Commit: 596aa077e472e89a3d8598fca14f760cc88ced1b
Parent: 550fc79ab344fe3e953d229906a08c148bb2d5f7
Author: Randy Palamar
Date: Mon, 19 May 2025 10:19:51 -0600
cleanup unaligned reads
Diffstat:
| M | elfinspect.c | | | 140 | ++++++++++++++++++++++++++++++++++++++++++------------------------------------- |
1 file changed, 74 insertions(+), 66 deletions(-)
diff --git a/elfinspect.c b/elfinspect.c
@@ -653,7 +653,7 @@ da_reserve_(Arena *a, void *data, s16 *capacity, iz needed, iz align, iz size)
}
function str8
-c_str_to_str8(u8 *c_str)
+str8_from_c_str(u8 *c_str)
{
str8 result = {.data = c_str};
if (c_str) while (*c_str) c_str++;
@@ -671,7 +671,7 @@ str8_equal(str8 a, str8 b)
}
function str8
-str8_chop(str8 a, iz length)
+str8_chop_at(str8 a, iz length)
{
str8 result = {0};
if (length < a.len) {
@@ -681,24 +681,6 @@ str8_chop(str8 a, iz length)
return result;
}
-function iz
-str8_read_uleb128(str8 a, u64 *uleb128)
-{
- /* TODO(rnp): check for overflow ... */
- iz result = 0;
- iz shift = 0;
- u64 n = 0;
- while (result < a.len) {
- u8 byte = a.data[result++];
- n |= (u64)(byte & 0x7F) << shift;
- if ((byte & 0x80) == 0)
- break;
- shift += 7;
- }
- *uleb128 = n;
- return result;
-}
-
function str8_reader
str8_reader_from_str8(str8 s)
{
@@ -708,6 +690,15 @@ str8_reader_from_str8(str8 s)
return result;
}
+function u8
+str8_read_u8(str8_reader *r)
+{
+ u8 result = 0;
+ r->errors |= r->index + 1 > r->count;
+ if (!r->errors) result = r->data[r->index++];
+ return result;
+}
+
function u16
str8_read_u16(str8_reader *r, b32 big_endian)
{
@@ -747,6 +738,22 @@ str8_read_u64(str8_reader *r, b32 big_endian)
return result;
}
+function u64
+str8_read_uleb128(str8_reader *r)
+{
+ /* TODO(rnp): check for overflow ... */
+ iz shift = 0;
+ u64 result = 0;
+ while (r->index < r->count) {
+ u8 byte = r->data[r->index++];
+ result |= (u64)(byte & 0x7F) << shift;
+ if ((byte & 0x80) == 0)
+ break;
+ shift += 7;
+ }
+ return result;
+}
+
function void
print_u64(u64 v)
{
@@ -844,7 +851,7 @@ elf_header_from_file(ELFHeader *eh, str8 file)
eh->abi = file.data[7];
eh->abi_version = file.data[8];
- str8_reader reader = str8_reader_from_str8(str8_chop(file, 16));
+ str8_reader reader = str8_reader_from_str8(str8_chop_at(file, 16));
b32 big_endian = eh->endianness == EEK_BIG;
eh->kind = str8_read_u16(&reader, big_endian);
eh->machine = str8_read_u16(&reader, big_endian);
@@ -927,13 +934,13 @@ elf_extract_section_headers(Arena *a, str8 file, ELFHeader *eh)
ELFSectionHeader *result = alloc(a, ELFSectionHeader, sections);
for (u32 i = 0; i < sections; i++) {
iz offset = eh->section_header_offset + eh->section_header_entry_size * i;
- elf_section_header_from_str8(result + i, str8_chop(file, offset),
+ elf_section_header_from_str8(result + i, str8_chop_at(file, offset),
eh->endianness == EEK_BIG, eh->format == EF_32);
}
u8 *str_tab = file.data + result[eh->section_header_name_table_index].offset;
for (u32 i = 0; i < sections; i++)
- result[i].name = c_str_to_str8(str_tab + result[i].name_table_offset);
+ result[i].name = str8_from_c_str(str_tab + result[i].name_table_offset);
return result;
}
@@ -953,39 +960,34 @@ elf_lookup_section(str8 name, str8 file, ELFSectionHeader *shs, u32 sections_cou
return result;
}
-function iz
-dwarf_read_unit_header(DWARFUnitHeader *duh, str8 store)
+function void
+dwarf_read_unit_header(str8_reader *store, DWARFUnitHeader *duh)
{
- iz result = 0;
/* TODO(rnp): context containing endianess, dwarf size */
- duh->dwarf_64 = *(u32 *)store.data == 0xffffffff;
- if (duh->dwarf_64) { result += 12; duh->length = *(u64 *)(store.data + 4); }
- else { result += 4; duh->length = *(u32 *)(store.data); }
- duh->version = *(u16 *)(store.data + result);
- result += 2;
- if (duh->version == 5) duh->kind = store.data[result++];
- duh->address_size = store.data[result++];
- if (duh->dwarf_64) { duh->abbreviation_offset = *(u64 *)(store.data + result); result += 8; }
- else { duh->abbreviation_offset = *(u32 *)(store.data + result); result += 4; }
- return result;
+ u32 test_length = str8_read_u32(store, 0);
+ duh->dwarf_64 = test_length == 0xffffffff;
+ if (duh->dwarf_64) duh->length = str8_read_u64(store, 0);
+ else duh->length = test_length;
+ duh->version = str8_read_u16(store, 0);
+ if (duh->version == 5) duh->kind = str8_read_u8(store);
+ duh->address_size = str8_read_u8(store);
+ if (duh->dwarf_64) duh->abbreviation_offset = str8_read_u64(store, 0);
+ else duh->abbreviation_offset = str8_read_u32(store, 0);
