criu/log: properly handle truncated length from vsnprintf #2819
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vsnprintf does not always return the number of bytes actually written to the buffer. If the output was truncated due to the buffer limit, the return value is the total number of bytes which WOULD have been written to the final string if enough space had been available. This means we must cap the return value to the buffer size excluding the terminating null byte to correctly calculate the log entry size. Signed-off-by: Andrei Vagin <avagin@google.com>
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One more (minor) issue found.
Using sizeof(hdr) where hdr is a pointer gives the size of the pointer, not the size of the structure it points to. Reported-by: Kir Kolyshkin <kolyshkin@gmail.com> Signed-off-by: Andrei Vagin <avagin@gmail.com>
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This was referenced Nov 12, 2025
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vsnprintf does not always return the number of bytes actually written to the buffer.
If the output was truncated due to the buffer limit, the return value is the total number of bytes which WOULD have been written to the final string if enough space had been available.
This means we must cap the return value to the buffer size excluding the terminating null byte to correctly calculate the log entry size.
Fixes #2781