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// file : msvc-filter/msvc-filter.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#include <sys/time.h> // timeval
#include <sys/select.h>
#include <ios> // ios_base::failure
#include <string>
#include <cstring> // strchr()
#include <ostream>
#include <iostream>
#include <algorithm> // max()
#include <system_error>
#include <unordered_map>
#include <butl/path> // path::traits::realize()
#include <butl/utility> // alpha()
#include <butl/process>
#include <butl/fdstream>
using namespace std;
using namespace butl;
// Cached mapping of Windows paths to the corresponding POSIX paths.
//
static unordered_map<string, string> path_cache;
inline static bool
path_separator (char c)
{
return c == '\\' || c == '/';
}
// Replace absolute Windows paths encountered in the line with their POSIX
// representation. Write the result followed by a newline to the stream. Throw
// ostream::failure on IO failures, system_error on others.
//
static void
filter (const char* s, size_t n, ostream& os)
{
// Strip the terminating 0xOD character if present.
//
if (n > 0 && s[n - 1] == '\r')
--n;
// Translate absolute Windows paths back to POSIX. The hard part here is to
// determing the end of the path. For example, the error location has the
// 'X:\...\foo(10):' form. However, we cannot assume that '(' ends the path;
// remember 'Program Files (x86)'.
//
// To sidestep this whole mess we are going to use this trick: instead of
// translating the whole path we will only translate its directory part,
// that is, the longest part that still ends with the directory
// separator. We will also still recognize ':' and '\'' as path terminators
// as well as space if it is the first character in the component.
//
// We also pass the path through realpath in order to get the actual path
// rather than Wine's dosdevices links.
//
const char* b (s);
const char* e (s + n);
for (;;)
{
const char* p (b);
// Line tail should be at least 3 characters long to contain an absolute
// Windows path.
//
bool no_path (e - b < 3);
if (!no_path)
{
// An absolute path must begin with [A-Za-z]:[\/] (like C:\).
//
const char* pe (e - 3);
for (; p != pe; ++p)
{
if (alpha (p[0]) && p[1] == ':' && path_separator (p[2]))
break;
}
no_path = p == pe;
}
// Bail out if we reached the end of the line with no path found.
//
if (no_path)
{
os.write (b, e - b);
os.put ('\n');
break;
}
os.write (b, p - b); // Print characters that preceed the path.
b = p; // Beginnig of the path.
const char* pe (p + 3); // End of the last path component.
for (p = pe; p != e; ++p)
{
char c (*p);
if (c == ':' || c == '\'' || (p == pe && c == ' '))
break;
if (path_separator (c))
pe = p + 1;
}
// Convert the Windows directory path to POSIX. First check if the mapping
// is already cached.
//
string d (b, pe - b);
auto i (path_cache.find (d));
b = pe;
if (i == path_cache.end ())
{
const char* args[] = {"winepath", "-u", d.c_str (), nullptr};
// Redirect stderr to /dev/null not to mess the output (read more in
// main()).
//
process pr (args, 0, -1, -2);
ifdstream is (pr.in_ofd);
string pd;
getline (is, pd);
is.close ();
// It's unknown what can cause winepath to fail. At least not a
// non-existent path. Anyway will consider it fatal.
//
if (!pr.wait ())
throw system_error (ECHILD, system_category ());
try
{
path::traits::realize (pd);
assert (!pd.empty ());
// Restore the trailing slash.
//
if (pd.back () != '/')
pd += '/';
}
catch (const invalid_path&)
{
// The path doesn't exist. Let's keep it as provided by winepath.
}
i = path_cache.emplace (move (d), move (pd)).first;
}
os.write (i->second.c_str (), i->second.size ());
}
}
int
main (int argc, char* argv[])
try
{
auto print_usage = [argv]()
{
cerr << "usage: " << argv[0]
<< " <diag> <wine-path> <program-path> [arguments]" << endl;
};
if (argc < 2)
{
cerr << "error: diag stream file descriptor expected" << endl;
print_usage ();
return 1;
}
string d (argv[1]);
if (d != "1" && d != "2")
{
cerr << "error: invalid diag stream file descriptor" << endl;
print_usage ();
return 1;
}
size_t diag (stoi (d));
if (argc < 3)
{
cerr << "error: wine path expected" << endl;
print_usage ();
return 1;
}
if (argc < 4)
{
cerr << "error: program path expected" << endl;
print_usage ();
return 1;
}
// After arguments are validated we will not be printing error messages on
// failures not to mess the filtered output of the child Windows process.
// Note that in the case of a failure the text from STDERR can be treated by
// the calling process as a build tool diagnostics so our message most
// likelly would be misinterpreted.
//
// The reason we still print error message on the arguments parsing failure
// is that it is likely to be a program misuse rather than runtime error.
