49  Types

Rizin supports C-syntax data type definitions. Most of the related commands are located in t namespace:

[0x000051c0]> t?
Usage: t[?]   # Types, noreturn, signatures, C parser and more
| t[j*] [<type>] # List all types / Show type information
| t- <type>      # Remove the type
| t-*            # Remove all types
| tc[dc]         # List loaded types in C format
| td <type>      # Define type from C definition
| te[jbcdf]      # List loaded enums
| tf[j-c?]       # List loaded functions definitions
| tn[j-?]        # Manage noreturn function attributes and marks
| to[es]         # Open C header file and load types from it
| tp[vx]         # Print formatted type casted to the address
| ts[jlcd]       # List loaded structures
| tt[jc]         # List loaded typedefs
| tu[jlcd]       # List loaded unions
| tx[fgl]        # Type xrefs

Note that the basic (atomic) types are not those from the C standard - not char, _Bool, or short. Because those types can be different from one platform to another, rizin uses definite types like as int8_t or uint64_t and will convert int to int32_t or int64_t depending on the binary or debuggee platform/compiler.

Basic types can be listed using the t command. For structured types, you can use ts, tu, or te for structs, unions, and enums, respectively:

[0x000051c0]> t
char *
long long

49.0.1 Loading types

There are three easy ways to define a new type: * Passing a string to the td command * Passing a file with the to <filename> command * Using your defined cfg.editor by calling the the to - command

[0x000051c0]> td "struct foo {char* a; int b;}"
[0x000051c0]> cat ~/rizin-regressions/bins/headers/s3.h
struct S1 {
    int x[3];
    int y[4];
    int z;
[0x000051c0]> to ~/rizin-regressions/bins/headers/s3.h
[0x000051c0]> ts

Also, note there is a config option to specify include directories for types parsing

[0x00000000]> el~dir.type
dir.types: Default path to look for cparse type files
[0x00000000]> e dir.types

49.0.2 Printing types

Notice below we have used ts command, which basically converts the C type description into the sequence of pf commands. See more about print format.

The tp command uses the pf string to print all the members of type at the current offset/given address:

[0x000051c0]> ts foo
pf zd a b
[0x000051c0]> tp foo
 a : 0x000051c0 = 'hello'
 b : 0x000051cc = 10
[0x000051c0]> tp foo 0x000053c0
 a : 0x000053c0 = 'world'
 b : 0x000053cc = 20

Also, you could fill your own data into the struct and print it using tpx command

[0x000051c0]> tpx foo 4141414144141414141442001000000
 a : 0x000051c0 = AAAAD.....B
 b : 0x000051cc = 16

49.0.3 Linking Types

The tp command only performs a temporary cast. We can use the avga command to define a global variable of a specified type, which is linked to an address.

[0x000051c0]> avga struct_1 S1 @ 0x51cf
[0x000051c0]> avg
global struct S1 struct_1 @ 0x000051cf

Moreover, the link will be shown in the disassembly output or visual mode:

[0x000051c0 15% 300 /bin/ls]> pd $r @ entry0
 ;-- entry0:
 0x000051c0      xor ebp, ebp
 0x000051c2      mov r9, rdx
 0x000051c5      pop rsi
 0x000051c6      mov rdx, rsp
 0x000051c9      and rsp, 0xfffffffffffffff0
 0x000051cd      push rax
 0x000051ce      push rsp
(S1 struct_1)
 x : 0x000051cf = [ 2315619660, 1207959810, 34803085 ]
 y : 0x000051db = [ 2370306049, 4293315645, 3860201471, 4093649307 ]
 z : 0x000051eb = 4464399
 0x000051f0      lea rdi, loc._edata         ; 0x21f248
 0x000051f7      push rbp
 0x000051f8      lea rax, loc._edata         ; 0x21f248
 0x000051ff      cmp rax, rdi
 0x00005202      mov rbp, rsp

Once the struct is linked, rizin tries to propagate structure offset in the function at the current offset, to run this analysis on the whole program or at any targeted functions after all structs are linked you have aat command:

[0x00000000]> aa?
| aat [<func_name>] # Analyze all/given function to convert immediate to linked structure offsets

Note sometimes the emulation may not be accurate, for example as below :

|0x000006da  push rbp
|0x000006db  mov rbp, rsp
|0x000006de  sub rsp, 0x10
|0x000006e2  mov edi, 0x20               ; "@"
|0x000006e7  call sym.imp.malloc         ;  void *malloc(size_t size)
|0x000006ec  mov qword [local_8h], rax
|0x000006f0  mov rax, qword [local_8h]

The return value of malloc may differ between two emulations, so you have to set the hint for return value manually using ahr command, so run tl or aat command after setting up the return value hint.

[0x000006da]> ah?
| ahr <return>         # Set function return value hint

49.0.4 Structure Immediates

There is one more important aspect of using types in rizin - using aht you can change the immediate in the opcode to the structure offset. Let’s see a simple example of [R]SI-relative addressing

[0x000052f0]> pd 1
0x000052f0      mov rax, qword [rsi + 8]    ; [0x8:8]=0

Here 8 - is some offset in the memory, where rsi probably holds some structure pointer. Imagine that we have the following structures

[0x000052f0]> td "struct ms { char b[8]; int member1; int member2; };"
[0x000052f0]> td "struct ms1 { uint64_t a; int member1; };"
[0x000052f0]> td "struct ms2 { uint16_t a; int64_t b; int member1; };"

Now we need to set the proper structure member offset instead of 8 in this instruction. At first, we need to list available types matching this offset:

[0x000052f0]> ahts 8

Note, that ms2 is not listed, because it has no members with offset 8. After listing available options we can link it to the chosen offset at the current address:

[0x000052f0]> aht ms1.member1
[0x000052f0]> pd 1
0x000052f0      488b4608       mov rax, qword [rsi + ms1.member1]    ; [0x8:8]=0

49.0.5 Managing enums

  • Printing all fields in enum using te command
[0x00000000]> td "enum Foo {COW=1,BAR=2};"
[0x00000000]> te Foo
COW = 0x1
BAR = 0x2
  • Finding matching enum member for given bitfield and vice-versa
[0x00000000]> te Foo 0x1
[0x00000000]> teb Foo COW