mirrors/cosmopolitan
1
0
Fork 0
mirror of https://github.com/jart/cosmopolitan.git synced 2025-08-09 03:10:27 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Make ape.S shell script magic less prone to accidental breakage

Browse source 
The metal boot sector code was wrapped in a single-quoted
string, like so:

    MZqFpD='
    ...MZ HEADER...
    ...E_LFANEW...
    ...BIOS BOOT SECTOR...'

This might break the shell code loader if the boot sector code
contains a 0x27 (single quote) byte.  This patch wraps the
boot sector code in a here-document instead:

    MZqFpD='
    ...MZ HEADER...' <<'@'
    ...E_LFANEW...
    ...BIOS BOOT SECTOR...
    @

This is harder to break — when interpreted as a shell script,
the code can only accidentally terminate the here-document
if there is a "\n@\n" sequence inside the BIOS boot portion.
This commit is contained in:
tkchia 2022-09-28 17:07:25 +00:00
parent 09811e739f
commit 0bf8e580c9
1 changed files with 2 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

3
ape/ape.S
View file

@ -125,6 +125,7 @@ ape_mz: .asciz "MZqFpD='\n" # Mark 'Zibo' Joseph Zbikowski
.org 0x24 # MZ: bytes reserved for you
.ascii "JT" # MZ: OEM identifier
.short 0 # MZ: OEM information
.ascii "' <<'@'\n"
.org 0x40-4 # MZ: bytes reserved for you
#if SupportsWindows() || SupportsMetal()
.long RVA(ape_pe) # PE: the new technology
@ -549,7 +550,7 @@ ape_disk:
the bourne executable & linkable format */
#if SupportsWindows() || SupportsMetal() || SupportsXnu()
apesh: .ascii "'\n#'\"\n" # sixth edition shebang
apesh: .ascii "\n@\n#'\"\n" # sixth edition shebang
// Until all operating systems can be updated to support APE,
// we have a beautiful, yet imperfect workaround, which is to
// modify the binary to follow the local system's convention.