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 #ifndef __WXOSX__
 134     else // not in "module(funcname+offset)" format
 135     {
 136         m_module = syminfo;
 137     }
 138 #endif // !__WXOSX__
 139 }
 140
 141
 142 // ----------------------------------------------------------------------------
 143 // wxStackWalker
 144 // ----------------------------------------------------------------------------
 145
 146 // that many frames should be enough for everyone
 147 #define MAX_FRAMES          200
 148
 149 // we need a char buffer big enough to contain a call to addr2line with
 150 // up to MAX_FRAMES addresses !
 151 // NB: %p specifier will print the pointer in hexadecimal form
 152 //     and thus will require 2 chars for each byte + 3 for the
 153 //     " 0x" prefix
 154 #define CHARS_PER_FRAME    (sizeof(void*) * 2 + 3)
 155
 156 // BUFSIZE will be 2250 for 32 bit machines
 157 #define BUFSIZE            (50 + MAX_FRAMES*CHARS_PER_FRAME)
 158
 159 // static data
 160 void *wxStackWalker::ms_addresses[MAX_FRAMES];
 161 char **wxStackWalker::ms_symbols = NULL;
 162 int wxStackWalker::m_depth = 0;
 163 wxString wxStackWalker::ms_exepath;
 164 static char g_buf[BUFSIZE];
 165
 166
 167 void wxStackWalker::SaveStack(size_t maxDepth)
 168 {
 169     // read all frames required
 170     maxDepth = wxMin(WXSIZEOF(ms_addresses)/sizeof(void*), maxDepth);
 171     m_depth = backtrace(ms_addresses, maxDepth*sizeof(void*));
 172     if ( !m_depth )
 173         return;
 174
 175     ms_symbols = backtrace_symbols(ms_addresses, m_depth);
 176 }
 177
 178 void wxStackWalker::ProcessFrames(size_t skip)
 179 {
 180     wxStackFrame frames[MAX_FRAMES];
 181
 182     if (!ms_symbols || !m_depth)
 183         return;
 184
 185     // we have 3 more "intermediate" frames which the calling code doesn't know
 186     // about, account for them
 187     skip += 3;
 188
 189     // call addr2line only once since this call may be very slow
 190     // (it has to load in memory the entire EXE of this app which may be quite
 191     //  big, especially if it contains debug info and is compiled statically!)
 192     int towalk = InitFrames(frames, m_depth - skip, &ms_addresses[skip], &ms_symbols[skip]);
 193
 194     // now do user-defined operations on each frame
 195     for ( int n = 0; n < towalk - (int)skip; n++ )
 196         OnStackFrame(frames[n]);
 197 }
 198
 199 void wxStackWalker::FreeStack()
 200 {
 201     // ms_symbols has been allocated by backtrace_symbols() and it's the responsibility
 202     // of the caller, i.e. us, to free that pointer
 203     if (ms_symbols)
 204         free( ms_symbols );
 205     ms_symbols = NULL;
 206     m_depth = 0;
 207 }
 208
 209 namespace
 210 {
 211
 212 // Helper function to read a line from the file and return it without the
 213 // trailing newline. Line number is only used for error reporting.
