3439 discarded sections shouldn't end up on output lists

[illumos-gate.git] / usr / src / cmd / sgs / libld / common / place.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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 (c) 1988 AT&T
 *        All Rights Reserved
 *
 * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2012, Joyent, Inc. All rights reserved.
 */

/*
 * Map file parsing and input section to output segment mapping.
 */
#include        <stdio.h>
#include        <string.h>
#include        <debug.h>
#include        "msg.h"
#include        "_libld.h"

/*
 * Each time a section is placed, the function set_addralign()
 * is called.  This function performs:
 *
 * -    if the section is from an external file, check if this is empty or not.
 *      If not, we know the segment this section will belong needs a program
 *      header. (Of course, the program is needed only if this section falls
 *      into a loadable segment.)
 * -    compute the Least Common Multiplier for setting the segment alignment.
 */
static void
set_addralign(Ofl_desc *ofl, Os_desc *osp, Is_desc *isp)
{
        Shdr    *shdr = isp->is_shdr;

        /* A discarded section has no influence on the output */
        if (isp->is_flags & FLG_IS_DISCARD)
                return;

        /*
         * If this section has data or will be assigned data
         * later, mark this segment not-empty.
         */
        if ((shdr->sh_size != 0) ||
            ((isp->is_flags & FLG_IS_EXTERNAL) == 0))
                osp->os_sgdesc->sg_flags |= FLG_SG_PHREQ;

        if ((ofl->ofl_dtflags_1 & DF_1_NOHDR) &&
            (osp->os_sgdesc->sg_phdr).p_type != PT_LOAD)
                return;

        osp->os_sgdesc->sg_align =
            ld_lcm(osp->os_sgdesc->sg_align, shdr->sh_addralign);
}

/*
 * Return the first input descriptor for a given output descriptor,
 * or NULL if there are none.
 */

Is_desc *
ld_os_first_isdesc(Os_desc *osp)
{
        int i;

        for (i = 0; i < OS_ISD_NUM; i++) {
                APlist *ap_isdesc = osp->os_isdescs[i];

                if (aplist_nitems(ap_isdesc) > 0)
                        return ((Is_desc *)ap_isdesc->apl_data[0]);
        }

        return (NULL);
}

/*
 * Attach an input section to an output section
 *
 * entry:
 *      ofl - File descriptor
 *      osp - Output section descriptor
 *      isp - Input section descriptor
 *      mapfile_sort - True (1) if segment supports mapfile specified ordering
 *              of otherwise unordered input sections, and False (0) otherwise.
 *
 * exit:
 *      - The input section has been attached to the output section
 *      - If the input section is a candidate for string table merging,
 *              then it is appended to the output section's list of merge
 *              candidates (os_mstridescs).
 *
 *      On success, returns True (1). On failure, False (0).
 */
static int
os_attach_isp(Ofl_desc *ofl, Os_desc *osp, Is_desc *isp, int mapfile_sort)
{
        Aliste  init_arritems;
        int     os_isdescs_idx, do_append = 1;

        if ((isp->is_flags & FLG_IS_ORDERED) == 0) {
                init_arritems = AL_CNT_OS_ISDESCS;
                os_isdescs_idx = OS_ISD_DEFAULT;

                /*
                 * If section ordering was specified for an unordered section
                 * via the mapfile, then search in the OS_ISD_DEFAULT list
                 * and insert it in the specified position. Ordered sections
                 * are placed in ascending order before unordered sections
                 * (sections with an is_ordndx value of zero).
                 *
                 * If no mapfile ordering was specified, we append it in
                 * the usual way below.
                 */
                if (mapfile_sort && (isp->is_ordndx > 0)) {
                        APlist *ap_isdesc = osp->os_isdescs[OS_ISD_DEFAULT];
                        Aliste  idx2;
                        Is_desc *isp2;

                        for (APLIST_TRAVERSE(ap_isdesc, idx2, isp2)) {
                                if (isp2->is_ordndx &&
                                    (isp2->is_ordndx <= isp->is_ordndx))
                                                continue;

                                if (aplist_insert(
                                    &osp->os_isdescs[OS_ISD_DEFAULT],
                                    isp, init_arritems, idx2) == NULL)
                                        return (0);
                                do_append = 0;
                                break;
                        }
                }
        } else {                /* Ordered section (via shdr flags) */
                Word shndx;

                /* SHF_ORDERED uses sh_info, SHF_LINK_ORDERED uses sh_link */
                shndx = (isp->is_shdr->sh_flags & SHF_ORDERED) ?
                    isp->is_shdr->sh_info : isp->is_shdr->sh_link;

                if (shndx == SHN_BEFORE) {
                        init_arritems = AL_CNT_OS_ISDESCS_BA;
                        os_isdescs_idx = OS_ISD_BEFORE;
                } else if (shndx == SHN_AFTER) {
                        init_arritems = AL_CNT_OS_ISDESCS_BA;
                        os_isdescs_idx = OS_ISD_AFTER;
                } else {
                        init_arritems = AL_CNT_OS_ISDESCS;
                        os_isdescs_idx = OS_ISD_ORDERED;
                }
        }

        /*
         * If we didn't insert a section into the default list using
         * mapfile specified ordering above, then append the input
         * section to the appropriate list.
         */
        if (do_append && aplist_append(&(osp->os_isdescs[os_isdescs_idx]),
            isp, init_arritems) == NULL)
                return (0);
        isp->is_osdesc = osp;

