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| author | Kartik Agaram <vc@akkartik.com> | 2019-05-04 14:57:04 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2019-05-04 14:57:04 -0700 |
| commit | 8591331a7f674d71c50ea0f560e1412d56001801 (patch) | |
| tree | b08452f3256244d54bfe4234cce49841ac120bc2 | |
| parent | 37aa2bf3e8c3b22c6b87925148cf938d1c1cc185 (diff) | |
| download | mu-8591331a7f674d71c50ea0f560e1412d56001801.tar.gz | |
5143 - add a bounds check
We'll just loudly abort the entire program if the output stream isn't large enough to accept all the characters we want to print.
| -rw-r--r-- | subx/074print-int-decimal.subx | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/subx/074print-int-decimal.subx b/subx/074print-int-decimal.subx index 7f9dadc5..c6f4951c 100644 --- a/subx/074print-int-decimal.subx +++ b/subx/074print-int-decimal.subx @@ -27,9 +27,11 @@ print-int32-decimal: # out : (address stream), n : int32 # push '-' # w = out->write # curr = &out->data[out->write] + # max = &out->data[out->length] # while true # pop into EAX # if (EAX == sentinel) break + # if (curr >= max) abort # *curr = AL # ++curr # ++w @@ -45,6 +47,7 @@ print-int32-decimal: # out : (address stream), n : int32 50/push-EAX 51/push-ECX 52/push-EDX + 53/push-EBX 57/push-EDI # ten/ECX = 10 b9/copy-to-ECX 0xa/imm32 @@ -78,12 +81,18 @@ $print-int32-decimal:write: 8b/copy 0/mod/indirect 7/rm32/EDI . . . 2/r32/EDX . . # copy *EDI to EDX # curr/ECX = &out->data[out->write] 8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 2/index/EDX . 1/r32/ECX 0xc/disp8 . # copy EBX+EDX+12 to ECX + # max/EBX = &out->data[out->length] + 8b/copy 1/mod/*+disp8 7/rm32/EDI . . . 3/r32/EBX 8/disp8 . # copy *(EDI+8) to EBX + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 3/index/EBX . 3/r32/EBX 0xc/disp8 . # copy EDI+EBX+12 to EBX $print-int32-decimal:write-loop: # pop into EAX 58/pop-to-EAX # if (EAX == sentinel) break 3d/compare-EAX-and 0/imm32/sentinel 74/jump-if-equal $print-int32-decimal:write-break/disp8 + # if (curr >= max) abort + 39/compare 3/mod/direct 1/rm32/ECX . . . 3/r32/EBX . . # compare ECX with EBX + 7d/jump-if-greater-or-equal $print-int32-decimal:abort/disp8 # *curr = AL 88/copy-byte 0/mod/indirect 1/rm32/ECX . . . 0/r32/AL . . # copy AL to byte at *ECX # ++curr @@ -97,6 +106,7 @@ $print-int32-decimal:write-break: $print-int32-decimal:end: # . restore registers 5f/pop-to-EDI + 5b/pop-to-EBX 5a/pop-to-EDX 59/pop-to-ECX 58/pop-to-EAX |