// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * elf.c - ELF access library
 *
 * Adapted from kpatch (https://github.com/dynup/kpatch):
 * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>
#include <linux/align.h>
#include <linux/kernel.h>
#include <linux/interval_tree_generic.h>
#include <linux/log2.h>
#include <objtool/builtin.h>
#include <objtool/elf.h>
#include <objtool/warn.h>

static inline u32 str_hash(const char *str)
{
        return jhash(str, strlen(str), 0);
}

#define __elf_table(name)       (elf->name##_hash)
#define __elf_bits(name)        (elf->name##_bits)

#define __elf_table_entry(name, key) \
        __elf_table(name)[hash_min(key, __elf_bits(name))]

#define elf_hash_add(name, node, key)                                   \
({                                                                      \
        struct elf_hash_node *__node = node;                            \
        __node->next = __elf_table_entry(name, key);                    \
        __elf_table_entry(name, key) = __node;                          \
})

static inline void __elf_hash_del(struct elf_hash_node *node,
                                  struct elf_hash_node **head)
{
        struct elf_hash_node *cur, *prev;

        if (node == *head) {
                *head = node->next;
                return;
        }

        for (prev = NULL, cur = *head; cur; prev = cur, cur = cur->next) {
                if (cur == node) {
                        prev->next = cur->next;
                        break;
                }
        }
}

#define elf_hash_del(name, node, key) \
        __elf_hash_del(node, &__elf_table_entry(name, key))

#define elf_list_entry(ptr, type, member)                               \
({                                                                      \
        typeof(ptr) __ptr = (ptr);                                      \
        __ptr ? container_of(__ptr, type, member) : NULL;               \
})

#define elf_hash_for_each_possible(name, obj, member, key)              \
        for (obj = elf_list_entry(__elf_table_entry(name, key), typeof(*obj), member); \
             obj;                                                       \
             obj = elf_list_entry(obj->member.next, typeof(*(obj)), member))

#define elf_alloc_hash(name, size)                                      \
({                                                                      \
        __elf_bits(name) = max(10, ilog2(size));                        \
        __elf_table(name) = mmap(NULL, sizeof(struct elf_hash_node *) << __elf_bits(name), \
                                 PROT_READ|PROT_WRITE,                  \
                                 MAP_PRIVATE|MAP_ANON, -1, 0);          \
        if (__elf_table(name) == (void *)-1L) {                         \
                ERROR_GLIBC("mmap fail " #name);                        \
                __elf_table(name) = NULL;                               \
        }                                                               \
        __elf_table(name);                                              \
})

static inline unsigned long __sym_start(struct symbol *s)
{
        return s->offset;
}

static inline unsigned long __sym_last(struct symbol *s)
{
        return s->offset + (s->len ? s->len - 1 : 0);
}

INTERVAL_TREE_DEFINE(struct symbol, node, unsigned long, __subtree_last,
                     __sym_start, __sym_last, static inline __maybe_unused,
                     __sym)

#define __sym_for_each(_iter, _tree, _start, _end)                      \
        for (_iter = __sym_iter_first((_tree), (_start), (_end));       \
             _iter; _iter = __sym_iter_next(_iter, (_start), (_end)))

struct symbol_hole {
        unsigned long key;
        const struct symbol *sym;
};

/*
 * Find the last symbol before @offset.
 */
static int symbol_hole_by_offset(const void *key, const struct rb_node *node)
{
        const struct symbol *s = rb_entry(node, struct symbol, node);
        struct symbol_hole *sh = (void *)key;

        if (sh->key < s->offset)
                return -1;

        if (sh->key >= s->offset + s->len) {
                sh->sym = s;
                return 1;
        }

        return 0;
}

struct section *find_section_by_name(const struct elf *elf, const char *name)
{
        struct section *sec;

        elf_hash_for_each_possible(section_name, sec, name_hash, str_hash(name)) {
                if (!strcmp(sec->name, name))
                        return sec;
        }

        return NULL;
}

static struct section *find_section_by_index(struct elf *elf,
                                             unsigned int idx)
{
        struct section *sec;

        elf_hash_for_each_possible(section, sec, hash, idx) {
                if (sec->idx == idx)
                        return sec;
        }

        return NULL;
}

static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
{
        struct symbol *sym;

        elf_hash_for_each_possible(symbol, sym, hash, idx) {
                if (sym->idx == idx)
                        return sym;
        }

        return NULL;
}

struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
{
        struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
        struct symbol *sym;

        __sym_for_each(sym, tree, offset, offset) {
                if (sym->offset == offset && !is_sec_sym(sym))
                        return sym->alias;
        }

        return NULL;
}

struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
{
        struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
        struct symbol *func;

        __sym_for_each(func, tree, offset, offset) {
                if (func->offset == offset && is_func_sym(func))
                        return func->alias;
        }

        return NULL;
}

struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
{
        struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
        struct symbol *sym = NULL, *tmp;

        __sym_for_each(tmp, tree, offset, offset) {
                if (tmp->len) {
                        if (!sym) {
                                sym = tmp;
                                continue;
                        }

                        if (sym->offset != tmp->offset || sym->len != tmp->len) {
                                /*
                                 * In the rare case of overlapping symbols,
                                 * pick the smaller one.
                                 *
                                 * TODO: outlaw overlapping symbols
                                 */
                                if (tmp->len < sym->len)
                                        sym = tmp;
                        }
                }
        }

        return sym ? sym->alias : NULL;
}

/*
 * Returns size of hole starting at @offset.
 */
int find_symbol_hole_containing(const struct section *sec, unsigned long offset)
{
        struct symbol_hole hole = {
                .key = offset,
                .sym = NULL,
        };
        struct rb_node *n;
        struct symbol *s;

        /*
         * Find the rightmost symbol for which @offset is after it.
         */
        n = rb_find(&hole, &sec->symbol_tree.rb_root, symbol_hole_by_offset);

        /* found a symbol that contains @offset */
        if (n)
                return 0; /* not a hole */