        /*
         * A section can be merged if the following are true:
         * -    The SHF_MERGE|SHF_STRINGS flags must be set
         * -    String table compression must not be disabled (-znocompstrtab)
         * -    Mapfile ordering must not have been used.
         * -    The section must not be ordered via section header flags.
         * -    It must not be the generated section being built to
         *      replace the sections on this list.
         */
        if (((isp->is_shdr->sh_flags & (SHF_MERGE | SHF_STRINGS)) !=
            (SHF_MERGE | SHF_STRINGS)) ||
            ((ofl->ofl_flags1 & FLG_OF1_NCSTTAB) != 0) ||
            !do_append ||
            ((isp->is_flags & (FLG_IS_ORDERED | FLG_IS_GNSTRMRG)) != 0))
                return (1);

        /*
         * Skip sections with (sh_entsize > 1) or (sh_addralign > 1).
         *
         * sh_entsize:
         *      We are currently only able to merge string tables containing
         *      strings with 1-byte (char) characters. Support for wide
         *      characters will require our string table compression code
         *      to be extended to handle larger character sizes.
         *
         * sh_addralign:
         *      Alignments greater than 1 would require our string table
         *      compression code to insert null bytes to move each
         *      string to the required alignment.
         */
        if ((isp->is_shdr->sh_entsize > 1) ||
            (isp->is_shdr->sh_addralign > 1)) {
                DBG_CALL(Dbg_sec_unsup_strmerge(ofl->ofl_lml, isp));
                return (1);
        }

        if (aplist_append(&osp->os_mstrisdescs, isp,
            AL_CNT_OS_MSTRISDESCS) == NULL)
                return (0);

        /*
         * The SHF_MERGE|SHF_STRINGS flags tell us that the program that
         * created the section intended it to be mergeable. The
         * FLG_IS_INSTRMRG flag says that we have done validity testing
         * and decided that it is safe to act on that hint.
         */
        isp->is_flags |= FLG_IS_INSTRMRG;

        return (1);
}

/*
 * Determine whether this input COMDAT section already exists for the associated
 * output section.  If so, then discard this input section.  Otherwise, this
 * must be the first COMDAT section, thus it is kept for future comparisons.
 */
static uintptr_t
add_comdat(Ofl_desc *ofl, Os_desc *osp, Is_desc *isp)
{
        Isd_node        isd, *isdp;
        avl_tree_t      *avlt;
        avl_index_t     where;

        /*
         * Create a COMDAT avl tree for this output section if required.
         */
        if ((avlt = osp->os_comdats) == NULL) {
                if ((avlt = libld_calloc(sizeof (avl_tree_t), 1)) == NULL)
                        return (S_ERROR);
                avl_create(avlt, isdavl_compare, sizeof (Isd_node),
                    SGSOFFSETOF(Isd_node, isd_avl));
                osp->os_comdats = avlt;
        }

        /*
         * A standard COMDAT section uses the section name as search key.
         */
        isd.isd_name = isp->is_name;
        isd.isd_hash = sgs_str_hash(isd.isd_name);

        if ((isdp = avl_find(avlt, &isd, &where)) != NULL) {
                isp->is_osdesc = osp;

                /*
                 * If this section hasn't already been identified as discarded,
                 * generate a suitable diagnostic.
                 */
                if ((isp->is_flags & FLG_IS_DISCARD) == 0) {
                        isp->is_flags |= FLG_IS_DISCARD;
                        isp->is_comdatkeep = isdp->isd_isp;
                        DBG_CALL(Dbg_sec_discarded(ofl->ofl_lml, isp,
                            isdp->isd_isp));
                }

                /*
                 * A discarded section does not require assignment to an output
                 * section.  However, if relaxed relocations have been enabled
                 * (either from -z relaxreloc, or asserted with .gnu.linkonce
                 * processing), then this section must still be assigned to an
                 * output section so that the sloppy relocation logic will have
                 * the information necessary to do its work.
                 */
                return (0);
        }

        /*
         * This is a new COMDAT section - so keep it.
         */
        if ((isdp = libld_calloc(sizeof (Isd_node), 1)) == NULL)
                return (S_ERROR);

        isdp->isd_name = isd.isd_name;
        isdp->isd_hash = isd.isd_hash;
        isdp->isd_isp = isp;

        avl_insert(avlt, isdp, where);
        return (1);
}

/*
 * Determine whether a GNU group COMDAT section name follows the convention
 *
 *      section-name.symbol-name
 *
 * Each section within the input file is compared to see if the full section
 * name matches the beginning of the COMDAT section, with a following '.'.
 * A pointer to the symbol name, starting with the '.' is returned so that the
 * caller can strip off the required section name.
 */
static char *
gnu_comdat_sym(Ifl_desc *ifl, Is_desc *gisp)
{
        size_t  ndx;

        for (ndx = 1; ndx < ifl->ifl_shnum; ndx++) {
                Is_desc *isp;
                size_t  ssize;

                if (((isp = ifl->ifl_isdesc[ndx]) == NULL) ||
                    (isp == gisp) || (isp->is_name == NULL))
                        continue;

                /*
                 * It's questionable whether this size should be cached in the
                 * Is_desc.  However, this seems an infrequent operation and
                 * adding Is_desc members can escalate memory usage for large
                 * link-edits.  For now, size the section name dynamically.
                 */
                ssize = strlen(isp->is_name);
                if ((strncmp(isp->is_name, gisp->is_name, ssize) == 0) &&
                    (gisp->is_name[ssize] == '.'))
                        return ((char *)&gisp->is_name[ssize]);
        }
        return (NULL);
}

