libctf/common/ctf_lib.c

	ctf_lib.c revision 2f970cc1769168576b3c809d4ebf309bf381acb3
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <ctf_impl.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <dlfcn.h>
#include <gelf.h>

#ifdef _LP64
static const char *_libctf_zlib = "/usr/lib/64/libz.so.1";
#else
static const char *_libctf_zlib = "/usr/lib/libz.so.1";
#endif

static struct {
    int (*z_uncompress)(uchar_t *, ulong_t *, const uchar_t *, ulong_t);
    const char *(*z_error)(int);
    void *z_dlp;
} zlib;

static size_t _PAGESIZE;
static size_t _PAGEMASK;

#pragma init(_libctf_init)
void
_libctf_init(void)
{
    const char *p = getenv("LIBCTF_DECOMPRESSOR");

    if (p != NULL)
        _libctf_zlib = p; /* use alternate decompression library */

    _libctf_debug = getenv("LIBCTF_DEBUG") != NULL;

    _PAGESIZE = getpagesize();
    _PAGEMASK = ~(_PAGESIZE - 1);
}

/*
 * Attempt to dlopen the decompression library and locate the symbols of
 * interest that we will need to call.  This information in cached so
 * that multiple calls to ctf_bufopen() do not need to reopen the library.
 */
void *
ctf_zopen(int *errp)
{
    ctf_dprintf("decompressing CTF data using %s\n", _libctf_zlib);

    if (zlib.z_dlp != NULL)
        return (zlib.z_dlp); /* library is already loaded */

    if (access(_libctf_zlib, R_OK) == -1)
        return (ctf_set_open_errno(errp, ECTF_ZMISSING));

    if ((zlib.z_dlp = dlopen(_libctf_zlib, RTLD_LAZY | RTLD_LOCAL)) == NULL)
        return (ctf_set_open_errno(errp, ECTF_ZINIT));

    zlib.z_uncompress = (int (*)()) dlsym(zlib.z_dlp, "uncompress");
    zlib.z_error = (const char *(*)()) dlsym(zlib.z_dlp, "zError");

    if (zlib.z_uncompress == NULL || zlib.z_error == NULL) {
        (void) dlclose(zlib.z_dlp);
        bzero(&zlib, sizeof (zlib));
        return (ctf_set_open_errno(errp, ECTF_ZINIT));
    }

    return (zlib.z_dlp);
}

/*
 * The ctf_bufopen() routine calls these subroutines, defined by <sys/zmod.h>,
 * which we then patch through to the functions in the decompression library.
 */
int
z_uncompress(void *dst, size_t *dstlen, const void *src, size_t srclen)
{
    return (zlib.z_uncompress(dst, (ulong_t *)dstlen, src, srclen));
}

const char *
z_strerror(int err)
{
    return (zlib.z_error(err));
}

/*
 * Convert a 32-bit ELF file header into GElf.
 */
static void
ehdr_to_gelf(const Elf32_Ehdr *src, GElf_Ehdr *dst)
{
    bcopy(src->e_ident, dst->e_ident, EI_NIDENT);
    dst->e_type = src->e_type;
    dst->e_machine = src->e_machine;
    dst->e_version = src->e_version;
    dst->e_entry = (Elf64_Addr)src->e_entry;
    dst->e_phoff = (Elf64_Off)src->e_phoff;
    dst->e_shoff = (Elf64_Off)src->e_shoff;
    dst->e_flags = src->e_flags;
    dst->e_ehsize = src->e_ehsize;
    dst->e_phentsize = src->e_phentsize;
    dst->e_phnum = src->e_phnum;
    dst->e_shentsize = src->e_shentsize;
    dst->e_shnum = src->e_shnum;
    dst->e_shstrndx = src->e_shstrndx;
}

