src/unix/stackwalk.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/unix/stackwalk.cpp
   3 // Purpose:     wxStackWalker implementation for Unix/glibc
   4 // Author:      Vadim Zeitlin
   5 // Modified by:
   6 // Created:     2005-01-18
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 2005 Vadim Zeitlin <vadim@wxwindows.org>
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 // ============================================================================
  13 // declarations
  14 // ============================================================================
  15
  16 // ----------------------------------------------------------------------------
  17 // headers
  18 // ----------------------------------------------------------------------------
  19
  20 #include "wx/wxprec.h"
  21
  22 #ifdef __BORLANDC__
  23     #pragma hdrstop
  24 #endif
  25
  26 #if wxUSE_STACKWALKER
  27
  28 #ifndef WX_PRECOMP
  29     #include "wx/string.h"
  30     #include "wx/app.h"
  31     #include "wx/log.h"
  32     #include "wx/utils.h"
  33 #endif
  34
  35 #include "wx/stackwalk.h"
  36 #include "wx/stdpaths.h"
  37
  38 #include <execinfo.h>
  39
  40 #ifdef HAVE_CXA_DEMANGLE
  41     #include <cxxabi.h>
  42 #endif // HAVE_CXA_DEMANGLE
  43
  44 // ----------------------------------------------------------------------------
  45 // tiny helper wrapper around popen/pclose()
  46 // ----------------------------------------------------------------------------
  47
  48 class wxStdioPipe
  49 {
  50 public:
  51     // ctor parameters are passed to popen()
  52     wxStdioPipe(const char *command, const char *type)
  53     {
  54         m_fp = popen(command, type);
  55     }
  56
  57     // conversion to stdio FILE
  58     operator FILE *() const { return m_fp; }
  59
  60     // dtor closes the pipe
  61     ~wxStdioPipe()
  62     {
  63         if ( m_fp )
  64             pclose(m_fp);
  65     }
  66
  67 private:
  68     FILE *m_fp;
  69
  70     wxDECLARE_NO_COPY_CLASS(wxStdioPipe);
  71 };
  72
  73 // ============================================================================
  74 // implementation
  75 // ============================================================================
  76
  77 // ----------------------------------------------------------------------------
  78 // wxStackFrame
  79 // ----------------------------------------------------------------------------
  80
  81 void wxStackFrame::OnGetName()
  82 {
  83     if ( !m_name.empty() )
  84         return;
  85
  86     // we already tried addr2line in wxStackWalker::InitFrames: it always
  87     // gives us demangled names (even if __cxa_demangle is not available) when
  88     // the function is part of the ELF (when it's in a shared object addr2line
  89     // will give "??") and because it seems less error-prone.
  90     // when it works, backtrace_symbols() sometimes returns incorrect results
  91
  92     // format is: "module(funcname+offset) [address]" but the part in
  93     // parentheses can be not present
  94     wxString syminfo = wxString::FromAscii(m_syminfo);
  95     const size_t posOpen = syminfo.find(wxT('('));
  96     if ( posOpen != wxString::npos )
  97     {
  98         const size_t posPlus = syminfo.find(wxT('+'), posOpen + 1);
  99         if ( posPlus != wxString::npos )
 100         {
 101             const size_t posClose = syminfo.find(wxT(')'), posPlus + 1);
 102             if ( posClose != wxString::npos )
 103             {
 104                 if ( m_name.empty() )
 105                 {
 106                     m_name.assign(syminfo, posOpen + 1, posPlus - posOpen - 1);
 107
 108 #ifdef HAVE_CXA_DEMANGLE
 109                     int rc = -1;
 110                     char *cppfunc = __cxxabiv1::__cxa_demangle
 111                                     (
 112                                         m_name.mb_str(),
 113                                         NULL, // output buffer (none, alloc it)
 114                                         NULL, // [out] len of output buffer
 115                                         &rc
 116                                     );
 117                     if ( rc == 0 )
 118                         m_name = wxString::FromAscii(cppfunc);
 119
 120                     free(cppfunc);
 121 #endif // HAVE_CXA_DEMANGLE
 122                 }
 123
 124                 unsigned long ofs;
 125                 if ( wxString(syminfo, posPlus + 1, posClose - posPlus - 1).
 126                         ToULong(&ofs, 0) )
 127                     m_offset = ofs;
 128             }
 129         }
 130
 131         m_module.assign(syminfo, posOpen);
 132     }
 133     else // not in "module(funcname+offset)" format
 134     {
 135         m_module = syminfo;
 136     }
 137 }
 138
 139
 140 // ----------------------------------------------------------------------------
 141 // wxStackWalker
 142 // ----------------------------------------------------------------------------
 143
 144 // that many frames should be enough for everyone
 145 #define MAX_FRAMES          200
 146
 147 // we need a char buffer big enough to contain a call to addr2line with
 148 // up to MAX_FRAMES addresses !
