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== code

# Problem: create a function which pushes n zeros on the stack.
# This is not a regular function, so it won't be idiomatic.
# Registers must be properly restored.
# Registers can be spilled, but that modifies the stack and needs to be
# cleaned up.

# This file is kinda like a research notebook, to interactively arrive at the
# solution. Nobody should have to do this without a computer. To run it:
#   $ ./translate_subx_debug init.linux tools/stack_array.subx  &&  bootstrap --debug --trace --dump run a.elf
# There are multiple versions. You'll need to uncomment exactly one.

# The final version has its own Entry, but the others share this one.
#? Entry:
#?     # . prologue
#?     89/<- %ebp 4/r32/esp
#?     #
#?     68/push 0xfcfdfeff/imm32
#?     b8/copy-to-eax 0x34353637/imm32
#? $dump-stack:
#?     (push-n-zero-bytes 0x20)
#? $dump-stack2:
#?     68/push 0x20202020/imm32
#? $dump-stack3:
#?     b8/copy-to-eax 1/imm32/exit
#?     cd/syscall 0x80/imm8

## 0

#? push-n-zero-bytes:  # n: int
#?     # . prologue
#?     55/push-ebp
#?     89/<- %ebp 4/r32/esp
#? $push-n-zero-bytes:end:
#?     # . epilogue
#?     89/<- %esp 5/r32/ebp
#?     5d/pop-to-ebp
#?     c3/return

# stack at dump-stack:
# 0 a: bdffffd0: 00000000     00000000     00000000      00000000
# 0 a: bdffffe0: 00000000     00000000     00000000      00000000
# 0 a: bdfffff0: 00000000     fcfdfeff     00000001      bf000000
#
# =>
#
# stack at dump-stack3:
# 0 a: stack:
# 0 a: bdffffd0: 00000000     00000000     00000000      00000000
# 0 a: bdffffe0: 00000000     00000000     bdfffff8/ebp  090000cc/ra
# 0 a: bdfffff0: 00000004/arg fcfdfeff     00000001      bf000000

## 1

#? push-n-zero-bytes:  # n: int
#?     # . prologue
#?     55/push-ebp
#?     89/<- %ebp 4/r32/esp
#?     # . save registers
#?     50/push-eax
#? $push-n-zero-bytes:end:
#?     # . restore registers
#?     58/pop-to-eax
#?     # . epilogue
#?     5d/pop-to-ebp
#?     c3/return

# stack at dump-stack3:
# 0 a: bdffffd0: 00000000 00000000 00000000 00000000
# 0 a: bdffffe0: 00000000 34353637 bdfffff8 090000d1
# 0 a: bdfffff0: 00000004 fcfdfeff 00000001 bf000000

## 2

#? push-n-zero-bytes:  # n: int
#?     # . prologue
#?     55/push-ebp
#?     89/<- %ebp 4/r32/esp
#?     # . save registers
#?     50/push-eax
#?     #
#?     8b/-> *(esp+8) 0/r32/eax
#?     2b/subtract *(ebp+8) 4/r32/esp
#?     89/<- *(esp+8) 0/r32/eax
#? $push-n-zero-bytes:end:
#?     # . restore registers
#?     58/pop-to-eax
#?     # . epilogue
#?     5d/pop-to-ebp
#?     c3/return

# stack at dump-stack3:
# 0 a: bdffff90: 00000000 00000000 00000000 00000000
# 0 a: bdffffa0: 00000000 00000000 00000000 00000000
# 0 a: bdffffb0: 00000000 00000000 00000000 00000000
# 0 a: bdffffc0: 00000000 00000000 00000000 090000d1
# 0 a: bdffffd0: 00000000 00000000 00000000 00000000
# 0 a: bdffffe0: 00000000 34353637 bdfffff8 090000d1
# 0 a: bdfffff0: 00000020 fcfdfeff 00000001 bf000000

## 3

#? push-n-zero-bytes:  # n: int
#?     # . prologue
#?     55/push-ebp
#?     89/<- %ebp 4/r32/esp
#?     # . save registers
#?     # -- esp = ebp
#?     50/push-eax
#?     # -- esp+8 = ebp+4
#?     8b/-> *(esp+8) 0/r32/eax
#?     2b/subtract *(ebp+8) 4/r32/esp
#?     89/<- *(esp+8) 0/r32/eax
#?     c7 0/subop/copy *(ebp+4) 0/imm32
#? $push-n-zero-bytes:end:
#?     # . restore registers
#?     58/pop-to-eax
#?     # . epilogue
#?     5d/pop-to-ebp
#?     c3/return