        /*
         * @offset >= sym->offset + sym->len, find symbol after it.
         * When hole.sym is empty, use the first node to compute the hole.
         * If there is no symbol in the section, the first node will be NULL,
         * in which case, -1 is returned to skip the whole section.
         */
        if (hole.sym)
                n = rb_next(&hole.sym->node);
        else
                n = rb_first_cached(&sec->symbol_tree);

        if (!n)
                return -1; /* until end of address space */

        /* hole until start of next symbol */
        s = rb_entry(n, struct symbol, node);
        return s->offset - offset;
}

struct symbol *find_func_containing(struct section *sec, unsigned long offset)
{
        struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
        struct symbol *func;

        __sym_for_each(func, tree, offset, offset) {
                if (is_func_sym(func))
                        return func->alias;
        }

        return NULL;
}

struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)
{
        struct symbol *sym;

        elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
                if (!strcmp(sym->name, name))
                        return sym;
        }

        return NULL;
}

/* Find local symbol with matching STT_FILE */
static struct symbol *find_local_symbol_by_file_and_name(const struct elf *elf,
                                                         struct symbol *file,
                                                         const char *name)
{
        struct symbol *sym;

        elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
                if (sym->bind == STB_LOCAL && sym->file == file &&
                    !strcmp(sym->name, name)) {
                        return sym;
                }
        }

        return NULL;
}

struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *name)
{
        struct symbol *sym;

        elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
                if (!strcmp(sym->name, name) && !is_local_sym(sym))
                        return sym;
        }

        return NULL;
}

struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
                                     unsigned long offset, unsigned int len)
{
        struct reloc *reloc, *r = NULL;
        struct section *rsec;
        unsigned long o;

        rsec = sec->rsec;
        if (!rsec)
                return NULL;

        for_offset_range(o, offset, offset + len) {
                elf_hash_for_each_possible(reloc, reloc, hash,
                                           sec_offset_hash(rsec, o)) {
                        if (reloc->sec != rsec)
                                continue;

                        if (reloc_offset(reloc) >= offset &&
                            reloc_offset(reloc) < offset + len) {
                                if (!r || reloc_offset(reloc) < reloc_offset(r))
                                        r = reloc;
                        }
                }
                if (r)
                        return r;
        }

        return NULL;
}

struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset)
{
        return find_reloc_by_dest_range(elf, sec, offset, 1);
}

static bool is_dwarf_section(struct section *sec)
{
        return !strncmp(sec->name, ".debug_", 7);
}

static int read_sections(struct elf *elf)
{
        Elf_Scn *s = NULL;
        struct section *sec;
        size_t shstrndx, sections_nr;
        int i;

        if (elf_getshdrnum(elf->elf, &sections_nr)) {
                ERROR_ELF("elf_getshdrnum");
                return -1;
        }

        if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
                ERROR_ELF("elf_getshdrstrndx");
                return -1;
        }

        if (!elf_alloc_hash(section, sections_nr) ||
            !elf_alloc_hash(section_name, sections_nr))
                return -1;

        elf->section_data = calloc(sections_nr, sizeof(*sec));
        if (!elf->section_data) {
                ERROR_GLIBC("calloc");
                return -1;
        }
        for (i = 0; i < sections_nr; i++) {
                sec = &elf->section_data[i];

                INIT_LIST_HEAD(&sec->symbol_list);

                s = elf_getscn(elf->elf, i);
                if (!s) {
                        ERROR_ELF("elf_getscn");
                        return -1;
                }

                sec->idx = elf_ndxscn(s);

                if (!gelf_getshdr(s, &sec->sh)) {
                        ERROR_ELF("gelf_getshdr");
                        return -1;
                }

                sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
                if (!sec->name) {
                        ERROR_ELF("elf_strptr");
                        return -1;
                }

                if (sec_size(sec) != 0 && !is_dwarf_section(sec)) {
                        sec->data = elf_getdata(s, NULL);
                        if (!sec->data) {
                                ERROR_ELF("elf_getdata");
                                return -1;
                        }
                        if (sec->data->d_off != 0 ||
                            sec->data->d_size != sec_size(sec)) {
                                ERROR("unexpected data attributes for %s", sec->name);
                                return -1;
                        }
                }

                list_add_tail(&sec->list, &elf->sections);
                elf_hash_add(section, &sec->hash, sec->idx);
                elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));

                if (is_reloc_sec(sec))
                        elf->num_relocs += sec_num_entries(sec);
        }

        if (opts.stats) {
                printf("nr_sections: %lu\n", (unsigned long)sections_nr);
                printf("section_bits: %d\n", elf->section_bits);
        }

        /* sanity check, one more call to elf_nextscn() should return NULL */
        if (elf_nextscn(elf->elf, s)) {
                ERROR("section entry mismatch");
                return -1;
        }

        return 0;
}

static const char *demangle_name(struct symbol *sym)
{
        char *str;

        if (!is_local_sym(sym))
                return sym->name;

        if (!is_func_sym(sym) && !is_object_sym(sym))
                return sym->name;

        if (!strstarts(sym->name, "__UNIQUE_ID_") && !strchr(sym->name, '.'))
                return sym->name;

        str = strdup(sym->name);
        if (!str) {
                ERROR_GLIBC("strdup");
                return NULL;
        }

        for (int i = strlen(str) - 1; i >= 0; i--) {
                char c = str[i];

                if (!isdigit(c) && c != '.') {
                        str[i + 1] = '\0';
                        break;
                }
        }

        return str;
}

static int elf_add_symbol(struct elf *elf, struct symbol *sym)
{
        struct list_head *entry;
        struct rb_node *pnode;
        struct symbol *iter;

        INIT_LIST_HEAD(&sym->pv_target);
        sym->alias = sym;

        sym->type = GELF_ST_TYPE(sym->sym.st_info);
        sym->bind = GELF_ST_BIND(sym->sym.st_info);

        if (is_file_sym(sym))
                elf->num_files++;

        sym->offset = sym->sym.st_value;
        sym->len = sym->sym.st_size;

        __sym_for_each(iter, &sym->sec->symbol_tree, sym->offset, sym->offset) {
                if (!is_undef_sym(iter) && iter->offset == sym->offset &&
                    iter->type == sym->type && iter->len == sym->len)
                        iter->alias = sym;
        }

