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elf-util: split out helper to parse build-id

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This commit is contained in:
Luca Boccassi 2021-11-18 00:51:41 +00:00
parent ea680f0524
commit 5564c6d802
1 changed files with 47 additions and 27 deletions
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74
src/shared/elf-util.c
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@ -245,13 +245,54 @@ static int parse_package_metadata(const char *name, JsonVariant *id_json, Elf *e
return 0;
}
/* Get the build-id out of an ELF object or a dwarf core module. */
static int parse_buildid(Dwfl_Module *mod, Elf *elf, const char *name, StackContext *c, JsonVariant **ret_id_json) {
_cleanup_(json_variant_unrefp) JsonVariant *id_json = NULL;
const unsigned char *id;
GElf_Addr id_vaddr;
ssize_t id_len;
int r;
assert(mod || elf);
assert(c);
if (mod)
id_len = dwfl_module_build_id(mod, &id, &id_vaddr);
else
id_len = dwelf_elf_gnu_build_id(elf, (const void **)&id);
if (id_len <= 0) {
/* If we don't find a build-id, note it in the journal message, and try
* anyway to find the package metadata. It's unlikely to have the latter
* without the former, but there's no hard rule. */
if (c->f)
fprintf(c->f, "Module %s without build-id.\n", name);
} else {
/* We will later parse package metadata json and pass it to our caller. Prepare the
* build-id in json format too, so that it can be appended and parsed cleanly. It
* will then be added as metadata to the journal message with the stack trace. */
r = json_build(&id_json, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("buildId", JSON_BUILD_HEX(id, id_len))));
if (r < 0)
return log_error_errno(r, "json_build on build-id failed: %m");
if (c->f) {
JsonVariant *build_id = json_variant_by_key(id_json, "buildId");
assert(build_id);
fprintf(c->f, "Module %s with build-id %s\n", name, json_variant_string(build_id));
}
}
if (ret_id_json)
*ret_id_json = TAKE_PTR(id_json);
return 0;
}
static int module_callback(Dwfl_Module *mod, void **userdata, const char *name, Dwarf_Addr start, void *arg) {
_cleanup_(json_variant_unrefp) JsonVariant *id_json = NULL;
StackContext *c = arg;
size_t n_program_headers;
GElf_Addr id_vaddr, bias;
const unsigned char *id;
int id_len, r;
GElf_Addr bias;
int r;
Elf *elf;
assert(mod);
@ -265,30 +306,9 @@ static int module_callback(Dwfl_Module *mod, void **userdata, const char *name,
* We proceed in a best-effort fashion - not all ELF objects might contain both or either.
* The build-id is easy, as libdwfl parses it during the dwfl_core_file_report() call and
* stores it separately in an internal library struct. */
id_len = dwfl_module_build_id(mod, &id, &id_vaddr);
if (id_len <= 0) {
/* If we don't find a build-id, note it in the journal message, and try
* anyway to find the package metadata. It's unlikely to have the latter
* without the former, but there's no hard rule. */
if (c->f)
fprintf(c->f, "Found module %s without build-id.\n", name);
} else {
JsonVariant *build_id;
/* We will later parse package metadata json and pass it to our caller. Prepare the
* build-id in json format too, so that it can be appended and parsed cleanly. It
* will then be added as metadata to the journal message with the stack trace. */
r = json_build(&id_json, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("buildId", JSON_BUILD_HEX(id, id_len))));
if (r < 0) {
log_error_errno(r, "json_build on build-id failed: %m");
return DWARF_CB_ABORT;
}
build_id = json_variant_by_key(id_json, "buildId");
assert_se(build_id);
if (c->f)
fprintf(c->f, "Found module %s with build-id: %s\n", name, json_variant_string(build_id));
}
r = parse_buildid(mod, NULL, name, c, &id_json);
if (r < 0)
return DWARF_CB_ABORT;
/* The .note.package metadata is more difficult. From the module, we need to get a reference
* to the ELF object first. We might be lucky and just get it from elfutils. */