# stack at dump-stack3:
# 0 a: bdffff90: 00000000 00000000 00000000 00000000
# 0 a: bdffffa0: 00000000 00000000 00000000 00000000
# 0 a: bdffffb0: 00000000 00000000 00000000 00000000
# 0 a: bdffffc0: 00000000 00000000 00000000 090000d1
# 0 a: bdffffd0: 20202020 00000000 00000000 00000000
# 0 a: bdffffe0: 00000000 34353637 bdfffff8 00000000
# 0 a: bdfffff0: 00000020 fcfdfeff 00000001 bf000000

## 4

#? push-n-zero-bytes:  # n: int
#?     # . prologue
#?     55/push-ebp
#?     89/<- %ebp 4/r32/esp
#?     # . save registers
#?     # -- esp = ebp
#?     50/push-eax
#?     # copy return address over
#?     # -- esp+8 = ebp+4
#?     8b/-> *(esp+8) 0/r32/eax
#?     2b/subtract *(ebp+8) 4/r32/esp
#?     89/<- *(esp+8) 0/r32/eax
#?     58/pop-to-eax
#?     c7 0/subop/copy *(ebp+8) 0/imm32
#?     c7 0/subop/copy *(ebp+4) 0/imm32
#?     c7 0/subop/copy *(ebp+0) 0/imm32
#?     c7 0/subop/copy *(ebp-4) 0/imm32
#?     # . epilogue
#?     5d/pop-to-ebp
#?     c3/return

# stack at dump-stack3:
# 0 a: bdffff90: 00000000 00000000 00000000 00000000
# 0 a: bdffffa0: 00000000 00000000 00000000 00000000
# 0 a: bdffffb0: 00000000 00000000 00000000 00000000
# 0 a: bdffffc0: 00000000 00000000 00000000 090000d1
# 0 a: bdffffd0: 20202020 00000000 00000000 00000000
# 0 a: bdffffe0: 00000000 00000000 00000000 00000000
# 0 a: bdfffff0: 00000000 fcfdfeff 00000001 bf000000

# Stack looks good now (the 20202020 marks where the array length 0x20 will
# go, and the next 0x20 bytes show the space for the array has been zeroed
# out).
# Final issue: ebp has been clobbered on return.

## 5

# I'd like to translate ebp to esp so we can stop pushing ebp. But we need to
# hold 'n' somewhere, which would require a register, which we then need to
# push.

#? push-n-zero-bytes:  # n: int
#?     55/push-ebp
#?     89/<- %ebp 4/r32/esp
#?     # -- esp = ebp
#?     50/push-eax
#? $push-n-zero-bytes:bulk-cleaning:
#? $push-n-zero-bytes:copy-ra:
#?     # -- esp+8 = ebp+4
#?     8b/-> *(esp+8) 0/r32/eax
#?     2b/subtract *(esp+0xc) 4/r32/esp
#?     # -- esp+8+n = ebp+4
#?     89/<- *(esp+8) 0/r32/eax
#?     58/pop-to-eax
#?     # -- esp+n = ebp
#? $push-n-zero-bytes:spot-cleaning:
#?     c7 0/subop/copy *(ebp+8) 0/imm32
#?     c7 0/subop/copy *(ebp+4) 0/imm32
#?     c7 0/subop/copy *(ebp+0) 0/imm32
#?     c7 0/subop/copy *(ebp-4) 0/imm32
#?     5d/pop-to-ebp
#?     c3/return

# stack at dump-stack3:
# 0 a: bdffff90: 00000000 00000000 00000000 00000000
# 0 a: bdffffa0: 00000000 00000000 00000000 00000000
# 0 a: bdffffb0: 00000000 00000000 00000000 00000000
# 0 a: bdffffc0: 00000000 00000000 00000000 090000d1
# 0 a: bdffffd0: 20202020 00000000 00000000 00000000
# 0 a: bdffffe0: 00000000 00000000 00000000 00000000
# 0 a: bdfffff0: 00000000 fcfdfeff 00000001 bf000000

