mirror of https://github.com/dynup/kpatch
lookup: parse Module.symvers in lookup_open()
Have lookup_open() also parse Module.symvers and add the resulting symbols
and their objnames to the lookup table. This code was essentially
cherry-picked from Josh Poimboeuf's lookup code found here:
8cdca59c88
That patch was modified to fix a bug in obj_read() (calling elf_end()
without strdup'ing the symbol name strings, which was causing null
dereferences) and to fix up the module name after reading it from
Module.symvers (replacing '-' with '_' and stripping the path prefixes).
Also, add lookup_exported_symbol_objname(), which looks up the objname of
an exported symbol by making use of the objname information obtained from
Module.symvers.
This commit is contained in:
Jessica Yu
parent
b6a15f3dd6
commit
58de46cb9e
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@ -2246,11 +2246,11 @@ static void kpatch_build_strings_section_data(struct kpatch_elf *kelf)
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}
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struct arguments {
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char *args[4];
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char *args[5];
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int debug;
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};
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static char args_doc[] = "original.o patched.o kernel-object output.o";
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static char args_doc[] = "original.o patched.o kernel-object output.o Module.symvers";
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static struct argp_option options[] = {
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{"debug", 'd', NULL, 0, "Show debug output" },
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@ -2269,13 +2269,13 @@ static error_t parse_opt (int key, char *arg, struct argp_state *state)
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arguments->debug = 1;
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break;
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case ARGP_KEY_ARG:
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if (state->arg_num >= 4)
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if (state->arg_num >= 5)
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/* Too many arguments. */
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argp_usage (state);
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arguments->args[state->arg_num] = arg;
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break;
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case ARGP_KEY_END:
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if (state->arg_num < 4)
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if (state->arg_num < 5)
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/* Not enough arguments. */
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argp_usage (state);
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break;
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@ -2296,6 +2296,7 @@ int main(int argc, char *argv[])
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struct section *sec, *symtab;
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struct symbol *sym;
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char *hint = NULL, *objname, *pos;
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char *mod_symvers_path;
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arguments.debug = 0;
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argp_parse (&argp, argc, argv, 0, NULL, &arguments);
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@ -2306,6 +2307,8 @@ int main(int argc, char *argv[])
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childobj = basename(arguments.args[0]);
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mod_symvers_path = arguments.args[4];
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kelf_base = kpatch_elf_open(arguments.args[0]);
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kelf_patched = kpatch_elf_open(arguments.args[1]);
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@ -2378,7 +2381,7 @@ int main(int argc, char *argv[])
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ERROR("FILE symbol not found in output. Stripped?\n");
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/* create symbol lookup table */
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lookup = lookup_open(arguments.args[2]);
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lookup = lookup_open(arguments.args[2], mod_symvers_path);
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/* extract module name (destructive to arguments.modulefile) */
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objname = basename(arguments.args[2]);
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@ -557,7 +557,7 @@ for i in $FILES; do
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fi
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cd $TEMPDIR
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if [[ -e "orig/$i" ]]; then
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"$TOOLSDIR"/create-diff-object "orig/$i" "patched/$i" "$KOBJFILE" "output/$i" 2>&1 |tee -a "$LOGFILE"
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"$TOOLSDIR"/create-diff-object "orig/$i" "patched/$i" "$KOBJFILE" "output/$i" "$OBJDIR/Module.symvers" 2>&1 |tee -a "$LOGFILE"
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rc="${PIPESTATUS[0]}"
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if [[ $rc = 139 ]]; then
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warn "create-diff-object SIGSEGV"
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@ -5,6 +5,7 @@
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* the symbol table of an ELF object.