/*
 * Convert a 32-bit ELF section header into GElf.
 */
static void
shdr_to_gelf(const Elf32_Shdr *src, GElf_Shdr *dst)
{
    dst->sh_name = src->sh_name;
    dst->sh_type = src->sh_type;
    dst->sh_flags = src->sh_flags;
    dst->sh_addr = src->sh_addr;
    dst->sh_offset = src->sh_offset;
    dst->sh_size = src->sh_size;
    dst->sh_link = src->sh_link;
    dst->sh_info = src->sh_info;
    dst->sh_addralign = src->sh_addralign;
    dst->sh_entsize = src->sh_entsize;
}

/*
 * In order to mmap a section from the ELF file, we must round down sh_offset
 * to the previous page boundary, and mmap the surrounding page.  We store
 * the pointer to the start of the actual section data back into sp->cts_data.
 */
const void *
ctf_sect_mmap(ctf_sect_t *sp, int fd)
{
    size_t pageoff = sp->cts_offset & ~_PAGEMASK;

    caddr_t base = mmap64(NULL, sp->cts_size + pageoff, PROT_READ,
        MAP_PRIVATE, fd, sp->cts_offset & _PAGEMASK);

    if (base != MAP_FAILED)
        sp->cts_data = base + pageoff;

    return (base);
}

/*
 * Since sp->cts_data has the adjusted offset, we have to again round down
 * to get the actual mmap address and round up to get the size.
 */
void
ctf_sect_munmap(const ctf_sect_t *sp)
{
    uintptr_t addr = (uintptr_t)sp->cts_data;
    uintptr_t pageoff = addr & ~_PAGEMASK;

    (void) munmap((void *)(addr - pageoff), sp->cts_size + pageoff);
}

/*
 * Open the specified file descriptor and return a pointer to a CTF container.
 * The file can be either an ELF file or raw CTF file.  The caller is
 * responsible for closing the file descriptor when it is no longer needed.
 */
ctf_file_t *
ctf_fdopen(int fd, int *errp)
{
    ctf_sect_t ctfsect, symsect, strsect;
    ctf_file_t *fp = NULL;

    struct stat64 st;
    ssize_t nbytes;

    union {
        ctf_preamble_t ctf;
        Elf32_Ehdr e32;
        GElf_Ehdr e64;
    } hdr;

    bzero(&ctfsect, sizeof (ctf_sect_t));
    bzero(&symsect, sizeof (ctf_sect_t));
    bzero(&strsect, sizeof (ctf_sect_t));
    bzero(&hdr.ctf, sizeof (hdr));

    if (fstat64(fd, &st) == -1)
        return (ctf_set_open_errno(errp, errno));

    if ((nbytes = pread64(fd, &hdr.ctf, sizeof (hdr), 0)) <= 0)
        return (ctf_set_open_errno(errp, nbytes < 0? errno : ECTF_FMT));

    /*
     * If we have read enough bytes to form a CTF header and the magic
     * string matches, attempt to interpret the file as raw CTF.
     */
    if (nbytes >= sizeof (ctf_preamble_t) &&
        hdr.ctf.ctp_magic == CTF_MAGIC) {
        if (hdr.ctf.ctp_version > CTF_VERSION)
            return (ctf_set_open_errno(errp, ECTF_CTFVERS));

        ctfsect.cts_data = mmap64(NULL, st.st_size, PROT_READ,
            MAP_PRIVATE, fd, 0);

        if (ctfsect.cts_data == MAP_FAILED)
            return (ctf_set_open_errno(errp, errno));

        ctfsect.cts_name = _CTF_SECTION;
        ctfsect.cts_type = SHT_PROGBITS;
        ctfsect.cts_flags = SHF_ALLOC;
        ctfsect.cts_size = (size_t)st.st_size;
        ctfsect.cts_entsize = 1;
        ctfsect.cts_offset = 0;

        if ((fp = ctf_bufopen(&ctfsect, NULL, NULL, errp)) == NULL)
            ctf_sect_munmap(&ctfsect);

