Commit: dfc435bc1331b31eb57d7e15d3317c5ec07ff732
Parent: 9d58b89cec83a2ac8b2bf12cba7e4c28a1ad368a
Author: Randy Palamar
Date: Mon, 19 May 2025 09:28:53 -0600
properly read section headers
Diffstat:
| M | elfinspect.c | | | 124 | ++++++++++++++++++++++++++++++++++++++++++++++++++++++------------------------- |
1 file changed, 85 insertions(+), 39 deletions(-)
diff --git a/elfinspect.c b/elfinspect.c
@@ -1,11 +1,15 @@
/* See LICENSE for license details. */
+
+/* TODO(rnp):
+ * [ ]: remove all the unaligned reads so that this compiles with optimizations on
+ */
#define local_persist static
#define global static
#define function static
/* TODO(rnp) platform specific */
-#define ASSERT(c) do { if (!(c)) asm("int3; nop"); } while (0)
-#define TODO(c) ASSERT(c)
+#define assert(c) do { if (!(c)) asm("int3; nop"); } while (0)
+#define TODO(c) assert(c)
#define countof(a) (sizeof(a) / sizeof(*a))
@@ -124,34 +128,28 @@ typedef enum {
} ELFSectionKind;
static_assert(sizeof(ELFSectionKind) == 4, "sizeof(ELFSectionKind) must be 4 bytes");
-/* X(ctype, name) */
-#define ELF_SECTION_HEADER_MEMBERS(ptrsize) \
- X(u32, name_table_offset) \
- X(ELFSectionKind, kind) \
- X(ptrsize, flags) \
- X(ptrsize, addr) \
- X(ptrsize, offset) \
- X(ptrsize, size) \
- X(u32, link) \
- X(u32, info) \
- X(ptrsize, addralign) \
- X(ptrsize, entsize)
-
-#define X(ctype, name) ctype name;
-typedef struct {ELF_SECTION_HEADER_MEMBERS(u32)} ELFSectionHeader32;
-typedef struct {ELF_SECTION_HEADER_MEMBERS(u64)} ELFSectionHeader64;
-#undef X
-
+/* X(ctype, read32, read64, name) */
+#define ELF_SECTION_HEADER_MEMBERS \
+ X(u32, u32, u32, name_table_offset) \
+ X(ELFSectionKind, u32, u32, kind) \
+ X(u64, u32, u64, flags) \
+ X(u64, u32, u64, addr) \
+ X(u64, u32, u64, offset) \
+ X(u64, u32, u64, size) \
+ X(u32, u32, u32, link) \
+ X(u32, u32, u32, info) \
+ X(u64, u32, u64, addralign) \
+ X(u64, u32, u64, entsize)
+
+#define X(ctype, r32, r64, name) ctype name;
typedef struct {
str8 name;
- union {
- ELFSectionHeader64 sh64;
- ELFSectionHeader32 sh32;
- };
+ ELF_SECTION_HEADER_MEMBERS
} ELFSectionHeader;
+#undef X
typedef struct {
- ELFSectionHeader *header;
+ ELFSectionHeader header;
str8 store;
} ELFSection;
@@ -604,9 +602,9 @@ function void *
alloc_(Arena *a, iz alignment, iz size, iz count)
{
iz capacity = a->end - a->beg;
- iz padding = -(uintptr_t)a->beg & alignment;
+ iz padding = -(uintptr_t)a->beg & (alignment - 1);
if ((capacity - padding) / size < count) {
- ASSERT(0 && "OOM: buy more ram lol");
+ assert(0 && "OOM: buy more ram lol");
}
u8 *result = a->beg + padding;
a->beg += padding + size * count;
@@ -862,22 +860,70 @@ elf_header_from_file(ELFHeader *eh, str8 file)
return result;
}
+function void
+elf_section_header32_from_str8(ELFSectionHeader *sh, str8 s, b32 big_endian)
+{
+ assert(s.len >= 0x28);
+ u8 *data = s.data;
+ if (big_endian) {
+ #define X(ctype, r32, r64, name) \
+ sh->name = r32 ##_host_from_be(data); data += sizeof(r32);
+ ELF_SECTION_HEADER_MEMBERS
+ #undef X
+ } else {
+ #define X(ctype, r32, r64, name) \
