[Emc-commit] [LinuxCNC/linuxcnc] 716a3a: fix: cast char to unsigned char in get_uint16 to p...

[andypugh <no...@gi...>]

  Branch: refs/heads/master
  Home:   https://github.com/LinuxCNC/linuxcnc
  Commit: 716a3ac7ca439ba1c8b80f1b6810530414c29508
      https://github.com/LinuxCNC/linuxcnc/commit/716a3ac7ca439ba1c8b80f1b6810530414c29508
  Author: is-primary-dev <215...@us...>
  Date:   2026-05-16 (Sat, 16 May 2026)

  Changed paths:
    M src/rtapi/uspace_rtapi_main.cc

  Log Message:
  -----------
  fix: cast char to unsigned char in get_uint16 to prevent sign-extension

std::vector<char> uses signed char on x86-64 GCC. When a byte >= 0x80
is cast directly to uint16_t, it sign-extends (e.g. 0xA3 becomes
0xFFA3), corrupting the deserialized argument length in the rtapi_app
socket protocol. This causes "arg size not in buffer range" errors for
any loadrt argument longer than 127 bytes.

Cast through unsigned char before widening to uint16_t. The companion
push_uint16 already masks with 0xff, so only the read side was affected.


  Commit: 2d341e419d2428457a4c89ef38a04e0484fe4d3f
      https://github.com/LinuxCNC/linuxcnc/commit/2d341e419d2428457a4c89ef38a04e0484fe4d3f
  Author: andypugh <an...@bo...>
  Date:   2026-05-24 (Sun, 24 May 2026)

  Changed paths:
    M src/rtapi/uspace_rtapi_main.cc

  Log Message:
  -----------
  Merge pull request #4035 from is-primary-dev/fix-rtapi-get-uint16-sign-extension

fix: cast char to unsigned char in get_uint16 to prevent sign-extension


Compare: https://github.com/LinuxCNC/linuxcnc/compare/8ea36d388ce0...2d341e419d24

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