/*
 * GNU .gnu.linkonce sections follow a naming convention that indicates the
 * required association with an output section.  Determine whether this input
 * section follows the convention, and if so return the appropriate output
 * section name.
 *
 *      .gnu.linkonce.b.*    -> .bss
 *      .gnu.linkonce.d.*    -> .data
 *      .gnu.linkonce.l.*    -> .ldata
 *      .gnu.linkonce.lb.*   -> .lbss
 *      .gnu.linkonce.lr.*   -> .lrodata
 *      .gnu.linkonce.r.*    -> .rodata
 *      .gnu.linkonce.s.*    -> .sdata
 *      .gnu.linkonce.s2.*   -> .sdata2
 *      .gnu.linkonce.sb.*   -> .sbss
 *      .gnu.linkonce.sb2.*  -> .sbss2
 *      .gnu.linkonce.t.*    -> .text
 *      .gnu.linkonce.tb.*   -> .tbss
 *      .gnu.linkonce.td.*   -> .tdata
 *      .gnu.linkonce.wi.*   -> .debug_info
 */
#define NSTR_CH1(ch) (*(nstr + 1) == (ch))
#define NSTR_CH2(ch) (*(nstr + 2) == (ch))
#define NSTR_CH3(ch) (*(nstr + 3) == (ch))

static const char *
gnu_linkonce_sec(const char *ostr)
{
        const char      *nstr = &ostr[MSG_SCN_GNU_LINKONCE_SIZE];

        switch (*nstr) {
        case 'b':
                if (NSTR_CH1('.'))
                        return (MSG_ORIG(MSG_SCN_BSS));
                break;
        case 'd':
                if (NSTR_CH1('.'))
                        return (MSG_ORIG(MSG_SCN_DATA));
                break;
        case 'l':
                if (NSTR_CH1('.'))
                        return (MSG_ORIG(MSG_SCN_LDATA));
                else if (NSTR_CH1('b') && NSTR_CH2('.'))
                        return (MSG_ORIG(MSG_SCN_LBSS));
                else if (NSTR_CH1('r') && NSTR_CH2('.'))
                        return (MSG_ORIG(MSG_SCN_LRODATA));
                break;
        case 'r':
                if (NSTR_CH1('.'))
                        return (MSG_ORIG(MSG_SCN_RODATA));
                break;
        case 's':
                if (NSTR_CH1('.'))
                        return (MSG_ORIG(MSG_SCN_SDATA));
                else if (NSTR_CH1('2') && NSTR_CH2('.'))
                        return (MSG_ORIG(MSG_SCN_SDATA2));
                else if (NSTR_CH1('b') && NSTR_CH2('.'))
                        return (MSG_ORIG(MSG_SCN_SBSS));
                else if (NSTR_CH1('b') && NSTR_CH2('2') && NSTR_CH3('.'))
                        return (MSG_ORIG(MSG_SCN_SBSS2));
                break;
        case 't':
                if (NSTR_CH1('.'))
                        return (MSG_ORIG(MSG_SCN_TEXT));
                else if (NSTR_CH1('b') && NSTR_CH2('.'))
                        return (MSG_ORIG(MSG_SCN_TBSS));
                else if (NSTR_CH1('d') && NSTR_CH2('.'))
                        return (MSG_ORIG(MSG_SCN_TDATA));
                break;
        case 'w':
                if (NSTR_CH1('i') && NSTR_CH2('.'))
                        return (MSG_ORIG(MSG_SCN_DEBUG_INFO));
                break;
        default:
                break;
        }

        /*
         * No special name match found.
         */
        return (ostr);
}
#undef  NSTR_CH1
#undef  NSTR_CH2
#undef  NSTR_CH3


/*
 * Initialize a path info buffer for use with ld_place_section().
 *
 * entry:
 *      ofl - Output descriptor
 *      ifl - Descriptor for input file, or NULL if there is none.
 *      info - Address of buffer to be initialized.
 *
 * exit:
 *      If this is an input file, and if the entrance criteria list
 *      contains at least one criteria that has a non-empty file string
 *      match list (ec_files), then the block pointed at by info is
 *      initialized, and info is returned.
 *
 *      If there is no input file, and/or no entrance criteria containing
 *      a non-empty ec_files list, then NULL is returned. This is not
 *      an error --- the NULL is simply an optimization, understood by
 *      ld_place_path(), that allows it to skip unnecessary work.
 */
Place_path_info *
ld_place_path_info_init(Ofl_desc *ofl, Ifl_desc *ifl, Place_path_info *info)
{
        /*
         * Return NULL if there is no input file (internally generated section)
         * or if the entrance criteria list does not contain any items that will
         * need to be compared to the path (all the ec_files lists are empty).
         */
        if ((ifl == NULL) || !(ofl->ofl_flags & FLG_OF_EC_FILES))
                return (NULL);

        info->ppi_path = ifl->ifl_name;
        info->ppi_path_len = strlen(info->ppi_path);
        info->ppi_isar = (ifl->ifl_flags & FLG_IF_EXTRACT) != 0;

        /*
         * The basename is the final segment of the path, equivalent to
         * the path itself if there are no '/' delimiters.
         */
        info->ppi_bname = strrchr(info->ppi_path, '/');
        if (info->ppi_bname == NULL)
                info->ppi_bname = info->ppi_path;
        else
                info->ppi_bname++;      /* Skip leading '/' */
        info->ppi_bname_len =
            info->ppi_path_len - (info->ppi_bname - info->ppi_path);

        /*
         * For an archive, the object name is the member name, which is
         * enclosed in () at the end of the name string. Otherwise, it is
         * the same as the basename.
         */
        if (info->ppi_isar) {
                info->ppi_oname = strrchr(info->ppi_bname, '(');
                /* There must be an archive member suffix delimited by parens */
                assert((info->ppi_bname[info->ppi_bname_len - 1] == ')') &&
                    (info->ppi_oname != NULL));
                info->ppi_oname++;      /* skip leading '(' */
                info->ppi_oname_len = info->ppi_bname_len -
                    (info->ppi_oname - info->ppi_bname + 1);
        } else {
                info->ppi_oname = info->ppi_bname;
                info->ppi_oname_len = info->ppi_bname_len;
        }

        return (info);
}

/*
 * Compare an input section path to the file comparison list the given
 * entrance criteria.
 *
 * entry:
 *      path_info - A non-NULL Place_path_info block for the file
 *              containing the input section, initialized by
 *              ld_place_path_info_init()
 *      enp - Entrance criteria with a non-empty ec_files list of file
 *              comparisons to be carried out.
 *
 * exit:
 *      Return TRUE if a match is seen, and FALSE otherwise.
 */
static Boolean
eval_ec_files(Place_path_info *path_info, Ent_desc *enp)
{
        Aliste          idx;
        Ent_desc_file   *edfp;
        size_t          cmp_len;
        const char      *cmp_str;

        for (ALIST_TRAVERSE(enp->ec_files, idx, edfp)) {
                Word    type = edfp->edf_flags & TYP_ECF_MASK;