        __sym_insert(sym, &sym->sec->symbol_tree);
        pnode = rb_prev(&sym->node);
        if (pnode)
                entry = &rb_entry(pnode, struct symbol, node)->list;
        else
                entry = &sym->sec->symbol_list;
        list_add(&sym->list, entry);

        list_add_tail(&sym->global_list, &elf->symbols);
        elf_hash_add(symbol, &sym->hash, sym->idx);
        elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));

        if (is_func_sym(sym) &&
            (strstarts(sym->name, "__pfx_") ||
             strstarts(sym->name, "__cfi_") ||
             strstarts(sym->name, "__pi___pfx_") ||
             strstarts(sym->name, "__pi___cfi_")))
                sym->prefix = 1;

        if (strstarts(sym->name, ".klp.sym"))
                sym->klp = 1;

        if (!sym->klp && !is_sec_sym(sym) && strstr(sym->name, ".cold")) {
                sym->cold = 1;

                /*
                 * Clang doesn't mark cold subfunctions as STT_FUNC, which
                 * breaks several objtool assumptions.  Fake it.
                 */
                sym->type = STT_FUNC;
        }

        sym->pfunc = sym->cfunc = sym;

        sym->demangled_name = demangle_name(sym);
        if (!sym->demangled_name)
                return -1;

        return 0;
}

static int read_symbols(struct elf *elf)
{
        struct section *symtab, *symtab_shndx, *sec;
        struct symbol *sym, *pfunc, *file = NULL;
        int symbols_nr, i;
        char *coldstr;
        Elf_Data *shndx_data = NULL;
        Elf32_Word shndx;

        symtab = find_section_by_name(elf, ".symtab");
        if (symtab) {
                symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
                if (symtab_shndx)
                        shndx_data = symtab_shndx->data;

                symbols_nr = sec_num_entries(symtab);
        } else {
                /*
                 * A missing symbol table is actually possible if it's an empty
                 * .o file. This can happen for thunk_64.o. Make sure to at
                 * least allocate the symbol hash tables so we can do symbol
                 * lookups without crashing.
                 */
                symbols_nr = 0;
        }

        if (!elf_alloc_hash(symbol, symbols_nr) ||
            !elf_alloc_hash(symbol_name, symbols_nr))
                return -1;

        elf->symbol_data = calloc(symbols_nr, sizeof(*sym));
        if (!elf->symbol_data) {
                ERROR_GLIBC("calloc");
                return -1;
        }

        INIT_LIST_HEAD(&elf->symbols);

        for (i = 0; i < symbols_nr; i++) {
                sym = &elf->symbol_data[i];

                sym->idx = i;

                if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
                                      &shndx)) {
                        ERROR_ELF("gelf_getsymshndx");
                        return -1;
                }

                sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
                                       sym->sym.st_name);
                if (!sym->name) {
                        ERROR_ELF("elf_strptr");
                        return -1;
                }

                if ((sym->sym.st_shndx > SHN_UNDEF &&
                     sym->sym.st_shndx < SHN_LORESERVE) ||
                    (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) {
                        if (sym->sym.st_shndx != SHN_XINDEX)
                                shndx = sym->sym.st_shndx;

                        sym->sec = find_section_by_index(elf, shndx);
                        if (!sym->sec) {
                                ERROR("couldn't find section for symbol %s", sym->name);
                                return -1;
                        }
                        if (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) {
                                sym->name = sym->sec->name;
                                sym->sec->sym = sym;
                        }
                } else
                        sym->sec = find_section_by_index(elf, 0);

                if (elf_add_symbol(elf, sym))
                        return -1;

                if (sym->type == STT_FILE)
                        file = sym;
                else if (sym->bind == STB_LOCAL)
                        sym->file = file;
        }

        if (opts.stats) {
                printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
                printf("symbol_bits: %d\n", elf->symbol_bits);
        }

        /* Create parent/child links for any cold subfunctions */
        list_for_each_entry(sec, &elf->sections, list) {
                sec_for_each_sym(sec, sym) {
                        char *pname;
                        size_t pnamelen;

                        if (!sym->cold)
                                continue;

                        coldstr = strstr(sym->name, ".cold");
                        if (!coldstr) {
                                ERROR("%s(): cold subfunction without \".cold\"?", sym->name);
                                return -1;
                        }

                        pnamelen = coldstr - sym->name;
                        pname = strndup(sym->name, pnamelen);
                        if (!pname) {
                                ERROR("%s(): failed to allocate memory", sym->name);
                                return -1;
                        }

                        pfunc = find_local_symbol_by_file_and_name(elf, sym->file, pname);
                        if (!pfunc)
                                pfunc = find_global_symbol_by_name(elf, pname);
                        free(pname);

                        if (!pfunc) {
                                ERROR("%s(): can't find parent function", sym->name);
                                return -1;
                        }

                        sym->pfunc = pfunc->alias;
                        pfunc->cfunc = sym;
                        pfunc->alias->cfunc = sym;

                        /*
                         * Unfortunately, -fnoreorder-functions puts the child
                         * inside the parent.  Remove the overlap so we can
                         * have sane assumptions.
                         *
                         * Note that pfunc->len now no longer matches
                         * pfunc->sym.st_size.
                         */
                        if (sym->sec == pfunc->sec &&
                            sym->offset >= pfunc->offset &&
                            sym->offset + sym->len == pfunc->offset + pfunc->len) {
                                pfunc->len -= sym->len;
                        }
                }
        }

        return 0;
}

static int mark_group_syms(struct elf *elf)
{
        struct section *symtab, *sec;
        struct symbol *sym;

        symtab = find_section_by_name(elf, ".symtab");
        if (!symtab) {
                ERROR("no .symtab");
                return -1;
        }

        for_each_sec(elf, sec) {
                if (sec->sh.sh_type == SHT_GROUP &&
                    sec->sh.sh_link == symtab->idx) {
                        sym = find_symbol_by_index(elf, sec->sh.sh_info);
                        if (!sym) {
                                ERROR("%s: can't find SHT_GROUP signature symbol",
                                      sec->name);
                                return -1;
                        }