# Bah. May be simpler to just create a new segment of global space for this
# function.

## 6

#? push-n-zero-bytes:  # n: int
#?     89/<- *Push-n-zero-bytes-ebp 5/r32/ebp  # spill ebp without affecting stack
#?     89/<- %ebp 4/r32/esp
#?     # -- esp = ebp
#?     50/push-eax
#? $push-n-zero-bytes:bulk-cleaning:
#? $push-n-zero-bytes:copy-ra:
#?     # -- esp+8 = ebp+4
#?     # -- esp+4 = ebp
#?     8b/-> *(esp+4) 0/r32/eax
#?     2b/subtract *(ebp+4) 4/r32/esp
#?     # -- esp+4+n = ebp
#?     89/<- *(esp+4) 0/r32/eax
#?     58/pop-to-eax
#?     # -- esp+n = ebp
#? $push-n-zero-bytes:spot-cleaning:
#?     c7 0/subop/copy *(ebp+4) 0/imm32
#?     c7 0/subop/copy *(ebp+0) 0/imm32
#?     c7 0/subop/copy *(ebp-4) 0/imm32
#?     c7 0/subop/copy *(ebp-8) 0/imm32
#?     8b/-> *Push-n-zero-bytes-ebp 5/r32/ebp  # restore spill
#?     c3/return
#? 
#? == data
#? Push-n-zero-bytes-ebp:  # (addr int)
#?   0/imm32
#? == code

# stack at dump-stack3:
# 0 a: bdffff90: 00000000 00000000 00000000 00000000
# 0 a: bdffffa0: 00000000 00000000 00000000 00000000
# 0 a: bdffffb0: 00000000 00000000 00000000 00000000
# 0 a: bdffffc0: 00000000 00000000 00000000 090000d1
# 0 a: bdffffd0: 20202020 00000000 00000000 00000000
# 0 a: bdffffe0: 00000000 00000000 00000000 00000000
# 0 a: bdfffff0: 00000000 fcfdfeff 00000001 bf000000

# Ok, we're there. Now start using zero-out rather than spot-cleaning.

## 7: we need to zero out the return address, but we can't do it inside the function.
## So we'll change the signature slightly.
## Before: clear N bytes and then push N as the array length.
## After: clear N bytes, set *esp to N.
## The helper adds and clears N bytes *before* esp. esp can't be cleared since
## it contains the return address.

#? Entry:
#?     # . prologue
#?     89/<- %ebp 4/r32/esp
#?     #
#?     68/push 0xfcfdfeff/imm32
#?     b8/copy-to-eax 0x34353637/imm32
#? $dump-stack0:
#?     (push-n-zero-bytes 0x20)
#? $dump-stack9:
#?     c7 0/subop/copy *esp 0x20/imm32
#? $dump-stacka:
#?     b8/copy-to-eax 1/imm32/exit
#?     cd/syscall 0x80/imm8
#? 
#? push-n-zero-bytes:  # n: int
#? $push-n-zero-bytes:prologue:
#?     89/<- *Push-n-zero-bytes-ebp 5/r32/ebp  # spill ebp without affecting stack
#?     89/<- %ebp 4/r32/esp
#? $push-n-zero-bytes:copy-ra:
#? $dump-stack1:
#?     # -- esp = ebp
#?     50/push-eax
#? $dump-stack2:
#?     # -- esp+8 = ebp+4
#?     # -- esp+4 = ebp
#?     8b/-> *(esp+4) 0/r32/eax
#? $dump-stack3:
#?     2b/subtract *(ebp+4) 4/r32/esp
#? $dump-stack4:
#?     # -- esp+4+n = ebp
#?     89/<- *(esp+4) 0/r32/eax
#? $dump-stack5:
#?     58/pop-to-eax
#?     # -- esp+n = ebp
#? $push-n-zero-bytes:bulk-cleaning:
#? $dump-stack6:
#?     89/<- *Push-n-zero-bytes-esp 4/r32/esp
#?     81 0/subop/add *Push-n-zero-bytes-esp 4/imm32
#? $dump-stack7:
#?     (zero-out *Push-n-zero-bytes-esp *(ebp+4))  # n
#? $push-n-zero-bytes:epilogue:
#? $dump-stack8:
#?     8b/-> *Push-n-zero-bytes-ebp 5/r32/ebp  # restore spill
#?     c3/return
#? 
#? zero-out:  # start: (addr byte), len: int
#?     # pseudocode:
#?     #   curr/esi = start
#?     #   i/ecx = 0
#?     #   while true
#?     #     if (i >= len) break
#?     #     *curr = 0
#?     #     ++curr
#?     #     ++i
#?     #
#?     # . prologue
#?     55/push-ebp
#?     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
#?     # . save registers
#?     50/push-eax
#?     51/push-ecx
#?     52/push-edx
#?     56/push-esi
#?     # curr/esi = start
#?     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
#?     # var i/ecx: int = 0
#?     31/xor                          3/mod/direct    1/rm32/ecx    .           .             .           1/r32/ecx   .               .                 # clear ecx
#?     # edx = len
#?     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           2/r32/edx   0xc/disp8       .                 # copy *(ebp+12) to edx
#? $zero-out:loop:
#?     # if (i >= len) break
#?     39/compare                      3/mod/direct    1/rm32/ecx    .           .             .           2/r32/edx   .               .                 # compare ecx with edx
#?     7d/jump-if->=  $zero-out:end/disp8
#?     # *curr = 0
#?     c6          0/subop/copy        0/mod/direct    6/rm32/esi    .           .             .           .           .               0/imm8            # copy byte to *esi
#?     # ++curr
#?     46/increment-esi
#?     # ++i
#?     41/increment-ecx
#?     eb/jump  $zero-out:loop/disp8
#? $zero-out:end:
#?     # . restore registers
#?     5e/pop-to-esi
#?     5a/pop-to-edx
#?     59/pop-to-ecx
#?     58/pop-to-eax
#?     # . epilogue
#?     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
#?     5d/pop-to-ebp
#?     c3/return
#? 
#? == data
#? Push-n-zero-bytes-ebp:  # (addr int)
#?   0/imm32
#? Push-n-zero-bytes-esp:  # (addr int)
#?   0/imm32
#? == code