        return (fp);
    }

    /*
     * If we have read enough bytes to form an ELF header and the magic
     * string matches, attempt to interpret the file as an ELF file.  We
     * do our own largefile ELF processing, and convert everything to
     * GElf structures so that clients can operate on any data model.
     */
    if (nbytes >= sizeof (Elf32_Ehdr) &&
        bcmp(&hdr.e32.e_ident[EI_MAG0], ELFMAG, SELFMAG) == 0) {
#ifdef  _BIG_ENDIAN
        uchar_t order = ELFDATA2MSB;
#else
        uchar_t order = ELFDATA2LSB;
#endif
        GElf_Half i, n;
        GElf_Shdr *sp;

        void *strs_map;
        size_t strs_mapsz;
        const char *strs;

        if (hdr.e32.e_ident[EI_DATA] != order)
            return (ctf_set_open_errno(errp, ECTF_ENDIAN));
        if (hdr.e32.e_version != EV_CURRENT)
            return (ctf_set_open_errno(errp, ECTF_ELFVERS));

        if (hdr.e32.e_ident[EI_CLASS] == ELFCLASS64) {
            if (nbytes < sizeof (GElf_Ehdr))
                return (ctf_set_open_errno(errp, ECTF_FMT));
        } else {
            Elf32_Ehdr e32 = hdr.e32;
            ehdr_to_gelf(&e32, &hdr.e64);
        }

        if (hdr.e64.e_shstrndx >= hdr.e64.e_shnum)
            return (ctf_set_open_errno(errp, ECTF_CORRUPT));

        n = hdr.e64.e_shnum;
        nbytes = sizeof (GElf_Shdr) * n;

        if ((sp = malloc(nbytes)) == NULL)
            return (ctf_set_open_errno(errp, errno));

        /*
         * Read in and convert to GElf the array of Shdr structures
         * from e_shoff so we can locate sections of interest.
         */
        if (hdr.e32.e_ident[EI_CLASS] == ELFCLASS32) {
            Elf32_Shdr *sp32;

            nbytes = sizeof (Elf32_Shdr) * n;

            if ((sp32 = malloc(nbytes)) == NULL || pread64(fd,
                sp32, nbytes, hdr.e64.e_shoff) != nbytes) {
                free(sp);
                return (ctf_set_open_errno(errp, errno));
            }

            for (i = 0; i < n; i++)
                shdr_to_gelf(&sp32[i], &sp[i]);

            free(sp32);

        } else if (pread64(fd, sp, nbytes, hdr.e64.e_shoff) != nbytes) {
            free(sp);
            return (ctf_set_open_errno(errp, errno));
        }

        /*
         * Now mmap the section header strings section so that we can
         * perform string comparison on the section names.
         */
        strs_mapsz = sp[hdr.e64.e_shstrndx].sh_size +
            (sp[hdr.e64.e_shstrndx].sh_offset & ~_PAGEMASK);

        strs_map = mmap64(NULL, strs_mapsz, PROT_READ, MAP_PRIVATE,
            fd, sp[hdr.e64.e_shstrndx].sh_offset & _PAGEMASK);

        strs = (const char *)strs_map +
            (sp[hdr.e64.e_shstrndx].sh_offset & ~_PAGEMASK);

        if (strs_map == MAP_FAILED) {
            free(sp);
            return (ctf_set_open_errno(errp, ECTF_MMAP));
        }

        /*
         * Iterate over the section header array looking for the CTF
         * section and symbol table.  The strtab is linked to symtab.
         */
        for (i = 0; i < n; i++) {
            const GElf_Shdr *shp = &sp[i];
            const GElf_Shdr *lhp = &sp[shp->sh_link];

            if (shp->sh_link >= hdr.e64.e_shnum)
                continue; /* corrupt sh_link field */

            if (shp->sh_name >= sp[hdr.e64.e_shstrndx].sh_size ||
                lhp->sh_name >= sp[hdr.e64.e_shstrndx].sh_size)
                continue; /* corrupt sh_name field */

            if (shp->sh_type == SHT_PROGBITS &&
                strcmp(strs + shp->sh_name, _CTF_SECTION) == 0) {
                ctfsect.cts_name = strs + shp->sh_name;
                ctfsect.cts_type = shp->sh_type;
                ctfsect.cts_flags = shp->sh_flags;
                ctfsect.cts_size = shp->sh_size;
                ctfsect.cts_entsize = shp->sh_entsize;
                ctfsect.cts_offset = (off64_t)shp->sh_offset;