                        sym->group_sec = sec;
                }
        }

        return 0;
}

/*
 * @sym's idx has changed.  Update the relocs which reference it.
 */
static int elf_update_sym_relocs(struct elf *elf, struct symbol *sym)
{
        struct reloc *reloc;

        for (reloc = sym->relocs; reloc; reloc = sym_next_reloc(reloc))
                set_reloc_sym(elf, reloc, reloc->sym->idx);

        return 0;
}

/*
 * The libelf API is terrible; gelf_update_sym*() takes a data block relative
 * index value, *NOT* the symbol index. As such, iterate the data blocks and
 * adjust index until it fits.
 *
 * If no data block is found, allow adding a new data block provided the index
 * is only one past the end.
 */
static int elf_update_symbol(struct elf *elf, struct section *symtab,
                             struct section *symtab_shndx, struct symbol *sym)
{
        Elf32_Word shndx;
        Elf_Data *symtab_data = NULL, *shndx_data = NULL;
        Elf64_Xword entsize = symtab->sh.sh_entsize;
        int max_idx, idx = sym->idx;
        Elf_Scn *s, *t = NULL;
        bool is_special_shndx = sym->sym.st_shndx >= SHN_LORESERVE &&
                                sym->sym.st_shndx != SHN_XINDEX;

        shndx = is_special_shndx ? sym->sym.st_shndx : sym->sec->idx;

        s = elf_getscn(elf->elf, symtab->idx);
        if (!s) {
                ERROR_ELF("elf_getscn");
                return -1;
        }

        if (symtab_shndx) {
                t = elf_getscn(elf->elf, symtab_shndx->idx);
                if (!t) {
                        ERROR_ELF("elf_getscn");
                        return -1;
                }
        }

        for (;;) {
                /* get next data descriptor for the relevant sections */
                symtab_data = elf_getdata(s, symtab_data);
                if (t)
                        shndx_data = elf_getdata(t, shndx_data);

                /* end-of-list */
                if (!symtab_data) {
                        /*
                         * Over-allocate to avoid O(n^2) symbol creation
                         * behaviour.  The down side is that libelf doesn't
                         * like this; see elf_truncate_section() for the fixup.
                         */
                        int num = max(1U, sym->idx/3);
                        void *buf;

                        if (idx) {
                                /* we don't do holes in symbol tables */
                                ERROR("index out of range");
                                return -1;
                        }

                        /* if @idx == 0, it's the next contiguous entry, create it */
                        symtab_data = elf_newdata(s);
                        if (t)
                                shndx_data = elf_newdata(t);

                        buf = calloc(num, entsize);
                        if (!buf) {
                                ERROR_GLIBC("calloc");
                                return -1;
                        }

                        symtab_data->d_buf = buf;
                        symtab_data->d_size = num * entsize;
                        symtab_data->d_align = 1;
                        symtab_data->d_type = ELF_T_SYM;

                        mark_sec_changed(elf, symtab, true);
                        symtab->truncate = true;

                        if (t) {
                                buf = calloc(num, sizeof(Elf32_Word));
                                if (!buf) {
                                        ERROR_GLIBC("calloc");
                                        return -1;
                                }

                                shndx_data->d_buf = buf;
                                shndx_data->d_size = num * sizeof(Elf32_Word);
                                shndx_data->d_align = sizeof(Elf32_Word);
                                shndx_data->d_type = ELF_T_WORD;

                                mark_sec_changed(elf, symtab_shndx, true);
                                symtab_shndx->truncate = true;
                        }

                        break;
                }

                /* empty blocks should not happen */
                if (!symtab_data->d_size) {
                        ERROR("zero size data");
                        return -1;
                }

                /* is this the right block? */
                max_idx = symtab_data->d_size / entsize;
                if (idx < max_idx)
                        break;

                /* adjust index and try again */
                idx -= max_idx;
        }

        /* something went side-ways */
        if (idx < 0) {
                ERROR("negative index");
                return -1;
        }

        /* setup extended section index magic and write the symbol */
        if (shndx < SHN_LORESERVE || is_special_shndx) {
                sym->sym.st_shndx = shndx;
                if (!shndx_data)
                        shndx = 0;
        } else {
                sym->sym.st_shndx = SHN_XINDEX;
                if (!shndx_data) {
                        ERROR("no .symtab_shndx");
                        return -1;
                }
        }

        if (!gelf_update_symshndx(symtab_data, shndx_data, idx, &sym->sym, shndx)) {
                ERROR_ELF("gelf_update_symshndx");
                return -1;
        }

        return 0;
}

struct symbol *elf_create_symbol(struct elf *elf, const char *name,
                                 struct section *sec, unsigned int bind,
                                 unsigned int type, unsigned long offset,
                                 size_t size)
{
        struct section *symtab, *symtab_shndx;
        Elf32_Word first_non_local, new_idx;
        struct symbol *old, *sym;

        sym = calloc(1, sizeof(*sym));
        if (!sym) {
                ERROR_GLIBC("calloc");
                return NULL;
        }

        sym->name = strdup(name);
        if (!sym->name) {
                ERROR_GLIBC("strdup");
                return NULL;
        }

        if (type != STT_SECTION) {
                sym->sym.st_name = elf_add_string(elf, NULL, sym->name);
                if (sym->sym.st_name == -1)
                        return NULL;
        }

        if (sec) {
                sym->sec = sec;
        } else {
                sym->sec = find_section_by_index(elf, 0);
                if (!sym->sec) {
                        ERROR("no NULL section");
                        return NULL;
                }
        }

        sym->sym.st_info  = GELF_ST_INFO(bind, type);
        sym->sym.st_value = offset;
        sym->sym.st_size  = size;

        symtab = find_section_by_name(elf, ".symtab");
        if (!symtab) {
                ERROR("no .symtab");
                return NULL;
        }

        symtab_shndx = find_section_by_name(elf, ".symtab_shndx");

        new_idx = sec_num_entries(symtab);

        if (bind != STB_LOCAL)
                goto non_local;