# stack at dump-stack0:
# 0 a: bdffffb0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffc0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffd0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffe0:  00000000   00000000   00000000   00000000 
# 0 a: bdfffff0:  00000000  [fcfdfeff]  00000001   bf000000 

# desired state after push-n-zero-bytes:
# 0 a: bdffff90:  00000000   00000000   00000000   00000000 
# 0 a: bdffffa0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffb0:  00000000   00000000   00000000   bdffffec 
# 0 a: bdffffc0:  0900012a   bdffffd0   00000020   090000d1 
# 0 a: bdffffd0: [rrrrrrrr]  00000000   00000000   00000000 
# 0 a: bdffffe0:  00000000   00000000   00000000   00000000 
# 0 a: bdfffff0:  00000000   fcfdfeff   00000001   bf000000 

# Stack pointer contains ra is caller's responsibility to over-write with array length.

# actual state:
# 0 a: bdffff90:  00000000   00000000   00000000   00000000
# 0 a: bdffffa0:  00000000   00000000   00000000   00000000
# 0 a: bdffffb0:  00000000   00000000   00000000   bdffffec
# 0 a: bdffffc0:  0900012a   bdffffd0   00000020   090000d1
# 0 a: bdffffd0:  00000000  [00000000]  00000000   00000000
# 0 a: bdffffe0:  00000000   00000000   00000000   00000000
# 0 a: bdfffff0:  00000020   fcfdfeff   00000001   bf000000