 214 bool ReadLine(FILE* fp, unsigned long num, wxString* line)
 215 {
 216     if ( !fgets(g_buf, WXSIZEOF(g_buf), fp) )
 217     {
 218         wxLogDebug(wxS("cannot read address information for stack frame #%lu"),
 219                    num);
 220         return false;
 221     }
 222
 223     *line = wxString::FromAscii(g_buf);
 224     line->RemoveLast();
 225
 226     return true;
 227 }
 228
 229 } // anonymous namespace
 230
 231 int wxStackWalker::InitFrames(wxStackFrame *arr, size_t n, void **addresses, char **syminfo)
 232 {
 233     // we need to launch addr2line tool to get this information and we need to
 234     // have the program name for this
 235     wxString exepath = wxStackWalker::GetExePath();
 236     if ( exepath.empty() )
 237     {
 238         exepath = wxStandardPaths::Get().GetExecutablePath();
 239         if ( exepath.empty() )
 240         {
 241             wxLogDebug(wxT("Cannot parse stack frame because the executable ")
 242                        wxT("path could not be detected"));
 243             return 0;
 244         }
 245     }
 246
 247     // build the command line for executing addr2line or atos under OS X using
 248     // char* directly to avoid the conversions from Unicode
 249 #ifdef __WXOSX__
 250     int len = snprintf(g_buf, BUFSIZE, "atos -p %d", (int)getpid());
 251 #else
 252     int len = snprintf(g_buf, BUFSIZE, "addr2line -C -f -e \"%s\"", (const char*) exepath.mb_str());
 253 #endif
 254     len = (len <= 0) ? strlen(g_buf) : len;     // in case snprintf() is broken
 255     for (size_t i=0; i<n; i++)
 256     {
 257         snprintf(&g_buf[len], BUFSIZE - len, " %p", addresses[i]);
 258         len = strlen(g_buf);
 259     }
 260
 261     //wxLogDebug(wxT("piping the command '%s'"), g_buf);  // for debug only
 262
 263     wxStdioPipe fp(g_buf, "r");
 264     if ( !fp )
 265         return 0;
 266
 267     // parse the output reusing the same buffer to avoid any big memory
 268     // allocations which could fail if our program is in a bad state
 269     wxString name, filename;
 270     unsigned long line = 0,
 271                   curr = 0;
 272     for  ( size_t i = 0; i < n; i++ )
 273     {
 274 #ifdef __WXOSX__
 275         wxString buffer;
 276         if ( !ReadLine(fp, i, &buffer) )
 277             return false;
 278
 279         line = 0;
 280         filename.clear();
 281
 282         // We can get back either the string in the following format:
 283         //
 284         //      func(args) (in module) (file:line)
 285         //
 286         // or just the same address back if it couldn't be resolved.
 287         const size_t posIn = buffer.find("(in ");
 288         if ( posIn != wxString::npos )
 289         {
 290             name.assign(buffer, 0, posIn);
 291
 292             size_t posAt = buffer.find(") (", posIn + 3);
 293             if ( posAt != wxString::npos )
 294             {
 295                 posAt += 3; // Skip ") ("
 296
 297                 // Discard the two last characters which are ")\n"
 298                 wxString location(buffer, posAt, buffer.length() - posAt - 2);
 299
 300                 wxString linenum;
 301                 filename = location.BeforeFirst(':', &linenum);
 302                 if ( !linenum.empty() )
 303                     linenum.ToULong(&line);
 304             }
 305         }
 306 #else // !__WXOSX__
 307         // 1st line has function name
 308         if ( !ReadLine(fp, i, &name) )
 309             return false;
 310
 311         name = wxString::FromAscii(g_buf);
 312         name.RemoveLast(); // trailing newline
 313
 314         if ( name == wxT("??") )
 315             name.clear();
 316
 317         // 2nd one -- the file/line info
 318         if ( !ReadLine(fp, i, &filename) )
 319             return false;
 320
 321         const size_t posColon = filename.find(wxT(':'));
 322         if ( posColon != wxString::npos )
 323         {
 324             // parse line number (it's ok if it fails, this will just leave
 325             // line at its current, invalid, 0 value)
 326             wxString(filename, posColon + 1, wxString::npos).ToULong(&line);
 327
 328             // remove line number from 'filename'
 329             filename.erase(posColon);
 330             if ( filename == wxT("??") )
 331                 filename.clear();
 332         }
 333         else
 334         {
 335             wxLogDebug(wxT("Unexpected addr2line format: \"%s\" - ")
 336                        wxT("the semicolon is missing"),
 337                        filename.c_str());
 338         }
 339 #endif // __WXOSX__/!__WXOSX__
 340
 341         // now we've got enough info to initialize curr-th stack frame
 342         // (at worst, only addresses[i] and syminfo[i] have been initialized,
 343         //  but wxStackFrame::OnGetName may still be able to get function name):
 344         arr[curr++].Set(name, filename, syminfo[i], i, line, addresses[i]);
 345     }
 346
 347     return curr;
 348 }
 349
 350 void wxStackWalker::Walk(size_t skip, size_t maxDepth)
 351 {
 352     // read all frames required
 353     SaveStack(maxDepth);
 354
 355     // process them
 356     ProcessFrames(skip);
 357
 358     // cleanup
 359     FreeStack();
 360 }
 361
 362 #endif // wxUSE_STACKWALKER