        /*
         * Move the first global symbol, as per sh_info, into a new, higher
         * symbol index. This frees up a spot for a new local symbol.
         */
        first_non_local = symtab->sh.sh_info;
        old = find_symbol_by_index(elf, first_non_local);
        if (old) {

                elf_hash_del(symbol, &old->hash, old->idx);
                elf_hash_add(symbol, &old->hash, new_idx);
                old->idx = new_idx;

                if (elf_update_symbol(elf, symtab, symtab_shndx, old)) {
                        ERROR("elf_update_symbol move");
                        return NULL;
                }

                if (elf_update_sym_relocs(elf, old))
                        return NULL;

                if (old->group_sec) {
                        old->group_sec->sh.sh_info = new_idx;
                        mark_sec_changed(elf, old->group_sec, true);
                }

                new_idx = first_non_local;
        }

        /*
         * Either way, we will add a LOCAL symbol.
         */
        symtab->sh.sh_info += 1;

non_local:
        sym->idx = new_idx;
        if (sym->idx && elf_update_symbol(elf, symtab, symtab_shndx, sym))
                return NULL;

        symtab->sh.sh_size += symtab->sh.sh_entsize;
        mark_sec_changed(elf, symtab, true);

        if (symtab_shndx) {
                symtab_shndx->sh.sh_size += sizeof(Elf32_Word);
                mark_sec_changed(elf, symtab_shndx, true);
        }

        if (elf_add_symbol(elf, sym))
                return NULL;

        return sym;
}

struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec)
{
        struct symbol *sym = calloc(1, sizeof(*sym));

        sym = elf_create_symbol(elf, sec->name, sec, STB_LOCAL, STT_SECTION, 0, 0);
        if (!sym)
                return NULL;

        sec->sym = sym;

        return sym;
}

struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
                             unsigned int reloc_idx, unsigned long offset,
                             struct symbol *sym, s64 addend, unsigned int type)
{
        struct reloc *reloc, empty = { 0 };

        if (reloc_idx >= sec_num_entries(rsec)) {
                ERROR("%s: bad reloc_idx %u for %s with %d relocs",
                      __func__, reloc_idx, rsec->name, sec_num_entries(rsec));
                return NULL;
        }

        reloc = &rsec->relocs[reloc_idx];

        if (memcmp(reloc, &empty, sizeof(empty))) {
                ERROR("%s: %s: reloc %d already initialized!",
                      __func__, rsec->name, reloc_idx);
                return NULL;
        }

        reloc->sec = rsec;
        reloc->sym = sym;

        set_reloc_offset(elf, reloc, offset);
        set_reloc_sym(elf, reloc, sym->idx);
        set_reloc_type(elf, reloc, type);
        set_reloc_addend(elf, reloc, addend);

        elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
        set_sym_next_reloc(reloc, sym->relocs);
        sym->relocs = reloc;

        return reloc;
}

struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
                                      unsigned long offset,
                                      unsigned int reloc_idx,
                                      struct section *insn_sec,
                                      unsigned long insn_off)
{
        struct symbol *sym = insn_sec->sym;
        s64 addend = insn_off;

        if (!is_text_sec(insn_sec)) {
                ERROR("bad call to %s() for data symbol %s", __func__, sym->name);
                return NULL;
        }

        if (!sym) {
                /*
                 * Due to how weak functions work, we must use section based
                 * relocations. Symbol based relocations would result in the
                 * weak and non-weak function annotations being overlaid on the
                 * non-weak function after linking.
                 */
                sym = elf_create_section_symbol(elf, insn_sec);
                if (!sym)
                        return NULL;
        }

        return elf_init_reloc(elf, sec->rsec, reloc_idx, offset, sym, addend,
                              elf_text_rela_type(elf));
}

struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,
                                      unsigned long offset,
                                      unsigned int reloc_idx,
                                      struct symbol *sym,
                                      s64 addend)
{
        if (is_text_sec(sec)) {
                ERROR("bad call to %s() for text symbol %s", __func__, sym->name);
                return NULL;
        }

        return elf_init_reloc(elf, sec->rsec, reloc_idx, offset, sym, addend,
                              elf_data_rela_type(elf));
}

static int read_relocs(struct elf *elf)
{
        unsigned long nr_reloc, max_reloc = 0;
        struct section *rsec;
        struct reloc *reloc;
        unsigned int symndx;
        struct symbol *sym;
        int i;

        if (!elf_alloc_hash(reloc, elf->num_relocs))
                return -1;

        list_for_each_entry(rsec, &elf->sections, list) {
                if (!is_reloc_sec(rsec))
                        continue;

                rsec->base = find_section_by_index(elf, rsec->sh.sh_info);
                if (!rsec->base) {
                        ERROR("can't find base section for reloc section %s", rsec->name);
                        return -1;
                }

                rsec->base->rsec = rsec;

                /* nr_alloc_relocs=0: libelf owns d_buf */
                rsec->nr_alloc_relocs = 0;

                rsec->relocs = calloc(sec_num_entries(rsec), sizeof(*reloc));
                if (!rsec->relocs) {
                        ERROR_GLIBC("calloc");
                        return -1;
                }

                nr_reloc = 0;
                for (i = 0; i < sec_num_entries(rsec); i++) {
                        reloc = &rsec->relocs[i];

                        reloc->sec = rsec;
                        symndx = reloc_sym(reloc);
                        reloc->sym = sym = find_symbol_by_index(elf, symndx);
                        if (!reloc->sym) {
                                ERROR("can't find reloc entry symbol %d for %s", symndx, rsec->name);
                                return -1;
                        }

                        elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
                        set_sym_next_reloc(reloc, sym->relocs);
                        sym->relocs = reloc;

                        nr_reloc++;
                }
                max_reloc = max(max_reloc, nr_reloc);
        }

        if (opts.stats) {
                printf("max_reloc: %lu\n", max_reloc);
                printf("num_relocs: %lu\n", elf->num_relocs);
                printf("reloc_bits: %d\n", elf->reloc_bits);
        }

        return 0;
}

struct elf *elf_open_read(const char *name, int flags)
{
        struct elf *elf;
        Elf_Cmd cmd;

        elf_version(EV_CURRENT);

        elf = malloc(sizeof(*elf));
        if (!elf) {
                ERROR_GLIBC("malloc");
                return NULL;
        }
        memset(elf, 0, sizeof(*elf));