# Couple of issues. But where does the return address disappear to?

## 8:

#? Entry:
#?     # . prologue
#?     89/<- %ebp 4/r32/esp
#?     #
#?     68/push 0xfcfdfeff/imm32
#?     b8/copy-to-eax 0x34353637/imm32
#? $dump-stack0:
#?     (push-n-zero-bytes 0x20)
#? $dump-stack9:
#?     68/push 0x20/imm32
#? #?     c7 0/subop/copy *esp 0x20/imm32
#? $dump-stacka:
#?     b8/copy-to-eax 1/imm32/exit
#?     cd/syscall 0x80/imm8
#? 
#? push-n-zero-bytes:  # n: int
#? $push-n-zero-bytes:prologue:
#?     89/<- *Push-n-zero-bytes-ebp 5/r32/ebp  # spill ebp without affecting stack
#?     89/<- %ebp 4/r32/esp
#? $push-n-zero-bytes:copy-ra:
#? $dump-stack1:
#?     # -- esp = ebp
#?     50/push-eax
#? $dump-stack2:
#?     # -- esp+8 = ebp+4
#?     # -- esp+4 = ebp
#?     8b/-> *(esp+4) 0/r32/eax
#? $dump-stack3:
#?     2b/subtract *(ebp+4) 4/r32/esp
#? $dump-stack4:
#?     # -- esp+4+n = ebp
#?     89/<- *(esp+4) 0/r32/eax
#? $dump-stack5:
#?     58/pop-to-eax
#?     # -- esp+n = ebp
#? $push-n-zero-bytes:bulk-cleaning:
#? $dump-stack6:
#?     89/<- *Push-n-zero-bytes-esp 4/r32/esp
#?     81 0/subop/add *Push-n-zero-bytes-esp 4/imm32
#? $dump-stack7:
#?     (zero-out *Push-n-zero-bytes-esp *(ebp+4))  # n
#? $push-n-zero-bytes:epilogue:
#? $dump-stack8:
#?     8b/-> *Push-n-zero-bytes-ebp 5/r32/ebp  # restore spill
#?     c3/return
#? 
#? zero-out:  # start: (addr byte), len: int
#?     # pseudocode:
#?     #   curr/esi = start
#?     #   i/ecx = 0
#?     #   while true
#?     #     if (i >= len) break
#?     #     *curr = 0
#?     #     ++curr
#?     #     ++i
#?     #
#?     # . prologue
#?     55/push-ebp
#?     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
#?     # . save registers
#?     50/push-eax
#?     51/push-ecx
#?     52/push-edx
#?     56/push-esi
#?     # curr/esi = start
#?     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
#?     # var i/ecx: int = 0
#?     31/xor                          3/mod/direct    1/rm32/ecx    .           .             .           1/r32/ecx   .               .                 # clear ecx
#?     # edx = len
#?     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           2/r32/edx   0xc/disp8       .                 # copy *(ebp+12) to edx
#? $zero-out:loop:
#?     # if (i >= len) break
#?     39/compare                      3/mod/direct    1/rm32/ecx    .           .             .           2/r32/edx   .               .                 # compare ecx with edx
#?     7d/jump-if->=  $zero-out:end/disp8
#?     # *curr = 0
#?     c6          0/subop/copy        0/mod/direct    6/rm32/esi    .           .             .           .           .               0/imm8            # copy byte to *esi
#?     # ++curr
#?     46/increment-esi
#?     # ++i
#?     41/increment-ecx
#?     eb/jump  $zero-out:loop/disp8
#? $zero-out:end:
#?     # . restore registers
#?     5e/pop-to-esi
#?     5a/pop-to-edx
#?     59/pop-to-ecx
#?     58/pop-to-eax
#?     # . epilogue
#?     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
#?     5d/pop-to-ebp
#?     c3/return
#? 
#? == data
#? Push-n-zero-bytes-ebp:  # (addr int)
#?   0/imm32
#? Push-n-zero-bytes-esp:  # (addr int)
#?   0/imm32
#? == code

# stack at dump-stack0:
# 0 a: bdffffb0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffc0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffd0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffe0:  00000000   00000000   00000000   00000000 
# 0 a: bdfffff0:  00000000  [fcfdfeff]  00000001   bf000000 

# desired state after push-n-zero-bytes:
# 0 a: bdffff90:  00000000   00000000   00000000   00000000 
# 0 a: bdffffa0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffb0:  00000000   00000000   00000000   bdffffec 
# 0 a: bdffffc0:  0900012a   bdffffd0   00000020   090000d1 
# 0 a: bdffffd0: [rrrrrrrr]  00000000   00000000   00000000 
# 0 a: bdffffe0:  00000000   00000000   00000000   00000000 
# 0 a: bdfffff0:  00000000   fcfdfeff   00000001   bf000000 

# actual state:
# 0 a: bdffff90:  00000000   00000000   00000000   00000000
# 0 a: bdffffa0:  00000000   00000000   00000000   00000000
# 0 a: bdffffb0:  00000000   00000000   00000000   bdffffec
# 0 a: bdffffc0:  09000124   bdffffd0   00000020   090000d1
# 0 a: bdffffd0: [00000000]  00000000   00000000   00000000
# 0 a: bdffffe0:  00000000   00000000   00000000   00000000
# 0 a: bdfffff0:  00000020   fcfdfeff   00000001   bf000000

# Ok, just one diff, at bdfffff0

## 9:

Entry:
    # . prologue
    89/<- %ebp 4/r32/esp
    #
    68/push 0xfcfdfeff/imm32
    b8/copy-to-eax 0x34353637/imm32
$dump-stack0:
    (push-n-zero-bytes 0x20)
$dump-stack9:
    68/push 0x20/imm32
$dump-stacka:
    b8/copy-to-eax 1/imm32/exit
    cd/syscall 0x80/imm8