+ sh->name = r32 ##_host_from_le(data); data += sizeof(r32);
+ ELF_SECTION_HEADER_MEMBERS
+ #undef X
+ }
+}
+
+function void
+elf_section_header64_from_str8(ELFSectionHeader *sh, str8 s, b32 big_endian)
+{
+ assert(s.len >= 0x40);
+ u8 *data = s.data;
+ if (big_endian) {
+ #define X(ctype, r32, r64, name) \
+ sh->name = r64 ##_host_from_be(data); data += sizeof(r64);
+ ELF_SECTION_HEADER_MEMBERS
+ #undef X
+ } else {
+ #define X(ctype, r32, r64, name) \
+ sh->name = r64 ##_host_from_le(data); data += sizeof(r64);
+ ELF_SECTION_HEADER_MEMBERS
+ #undef X
+ }
+}
+
+function b32
+elf_section_header_from_str8(ELFSectionHeader *sh, str8 s, b32 big_endian, b32 is32bit)
+{
+ b32 result = s.len >= 0x40 || (is32bit && s.len >= 0x28);
+ if (result) {
+ if (is32bit) elf_section_header32_from_str8(sh, s, big_endian);
+ else elf_section_header64_from_str8(sh, s, big_endian);
+ }
+ return result;
+}
+
function ELFSectionHeader *
elf_extract_section_headers(Arena *a, str8 file, ELFHeader *eh)
{
- TODO(eh->format == EF_64);
- TODO(eh->endianness == EEK_LITTLE);
- TODO(file.len >= eh->section_header_offset + eh->section_header_entry_size * eh->section_header_count);
+ /* TODO(rnp): */
+ assert(file.len >= eh->section_header_offset + eh->section_header_entry_size * eh->section_header_count);
+
u32 sections = eh->section_header_count;
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;
- result[i].sh64 = *(ELFSectionHeader64 *)(file.data + offset);
+ elf_section_header_from_str8(result + i, str8_chop(file, offset),
+ eh->endianness == EEK_BIG, eh->format == EF_32);
}
- u8 *str_tab = file.data + result[eh->section_header_name_table_index].sh64.offset;
+ 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].sh64.name_table_offset);
+ result[i].name = c_str_to_str8(str_tab + result[i].name_table_offset);
return result;
}
@@ -888,9 +934,9 @@ elf_lookup_section(str8 name, str8 file, ELFSectionHeader *shs, u32 sections_cou
ELFSection result = {0};
for (u32 i = 0; i < sections_count; i++) {
if (str8_equal(shs[i].name, name)) {
- result.header = shs + i;
- result.store.data = file.data + shs[i].sh64.offset;
- result.store.len = shs[i].sh64.size;
+ result.header = shs[i];
+ result.store.data = file.data + shs[i].offset;
+ result.store.len = shs[i].size;
break;
}
}
@@ -935,7 +981,7 @@ dwarf_parse_abbrevation(Arena *a, DWARFAbbreviation *abbrv, str8 table)
if (attr_kind) {
*da_push(a, abbrv) = (DWARFAttribute){attr_kind, form_kind};
} else {
- ASSERT(form_kind == 0);
+ assert(form_kind == 0);
break;
}
}
@@ -1002,7 +1048,7 @@ elfinspect(Arena arena, str8 file)
case DATK_LANGUAGE: printf("language: "); break;
case DATK_ADDR_BASE: printf("addr base: "); break;
case DATK_LOCLISTS_BASE: printf("loc list base: "); break;
- default: ASSERT(0); break;
+ default: assert(0); break;
}
switch (attr.form_kind) {
@@ -1022,7 +1068,7 @@ elfinspect(Arena arena, str8 file)
d_info_reader = str8_chop(d_info_reader, 4);
printf("%u", data);
} break;
- default: ASSERT(0); break;
+ default: assert(0); break;
}
printf("\n");
}