        INIT_LIST_HEAD(&elf->sections);

        elf->fd = open(name, flags);
        if (elf->fd == -1) {
                fprintf(stderr, "objtool: Can't open '%s': %s\n",
                        name, strerror(errno));
                goto err;
        }

        elf->name = strdup(name);
        if (!elf->name) {
                ERROR_GLIBC("strdup");
                return NULL;
        }

        if ((flags & O_ACCMODE) == O_RDONLY)
                cmd = ELF_C_READ_MMAP;
        else if ((flags & O_ACCMODE) == O_RDWR)
                cmd = ELF_C_RDWR;
        else /* O_WRONLY */
                cmd = ELF_C_WRITE;

        elf->elf = elf_begin(elf->fd, cmd, NULL);
        if (!elf->elf) {
                ERROR_ELF("elf_begin");
                goto err;
        }

        if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
                ERROR_ELF("gelf_getehdr");
                goto err;
        }

        if (read_sections(elf))
                goto err;

        if (read_symbols(elf))
                goto err;

        if (mark_group_syms(elf))
                goto err;

        if (read_relocs(elf))
                goto err;

        return elf;

err:
        elf_close(elf);
        return NULL;
}

struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name)
{
        struct section *null, *symtab, *strtab, *shstrtab;
        char *tmp_name;
        struct symbol *sym;
        struct elf *elf;

        elf_version(EV_CURRENT);

        elf = calloc(1, sizeof(*elf));
        if (!elf) {
                ERROR_GLIBC("calloc");
                return NULL;
        }

        INIT_LIST_HEAD(&elf->sections);

        tmp_name = malloc(strlen(name) + 8);
        if (!tmp_name) {
                ERROR_GLIBC("malloc");
                return NULL;
        }

        sprintf(tmp_name, "%s.XXXXXX", name);

        elf->fd = mkstemp(tmp_name);
        if (elf->fd == -1) {
                ERROR_GLIBC("can't create tmp file");
                exit(1);
        }

        elf->tmp_name = tmp_name;

        elf->name = strdup(name);
        if (!elf->name) {
                ERROR_GLIBC("strdup");
                return NULL;
        }

        elf->elf = elf_begin(elf->fd, ELF_C_WRITE, NULL);
        if (!elf->elf) {
                ERROR_ELF("elf_begin");
                return NULL;
        }

        if (!gelf_newehdr(elf->elf, ELFCLASS64)) {
                ERROR_ELF("gelf_newehdr");
                return NULL;
        }

        memcpy(&elf->ehdr, ehdr, sizeof(elf->ehdr));

        if (!gelf_update_ehdr(elf->elf, &elf->ehdr)) {
                ERROR_ELF("gelf_update_ehdr");
                return NULL;
        }

        INIT_LIST_HEAD(&elf->symbols);

        if (!elf_alloc_hash(section,            1000) ||
            !elf_alloc_hash(section_name,       1000) ||
            !elf_alloc_hash(symbol,             10000) ||
            !elf_alloc_hash(symbol_name,        10000) ||
            !elf_alloc_hash(reloc,              100000))
                return NULL;

        null            = elf_create_section(elf, NULL, 0, 0, SHT_NULL, 0, 0);
        shstrtab        = elf_create_section(elf, NULL, 0, 0, SHT_STRTAB, 1, 0);
        strtab          = elf_create_section(elf, NULL, 0, 0, SHT_STRTAB, 1, 0);

        if (!null || !shstrtab || !strtab)
                return NULL;

        null->name      = "";
        shstrtab->name  = ".shstrtab";
        strtab->name    = ".strtab";

        null->sh.sh_name        = elf_add_string(elf, shstrtab, null->name);
        shstrtab->sh.sh_name    = elf_add_string(elf, shstrtab, shstrtab->name);
        strtab->sh.sh_name      = elf_add_string(elf, shstrtab, strtab->name);

        if (null->sh.sh_name == -1 || shstrtab->sh.sh_name == -1 || strtab->sh.sh_name == -1)
                return NULL;

        elf_hash_add(section_name, &null->name_hash,            str_hash(null->name));
        elf_hash_add(section_name, &strtab->name_hash,          str_hash(strtab->name));
        elf_hash_add(section_name, &shstrtab->name_hash,        str_hash(shstrtab->name));

        if (elf_add_string(elf, strtab, "") == -1)
                return NULL;

        symtab = elf_create_section(elf, ".symtab", 0x18, 0x18, SHT_SYMTAB, 0x8, 0);
        if (!symtab)
                return NULL;

        symtab->sh.sh_link = strtab->idx;
        symtab->sh.sh_info = 1;

        elf->ehdr.e_shstrndx = shstrtab->idx;
        if (!gelf_update_ehdr(elf->elf, &elf->ehdr)) {
                ERROR_ELF("gelf_update_ehdr");
                return NULL;
        }

        sym = calloc(1, sizeof(*sym));
        if (!sym) {
                ERROR_GLIBC("calloc");
                return NULL;
        }

        sym->name = "";
        sym->sec = null;
        elf_add_symbol(elf, sym);

        return elf;
}

unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str)
{
        unsigned int offset;

        if (!strtab)
                strtab = find_section_by_name(elf, ".strtab");
        if (!strtab) {
                ERROR("can't find .strtab section");
                return -1;
        }

        if (!strtab->sh.sh_addralign) {
                ERROR("'%s': invalid sh_addralign", strtab->name);
                return -1;
        }

        offset = ALIGN(strtab->sh.sh_size, strtab->sh.sh_addralign);

        if (!elf_add_data(elf, strtab, str, strlen(str) + 1))
                return -1;

        return offset;
}

void *elf_add_data(struct elf *elf, struct section *sec, const void *data, size_t size)
{
        unsigned long offset;
        Elf_Scn *s;

