for (i = 0; i < count; i++) {
                if (dyn[i].d_tag != DT_FLAGS_1)
                        continue;

                pie = (dyn[i].d_un.d_val & DF_1_PIE) != 0;
                break;
        }

        free(copy);
        return (pie);
}

static int
is_executable(const char *fname, int fd, int *is_shlib, int *type)
{
        Elf *elf;
        GElf_Ehdr ehdr;
        GElf_Phdr phdr;
        bool dynamic, freebsd, pie;
        int i;

        *is_shlib = 0;
        *type = TYPE_UNKNOWN;
        dynamic = false;
        freebsd = false;
        pie = false;

        if (elf_version(EV_CURRENT) == EV_NONE) {
                warnx("unsupported libelf");
                return (0);
        }
        elf = elf_begin(fd, ELF_C_READ, NULL);
        if (elf == NULL) {
                warnx("%s: %s", fname, elf_errmsg(0));
                return (0);
        }
        if (elf_kind(elf) != ELF_K_ELF) {
                elf_end(elf);
                warnx("%s: not a dynamic ELF executable", fname);
                return (0);
        }
        if (gelf_getehdr(elf, &ehdr) == NULL) {
                warnx("%s: %s", fname, elf_errmsg(0));
                elf_end(elf);
                return (0);
        }

        *type = TYPE_ELF;
#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
        if (gelf_getclass(elf) == ELFCLASS32) {
                *type = TYPE_ELF32;
        }
#endif

        freebsd = ehdr.e_ident[EI_OSABI] == ELFOSABI_FREEBSD;
        for (i = 0; i < ehdr.e_phnum; i++) {
                if (gelf_getphdr(elf, i, &phdr) == NULL) {
                        warnx("%s: %s", fname, elf_errmsg(0));
                        elf_end(elf);
                        return (0);
                }
                switch (phdr.p_type) {
                case PT_NOTE:
                        if (ehdr.e_ident[EI_OSABI] == ELFOSABI_NONE && !freebsd)
                                freebsd = has_freebsd_abi_tag(fname, elf, &ehdr,
                                    phdr.p_offset, phdr.p_filesz);
                        break;
                case PT_DYNAMIC:
                        dynamic = true;
                        if (ehdr.e_type == ET_DYN)
                                pie = is_pie(fname, elf, &ehdr, phdr.p_offset,
                                    phdr.p_filesz);
                        break;
                }
        }

        if (!dynamic) {
                elf_end(elf);
                warnx("%s: not a dynamic ELF executable", fname);
                return (0);
        }

        if (ehdr.e_type == ET_DYN && !pie) {
                *is_shlib = 1;

                if (!freebsd) {
                        elf_end(elf);
                        warnx("%s: not a FreeBSD ELF shared object", fname);
                        return (0);
                }
        }

        elf_end(elf);
        return (1);
}