                /*
                 * Determine the starting character, and # of characters,
                 * from the file path to compare against this entrance criteria
                 * file string.
                 */
                if (type == TYP_ECF_OBJNAME) {
                        cmp_str = path_info->ppi_oname;
                        cmp_len = path_info->ppi_oname_len;
                } else {
                        int ar_stat_diff = path_info->ppi_isar !=
                            ((edfp->edf_flags & FLG_ECF_ARMEMBER) != 0);

                        /*
                         * If the entrance criteria specifies an archive member
                         * and the file does not, then there can be no match.
                         */

                        if (ar_stat_diff && !path_info->ppi_isar)
                                continue;

                        if (type == TYP_ECF_PATH) {
                                cmp_str = path_info->ppi_path;
                                cmp_len = path_info->ppi_path_len;
                        } else {        /* TYP_ECF_BASENAME */
                                cmp_str = path_info->ppi_bname;
                                cmp_len = path_info->ppi_bname_len;
                        }

                        /*
                         * If the entrance criteria does not specify an archive
                         * member and the file does, then a match just requires
                         * the paths (without the archive member) to match.
                         * Reduce the length to not include the ar member or
                         * the '(' that precedes it.
                         */
                        if (ar_stat_diff && path_info->ppi_isar)
                                cmp_len = path_info->ppi_oname - cmp_str - 1;
                }

                /*
                 * Compare the resulting string to the one from the
                 * entrance criteria.
                 */
                if ((cmp_len == edfp->edf_name_len) &&
                    (strncmp(edfp->edf_name, cmp_str, cmp_len) == 0))
                        return (TRUE);
        }

        return (FALSE);
}

/*
 * Replace the section header for the given input section with a new section
 * header of the specified type. All values in the replacement header other
 * than the type retain their previous values.
 *
 * entry:
 *      isp - Input section to replace
 *      sh_type - New section type to apply
 *
 * exit:
 *      Returns the pointer to the new section header on success, and
 *      NULL for failure.
 */
static Shdr *
isp_convert_type(Is_desc *isp, Word sh_type)
{
        Shdr    *shdr;

        if ((shdr = libld_malloc(sizeof (Shdr))) == NULL)
                return (NULL);
        *shdr = *isp->is_shdr;
        isp->is_shdr = shdr;
        shdr->sh_type = sh_type;
        return (shdr);
}

/*
 * Issue a fatal warning for the given .eh_frame section, which
 * cannot be merged with the existing .eh_frame output section.
 */
static void
eh_frame_muldef(Ofl_desc *ofl, Is_desc *isp)
{
        Sg_desc *sgp;
        Is_desc *isp1;
        Os_desc *osp;
        Aliste  idx1, idx2, idx3;

        /*
         * Locate the .eh_frame output section, and use the first section
         * assigned to it in the error message. The user can then compare
         * the two sections to determine what attribute prevented the merge.
         */
        for (APLIST_TRAVERSE(ofl->ofl_segs, idx1, sgp)) {
                for (APLIST_TRAVERSE(sgp->sg_osdescs, idx2, osp)) {
                        if ((osp->os_flags & FLG_OS_EHFRAME) == 0)
                                continue;

                        for (idx3 = 0; idx3 < OS_ISD_NUM; idx3++) {
                                APlist *lst = osp->os_isdescs[idx3];

                                if (aplist_nitems(lst) == 0)
                                        continue;

                                isp1 = lst->apl_data[0];
                                ld_eprintf(ofl, ERR_FATAL,
                                    MSG_INTL(MSG_UPD_MULEHFRAME),
                                    isp1->is_file->ifl_name,
                                    EC_WORD(isp1->is_scnndx), isp1->is_name,
                                    isp->is_file->ifl_name,
                                    EC_WORD(isp->is_scnndx), isp->is_name);
                                return;
                        }
                }
        }
}

/*
 * Place a section into the appropriate segment and output section.
 *
 * entry:
 *      ofl - File descriptor
 *      isp - Input section descriptor of section to be placed.
 *      path_info - NULL, or pointer to Place_path_info buffer initialized
 *              by ld_place_path_info_init() for the file associated to isp,
 *              for use in processing entrance criteria with non-empty
 *              file matching string list (ec_files)
 *      ident - Section identifier, used to order sections relative to
 *              others within the output segment.
 *      alt_os_name - If non-NULL, the name of the output section to place
 *              isp into. If NULL, input sections go to an output section
 *              with the same name as the input section.
 */
Os_desc *
ld_place_section(Ofl_desc *ofl, Is_desc *isp, Place_path_info *path_info,
    int ident, const char *alt_os_name)
{
        Ent_desc        *enp;
        Sg_desc         *sgp;
        Os_desc         *osp;
        Aliste          idx1, iidx;
        int             os_ndx;
        Shdr            *shdr = isp->is_shdr;
        Xword           shflagmask, shflags = shdr->sh_flags;
        Ifl_desc        *ifl = isp->is_file;
        char            *oname, *sname;
        uint_t          onamehash;
        Boolean         is_ehframe = (isp->is_flags & FLG_IS_EHFRAME) != 0;

