server: decode Windows OEM output to UTF-8 in built-in tools - #26597
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allozaur merged 1 commit intoAug 4, 2026
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a child process writes in the OEM code page, which is not UTF-8 on a western Windows install, so accented output reaches the JSON layer as invalid bytes and gets replaced there, silently losing the characters run() spawns without a console, so the child never inherits the console code page and GetOEMCP is the one that applies decode with MB_ERR_INVALID_CHARS so a wrong code page returns the text untouched instead of emitting replacement characters, and pass text that already decodes as UTF-8 through so a child emitting UTF-8 is never decoded twice the check drops an incomplete trailing sequence before validating, since a streamed chunk can end in the middle of a multi-byte character
ngxson
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Aug 4, 2026
allozaur
approved these changes
Aug 4, 2026
smalinin
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Aug 4, 2026
…g#26597) a child process writes in the OEM code page, which is not UTF-8 on a western Windows install, so accented output reaches the JSON layer as invalid bytes and gets replaced there, silently losing the characters run() spawns without a console, so the child never inherits the console code page and GetOEMCP is the one that applies decode with MB_ERR_INVALID_CHARS so a wrong code page returns the text untouched instead of emitting replacement characters, and pass text that already decodes as UTF-8 through so a child emitting UTF-8 is never decoded twice the check drops an incomplete trailing sequence before validating, since a streamed chunk can end in the middle of a multi-byte character
satindergrewal
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Aug 11, 2026
…g#26597) a child process writes in the OEM code page, which is not UTF-8 on a western Windows install, so accented output reaches the JSON layer as invalid bytes and gets replaced there, silently losing the characters run() spawns without a console, so the child never inherits the console code page and GetOEMCP is the one that applies decode with MB_ERR_INVALID_CHARS so a wrong code page returns the text untouched instead of emitting replacement characters, and pass text that already decodes as UTF-8 through so a child emitting UTF-8 is never decoded twice the check drops an incomplete trailing sequence before validating, since a streamed chunk can end in the middle of a multi-byte character
satindergrewal
pushed a commit
to satindergrewal/llama.cpp
that referenced
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Aug 12, 2026
…g#26597) a child process writes in the OEM code page, which is not UTF-8 on a western Windows install, so accented output reaches the JSON layer as invalid bytes and gets replaced there, silently losing the characters run() spawns without a console, so the child never inherits the console code page and GetOEMCP is the one that applies decode with MB_ERR_INVALID_CHARS so a wrong code page returns the text untouched instead of emitting replacement characters, and pass text that already decodes as UTF-8 through so a child emitting UTF-8 is never decoded twice the check drops an incomplete trailing sequence before validating, since a streamed chunk can end in the middle of a multi-byte character
brittlewis12
pushed a commit
to brittlewis12/llama.cpp
that referenced
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Aug 17, 2026
…g#26597) a child process writes in the OEM code page, which is not UTF-8 on a western Windows install, so accented output reaches the JSON layer as invalid bytes and gets replaced there, silently losing the characters run() spawns without a console, so the child never inherits the console code page and GetOEMCP is the one that applies decode with MB_ERR_INVALID_CHARS so a wrong code page returns the text untouched instead of emitting replacement characters, and pass text that already decodes as UTF-8 through so a child emitting UTF-8 is never decoded twice the check drops an incomplete trailing sequence before validating, since a streamed chunk can end in the middle of a multi-byte character
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Overview
Built-in tool output on Windows is decoded from the OEM code page instead of reaching the JSON layer as invalid bytes, which silently replaced every accented character with U+FFFD.
Additional information
Follow-up for #26518 but not only that.
Before
After
Requirements