 149 // NB: %p specifier will print the pointer in hexadecimal form
 150 //     and thus will require 2 chars for each byte + 3 for the
 151 //     " 0x" prefix
 152 #define CHARS_PER_FRAME    (sizeof(void*) * 2 + 3)
 153
 154 // BUFSIZE will be 2250 for 32 bit machines
 155 #define BUFSIZE            (50 + MAX_FRAMES*CHARS_PER_FRAME)
 156
 157 // static data
 158 void *wxStackWalker::ms_addresses[MAX_FRAMES];
 159 char **wxStackWalker::ms_symbols = NULL;
 160 int wxStackWalker::m_depth = 0;
 161 wxString wxStackWalker::ms_exepath;
 162 static char g_buf[BUFSIZE];
 163
 164
 165 void wxStackWalker::SaveStack(size_t maxDepth)
 166 {
 167     // read all frames required
 168     maxDepth = wxMin(WXSIZEOF(ms_addresses)/sizeof(void*), maxDepth);
 169     m_depth = backtrace(ms_addresses, maxDepth*sizeof(void*));
 170     if ( !m_depth )
 171         return;
 172
 173     ms_symbols = backtrace_symbols(ms_addresses, m_depth);
 174 }
 175
 176 void wxStackWalker::ProcessFrames(size_t skip)
 177 {
 178     wxStackFrame frames[MAX_FRAMES];
 179
 180     if (!ms_symbols || !m_depth)
 181         return;
 182
 183     // we have 3 more "intermediate" frames which the calling code doesn't know
 184     // about, account for them
 185     skip += 3;
 186
 187     // call addr2line only once since this call may be very slow
 188     // (it has to load in memory the entire EXE of this app which may be quite
 189     //  big, especially if it contains debug info and is compiled statically!)
 190     int towalk = InitFrames(frames, m_depth - skip, &ms_addresses[skip], &ms_symbols[skip]);
 191
 192     // now do user-defined operations on each frame
 193     for ( int n = 0; n < towalk - (int)skip; n++ )
 194         OnStackFrame(frames[n]);
 195 }
 196
 197 void wxStackWalker::FreeStack()
 198 {
 199     // ms_symbols has been allocated by backtrace_symbols() and it's the responsibility
 200     // of the caller, i.e. us, to free that pointer
 201     if (ms_symbols)
 202         free( ms_symbols );
 203     ms_symbols = NULL;
 204     m_depth = 0;
 205 }
 206
 207 int wxStackWalker::InitFrames(wxStackFrame *arr, size_t n, void **addresses, char **syminfo)
 208 {
 209     // we need to launch addr2line tool to get this information and we need to
 210     // have the program name for this
 211     wxString exepath = wxStackWalker::GetExePath();
 212     if ( exepath.empty() )
 213     {
 214         exepath = wxStandardPaths::Get().GetExecutablePath();
 215         if ( exepath.empty() )
 216         {
 217             wxLogDebug(wxT("Cannot parse stack frame because the executable ")
 218                        wxT("path could not be detected"));
 219             return 0;
 220         }
 221     }
 222
 223     // build the (long) command line for executing addr2line in an optimized way
 224     // (e.g. use always chars, even in Unicode build: popen() always takes chars)
 225     int len = snprintf(g_buf, BUFSIZE, "addr2line -C -f -e \"%s\"", (const char*) exepath.mb_str());
 226     len = (len <= 0) ? strlen(g_buf) : len;     // in case snprintf() is broken
 227     for (size_t i=0; i<n; i++)
 228     {
 229         snprintf(&g_buf[len], BUFSIZE - len, " %p", addresses[i]);
 230         len = strlen(g_buf);
 231     }
 232
 233     //wxLogDebug(wxT("piping the command '%s'"), g_buf);  // for debug only
 234
 235     wxStdioPipe fp(g_buf, "r");
 236     if ( !fp )
 237         return 0;
 238
 239     // parse addr2line output (should be exactly 2 lines for each address)
 240     // reusing the g_buf used for building the command line above
 241     wxString name, filename;
 242     unsigned long line = 0,
 243                   curr = 0;
 244     for  ( size_t i = 0; i < n; i++ )
 245     {
 246         // 1st line has function name
 247         if ( fgets(g_buf, WXSIZEOF(g_buf), fp) )
 248         {
 249             name = wxString::FromAscii(g_buf);
 250             name.RemoveLast(); // trailing newline
 251
 252             if ( name == wxT("??") )
 253                 name.clear();
 254         }
 255         else
 256         {
 257             wxLogDebug(wxT("cannot read addr2line output for stack frame #%lu"),
 258                        (unsigned long)i);
 259             return false;
 260         }
 261
 262         // 2nd one -- the file/line info
 263         if ( fgets(g_buf, WXSIZEOF(g_buf), fp) )
 264         {
 265             filename = wxString::FromAscii(g_buf);
 266             filename.RemoveLast();
 267
 268             const size_t posColon = filename.find(wxT(':'));
 269             if ( posColon != wxString::npos )
 270             {
 271                 // parse line number (it's ok if it fails, this will just leave
 272                 // line at its current, invalid, 0 value)
 273                 wxString(filename, posColon + 1, wxString::npos).ToULong(&line);
 274
 275                 // remove line number from 'filename'
 276                 filename.erase(posColon);
 277                 if ( filename == wxT("??") )
 278                     filename.clear();
 279             }
 280             else
 281             {
 282                 wxLogDebug(wxT("Unexpected addr2line format: \"%s\" - ")
 283                            wxT("the semicolon is missing"),
 284                            filename.c_str());
 285             }
 286         }
 287
 288         // now we've got enough info to initialize curr-th stack frame
 289         // (at worst, only addresses[i] and syminfo[i] have been initialized,
 290         //  but wxStackFrame::OnGetName may still be able to get function name):
 291         arr[curr++].Set(name, filename, syminfo[i], i, line, addresses[i]);
 292     }
 293
 294     return curr;
 295 }
 296
 297 void wxStackWalker::Walk(size_t skip, size_t maxDepth)
 298 {
 299     // read all frames required
 300     SaveStack(maxDepth);
 301
 302     // process them
 303     ProcessFrames(skip);
 304
 305     // cleanup
 306     FreeStack();
 307 }
 308
 309 #endif // wxUSE_STACKWALKER