//
// If diag is 1 then both stdout and stderr of the child process are read and
// filtered (achieved by redirecting stdout to stderr). Otherwise the data
// read from child stdout is proxied to own stdout (sounds redundant but
// prevents Windows process from writing to /dev/null directly which is known
// to be super slow). The filtered data is written to the diag file
// descriptor.
//
process pr (const_cast <const char**> (&argv[2]), 0, diag == 1 ? 2 : -1, -1);
// Stream to filter from.
//
ifdstream isf (pr.in_efd, fdstream_mode::non_blocking);
// Stream to proxy from.
//
ifdstream isp (diag == 1 ? -1 : pr.in_ofd, fdstream_mode::non_blocking);
ostream& osf (diag == 1 ? cout : cerr); // Stream to filter to.
ostream* osp (diag == 1 ? nullptr : &cout); // Stream to proxy to.
// The presense of proxy input and output streams must be correlated.
//
assert (isp.is_open () == (osp != nullptr));
// Will be using ostream::write() solely, so badbit is the only one which
// needs to be set.
//
osf.exceptions (ostream::badbit);
if (osp != nullptr)
osp->exceptions (ostream::badbit);
const size_t nbuf (8192);
char buf[nbuf + 1]; // Reserve one extra for terminating '\0'.
bool terminated (false); // Required for Wine bug workaround (see below).
string line; // Incomplete line.
while (isf.is_open () || isp.is_open ())
{
// Use timeout to workaround the wineserver bug: sometimes the file
// descriptor that corresponds to the redirected STDERR of a Windows
// process is not closed when that process is terminated. So if STDERR is
// redirected to a pipe (as in our case) the reading peer does not receive
// EOF and hangs forever. We will consider the no-data 100 ms period for an
// exited process to represent such a situation.
//
// Note that it is wineserver who owns the corresponding file descriptor
// not a wine process which runs the Windows program.
//
// Note also that some implementations of select() can modify the timeout
// value so it is essential to reinitialize it prior to every select()
// call.
//
timeval timeout {0, 100000};
fd_set rd;
FD_ZERO (&rd);
if (isf.is_open ())
FD_SET (isf.fd (), &rd);
if (isp.is_open ())
FD_SET (isp.fd (), &rd);
int r (select (max (isf.fd (), isp.fd ()) + 1,
&rd,
nullptr,
nullptr,
&timeout));
if (r == -1)
{
if (errno == EINTR)
continue;
throw system_error (errno, system_category ());
}
// Timeout occured. Apply wineserver bug workaround if required.
//
bool status;
if (r == 0 && pr.try_wait (status))
{
if (!status)
// Handle the child failure outside the loop.
//
break;
// Presumably end of the data reached.
//
if (!terminated)
{
// We don't know when the process exited. It possibly wasn't writing
// to the output for quite a long time before terminating a nanosecond
// ago. But let's wait for another timeout to be sure that the process
// has terminated a long (enough) time ago.
//
terminated = true;
continue;
}
break;
}
// Proxy the data if requested.
//
if (FD_ISSET (isp.fd (), &rd))
{
for (;;)
{
// The only leagal way to read from non-blocking ifdstream.
//
streamsize n (isp.readsome (buf, nbuf));
if (isp.eof ())
{
// End of the data to be proxied reached.
//
isp.close ();
break;
}
if (n == 0)
break; // No data available, try later.
assert (osp != nullptr);
osp->write (buf, n);
}
}
// Read & filter.
//
if (FD_ISSET (isf.fd (), &rd))
{
for (;;)
{
// The only leagal way to read from non-blocking ifdstream.
//
streamsize n (isf.readsome (buf, nbuf));
if (isf.eof ())
{
// End of the data to be filtered reached.
//
isf.close ();
break;
}
if (n == 0)
break; // No data available, try later.
// Filter buffer content line by line. Concatenate the line with an
// incomplete one if produced on the previous iteration. Save the last
// line if incomplete (not terminated with '\n').
//
buf[n] = '\0';
const char* b (buf);
for (;;)
{
const char* le (strchr (b, '\n'));
if (le == nullptr)
{
line += b;
break;
}
if (!line.empty ())
{
line.append (b, le - b);
filter (line.c_str (), line.size (), osf);
line.clear ();
}
else
filter (b, le - b, osf);
b = le + 1; // Skip the newline character.
}
}
}
}
if (!line.empty ())
filter (line.c_str (), line.size (), osf);
isf.close ();
isp.close ();
// Passing through the exact child process exit status on failure tends to be
// a bit hairy as involves usage of WIFEXITED(), WEXITSTATUS() and handling
// the situation when the process is terminated with a signal and so exit
// code is unavailable. Lets implement when really required.
//
return pr.wait () ? 0 : 1;
}
catch (const ios_base::failure&)
{
return 1;
}
// Also handles process_error exception (derived from system_error).
//
catch (const system_error&)
{
return 1;
}
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