Using `tp` when sizeof(type) > block size results in zeros in values

[hexagonal-sun]

When using tp with a type that is greater than block size, all fields that are printed beyond the block boundary are silently set to 0.

Work environment

Questions	Answers
OS/arch/bits (mandatory)	Arch linux x86_64
File format of the file you reverse (mandatory)	Binary image file
Architecture/bits of the file (mandatory)	N/A
r2 -v full output, not truncated (mandatory)	radare2 4.3.1 0 @ linux-x86-64 git.4.3.1 commit: unknown build: 2020-03-20__16:02:58

Expected behavior

I would have expected r2 to have at least printed a warning that sizeof(type) is greater than the block boundary and therefore those fields have an incorrect value.

Another alternative is for r2 to temporarily set the block size to match that of the type being printed so all fields have the correct value.

Actual behavior

All fields beyond block boundary are set to 0.

Steps to reproduce the behavior

Create a binary file:

$ yes | dd of=/tmp/test bs=1 count=1024

Load that file into r2, set a block size smaller than a type and print:

r2 /tmp/test/
[0x00000000]> b 10
[0x00000000]> "td struct foobar{uint32_t a; uint32_t b; uint32_t c; uint32_t d;}"
[0x00000000]> tp foobar
 a : 0x00000000 = 175704697
 b : 0x00000004 = 175704697
 c : 0x00000008 = 2681
 d : 0x0000000c = 0
[0x00000000]> 

If block size is increased correct values are returned:

[0x00000000]> b 16
[0x00000000]> tp foobar
 a : 0x00000000 = 175704697
 b : 0x00000004 = 175704697
 c : 0x00000008 = 175704697
 d : 0x0000000c = 175704697
[0x00000000]>