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config/Parser: add ParseSize()

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Supports suffixes such as "kB" and "MB".
This commit is contained in:
Max Kellermann
2019-05-29 22:44:05 +02:00
parent af7970337b
commit 4eb101f046
4 changed files with 83 additions and 6 deletions
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67
src/config/Parser.cxx
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@@ -19,6 +19,7 @@
#include "Parser.hxx"
#include "util/RuntimeError.hxx"
#include "util/StringStrip.hxx"
#include "util/StringUtil.hxx"
bool
@@ -35,3 +36,69 @@ ParseBool(const char *value)
throw FormatRuntimeError("Not a valid boolean (\"yes\" or \"no\"): \"%s\"", value);
}
template<size_t OPERAND>
static size_t
Multiply(size_t value)
{
static constexpr size_t MAX_INPUT = SIZE_MAX / OPERAND;
if (value > MAX_INPUT)
throw std::runtime_error("Value too large");
return value * OPERAND;
}
size_t
ParseSize(const char *s, size_t default_factor)
{
char *endptr;
size_t value = strtoul(s, &endptr, 10);
if (endptr == s)
throw std::runtime_error("Failed to parse integer");
static constexpr size_t KILO = 1024;
static constexpr size_t MEGA = 1024 * KILO;
static constexpr size_t GIGA = 1024 * MEGA;
s = StripLeft(endptr);
bool apply_factor = false;
switch (*s) {
case 'k':
value = Multiply<KILO>(value);
++s;
break;
case 'M':
value = Multiply<MEGA>(value);
++s;
break;
case 'G':
value = Multiply<GIGA>(value);
++s;
break;
case '\0':
apply_factor = true;
break;
default:
throw std::runtime_error("Unknown size suffix");
}
/* ignore 'B' for "byte" */
if (*s == 'B') {
apply_factor = false;
++s;
}
if (*s != '\0')
throw std::runtime_error("Unknown size suffix");
if (apply_factor)
value *= default_factor;
return value;
}