Thread: Almost there, just need help with names

Think I fixed the corrupt symbol info now (well almost), still trying to figure out the name bit though

Code:

...
u16 shent_pos = seg_shead->pos + (sizeof(shead64_t) * s) + 24;
memset( shent, 0, sizeof(shead64_t) );
shent->sh_type = SHEAD_TYPE_NULL;
shent->sh_name = OffsetOfSymbol( segv, txt );
shent->sh_addr = this->pos;
shent->sh_size = this->mem.size;
shent->sh_offset = (this->pos > shent_pos) ? (this->pos - shent_pos) : -(shent_pos - this->pos);
...
memset( named, 0, sizeof(named64_t) );
named->st_name = OffsetOfSymbol( segv, txt );
...

Code:

Symbol table '' contains 6 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 0000000000000022   256 SECTION LOCAL  DEFAULT  UND 
     2: 0000000000000040     0 NOTYPE  LOCAL  DEFAULT  UND <corrupt>
     3: 0000000000000001 0x200000013 NOTYPE  LOCAL  DEFAULT  UND 
     4: 0000000000000140   104 NOTYPE  LOCAL  DEFAULT  UND <corrupt>
     5: 0000000600000001     0 NOTYPE  LOCAL  DEFAULT  UND <corrupt>

Is or is this not the correct point to be calculating the offset to fill the sh_offset parameter of section headers from? I believe this to be why I'm not getting the expected strings show up in readelf.

Code:

// ->pos is the address given to the elf header parameter e_shoff
// shead64_t is my typedef for my section header struct (followed defined sizes)
u16 shent_pos = seg_shead->pos + (sizeof(shead64_t) * (s));
u16 param_pos = shent_pos + 32;

Edit:
Never mind, finally noticed a comment in the documentation I mentioned, tried this:

Code:

shent->sh_offset = this->pos;

and finally got my expected strings.

At last my first correctly formatted executable, albeit non-functional:

Code:

misty alpha
Creating test.elf
Writing Elf Header...
Writing Program Headers...
Writing Segment Headers...
Writing Symbol Pool...
Writing Symbols...
Writing Coded Area...
Flushing file...
./test.elf
Segmentation fault
readelf -all test.elf
ELF Header:
  Magic:   7f 45 4c 46 02 01 01 ff 00 00 00 00 00 00 00 00 
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            <unknown: ff>
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           Advanced Micro Devices X86-64
  Version:                           0x1
  Entry point address:               0x278
  Start of program headers:          64 (bytes into file)
  Start of section headers:          232 (bytes into file)
  Flags:                             0x0
  Size of this header:               64 (bytes)
  Size of program headers:           56 (bytes)
  Number of program headers:         3
  Size of section headers:           64 (bytes)
  Number of section headers:         3
  Section header string table index: 1
readelf: Warning: Section 2 has an out of range sh_info value of 6

Section Headers:
  [Nr] Name              Type             Address           Offset
       Size              EntSize          Flags  Link  Info  Align
  [ 0]                   NULL             0000000000000000  00000000
       0000000000000000  0000000000000000           0     0     0
  [ 1] .shstrtab         STRTAB           00000000000001a8  000001a8
       0000000000000040  0000000000000001  AS       0     0     0
  [ 2] .symtab           SYMTAB           00000000000001e8  000001e8
       0000000000000090  0000000000000018 WAI       1     6     0
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  l (large), p (processor specific)

There are no section groups in this file.

Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  NULL           0x0000000000000000 0x0000000000000000 0x0000000000000000
                 0x0000000000000000 0x0000000000000000         0x0
  PHDR           0x0000000000000000 0x0000000000000040 0x0000000000000040
                 0x00000000000000a8 0x00000000000000a8  R      0x0
  LOAD           0x0000000000000000 0x0000000000000278 0x0000000000000278
                 0x0000000000000006 0x0000000000000006  RWE    0x0

 Section to Segment mapping:
  Segment Sections...
   00     
   01     
   02     

There is no dynamic section in this file.

There are no relocations in this file.

The decoding of unwind sections for machine type Advanced Micro Devices X86-64 is not currently supported.

Symbol table '.symtab' contains 6 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 00000000000001a8    64 COMMON  WEAK   DEFAULT  COM .shstrtab
     2: 00000000000001e8   144 COMMON  WEAK   DEFAULT  COM .symtab
     3: 0000000000000278     6 FILE    LOCAL  DEFAULT  ABS mitsy.c
     4: 0000000000000278     2 FUNC    GLOBAL DEFAULT  COM _start
     5: 000000000000027a     4 FUNC    GLOBAL DEFAULT  COM main

No version information found in this file.
Exiting...


------------------
(program exited with code: 0)
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