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*
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* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
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* Copyright (C) 2014 Josh Poimboeuf <jpoimboe@redhat.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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@ -24,6 +25,8 @@
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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#include <ctype.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <stdio.h>
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@ -31,29 +34,38 @@
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#include <error.h>
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#include <gelf.h>
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#include <unistd.h>
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#include <libgen.h>
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#include "lookup.h"
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#define ERROR(format, ...) \
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error(1, 0, "%s: %d: " format, __FUNCTION__, __LINE__, ##__VA_ARGS__)
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struct symbol {
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struct object_symbol {
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unsigned long value;
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unsigned long size;
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char *name;
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int type, bind, skip;
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};
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struct lookup_table {
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int fd, nr;
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Elf *elf;
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struct symbol *syms;
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struct export_symbol {
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char *name;
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char *objname;
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};
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#define for_each_symbol(ndx, iter, table) \
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for (ndx = 0, iter = table->syms; ndx < table->nr; ndx++, iter++)
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struct lookup_table {
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int obj_nr, exp_nr;
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struct object_symbol *obj_syms;
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struct export_symbol *exp_syms;
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};
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struct lookup_table *lookup_open(char *path)
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#define for_each_obj_symbol(ndx, iter, table) \
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for (ndx = 0, iter = table->obj_syms; ndx < table->obj_nr; ndx++, iter++)
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#define for_each_exp_symbol(ndx, iter, table) \
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for (ndx = 0, iter = table->exp_syms; ndx < table->exp_nr; ndx++, iter++)
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static void obj_read(struct lookup_table *table, char *path)
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{
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Elf *elf;
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int fd, i, len;
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@ -62,8 +74,7 @@ struct lookup_table *lookup_open(char *path)
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GElf_Sym sym;
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Elf_Data *data;
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char *name;
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struct lookup_table *table;
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struct symbol *mysym;
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struct object_symbol *mysym;
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size_t shstrndx;
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if ((fd = open(path, O_RDONLY, 0)) < 0)
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@ -102,18 +113,13 @@ struct lookup_table *lookup_open(char *path)
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len = sh.sh_size / sh.sh_entsize;
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table = malloc(sizeof(*table));
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if (!table)
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ERROR("malloc table");
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table->syms = malloc(len * sizeof(struct symbol));
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if (!table->syms)
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ERROR("malloc table.syms");
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memset(table->syms, 0, len * sizeof(struct symbol));
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table->nr = len;
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table->fd = fd;
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table->elf = elf;
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table->obj_syms = malloc(len * sizeof(*table->obj_syms));
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if (!table->obj_syms)
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ERROR("malloc table.obj_syms");
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memset(table->obj_syms, 0, len * sizeof(*table->obj_syms));
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table->obj_nr = len;
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for_each_symbol(i, mysym, table) {
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for_each_obj_symbol(i, mysym, table) {
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if (!gelf_getsym(data, i, &sym))
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ERROR("gelf_getsym");
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@ -130,29 +136,107 @@ struct lookup_table *lookup_open(char *path)
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mysym->size = sym.st_size;
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mysym->type = GELF_ST_TYPE(sym.st_info);
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mysym->bind = GELF_ST_BIND(sym.st_info);
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mysym->name = name;
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mysym->name = strdup(name);
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if (!mysym->name)
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ERROR("strdup");
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}
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close(fd);
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elf_end(elf);
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}
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/* Strip the path and replace '-' with '_' */
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static char *make_modname(char *modname)
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{
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char *cur;
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if (!modname)
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return NULL;
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cur = modname;
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while (*cur != '\0') {
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if (*cur == '-')
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*cur = '_';
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cur++;
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}
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return basename(modname);
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}
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static void symvers_read(struct lookup_table *table, char *path)
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{
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FILE *file;
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unsigned int crc, i = 0;
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char name[256], mod[256], export[256];
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char *objname, *symname;
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if ((file = fopen(path, "r")) < 0)
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ERROR("fopen");
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while (fscanf(file, "%x %s %s %s\n",
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&crc, name, mod, export) != EOF)
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table->exp_nr++;
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table->exp_syms = malloc(table->exp_nr * sizeof(*table->exp_syms));
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if (!table->exp_syms)
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ERROR("malloc table.exp_syms");
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memset(table->exp_syms, 0,
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table->exp_nr * sizeof(*table->exp_syms));
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rewind(file);
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while (fscanf(file, "%x %s %s %s\n",
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&crc, name, mod, export) != EOF) {
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symname = strdup(name);