        if (!sec->sh.sh_addralign) {
                ERROR("'%s': invalid sh_addralign", sec->name);
                return NULL;
        }

        s = elf_getscn(elf->elf, sec->idx);
        if (!s) {
                ERROR_ELF("elf_getscn");
                return NULL;
        }

        sec->data = elf_newdata(s);
        if (!sec->data) {
                ERROR_ELF("elf_newdata");
                return NULL;
        }

        sec->data->d_buf = calloc(1, size);
        if (!sec->data->d_buf) {
                ERROR_GLIBC("calloc");
                return NULL;
        }

        if (data)
                memcpy(sec->data->d_buf, data, size);

        sec->data->d_size = size;
        sec->data->d_align = sec->sh.sh_addralign;

        offset = ALIGN(sec->sh.sh_size, sec->sh.sh_addralign);
        sec->sh.sh_size = offset + size;

        mark_sec_changed(elf, sec, true);

        return sec->data->d_buf;
}

struct section *elf_create_section(struct elf *elf, const char *name,
                                   size_t size, size_t entsize,
                                   unsigned int type, unsigned int align,
                                   unsigned int flags)
{
        struct section *sec, *shstrtab;
        Elf_Scn *s;

        if (name && find_section_by_name(elf, name)) {
                ERROR("section '%s' already exists", name);
                return NULL;
        }

        sec = calloc(1, sizeof(*sec));
        if (!sec) {
                ERROR_GLIBC("calloc");
                return NULL;
        }

        INIT_LIST_HEAD(&sec->symbol_list);

        /* don't actually create the section, just the data structures */
        if (type == SHT_NULL)
                goto add;

        s = elf_newscn(elf->elf);
        if (!s) {
                ERROR_ELF("elf_newscn");
                return NULL;
        }

        sec->idx = elf_ndxscn(s);

        if (size) {
                sec->data = elf_newdata(s);
                if (!sec->data) {
                        ERROR_ELF("elf_newdata");
                        return NULL;
                }

                sec->data->d_size = size;
                sec->data->d_align = 1;

                sec->data->d_buf = calloc(1, size);
                if (!sec->data->d_buf) {
                        ERROR_GLIBC("calloc");
                        return NULL;
                }
        }

        if (!gelf_getshdr(s, &sec->sh)) {
                ERROR_ELF("gelf_getshdr");
                return NULL;
        }

        sec->sh.sh_size = size;
        sec->sh.sh_entsize = entsize;
        sec->sh.sh_type = type;
        sec->sh.sh_addralign = align;
        sec->sh.sh_flags = flags;

        if (name) {
                sec->name = strdup(name);
                if (!sec->name) {
                        ERROR("strdup");
                        return NULL;
                }

                /* Add section name to .shstrtab (or .strtab for Clang) */
                shstrtab = find_section_by_name(elf, ".shstrtab");
                if (!shstrtab) {
                        shstrtab = find_section_by_name(elf, ".strtab");
                        if (!shstrtab) {
                                ERROR("can't find .shstrtab or .strtab");
                                return NULL;
                        }
                }
                sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
                if (sec->sh.sh_name == -1)
                        return NULL;

                elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
        }

add:
        list_add_tail(&sec->list, &elf->sections);
        elf_hash_add(section, &sec->hash, sec->idx);

        mark_sec_changed(elf, sec, true);

        return sec;
}

static int elf_alloc_reloc(struct elf *elf, struct section *rsec)
{
        struct reloc *old_relocs, *old_relocs_end, *new_relocs;
        unsigned int nr_relocs_old = sec_num_entries(rsec);
        unsigned int nr_relocs_new = nr_relocs_old + 1;
        unsigned long nr_alloc;
        struct symbol *sym;

        if (!rsec->data) {
                rsec->data = elf_newdata(elf_getscn(elf->elf, rsec->idx));
                if (!rsec->data) {
                        ERROR_ELF("elf_newdata");
                        return -1;
                }

                rsec->data->d_align = 1;
                rsec->data->d_type = ELF_T_RELA;
                rsec->data->d_buf = NULL;
        }

        rsec->data->d_size = nr_relocs_new * elf_rela_size(elf);
        rsec->sh.sh_size   = rsec->data->d_size;

        nr_alloc = max(64UL, roundup_pow_of_two(nr_relocs_new));
        if (nr_alloc <= rsec->nr_alloc_relocs)
                return 0;

        if (rsec->data->d_buf && !rsec->nr_alloc_relocs) {
                void *orig_buf = rsec->data->d_buf;

                /*
                 * The original d_buf is owned by libelf so it can't be
                 * realloced.
                 */
                rsec->data->d_buf = malloc(nr_alloc * elf_rela_size(elf));
                if (!rsec->data->d_buf) {
                        ERROR_GLIBC("malloc");
                        return -1;
                }
                memcpy(rsec->data->d_buf, orig_buf,
                       nr_relocs_old * elf_rela_size(elf));
        } else {
                rsec->data->d_buf = realloc(rsec->data->d_buf,
                                            nr_alloc * elf_rela_size(elf));
                if (!rsec->data->d_buf) {
                        ERROR_GLIBC("realloc");
                        return -1;
                }
        }

        rsec->nr_alloc_relocs = nr_alloc;

        old_relocs = rsec->relocs;
        new_relocs = calloc(nr_alloc, sizeof(struct reloc));
        if (!new_relocs) {
                ERROR_GLIBC("calloc");
                return -1;
        }

        if (!old_relocs)
                goto done;

        /*
         * The struct reloc's address has changed.  Update all the symbols and
         * relocs which reference it.
         */

        old_relocs_end = &old_relocs[nr_relocs_old];
        for_each_sym(elf, sym) {
                struct reloc *reloc;

                reloc = sym->relocs;
                if (!reloc)
                        continue;

                if (reloc >= old_relocs && reloc < old_relocs_end)
                        sym->relocs = &new_relocs[reloc - old_relocs];

                while (1) {
                        struct reloc *next_reloc = sym_next_reloc(reloc);

                        if (!next_reloc)
                                break;

                        if (next_reloc >= old_relocs && next_reloc < old_relocs_end)
                                set_sym_next_reloc(reloc, &new_relocs[next_reloc - old_relocs]);

