69 lines
2.9 KiB
C
69 lines
2.9 KiB
C
// 31 may 2019
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// only requires strsafe_header.h if you don't define sharedbitsStatic as static
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#include "start.h"
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#ifdef sharedbitsInternalError
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#define sharedbitsprivInternalError sharedbitsInternalError
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#else
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#define sharedbitsprivInternalError sharedbitsPrefixName(InternalError)
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#ifdef sharedbitsStatic
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sharedbitsStatic
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#else
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extern
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#endif
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void sharedbitsprivInternalError(const char *fmt, ...);
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#endif
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#ifndef sharedbitsNoVsnprintf
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#ifdef sharedbitsStatic
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sharedbitsStatic
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#endif
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int sharedbitsPrefixName(Vsnprintf)(char *s, size_t n, const char *fmt, va_list ap)
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{
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#ifdef _WIN32
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int ret;
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if (s == NULL && n == 0)
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return _vscprintf(fmt, ap);
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// TODO figure out how to disambiguate between encoding errors (returns negative value; does not have documented errno values), other errors (returns negative value; errno == EINVAL), and truncations (returns -1; does not have documented errno values)
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ret = vsnprintf_s(s, n, _TRUNCATE, fmt, ap);
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if (ret == -1)
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// TODO make this safe
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return (int) n;
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return ret;
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#else
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return vsnprintf(s, n, fmt, ap);
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#endif
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}
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#endif
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#ifdef sharedbitsStatic
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sharedbitsStatic
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#endif
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char *sharedbitsPrefixName(Strncpy)(char *dest, const char *src, size_t n)
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{
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#ifdef _WIN32
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errno_t err;
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// because strncpy_s() doesn't do this
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memset(dest, '\0', n * sizeof (char));
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err = strncpy_s(dest, n, src, _TRUNCATE);
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if (err != 0 && err != STRUNCATE)
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// Yes folks, apparently strerror() is unsafe (it's not reentrant, but that's not the point of the MSVC security functions; that's about buffer overflows, and as you'll soon see there really is no need for what the "safe' version is given reentrancy concerns), and not only that, but the replacement, strerror_s(), requires copying and allocation! it's almost like they were TRYING to shove as many error conditions as possible in!
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// Oh, and you can't just use _sys_errlist[] to bypass this, because even that has a deprecation warning, telling you to use strerror() instead, which in turn sends you back to strerror_s()!
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// Of course, the fact _sys_errlist[] is a thing and that it's deprecated out of security and not reentrancy shows that the error strings returned by strerror()/strerror_s() are static and unchanging throughout the lifetime of the program, so a truly reentrant strerror_s() would just return the raw const string array directly, or a placeholder like "unknown error" otherwise, but that would be too easy!
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// And even better, there's no way to get the length of the error message, so you can't even dynamically allocate a large enough buffer if you wanted to!
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// (Furthermore, cppreference.com says there's strerrorlen_s(), but a) fuck C11, and b) MSDN does not concur.)
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// So, alas, you'll have to live with just having the error code; sorry.
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sharedbitsprivInternalError("error calling strncpy_s(): %d", err);
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return dest;
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#else
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return strncpy(dest, src, n);
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#endif
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}
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#undef sharedbitsprivInternalError
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#include "end.h"
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