Fix libc edge-case correctness bugs#122
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stikonas
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May 14, 2026
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Fix several libc edge cases that can write past caller buffers, copy past a shrunk allocation, leave unterminated strings, or continue after failed stream allocation.
The most important fixes cover
fgets,vsnprintf,strncpy,strnlen_s,memmove,realloc,setenv,fread, and failedfopen/fdopensetup. Reduced versions of the old code were validated with GCC AddressSanitizer/UBSan, which reproduced the buffer overflows, NULL write, and missing-return issues.