                        reloc = next_reloc;
                }
        }

        memcpy(new_relocs, old_relocs, nr_relocs_old * sizeof(struct reloc));

        for (int i = 0; i < nr_relocs_old; i++) {
                struct reloc *old = &old_relocs[i];
                struct reloc *new = &new_relocs[i];
                u32 key = reloc_hash(old);

                elf_hash_del(reloc, &old->hash, key);
                elf_hash_add(reloc, &new->hash, key);
        }

        free(old_relocs);
done:
        rsec->relocs = new_relocs;
        return 0;
}

struct section *elf_create_rela_section(struct elf *elf, struct section *sec,
                                        unsigned int nr_relocs)
{
        struct section *rsec;
        char *rsec_name;

        rsec_name = malloc(strlen(sec->name) + strlen(".rela") + 1);
        if (!rsec_name) {
                ERROR_GLIBC("malloc");
                return NULL;
        }
        strcpy(rsec_name, ".rela");
        strcat(rsec_name, sec->name);

        rsec = elf_create_section(elf, rsec_name, nr_relocs * elf_rela_size(elf),
                                  elf_rela_size(elf), SHT_RELA, elf_addr_size(elf),
                                  SHF_INFO_LINK);
        free(rsec_name);
        if (!rsec)
                return NULL;

        if (nr_relocs) {
                rsec->data->d_type = ELF_T_RELA;

                rsec->nr_alloc_relocs = nr_relocs;
                rsec->relocs = calloc(nr_relocs, sizeof(struct reloc));
                if (!rsec->relocs) {
                        ERROR_GLIBC("calloc");
                        return NULL;
                }
        }

        rsec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
        rsec->sh.sh_info = sec->idx;

        sec->rsec = rsec;
        rsec->base = sec;

        return rsec;
}

struct reloc *elf_create_reloc(struct elf *elf, struct section *sec,
                               unsigned long offset,
                               struct symbol *sym, s64 addend,
                               unsigned int type)
{
        struct section *rsec = sec->rsec;

        if (!rsec) {
                rsec = elf_create_rela_section(elf, sec, 0);
                if (!rsec)
                        return NULL;
        }

        if (find_reloc_by_dest(elf, sec, offset)) {
                ERROR_FUNC(sec, offset, "duplicate reloc");
                return NULL;
        }

        if (elf_alloc_reloc(elf, rsec))
                return NULL;

        mark_sec_changed(elf, rsec, true);

        return elf_init_reloc(elf, rsec, sec_num_entries(rsec) - 1, offset, sym,
                              addend, type);
}

struct section *elf_create_section_pair(struct elf *elf, const char *name,
                                        size_t entsize, unsigned int nr,
                                        unsigned int nr_relocs)
{
        struct section *sec;

        sec = elf_create_section(elf, name, nr * entsize, entsize,
                                 SHT_PROGBITS, 1, SHF_ALLOC);
        if (!sec)
                return NULL;

        if (!elf_create_rela_section(elf, sec, nr_relocs))
                return NULL;

        return sec;
}

int elf_write_insn(struct elf *elf, struct section *sec,
                   unsigned long offset, unsigned int len,
                   const char *insn)
{
        Elf_Data *data = sec->data;

        if (data->d_type != ELF_T_BYTE || data->d_off) {
                ERROR("write to unexpected data for section: %s", sec->name);
                return -1;
        }

        memcpy(data->d_buf + offset, insn, len);

        mark_sec_changed(elf, sec, true);

        return 0;
}

/*
 * When Elf_Scn::sh_size is smaller than the combined Elf_Data::d_size
 * do you:
 *
 *   A) adhere to the section header and truncate the data, or
 *   B) ignore the section header and write out all the data you've got?
 *
 * Yes, libelf sucks and we need to manually truncate if we over-allocate data.
 */
static int elf_truncate_section(struct elf *elf, struct section *sec)
{
        u64 size = sec_size(sec);
        bool truncated = false;
        Elf_Data *data = NULL;
        Elf_Scn *s;

        s = elf_getscn(elf->elf, sec->idx);
        if (!s) {
                ERROR_ELF("elf_getscn");
                return -1;
        }

        for (;;) {
                /* get next data descriptor for the relevant section */
                data = elf_getdata(s, data);
                if (!data) {
                        if (size) {
                                ERROR("end of section data but non-zero size left\n");
                                return -1;
                        }
                        return 0;
                }

                if (truncated) {
                        /* when we remove symbols */
                        ERROR("truncated; but more data\n");
                        return -1;
                }

                if (!data->d_size) {
                        ERROR("zero size data");
                        return -1;
                }

                if (data->d_size > size) {
                        truncated = true;
                        data->d_size = size;
                }

                size -= data->d_size;
        }
}

int elf_write(struct elf *elf)
{
        struct section *sec;
        Elf_Scn *s;

        /* Update changed relocation sections and section headers: */
        list_for_each_entry(sec, &elf->sections, list) {
                if (sec->truncate && elf_truncate_section(elf, sec))
                        return -1;

                if (sec_changed(sec)) {
                        s = elf_getscn(elf->elf, sec->idx);
                        if (!s) {
                                ERROR_ELF("elf_getscn");
                                return -1;
                        }

                        /* Note this also flags the section dirty */
                        if (!gelf_update_shdr(s, &sec->sh)) {
                                ERROR_ELF("gelf_update_shdr");
                                return -1;
                        }

                        mark_sec_changed(elf, sec, false);
                }
        }

        /* Make sure the new section header entries get updated properly. */
        elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);

        /* Write all changes to the file. */
        if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
                ERROR_ELF("elf_update");
                return -1;
        }

        elf->changed = false;

        return 0;
}

int elf_close(struct elf *elf)
{
        if (elf->elf)
                elf_end(elf->elf);

        if (elf->fd > 0)
                close(elf->fd);

        if (elf->tmp_name && rename(elf->tmp_name, elf->name))
                return -1;

        /*
         * NOTE: All remaining allocations are leaked on purpose.  Objtool is
         * about to exit anyway.
         */
        return 0;
}