        /*
         * Define any sections that must be thought of as referenced.  These
         * sections may not be referenced externally in a manner ld(1) can
         * discover, but they must be retained (ie. not removed by -zignore).
         */
        static const Msg RefSecs[] = {
                MSG_SCN_INIT,           /* MSG_ORIG(MSG_SCN_INIT) */
                MSG_SCN_FINI,           /* MSG_ORIG(MSG_SCN_FINI) */
                MSG_SCN_EX_RANGES,      /* MSG_ORIG(MSG_SCN_EX_RANGES) */
                MSG_SCN_EX_SHARED,      /* MSG_ORIG(MSG_SCN_EX_SHARED) */
                MSG_SCN_CTORS,          /* MSG_ORIG(MSG_SCN_CTORS) */
                MSG_SCN_DTORS,          /* MSG_ORIG(MSG_SCN_DTORS) */
                MSG_SCN_EHFRAME,        /* MSG_ORIG(MSG_SCN_EHFRAME) */
                MSG_SCN_EHFRAME_HDR,    /* MSG_ORIG(MSG_SCN_EHFRAME_HDR) */
                MSG_SCN_JCR,            /* MSG_ORIG(MSG_SCN_JCR) */
                0
        };

        DBG_CALL(Dbg_sec_in(ofl->ofl_lml, isp));

        /*
         * If this section identifies group members, or this section indicates
         * that it is a member of a group, determine whether the section is
         * still required.
         */
        if ((shflags & SHF_GROUP) || (shdr->sh_type == SHT_GROUP)) {
                Group_desc      *gdesc;

                if ((gdesc = ld_get_group(ofl, isp)) != NULL) {
                        DBG_CALL(Dbg_sec_group(ofl->ofl_lml, isp, gdesc));

                        /*
                         * If this group has been replaced by another group,
                         * then this section needs to be discarded.
                         */
                        if (gdesc->gd_oisc) {
                                isp->is_flags |= FLG_IS_DISCARD;

                                /*
                                 * Since we're discarding the section, we
                                 * can skip assigning it to an output section.
                                 * The exception is that if the user
                                 * specifies -z relaxreloc, then
                                 * we need to assign the output section so
                                 * that the sloppy relocation logic will have
                                 * the information necessary to do its work.
                                 */
                                if (!(ofl->ofl_flags1 & FLG_OF1_RLXREL))
                                        return (NULL);
                        }
                }

                /*
                 * SHT_GROUP sections can only be included into relocatable
                 * objects.
                 */
                if (shdr->sh_type == SHT_GROUP) {
                        if ((ofl->ofl_flags & FLG_OF_RELOBJ) == 0) {
                                isp->is_flags |= FLG_IS_DISCARD;
                                return (NULL);
                        }
                }
        }

        /*
         * Always assign SHF_TLS sections to the DATA segment (and then the
         * PT_TLS embedded inside of there).
         */
        if (shflags & SHF_TLS)
                shflags |= SHF_WRITE;

        /*
         * Traverse the entrance criteria list searching for a segment that
         * matches the input section we have.  If an entrance criterion is set
         * then there must be an exact match.  If we complete the loop without
         * finding a segment, then sgp will be NULL.
         */
        sgp = NULL;
        for (APLIST_TRAVERSE(ofl->ofl_ents, idx1, enp)) {

                /* Disabled segments are not available for assignment */
                if (enp->ec_segment->sg_flags & FLG_SG_DISABLED)
                        continue;

                /*
                 * If an entrance criteria doesn't have any of its fields
                 * set, it will match any section it is tested against.
                 * We set the FLG_EC_CATCHALL flag on these, primarily because
                 * it helps readers of our debug output to understand what
                 * the criteria means --- otherwise the user would just see
                 * that every field is 0, but might not understand the
                 * significance of that.
                 *
                 * Given that we set this flag, we can use it here as an
                 * optimization to short circuit all of the tests in this
                 * loop. Note however, that if we did not do this, the end
                 * result would be the same --- the empty criteria will sail
                 * past the following tests and reach the end of the loop.
                 */
                if (enp->ec_flags & FLG_EC_CATCHALL) {
                        sgp = enp->ec_segment;
                        break;
                }

                if (enp->ec_type && (enp->ec_type != shdr->sh_type))
                        continue;
                if (enp->ec_attrmask &&
                    /* LINTED */
                    (enp->ec_attrmask & enp->ec_attrbits) !=
                    (enp->ec_attrmask & shflags))
                        continue;
                if (enp->ec_is_name &&
                    (strcmp(enp->ec_is_name, isp->is_name) != 0))
                        continue;

                if ((alist_nitems(enp->ec_files) > 0) &&
                    ((path_info == NULL) || !eval_ec_files(path_info, enp)))
                        continue;

                /* All entrance criteria tests passed */
                sgp = enp->ec_segment;
                break;
        }

        /*
         * The final entrance criteria record is a FLG_EC_CATCHALL that points
         * at the final predefined segment "extra", and this final segment is
         * tagged FLG_SG_NODISABLE. Therefore, the above loop must always find
         * a segment.
         */
        assert(sgp != NULL);

        /*
         * Transfer the input section sorting key from the entrance criteria
         * to the input section. A non-zero value means that the section
         * will be sorted on this key amoung the other sections that have a
         * non-zero key. These sorted sections are collectively placed at the
         * head of the output section.
         *
         * If the sort key is 0, the section is placed after the sorted
         * sections in the order they are encountered.
         */
        isp->is_ordndx = enp->ec_ordndx;

        /* Remember that this entrance criteria has placed a section */
        enp->ec_flags |= FLG_EC_USED;

