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fix potential non-zero termination of a string buffer #2147

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Merged
merged 2 commits into from
May 3, 2018
Merged

fix potential non-zero termination of a string buffer #2147

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5907f68
fix potential non-zero termination of a string buffer
May 3, 2018
9609a52
simplify use of get_temporary_directory
May 3, 2018
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8 changes: 1 addition & 7 deletions src/goto-cc/compile.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -226,20 +226,14 @@ bool compilet::add_files_from_archive(
const std::string &file_name,
bool thin_archive)
{
#ifdef _WIN32
char td[MAX_PATH + 1];
#else
char td[] = "goto-cc.XXXXXX";
#endif

std::stringstream cmd;
FILE *stream;

std::string tstr = working_directory;

if(!thin_archive)
{
tstr = get_temporary_directory(td);
tstr = get_temporary_directory("goto-cc.XXXXXX");

if(tstr=="")
{
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19 changes: 10 additions & 9 deletions src/util/tempdir.cpp
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Expand Up @@ -15,7 +15,7 @@ Author: CM Wintersteiger
#endif

#include <cstdlib>
#include <cstring>
#include <vector>

#if defined(__linux__) || \
defined(__FreeBSD_kernel__) || \
Expand All @@ -34,17 +34,18 @@ std::string get_temporary_directory(const std::string &name_template)
std::string result;

#ifdef _WIN32
DWORD dwBufSize = MAX_PATH;
char lpPathBuffer[MAX_PATH];
DWORD dwBufSize = MAX_PATH+1;
char lpPathBuffer[MAX_PATH+1];
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The documentation of GetTempFileName says that it is a precondition that the path not be longer than MAX_PATH–14. Hence those changes seem unnecessary.

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Yes; but that may be subtle. The documentation of GetTempPathA says that the maximal return value is MAX_PATH+1; this is the length of the buffer required.

DWORD dwRetVal = GetTempPathA(dwBufSize, lpPathBuffer);

if(dwRetVal > dwBufSize || (dwRetVal == 0))
throw "GetTempPath failed"; // NOLINT(readability/throw)

char t[MAX_PATH];

strncpy(t, name_template.c_str(), MAX_PATH);
// GetTempFileNameA produces <path>\<pre><uuuu>.TMP
// where <pre> = "TLO"
// Thus, we must make the buffer 1+3+4+1+3=12 characters longer.

char t[MAX_PATH];
UINT uRetVal=GetTempFileNameA(lpPathBuffer, "TLO", 0, t);
if(uRetVal == 0)
throw "GetTempFileName failed"; // NOLINT(readability/throw)
Expand All @@ -64,9 +65,9 @@ std::string get_temporary_directory(const std::string &name_template)
prefixed_name_template+='/';
prefixed_name_template+=name_template;

char t[1000];
strncpy(t, prefixed_name_template.c_str(), 1000);
const char *td = mkdtemp(t);
std::vector<char> t(prefixed_name_template.begin(), prefixed_name_template.end());
t.push_back('\0'); // add the zero
const char *td = mkdtemp(t.data());
if(!td)
throw "mkdtemp failed";
result=std::string(td);
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