            } else if (shp->sh_type == SHT_SYMTAB) {
                symsect.cts_name = strs + shp->sh_name;
                symsect.cts_type = shp->sh_type;
                symsect.cts_flags = shp->sh_flags;
                symsect.cts_size = shp->sh_size;
                symsect.cts_entsize = shp->sh_entsize;
                symsect.cts_offset = (off64_t)shp->sh_offset;

                strsect.cts_name = strs + lhp->sh_name;
                strsect.cts_type = lhp->sh_type;
                strsect.cts_flags = lhp->sh_flags;
                strsect.cts_size = lhp->sh_size;
                strsect.cts_entsize = lhp->sh_entsize;
                strsect.cts_offset = (off64_t)lhp->sh_offset;
            }
        }

        free(sp); /* free section header array */

        if (ctfsect.cts_type == SHT_NULL) {
            (void) munmap(strs_map, strs_mapsz);
            return (ctf_set_open_errno(errp, ECTF_NOCTFDATA));
        }

        /*
         * Now mmap the CTF data, symtab, and strtab sections and
         * call ctf_bufopen() to do the rest of the work.
         */
        if (ctf_sect_mmap(&ctfsect, fd) == MAP_FAILED) {
            (void) munmap(strs_map, strs_mapsz);
            return (ctf_set_open_errno(errp, ECTF_MMAP));
        }

        if (symsect.cts_type != SHT_NULL &&
            strsect.cts_type != SHT_NULL) {
            if (ctf_sect_mmap(&symsect, fd) == MAP_FAILED ||
                ctf_sect_mmap(&strsect, fd) == MAP_FAILED) {
                (void) ctf_set_open_errno(errp, ECTF_MMAP);
                goto bad; /* unmap all and abort */
            }
            fp = ctf_bufopen(&ctfsect, &symsect, &strsect, errp);
        } else
            fp = ctf_bufopen(&ctfsect, NULL, NULL, errp);
bad:
        if (fp == NULL) {
            ctf_sect_munmap(&ctfsect);
            ctf_sect_munmap(&symsect);
            ctf_sect_munmap(&strsect);
        } else
            fp->ctf_flags |= LCTF_MMAP;

        (void) munmap(strs_map, strs_mapsz);
        return (fp);
    }

    return (ctf_set_open_errno(errp, ECTF_FMT));
}

/*
 * Open the specified file and return a pointer to a CTF container.  The file
 * can be either an ELF file or raw CTF file.  This is just a convenient
 * wrapper around ctf_fdopen() for callers.
 */
ctf_file_t *
ctf_open(const char *filename, int *errp)
{
    ctf_file_t *fp;
    int fd;

    if ((fd = open64(filename, O_RDONLY)) == -1) {
        if (errp != NULL)
            *errp = errno;
        return (NULL);
    }

    fp = ctf_fdopen(fd, errp);
    (void) close(fd);
    return (fp);
}

/*
 * Write the uncompressed CTF data stream to the specified file descriptor.
 * This is useful for saving the results of dynamic CTF containers.
 */
int
ctf_write(ctf_file_t *fp, int fd)
{
    const uchar_t *buf = fp->ctf_base;
    ssize_t resid = fp->ctf_size;
    ssize_t len;

    while (resid != 0) {
        if ((len = write(fd, buf, resid)) <= 0)
            return (ctf_set_errno(fp, errno));
        resid -= len;
        buf += len;
    }

    return (0);
}

/*
 * Set the CTF library client version to the specified version.  If version is
 * zero, we just return the default library version number.
 */
int
ctf_version(int version)
{
    if (version < 0) {
        errno = EINVAL;
        return (-1);
    }

    if (version > 0) {
        if (version > CTF_VERSION) {
            errno = ENOTSUP;
            return (-1);
        }
        ctf_dprintf("ctf_version: client using version %d\n", version);
        _libctf_version = version;
    }

    return (_libctf_version);
}