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if (!symname)
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perror("strdup");
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objname = strdup(mod);
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if (!objname)
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perror("strdup");
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/* Modifies objname in-place */
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objname = make_modname(objname);
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table->exp_syms[i].name = symname;
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table->exp_syms[i].objname = objname;
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i++;
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}
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fclose(file);
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}
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struct lookup_table *lookup_open(char *obj_path, char *symvers_path)
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{
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struct lookup_table *table;
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table = malloc(sizeof(*table));
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if (!table)
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ERROR("malloc table");
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memset(table, 0, sizeof(*table));
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obj_read(table, obj_path);
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symvers_read(table, symvers_path);
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return table;
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}
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void lookup_close(struct lookup_table *table)
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{
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elf_end(table->elf);
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close(table->fd);
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free(table->obj_syms);
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free(table->exp_syms);
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free(table);
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}
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int lookup_local_symbol(struct lookup_table *table, char *name, char *hint,
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struct lookup_result *result)
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{
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struct symbol *sym, *match = NULL;
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struct object_symbol *sym, *match = NULL;
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int i;
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unsigned long pos = 0;
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char *curfile = NULL;
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memset(result, 0, sizeof(*result));
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for_each_symbol(i, sym, table) {
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for_each_obj_symbol(i, sym, table) {
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if (sym->type == STT_FILE) {
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if (!strcmp(sym->name, hint)) {
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curfile = sym->name;
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@ -192,11 +276,11 @@ int lookup_local_symbol(struct lookup_table *table, char *name, char *hint,
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int lookup_global_symbol(struct lookup_table *table, char *name,
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struct lookup_result *result)
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{
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struct symbol *sym;
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struct object_symbol *sym;
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int i;
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memset(result, 0, sizeof(*result));
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for_each_symbol(i, sym, table)
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for_each_obj_symbol(i, sym, table) {
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if (!sym->skip && (sym->bind == STB_GLOBAL || sym->bind == STB_WEAK) &&
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!strcmp(sym->name, name)) {
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result->value = sym->value;
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@ -204,25 +288,50 @@ int lookup_global_symbol(struct lookup_table *table, char *name,
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result->pos = 0; /* always 0 for global symbols */
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return 0;
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}
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}
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return 1;
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}
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int lookup_is_exported_symbol(struct lookup_table *table, char *name)
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{
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struct symbol *sym;
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struct export_symbol *sym, *match = NULL;
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int i;
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char export[255] = "__ksymtab_";
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strncat(export, name, 254);
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for_each_exp_symbol(i, sym, table) {
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if (!strcmp(sym->name, name)) {
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if (match)
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ERROR("duplicate exported symbol found for %s", name);
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match = sym;
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}
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}
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for_each_symbol(i, sym, table)
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if (!sym->skip && !strcmp(sym->name, export))
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return 1;
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return 0;
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return !!match;
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}
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/*
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* lookup_exported_symbol_objname - find the object/module an exported
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* symbol belongs to.
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*/
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char *lookup_exported_symbol_objname(struct lookup_table *table, char *name)
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{
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struct export_symbol *sym, *match = NULL;
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int i;
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for_each_exp_symbol(i, sym, table) {
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if (!strcmp(sym->name, name)) {
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if (match)
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ERROR("duplicate exported symbol found for %s", name);
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match = sym;
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}
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}
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if (match)
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return match->objname;
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return NULL;
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}
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#if 0 /* for local testing */
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static void find_this(struct lookup_table *table, char *sym, char *hint)
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{
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@ -9,12 +9,13 @@ struct lookup_result {
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unsigned long pos;
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};
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struct lookup_table *lookup_open(char *path);
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struct lookup_table *lookup_open(char *obj_path, char *symvers_path);
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void lookup_close(struct lookup_table *table);
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int lookup_local_symbol(struct lookup_table *table, char *name, char *hint,
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struct lookup_result *result);
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int lookup_global_symbol(struct lookup_table *table, char *name,
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struct lookup_result *result);
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int lookup_is_exported_symbol(struct lookup_table *table, char *name);
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char *lookup_exported_symbol_objname(struct lookup_table *table, char *name);
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#endif /* _LOOKUP_H_ */
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