        /*
         * If our caller has supplied an alternative name for the output
         * section, then we defer to their request. Otherwise, the default
         * is to use the same name as that of the input section being placed.
         *
         * The COMDAT, SHT_GROUP and GNU name translations that follow have
         * the potential to alter this initial name.
         */
        oname = (char *)((alt_os_name == NULL) ? isp->is_name : alt_os_name);

        /*
         * Solaris section names may follow the convention:
         *
         *      section-name%symbol-name
         *
         * This convention has been used to order the layout of sections within
         * segments for objects built with the compilers -xF option.  However,
         * the final object should not contain individual section headers for
         * all such input sections, instead the symbol name is stripped from the
         * name to establish the final output section name.
         *
         * This convention has also been followed for COMDAT and sections
         * identified though SHT_GROUP data.
         *
         * Strip out the % from the section name for:
         *      - Non-relocatable objects
         *      - Relocatable objects if input section sorting is
         *        in force for the segment in question.
         */
        if (((ofl->ofl_flags & FLG_OF_RELOBJ) == 0) ||
            (sgp->sg_flags & FLG_SG_IS_ORDER)) {
                if ((sname = strchr(isp->is_name, '%')) != NULL) {
                        size_t  size = sname - isp->is_name;

                        if ((oname = libld_malloc(size + 1)) == NULL)
                                return ((Os_desc *)S_ERROR);
                        (void) strncpy(oname, isp->is_name, size);
                        oname[size] = '\0';
                        DBG_CALL(Dbg_sec_redirected(ofl->ofl_lml, isp, oname));
                }
        }

        /*
         * GNU section names may follow the convention:
         *
         *      .gnu.linkonce.*
         *
         * The .gnu.linkonce is a section naming convention that indicates a
         * COMDAT requirement.  Determine whether this section follows the GNU
         * pattern, and if so, determine whether this section should be
         * discarded or retained.  The comparison of is_name[1] with 'g'
         * is an optimization to skip using strncmp() too much. This is safe,
         * because we know the name is not NULL, and therefore must have
         * at least one character plus a NULL termination.
         */
        if (((ofl->ofl_flags & FLG_OF_RELOBJ) == 0) &&
            (isp->is_name == oname) && (isp->is_name[1] == 'g') &&
            (strncmp(MSG_ORIG(MSG_SCN_GNU_LINKONCE), isp->is_name,
            MSG_SCN_GNU_LINKONCE_SIZE) == 0)) {
                if ((oname =
                    (char *)gnu_linkonce_sec(isp->is_name)) != isp->is_name) {
                        DBG_CALL(Dbg_sec_redirected(ofl->ofl_lml, isp, oname));
                }

                /*
                 * Explicitly identify this section type as COMDAT.  Also,
                 * enable relaxed relocation processing, as this is typically
                 * a requirement with .gnu.linkonce sections.
                 */
                isp->is_flags |= FLG_IS_COMDAT;
                if ((ofl->ofl_flags1 & FLG_OF1_NRLXREL) == 0)
                        ofl->ofl_flags1 |= FLG_OF1_RLXREL;
                DBG_CALL(Dbg_sec_gnu_comdat(ofl->ofl_lml, isp, TRUE,
                    (ofl->ofl_flags1 & FLG_OF1_RLXREL) != 0));
        }

        /*
         * GNU section names may also follow the convention:
         *
         *      section-name.symbol-name
         *
         * This convention is used when defining SHT_GROUP sections of type
         * COMDAT.  Thus, any group processing will have discovered any group
         * sections, and this identification can be triggered by a pattern
         * match section names.
         */
        if (((ofl->ofl_flags & FLG_OF_RELOBJ) == 0) &&
            (isp->is_name == oname) && (isp->is_flags & FLG_IS_COMDAT) &&
            ((sname = gnu_comdat_sym(ifl, isp)) != NULL)) {
                size_t  size = sname - isp->is_name;

                if ((oname = libld_malloc(size + 1)) == NULL)
                        return ((Os_desc *)S_ERROR);
                (void) strncpy(oname, isp->is_name, size);
                oname[size] = '\0';
                DBG_CALL(Dbg_sec_redirected(ofl->ofl_lml, isp, oname));

                /*
                 * Enable relaxed relocation processing, as this is
                 * typically a requirement with GNU COMDAT sections.
                 */
                if ((ofl->ofl_flags1 & FLG_OF1_NRLXREL) == 0) {
                        ofl->ofl_flags1 |= FLG_OF1_RLXREL;
                        DBG_CALL(Dbg_sec_gnu_comdat(ofl->ofl_lml, isp,
                            FALSE, TRUE));
                }
        }

        /*
         * Assign a hash value now that the output section name has been
         * finalized.
         */
        onamehash = sgs_str_hash(oname);

        /*
         * Determine if output section ordering is turned on. If so, return
         * the appropriate ordering index for the section. This information
         * is derived from the Sg_desc->sg_os_order list that was built
         * up from the Mapfile.
         *
         * A value of 0 for os_ndx means that the section is not sorted
         * (i.e. is not found in the sg_os_order). The items in sg_os_order
         * are in the desired sort order, so adding 1 to their alist index
         * gives a suitable index for sorting.
         */
        os_ndx = 0;
        if (alist_nitems(sgp->sg_os_order) > 0) {
                Sec_order       *scop;

                for (ALIST_TRAVERSE(sgp->sg_os_order, idx1, scop)) {
                        if (strcmp(scop->sco_secname, oname) == 0) {
                                scop->sco_flags |= FLG_SGO_USED;
                                os_ndx = idx1 + 1;
                                break;
                        }
                }
        }

