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Add withBuffer

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... to avoid non-standard, unidiomatic alloca.
This commit is contained in:
Robert Hensing 2022-01-06 14:31:23 +01:00
parent d038a67bd3
commit 55c58580be
2 changed files with 21 additions and 18 deletions
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10
src/libstore/derivations.cc
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@ -272,15 +272,8 @@ Derivation parseDerivation(const Store & store, std::string && s, std::string_vi
static void printString(string & res, std::string_view s) static void printString(string & res, std::string_view s)
{ {
char * buf;
size_t bufSize = s.size() * 2 + 2; size_t bufSize = s.size() * 2 + 2;
std::unique_ptr<char[]> dynBuf; withBuffer<void, char>(bufSize, [&](char buf[]) {
if (bufSize < 0x10000) {
buf = (char *)alloca(bufSize);
} else {
dynBuf = decltype(dynBuf)(new char[bufSize]);
buf = dynBuf.get();
}
char * p = buf; char * p = buf;
*p++ = '"'; *p++ = '"';
for (auto c : s) for (auto c : s)
@ -291,6 +284,7 @@ static void printString(string & res, std::string_view s)
else *p++ = c; else *p++ = c;
*p++ = '"'; *p++ = '"';
res.append(buf, p - buf); res.append(buf, p - buf);
});
} }

9
src/libutil/util.hh
View file

@ -671,5 +671,14 @@ template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
std::string showBytes(uint64_t bytes); std::string showBytes(uint64_t bytes);
template<typename R = void, typename T = char> inline R withBuffer(size_t size, std::function<R (T[])> fun) {
if (size < 0x10000) {
T buf[size];
return fun(buf);
} else {
auto buf = std::unique_ptr<T[]>(new T[size]);
return fun(buf.get());
}
}
} }