push-n-zero-bytes:  # n: int
$push-n-zero-bytes:prologue:
    89/<- *Push-n-zero-bytes-ebp 5/r32/ebp  # spill ebp without affecting stack
    89/<- %ebp 4/r32/esp
$push-n-zero-bytes:copy-ra:
$dump-stack1:
    # -- esp = ebp
    50/push-eax
$dump-stack2:
    # -- esp+8 = ebp+4
    # -- esp+4 = ebp
    8b/-> *(esp+4) 0/r32/eax
$dump-stack3:
    2b/subtract *(ebp+4) 4/r32/esp
$dump-stack4:
    # -- esp+4+n = ebp
    89/<- *(esp+4) 0/r32/eax
$dump-stack5:
    58/pop-to-eax
    # -- esp+n = ebp
$push-n-zero-bytes:bulk-cleaning:
$dump-stack6:
    89/<- *Push-n-zero-bytes-esp 4/r32/esp
    81 0/subop/add *Push-n-zero-bytes-esp 4/imm32
$dump-stack7:
    81 0/subop/add *(ebp+4) 4/imm32
    (zero-out *Push-n-zero-bytes-esp *(ebp+4))  # n
$push-n-zero-bytes:epilogue:
$dump-stack8:
    8b/-> *Push-n-zero-bytes-ebp 5/r32/ebp  # restore spill
    c3/return

zero-out:  # start: (addr byte), len: int
    # pseudocode:
    #   curr/esi = start
    #   i/ecx = 0
    #   while true
    #     if (i >= len) break
    #     *curr = 0
    #     ++curr
    #     ++i
    #
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    50/push-eax
    51/push-ecx
    52/push-edx
    56/push-esi
    # curr/esi = start
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
    # var i/ecx: int = 0
    31/xor                          3/mod/direct    1/rm32/ecx    .           .             .           1/r32/ecx   .               .                 # clear ecx
    # edx = len
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           2/r32/edx   0xc/disp8       .                 # copy *(ebp+12) to edx
$zero-out:loop:
    # if (i >= len) break
    39/compare                      3/mod/direct    1/rm32/ecx    .           .             .           2/r32/edx   .               .                 # compare ecx with edx
    7d/jump-if->=  $zero-out:end/disp8
    # *curr = 0
    c6          0/subop/copy        0/mod/direct    6/rm32/esi    .           .             .           .           .               0/imm8            # copy byte to *esi
    # ++curr
    46/increment-esi
    # ++i
    41/increment-ecx
    eb/jump  $zero-out:loop/disp8
$zero-out:end:
    # . restore registers
    5e/pop-to-esi
    5a/pop-to-edx
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

== data
Push-n-zero-bytes-ebp:  # (addr int)
  0/imm32
Push-n-zero-bytes-esp:  # (addr int)
  0/imm32
== code

# stack at dump-stack0:
# 0 a: bdffffb0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffc0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffd0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffe0:  00000000   00000000   00000000   00000000 
# 0 a: bdfffff0:  00000000  [fcfdfeff]  00000001   bf000000 

# desired state after push-n-zero-bytes:
# 0 a: bdffff90:  00000000   00000000   00000000   00000000 
# 0 a: bdffffa0:  00000000   00000000   00000000   00000000 
# 0 a: bdffffb0:  00000000   00000000   00000000   bdffffec 
# 0 a: bdffffc0:  0900012a   bdffffd0   00000020   090000d1 
# 0 a: bdffffd0: [xxxxxxxx]  00000000   00000000   00000000 
# 0 a: bdffffe0:  00000000   00000000   00000000   00000000 
# 0 a: bdfffff0:  00000000   fcfdfeff   00000001   bf000000 

# actual state:
# 0 a: bdffff90:  00000000   00000000   00000000   00000000
# 0 a: bdffffa0:  00000000   00000000   00000000   00000000
# 0 a: bdffffb0:  00000000   00000000   00000000   bdffffec
# 0 a: bdffffc0:  0900012f   bdffffd0   00000024   090000d1
# 0 a: bdffffd0: [00000000]  00000000   00000000   00000000
# 0 a: bdffffe0:  00000000   00000000   00000000   00000000
# 0 a: bdfffff0:  00000000   fcfdfeff   00000001   bf000000
generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-11-06 10:29:37 +0000
ass='oid'>4d87267 ^ 
11074e0 ^



4120bca ^



















8af4130 ^

8af4130 ^

a0a2564 ^

dc4c58d ^

8af4130 ^



a0a2564 ^


4d87267 ^








8af4130 ^


b4f90ec ^

8af4130 ^




4120bca ^



4d87267 ^




11074e0 ^


8af4130 ^


4d87267 ^

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#define _BSD_SOURCE
#define _DEFAULT_SOURCE