        /*
         * Mask of section header flags to ignore when matching sections. We
         * are more strict with relocatable objects, ignoring only the order
         * flags, and keeping sections apart if they differ otherwise. This
         * follows the policy that sections in a relative object should only
         * be merged if their flags are the same, and avoids destroying
         * information prematurely. For final products however, we ignore all
         * flags that do not prevent a merge.
         */
        shflagmask =
            (ofl->ofl_flags & FLG_OF_RELOBJ) ? ALL_SHF_ORDER : ALL_SHF_IGNORE;

        /*
         * Traverse the input section list for the output section we have been
         * assigned. If we find a matching section simply add this new section.
         */
        iidx = 0;
        for (APLIST_TRAVERSE(sgp->sg_osdescs, idx1, osp)) {
                Shdr    *os_shdr = osp->os_shdr;

                /*
                 * An input section matches an output section if:
                 * -    The ident values match
                 * -    The names match
                 * -    Not a GROUP section
                 * -    Not a DTrace dof section
                 * -    Section types match
                 * -    Matching section flags, after screening out the
                 *      shflagmask flags.
                 *
                 * Section types are considered to match if any one of
                 * the following are true:
                 * -    The type codes are the same
                 * -    Both are .eh_frame sections (regardless of type code)
                 * -    The input section is COMDAT, and the output section
                 *      is SHT_PROGBITS.
                 */
                if ((ident == osp->os_identndx) &&
                    (ident != ld_targ.t_id.id_rel) &&
                    (onamehash == osp->os_namehash) &&
                    (shdr->sh_type != SHT_GROUP) &&
                    (shdr->sh_type != SHT_SUNW_dof) &&
                    ((shdr->sh_type == os_shdr->sh_type) ||
                    (is_ehframe && (osp->os_flags & FLG_OS_EHFRAME)) ||
                    ((shdr->sh_type == SHT_SUNW_COMDAT) &&
                    (os_shdr->sh_type == SHT_PROGBITS))) &&
                    ((shflags & ~shflagmask) ==
                    (os_shdr->sh_flags & ~shflagmask)) &&
                    (strcmp(oname, osp->os_name) == 0)) {
                        uintptr_t       err;

                        /*
                         * Process any COMDAT section, keeping the first and
                         * discarding all others.
                         */
                        if ((isp->is_flags & FLG_IS_COMDAT) &&
                            ((err = add_comdat(ofl, osp, isp)) != 1))
                                return ((Os_desc *)err);

                        /*
                         * Set alignment
                         */
                        set_addralign(ofl, osp, isp);

                        /*
                         * If this section is a non-empty TLS section indicate
                         * that a PT_TLS program header is required.
                         */
                        if ((shflags & SHF_TLS) && shdr->sh_size &&
                            ((ofl->ofl_flags & FLG_OF_RELOBJ) == 0))
                                ofl->ofl_flags |= FLG_OF_TLSPHDR;

                        /*
                         * Insert the input section descriptor on the proper
                         * output section descriptor list.
                         *
                         * If this segment requires input section ordering,
                         * honor any mapfile specified ordering for otherwise
                         * unordered sections by setting the mapfile_sort
                         * argument of os_attach_isp() to True.
                         */

                        if (os_attach_isp(ofl, osp, isp,
                            (sgp->sg_flags & FLG_SG_IS_ORDER) != 0) == 0)
                                return ((Os_desc *)S_ERROR);

                        /*
                         * If this input section and file is associated to an
                         * artificially referenced output section, make sure
                         * they are marked as referenced also. This ensures
                         * that this input section and file isn't eliminated
                         * when -zignore is in effect.
                         *
                         * See -zignore comments when creating a new output
                         * section below.
                         */
                        if (((ifl &&
                            (ifl->ifl_flags & FLG_IF_IGNORE)) || DBG_ENABLED) &&
                            (osp->os_flags & FLG_OS_SECTREF)) {
                                isp->is_flags |= FLG_IS_SECTREF;
                                if (ifl)
                                        ifl->ifl_flags |= FLG_IF_FILEREF;
                        }

                        DBG_CALL(Dbg_sec_added(ofl->ofl_lml, osp, sgp));
                        return (osp);
                }

                /*
                 * Do we need to worry about section ordering?
                 */
                if (os_ndx) {
                        if (osp->os_ordndx) {
                                if (os_ndx < osp->os_ordndx)
                                        /* insert section here. */
                                        break;
                                else {
                                        iidx = idx1 + 1;
                                        continue;
                                }
                        } else {
                                /* insert section here. */
                                break;
                        }
                } else if (osp->os_ordndx) {
                        iidx = idx1 + 1;
                        continue;
                }

                /*
                 * If the new sections identifier is less than that of the
                 * present input section we need to insert the new section
                 * at this point.
                 */
                if (ident < osp->os_identndx)
                        break;

                iidx = idx1 + 1;
        }

        /*
         * We are adding a new output section.  Update the section header
         * count and associated string size.
         *
         * If the input section triggering this output section has been marked
         * for discard, and if no other non-discarded input section comes along
         * to join it, then we will over count. We cannot know if this will
         * happen or not until all input is seen. Set FLG_OF_AJDOSCNT to
         * trigger a final count readjustment.
         */
        if (isp->is_flags & FLG_IS_DISCARD)
                ofl->ofl_flags |= FLG_OF_ADJOSCNT;
        ofl->ofl_shdrcnt++;
        if (st_insert(ofl->ofl_shdrsttab, oname) == -1)
                return ((Os_desc *)S_ERROR);

        /*
         * Create a new output section descriptor.
         */
        if ((osp = libld_calloc(sizeof (Os_desc), 1)) == NULL)
                return ((Os_desc *)S_ERROR);
        if ((osp->os_shdr = libld_calloc(sizeof (Shdr), 1)) == NULL)
                return ((Os_desc *)S_ERROR);

