[sanitizer] demangling of libbacktrace symbolization

[Alexey Samsonov]

I've landed this patch as a part of r199384.

On Fri, Jan 10, 2014 at 2:23 PM, Jakub Jelinek <jakub at redhat.com> wrote:
> Hi!
>
> As written in http://gcc.gnu.org/ml/gcc-patches/2013-12/msg00964.html ,
> I'd like to submit following small changes to the libbacktrace
> symbolization.  Apparently llvm-symbolizer symbolization demangles symbols
> by default, libbacktrace symbolization didn't and this patch fixes that.
> It is using cp-demangle for that which doesn't use
> malloc/calloc/realloc/free when called from libsanitizer.
>
> --- libsanitizer/sanitizer_common/sanitizer_symbolizer_libbacktrace.h.jj        2013-12-05 12:04:28.000000000 +0100
> +++ libsanitizer/sanitizer_common/sanitizer_symbolizer_libbacktrace.h   2013-12-10 11:01:26.777371566 +0100
> @@ -29,6 +29,8 @@ class LibbacktraceSymbolizer {
>
>    bool SymbolizeData(DataInfo *info);
>
> +  const char *Demangle(const char *name);
> +
>   private:
>    explicit LibbacktraceSymbolizer(void *state) : state_(state) {}
>
> --- libsanitizer/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc.jj      2013-12-05 12:04:28.000000000 +0100
> +++ libsanitizer/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc 2013-12-10 11:03:02.971876505 +0100
> @@ -513,6 +513,11 @@ class POSIXSymbolizer : public Symbolize
>      SymbolizerScope sym_scope(this);
>      if (internal_symbolizer_ != 0)
>        return internal_symbolizer_->Demangle(name);
> +    if (libbacktrace_symbolizer_ != 0) {
> +      const char *demangled = libbacktrace_symbolizer_->Demangle(name);
> +      if (demangled)
> +       return demangled;
> +    }
>      return DemangleCXXABI(name);
>    }
>
> --- libsanitizer/sanitizer_common/sanitizer_symbolizer_libbacktrace.cc.jj       2013-12-09 14:32:06.000000000 +0100
> +++ libsanitizer/sanitizer_common/sanitizer_symbolizer_libbacktrace.cc  2013-12-10 11:48:19.803830291 +0100
> @@ -20,6 +20,10 @@
>  # include "backtrace-supported.h"
>  # if SANITIZER_POSIX && BACKTRACE_SUPPORTED && !BACKTRACE_USES_MALLOC
>  #  include "backtrace.h"
> +#  if SANITIZER_CP_DEMANGLE
> +#   undef ARRAY_SIZE
> +#   include "demangle.h"
> +#  endif
>  # else
>  #  define SANITIZER_LIBBACKTRACE 0
>  # endif
> @@ -31,6 +35,60 @@ namespace __sanitizer {
>
>  namespace {
>
> +#if SANITIZER_CP_DEMANGLE
> +struct CplusV3DemangleData {
> +  char *buf;
> +  uptr size, allocated;
> +};
> +
> +extern "C" {
> +static void CplusV3DemangleCallback(const char *s, size_t l, void *vdata) {
> +  CplusV3DemangleData *data = (CplusV3DemangleData *)vdata;
> +  uptr needed = data->size + l + 1;
> +  if (needed > data->allocated) {
> +    data->allocated *= 2;
> +    if (needed > data->allocated)
> +      data->allocated = needed;
> +    char *buf = (char *)InternalAlloc(data->allocated);
> +    if (data->buf) {
> +      internal_memcpy(buf, data->buf, data->size);
> +      InternalFree(data->buf);
> +    }
> +    data->buf = buf;
> +  }
> +  internal_memcpy(data->buf + data->size, s, l);
> +  data->buf[data->size + l] = '\0';
> +  data->size += l;
> +}
> +}  // extern "C"
> +
> +char *CplusV3Demangle(const char *name, bool always_alloc) {
> +  CplusV3DemangleData data;
> +  data.buf = 0;
> +  data.size = 0;
> +  data.allocated = 0;
> +  if (cplus_demangle_v3_callback(name, DMGL_PARAMS | DMGL_ANSI,
> +                                CplusV3DemangleCallback, &data)) {
> +    if (data.size + 64 > data.allocated)
> +      return data.buf;
> +    char *buf = internal_strdup(data.buf);
> +    InternalFree(data.buf);
> +    return buf;
> +  }
> +  if (data.buf)
> +    InternalFree(data.buf);
> +  if (always_alloc)
> +    return internal_strdup(name);
> +  return 0;
> +}
> +#else
> +const char *CplusV3Demangle(const char *name, bool always_alloc) {
> +  if (always_alloc)
> +    return internal_strdup(name);
> +  return 0;
> +}
> +#endif
> +
>  struct SymbolizeCodeData {
>    AddressInfo *frames;
>    uptr n_frames;
> @@ -49,7 +107,7 @@ static int SymbolizeCodePCInfoCallback(v
>      info->Clear();
>      info->FillAddressAndModuleInfo(addr, cdata->module_name,
>                                     cdata->module_offset);
> -    info->function = internal_strdup(function);
> +    info->function = CplusV3Demangle(function, true);
>      if (filename)
>        info->file = internal_strdup(filename);
>      info->line = lineno;
> @@ -67,7 +125,7 @@ static void SymbolizeCodeCallback(void *
>      info->Clear();
>      info->FillAddressAndModuleInfo(addr, cdata->module_name,
>                                     cdata->module_offset);
> -    info->function = internal_strdup(symname);
> +    info->function = CplusV3Demangle(symname, true);
>      cdata->n_frames = 1;
>    }
>  }
> @@ -76,7 +134,7 @@ static void SymbolizeDataCallback(void *
>                                    uintptr_t symval, uintptr_t symsize) {
>    DataInfo *info = (DataInfo *)vdata;
>    if (symname && symval) {
> -    info->name = internal_strdup(symname);
> +    info->name = CplusV3Demangle(symname, true);
>      info->start = symval;
>      info->size = symsize;
>    }
> @@ -121,6 +179,17 @@ bool LibbacktraceSymbolizer::SymbolizeDa
>    return true;
>  }
>
> +const char *LibbacktraceSymbolizer::Demangle(const char *name) {
> +#if SANITIZER_CP_DEMANGLE
> +  const char *demangled = CplusV3Demangle(name, false);
> +  if (demangled)
> +    return demangled;
> +  return name;
> +#else
> +  return 0;
> +#endif
> +}
> +
>  #else  // SANITIZER_LIBBACKTRACE
>
>  LibbacktraceSymbolizer *LibbacktraceSymbolizer::get(LowLevelAllocator *alloc) {
> @@ -139,6 +208,10 @@ bool LibbacktraceSymbolizer::SymbolizeDa
>    return false;
>  }
>
> +const char *LibbacktraceSymbolizer::Demangle(const char *name) {
> +  return 0;
> +}
> +
>  #endif  // SANITIZER_LIBBACKTRACE
>
>  }  // namespace __sanitizer
>
>         Jakub



-- 
Alexey Samsonov, MSK