#define _XOPEN_SOURCE 700

#include <dirent.h>
#include <errno.h>
#include <fnmatch.h>
#include <getopt.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include "config.h"
#include "ignore.h"

extern char *__progname;

struct ignores *global_ignores;
struct ignores *config_ignores;
struct ignores *local_ignores;

struct switches {
	int count;
	int invert;
	int limit;
	int substring;
	int wholename;
};

int read_links = 0;

static void usage(char *error) {
	if (error != NULL) {
		fprintf(stderr, "Error: %s\n\n", error);
	}

	fprintf(stderr,
		"usage: %s [-d directory] [-c config] [-lsvw] pattern ...\n",
		__progname);
}

static int is_child(char *dirname) {
	if (strcmp("..", dirname) == 0 || strcmp(".", dirname) == 0) {
		return 0;
	}

	return 1;
}

static int excluded(const char *name) {
	if (!fnmatch("/proc/*", name, 0)) {
		return 1;
	}

	if (global_ignores != NULL) {
		for (int i = 0; i < global_ignores->size; i++) {
			int res = fnmatch(global_ignores->list[i], name, 0);

			if (res == 0) {
				return 1;
			}
		}
	}

	if (config_ignores != NULL) {
		for (int i = 0; i < config_ignores->size; i++) {
			int res = fnmatch(config_ignores->list[i], name, 0);

			if (res == 0) {
				return 1;
			}
		}
	}

	if (local_ignores != NULL) {
		for (int i = 0; i < local_ignores->size; i++) {
			int res = fnmatch(local_ignores->list[i], name, 0);

			if (res == 0) {
				return 1;
			}
		}
	}

	return 0;
}

/* return 1 if breaking early (e.g. reaching limit) otherwise return 0 */
static int recurse_find(char **patterns, int *pattern_count,
	const char *dirname, struct switches *switches) {
	DIR *dir;

	char path[MAXPATHLEN] = {'\0'};
	strcat(path, dirname);
	dir = opendir(path);

	if (dir != NULL && !excluded(dirname)) {
		struct dirent *entry;

		while ((entry = readdir(dir)) != NULL) {
			int matched = 0;
			int p = 0;

			char full_path[MAXPATHLEN] = {'\0'};
			strcat(full_path, path);

			if (full_path[strlen(full_path) - 1] != '/') {
				strcat(full_path, "/");
			}

			strcat(full_path, entry->d_name);

			struct stat entry_stat;

			if ((read_links ? stat : lstat)(full_path, &entry_stat)) {
				perror("stat");
				exit(EXIT_FAILURE);
				continue;
			}

			if (entry_stat.st_mode & S_IFDIR) {
				if (is_child(entry->d_name) && !excluded(entry->d_name)) {
					if (recurse_find(
							patterns, pattern_count, full_path, switches)) {
						closedir(dir);
						return 1;
					};
				}
			} else if (entry_stat.st_mode & S_IFREG) {
				if (excluded(entry->d_name)) {
					continue;
				}

				for (; p < *pattern_count; p++) {
					char *pattern = patterns[p];

					if (switches->substring) {
						if (strstr(
								switches->wholename ? full_path : entry->d_name,
								pattern) != NULL) {
							matched = 1;
						}
					} else {
						if (fnmatch(pattern,
								switches->wholename ? full_path : entry->d_name,
								0) == 0) {
							matched = 1;
						}
					}
				}

				if (switches->invert) {
					if (matched) {
						matched = 0;
					} else {
						matched = 1;
					}
				}
			}

			if (matched) {
				if (is_child(entry->d_name) != 0) {
					printf("%s\n", full_path);
				}

				if (switches->limit > 0 &&
					++switches->count == switches->limit) {
					closedir(dir);
					return 1;
				}
			}
		} /* while */

		closedir(dir);
	} /* if */

	return 0;
}

int main(int argc, char **argv) {
	struct switches switches = {
		.count = 0,
		.invert = 0,
		.limit = 0,
		.substring = 0,
		.wholename = 0,
	};

	int ch;
	char *remainder;
	size_t len = 0;
	const char *root = ".";
	FILE *fp;
	char cwd[MAXPATHLEN];
	int unmatched_error = 0;
	char wildcard = 0;
	char *override_config_file = NULL;

	if (getcwd(cwd, MAXPATHLEN) == NULL) {
		perror("getcwd");
		exit(EXIT_FAILURE);
	}

	char *xdg_config_home = getenv("XDG_CONFIG_HOME");
	char *home = getenv("HOME");

	while ((ch = getopt(argc, argv, "c:d:l:svw")) > -1) {
		switch (ch) {
		case 'c':
			override_config_file = optarg;
			break;

		case 'd':
			root = optarg;
			break;