        /*
         * Convert COMDAT section to PROGBITS as this the first section of the
         * output section.  Save any COMDAT section for later processing, as
         * additional COMDAT sections that match this section need discarding.
         */
        if ((shdr->sh_type == SHT_SUNW_COMDAT) &&
            ((shdr = isp_convert_type(isp, SHT_PROGBITS)) == NULL))
                return ((Os_desc *)S_ERROR);
        if ((isp->is_flags & FLG_IS_COMDAT) &&
            (add_comdat(ofl, osp, isp) == S_ERROR))
                return ((Os_desc *)S_ERROR);

        if (is_ehframe) {
                /*
                 * Executable or sharable objects can have at most a single
                 * .eh_frame section. Detect attempts to create more than
                 * one. This occurs if the input sections have incompatible
                 * attributes.
                 */
                if ((ofl->ofl_flags & FLG_OF_EHFRAME) &&
                    !(ofl->ofl_flags & FLG_OF_RELOBJ)) {
                        eh_frame_muldef(ofl, isp);
                        return ((Os_desc *)S_ERROR);
                }
                ofl->ofl_flags |= FLG_OF_EHFRAME;

                /*
                 * For .eh_frame sections, we always set the type to be the
                 * type specified by the ABI.  This allows .eh_frame sections
                 * of type SHT_PROGBITS to be correctly merged with .eh_frame
                 * sections of the ABI-defined type (e.g. SHT_AMD64_UNWIND),
                 * with the output being of the ABI-defined type.
                 */
                osp->os_shdr->sh_type = ld_targ.t_m.m_sht_unwind;
        } else {
                osp->os_shdr->sh_type = shdr->sh_type;
        }

        osp->os_shdr->sh_flags = shdr->sh_flags;
        osp->os_shdr->sh_entsize = shdr->sh_entsize;
        osp->os_name = oname;
        osp->os_namehash = onamehash;
        osp->os_ordndx = os_ndx;
        osp->os_sgdesc = sgp;
        if (is_ehframe)
                osp->os_flags |= FLG_OS_EHFRAME;

        if (ifl && (shdr->sh_type == SHT_PROGBITS)) {
                /*
                 * Try to preserve the intended meaning of sh_link/sh_info.
                 * See the translate_link() in update.c.
                 */
                osp->os_shdr->sh_link = shdr->sh_link;
                if (shdr->sh_flags & SHF_INFO_LINK)
                        osp->os_shdr->sh_info = shdr->sh_info;
        }

        /*
         * When -zignore is in effect, user supplied sections and files that are
         * not referenced from other sections, are eliminated from the object
         * being produced.  Some sections, although unreferenced, are special,
         * and must not be eliminated.  Determine if this new output section is
         * one of those special sections, and if so mark it artificially as
         * referenced.  Any input section and file associated to this output
         * section is also be marked as referenced, and thus won't be eliminated
         * from the final output.
         */
        if (ifl && ((ofl->ofl_flags1 & FLG_OF1_IGNPRC) || DBG_ENABLED)) {
                const Msg       *refsec;

                for (refsec = RefSecs; *refsec; refsec++) {
                        if (strcmp(osp->os_name, MSG_ORIG(*refsec)) == 0) {
                                osp->os_flags |= FLG_OS_SECTREF;

                                if ((ifl->ifl_flags & FLG_IF_IGNORE) ||
                                    DBG_ENABLED) {
                                        isp->is_flags |= FLG_IS_SECTREF;
                                        ifl->ifl_flags |= FLG_IF_FILEREF;
                                }
                                break;
                        }
                }
        }

        /*
         * Sections of type SHT_GROUP are added to the ofl->ofl_osgroups list,
         * so that they can be updated as a group later.
         */
        if ((shdr->sh_type == SHT_GROUP) &&
            ((isp->is_flags & FLG_IS_DISCARD) == 0) &&
            (aplist_append(&ofl->ofl_osgroups, osp,
            AL_CNT_OFL_OSGROUPS) == NULL))
                return ((Os_desc *)S_ERROR);

        /*
         * If this section is a non-empty TLS section indicate that a PT_TLS
         * program header is required.
         */
        if ((shflags & SHF_TLS) && shdr->sh_size &&
            ((ofl->ofl_flags & FLG_OF_RELOBJ) == 0))
                ofl->ofl_flags |= FLG_OF_TLSPHDR;

        /*
         * If a non-allocatable section is going to be put into a loadable
         * segment then turn on the allocate bit for this section and warn the
         * user that we have done so.  This could only happen through the use
         * of a mapfile.
         */
        if ((sgp->sg_phdr.p_type == PT_LOAD) &&
            ((osp->os_shdr->sh_flags & SHF_ALLOC) == 0)) {
                ld_eprintf(ofl, ERR_WARNING, MSG_INTL(MSG_SCN_NONALLOC),
                    ofl->ofl_name, osp->os_name, sgp->sg_name);
                osp->os_shdr->sh_flags |= SHF_ALLOC;
        }

        /*
         * Retain this sections identifier for future comparisons when placing
         * a section (after all sections have been processed this variable will
         * be used to hold the sections symbol index as we don't need to retain
         * the identifier any more).
         */
        osp->os_identndx = ident;

        /*
         * Set alignment.
         */
        set_addralign(ofl, osp, isp);

        if (os_attach_isp(ofl, osp, isp, 0) == 0)
                return ((Os_desc *)S_ERROR);

        DBG_CALL(Dbg_sec_created(ofl->ofl_lml, osp, sgp));

        /*
         * Insert the new section at the offset given by iidx.  If no position
         * for it was identified above, this will be index 0, causing the new
         * section to be prepended to the beginning of the section list.
         * Otherwise, it is the index following the section that was identified.
         */
        if (aplist_insert(&sgp->sg_osdescs, osp, AL_CNT_SG_OSDESC,
            iidx) == NULL)
                return ((Os_desc *)S_ERROR);
        return (osp);
}