}
function iz
dwarf_parse_abbrevation(Arena *a, DWARFAbbreviation *abbrv, str8 table)
{
+ str8_reader table_reader = str8_reader_from_str8(table);
iz table_start_size = table.len;
- iz result = 0;
- table = str8_chop(table, str8_read_uleb128(table, &abbrv->abbreviation_code));
- u64 abbrv_kind = 0;
- table = str8_chop(table, str8_read_uleb128(table, &abbrv_kind));
- abbrv->kind = abbrv_kind;
- if (table.len < 1) return table_start_size;
- abbrv->has_children = *table.data;
- table = str8_chop(table, 1);
+ abbrv->abbreviation_code = str8_read_uleb128(&table_reader);
+ abbrv->kind = str8_read_uleb128(&table_reader);
+ if (table_reader.count - table_reader.index < 1)
+ return table_start_size;
+ abbrv->has_children = str8_read_u8(&table_reader);
for (;;) {
- u64 attr_kind = 0, form_kind = 0;
- table = str8_chop(table, str8_read_uleb128(table, &attr_kind));
- table = str8_chop(table, str8_read_uleb128(table, &form_kind));
+ u64 attr_kind = str8_read_uleb128(&table_reader);
+ u64 form_kind = str8_read_uleb128(&table_reader);
TODO(form_kind != DFK_INDIRECT);
TODO(form_kind != DFK_IMPLICIT_CONST);
if (attr_kind) {
@@ -995,8 +997,7 @@ dwarf_parse_abbrevation(Arena *a, DWARFAbbreviation *abbrv, str8 table)
break;
}
}
- result = table_start_size - table.len;
- return result;
+ return table_reader.index;
}
function DWARFAbbreviation
@@ -1005,7 +1006,7 @@ dwarf_lookup_abbreviation(Arena *a, str8 table, u64 key)
DWARFAbbreviation result = {0};
while (key != result.abbreviation_code && table.len > 1) {
result.count = 0;
- table = str8_chop(table, dwarf_parse_abbrevation(a, &result, table));
+ table = str8_chop_at(table, dwarf_parse_abbrevation(a, &result, table));
}
return result;
}
@@ -1057,12 +1058,17 @@ elf_inspect_file(Arena arena, str8 file)
ELFSection debug_str = elf_lookup_section(str8(".debug_str"), file,
sections, header.section_header_count);
- str8 d_info_reader = debug_info.store;
+ /* TODO(rnp): cleanup */
+ if (debug_info.store.len == 0) {
+ printf("No Debug Info!\n");
+ return 0;
+ }
+
+ str8_reader d_info_reader = str8_reader_from_str8(debug_info.store);
DWARFUnitHeader d_info_header = {0};
- d_info_reader = str8_chop(d_info_reader, dwarf_read_unit_header(&d_info_header, d_info_reader));
- u64 abbreviation_code = 0;
- str8 abbreviation_table = str8_chop(debug_abbrv.store, d_info_header.abbreviation_offset);
- d_info_reader = str8_chop(d_info_reader, str8_read_uleb128(d_info_reader, &abbreviation_code));
+ dwarf_read_unit_header(&d_info_reader, &d_info_header);
+ str8 abbreviation_table = str8_chop_at(debug_abbrv.store, d_info_header.abbreviation_offset);
+ u64 abbreviation_code = str8_read_uleb128(&d_info_reader);
DWARFAbbreviation abbrv = dwarf_lookup_abbreviation(&arena, abbreviation_table, abbreviation_code);
printf("\nFirst DWARF DIE:\n");
@@ -1072,28 +1078,30 @@ elf_inspect_file(Arena arena, str8 file)
continue;
switch (attr.kind) {
- case DATK_PRODUCER: printf("producer: "); break;
- case DATK_LANGUAGE: printf("language: "); break;
- case DATK_ADDR_BASE: printf("addr base: "); break;
- case DATK_LOCLISTS_BASE: printf("loc list base: "); break;
+ case DATK_PRODUCER: printf("producer: "); break;
+ case DATK_LANGUAGE: printf("language: "); break;
+ case DATK_ADDR_BASE: printf("addr base: "); break;
+ case DATK_LOCLISTS_BASE: printf("loc list base: "); break;
+ case DATK_RNGLISTS_BASE: printf("range list base: "); break;
default: assert(0); break;
}
switch (attr.form_kind) {
case DFK_STRX1: {
- u32 str_offset_offset = *d_info_reader.data;
- d_info_reader = str8_chop(d_info_reader, 1);
- u32 str_offset = *(u32 *)(debug_str_offsets.store.data + str_offset_offset);
+ u32 str_offset_offset = str8_read_u8(&d_info_reader);
+ u32 str_offset;
+ if (header.endianness == EEK_BIG)
+ str_offset = u32_host_from_be(debug_str_offsets.store.data + str_offset_offset);
+ else
+ str_offset = u32_host_from_le(debug_str_offsets.store.data + str_offset_offset);
printf("%s", (char *)debug_str.store.data + str_offset);
} break;
case DFK_DATA2: {
- u32 data = *(u16 *)d_info_reader.data;
- d_info_reader = str8_chop(d_info_reader, 2);
+ u32 data = str8_read_u16(&d_info_reader, header.endianness == EEK_BIG);
printf("%u", data);
} break;
case DFK_SEC_OFFSET: {
- u32 data = *(u32 *)d_info_reader.data;
- d_info_reader = str8_chop(d_info_reader, 4);
+ u32 data = str8_read_u32(&d_info_reader, header.endianness == EEK_BIG);
printf("%u", data);
} break;
default: assert(0); break;