		case 'h':
			usage(NULL);
			exit(EXIT_SUCCESS);

		case 's':
			switches.substring = 1;
			break;

		case 'v':
			switches.invert = 1;
			break;

		case 'w':
			switches.wholename = 1;
			break;

		case 'l':
			do {
				int limit = strtol(optarg, &remainder, 10);

				if (limit < 0) {
					usage("Invalid limit.");
					exit(EXIT_FAILURE);
				}

				switches.limit = limit;
			} while (0);

			break;
		}
	}

	char config_file[xdg_config_home
						 ? (strlen(xdg_config_home) + strlen("ignore") + 3)
						 : (strlen(cwd) + strlen(".rfignore") + 1)];

	if (xdg_config_home) {
		sprintf(config_file, "%s/rf/%s", xdg_config_home, "config");
	} else {
		sprintf(config_file, "%s/.config/rf/%s", home, "config");
	}

	fp = fopen(override_config_file ? override_config_file : config_file, "r");

	if (fp != NULL) {
		while ((config_get(&len, fp)) != -1) {
			if (strlen(config_key) && strlen(config_value)) {
				if (strcmp(config_key, "symlinks") == 0) {
					if (strcmp(config_value, "true") == 0) {
						read_links = 1;
					} else if (strcmp(config_value, "false") == 0) {
						read_links = 0;
					} else {
						fprintf(stderr,
							"'%s' is not a valid value for property: %s.\n",
							config_value, config_key);
						exit(EXIT_FAILURE);
					}
				} else if (strcmp(config_key, "wholename") == 0) {
					if (strcmp(config_value, "true") == 0) {
						switches.wholename = 1;
					} else if (strcmp(config_value, "false") == 0) {
						/* default */
					} else {
						fprintf(stderr,
							"'%s' is not a valid value for property: %s.\n",
							config_value, config_key);
						exit(EXIT_FAILURE);
					}
				} else if (strcmp(config_key, "limit") == 0) {
					int limit = strtol(config_value, &remainder, 10);

					if (limit < 0) {
						fprintf(stderr, "Warning: Invalid limit, ignoring.");
					} else {
						switches.limit = limit;
					}
				} else if (strcmp(config_key, "unmatched error") == 0) {
					unmatched_error = 1;
				} else if (strcmp(config_key, "wildcard") == 0) {
					wildcard = config_value[0];
				}
			} else if (strlen(config_key)) {
				fprintf(stderr,
					"Warning: Ignoring empty config property '%s'.\n",
					config_key);
			}
		}

		fclose(fp);
	} else if (override_config_file) {
		perror("fopen");
		exit(EXIT_FAILURE);
	}

	char global_ignore_path[(strlen(home) + strlen(".rfignore") + 1)];
	char config_ignore_path[xdg_config_home
								? (strlen(xdg_config_home) + strlen("ignore") +
									  3)
								: (strlen(cwd) + strlen(".rfignore") + 1)];
	char local_ignore_path[strlen(cwd) + strlen(".rfignore") + 1];
	sprintf(global_ignore_path, "%s/%s", home, ".rfignore");
	sprintf(local_ignore_path, "%s/%s", cwd, ".rfignore");

	if (xdg_config_home) {
		sprintf(config_ignore_path, "%s/rf/%s", xdg_config_home, "ignore");
	} else {
		sprintf(config_ignore_path, "%s/.config/rf/%s", home, "ignore");
	}

	global_ignores = init_ignores(global_ignore_path);
	config_ignores = init_ignores(config_ignore_path);
	local_ignores = init_ignores(local_ignore_path);

	if (optind < argc) {
		int i = 0;
		int pattern_count = argc - optind;
		char **patterns = (char **)calloc(sizeof(char *), pattern_count);

		memset(patterns, '\0', optind);

		while (optind < argc) {
			patterns[i++] = argv[optind++];

			if (wildcard) {
				for (size_t j = 0; j < strlen(patterns[i - 1]); j++) {
					if (patterns[i - 1][j] == wildcard) {
						patterns[i - 1][j] = '*';
					}
				}
			}
		}

		if (recurse_find(patterns, &pattern_count, root, &switches)) {
			/* finished early because we reached the limit */
		};

		free(patterns);
		free_ignores(global_ignores);
		free_ignores(config_ignores);
		free_ignores(local_ignores);

		if (unmatched_error && switches.count == 0) {
			exit(EXIT_FAILURE);
		}
	} else {
		usage(NULL);
	}

	exit(EXIT_SUCCESS);
}
generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-11-06 10:29:40 +0000