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Improve format2ostream.

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Instead of looping to find a big enough buffer, we can call the
correct function to calculate it, remembering to add an extra
character for NUL termination.

We also correctly do a va_copy of the args to avoid crashes on
some platforms.
This commit is contained in:
Bruce Mitchener 2018-10-21 19:28:31 +07:00
parent 21cf218a9f
commit 129353542c
1 changed files with 15 additions and 31 deletions
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46
src/util/warning.cpp
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@ -16,8 +16,8 @@ Author:
Revision History:
--*/
#include<stdio.h>
#include<stdarg.h>
#include <stdio.h>
#include <stdarg.h>
#include "util/error_codes.h"
#include "util/util.h"
@ -86,38 +86,22 @@ void disable_error_msg_prefix() {
void format2ostream(std::ostream & out, char const* msg, va_list args) {
svector<char> buff;
#if !defined(_WINDOWS) && defined(_AMD64_)
// see comment below.
buff.resize(1024);
#else
buff.resize(128);
#endif
BEGIN_ERR_HANDLER();
while (true) {
int nc = VPRF(buff.c_ptr(), buff.size(), msg, args);
#if !defined(_WINDOWS) && defined(_AMD64_)
// For some strange reason, on Linux 64-bit version, va_list args is reset by vsnprintf.
// Z3 crashes when trying to use va_list args again.
// Hack: I truncate the message instead of expanding the buffer to make sure that
// va_list args is only used once.
END_ERR_HANDLER();
if (nc < 0) {
// vsnprintf didn't work, so we just print the msg
out << msg;
return;
}
if (nc >= static_cast<int>(buff.size())) {
// truncate the message
buff[buff.size() - 1] = 0;
}
out << buff.c_ptr();
return;
va_list args_copy;
va_copy(args_copy, args);
#ifdef _WINDOWS
size_t msg_len = _vscprintf(msg, args_copy);
#else
if (nc >= 0 && nc < static_cast<int>(buff.size()))
break; // success
buff.resize(buff.size()*2 + 1);
size_t msg_len = vsnprintf(NULL, 0, msg, args_copy);
#endif
}
va_end(args_copy);
// +1 is for NUL termination.
buff.resize(msg_len + 1);
VPRF(buff.c_ptr(), buff.size(), msg, args);
END_ERR_HANDLER();
out << buff.c_ptr();
}