The Tor Browser: tools/jprof/bfd.cpp@97036ab72558 (annotated)

tools/jprof/bfd.cpp@97036ab72558 (annotated)

tools/jprof/bfd.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 // vim:ts=8:sw=2:et:
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "leaky.h"
 #ifdef USE_BFD
 #include <stdio.h>
 #include <string.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <libgen.h>
 #include <bfd.h>
 #include <cxxabi.h>
 static bfd *try_debug_file(const char *filename, unsigned long crc32)
 {
   int fd = open(filename, O_RDONLY);
   if (fd < 0)
     return nullptr;
   unsigned char buf[4*1024];
   unsigned long crc = 0;
   while (1) {
     ssize_t count = read(fd, buf, sizeof(buf));
     if (count <= 0)
       break;
     crc = bfd_calc_gnu_debuglink_crc32(crc, buf, count);
   }
   close(fd);
   if (crc != crc32)
     return nullptr;
   bfd *object = bfd_openr(filename, nullptr);
   if (!bfd_check_format(object, bfd_object)) {
     bfd_close(object);
     return nullptr;
   }
   return object;
 }
 static bfd *find_debug_file(bfd *lib, const char *aFileName)
 {
   // check for a separate debug file with symbols
   asection *sect = bfd_get_section_by_name(lib, ".gnu_debuglink");
   if (!sect)
     return nullptr;
   bfd_size_type debuglinkSize = bfd_section_size (objfile->obfd, sect);
   char *debuglink = new char[debuglinkSize];
   bfd_get_section_contents(lib, sect, debuglink, 0, debuglinkSize);
   // crc checksum is aligned to 4 bytes, and after the NUL.
   int crc_offset = (int(strlen(debuglink)) & ~3) + 4;
   unsigned long crc32 = bfd_get_32(lib, debuglink + crc_offset);
   // directory component
   char *dirbuf = strdup(aFileName);
   const char *dir = dirname(dirbuf);
   static const char debug_subdir[] = ".debug";
   // This is gdb's default global debugging info directory, but gdb can
   // be instructed to use a different directory.
   static const char global_debug_dir[] = "/usr/lib/debug";
   char *filename =
     new char[strlen(global_debug_dir) + strlen(dir) + crc_offset + 3];
   // /path/debuglink
   sprintf(filename, "%s/%s", dir, debuglink);
   bfd *debugFile = try_debug_file(filename, crc32);
   if (!debugFile) {
     // /path/.debug/debuglink
     sprintf(filename, "%s/%s/%s", dir, debug_subdir, debuglink);
     debugFile = try_debug_file(filename, crc32);
     if (!debugFile) {
       // /usr/lib/debug/path/debuglink
       sprintf(filename, "%s/%s/%s", global_debug_dir, dir, debuglink);
       debugFile = try_debug_file(filename, crc32);
     }
   }
   delete[] filename;
   free(dirbuf);
   delete[] debuglink;
   return debugFile;
 }
 // Use an indirect array to avoid copying tons of objects
 Symbol ** leaky::ExtendSymbols(int num)
 {
   long n = numExternalSymbols + num;
   externalSymbols = (Symbol**)
                     realloc(externalSymbols,
                             (size_t) (sizeof(externalSymbols[0]) * n));
   Symbol *new_array = new Symbol[n];
   for (int i = 0; i < num; i++) {
     externalSymbols[i + numExternalSymbols] = &new_array[i];
   }
   lastSymbol = externalSymbols + n;
   Symbol **sp = externalSymbols + numExternalSymbols;
   numExternalSymbols = n;
   return sp;
 }
 #define NEXT_SYMBOL do { sp++; \
                          if (sp >= lastSymbol) { \
                            sp = ExtendSymbols(16384); \
                          } \
                        } while (0)
 void leaky::ReadSymbols(const char *aFileName, u_long aBaseAddress)
 {
   int initialSymbols = usefulSymbols;
   if (nullptr == externalSymbols) {
     externalSymbols = (Symbol**) calloc(sizeof(Symbol*),10000);
     Symbol *new_array = new Symbol[10000];
     for (int i = 0; i < 10000; i++) {
       externalSymbols[i] = &new_array[i];
     }
     numExternalSymbols = 10000;
   }
   Symbol** sp = externalSymbols + usefulSymbols;
   lastSymbol = externalSymbols + numExternalSymbols;
   // Create a dummy symbol for the library so, if it doesn't have any
   // symbols, we show it by library.
   (*sp)->Init(aFileName, aBaseAddress);
   NEXT_SYMBOL;
   bfd_boolean kDynamic = (bfd_boolean) false;
   static int firstTime = 1;
   if (firstTime) {
     firstTime = 0;
     bfd_init ();
   }
   bfd* lib = bfd_openr(aFileName, nullptr);
   if (nullptr == lib) {
     return;
   }
   if (!bfd_check_format(lib, bfd_object)) {
     bfd_close(lib);
     return;
   }
   bfd *symbolFile = find_debug_file(lib, aFileName);
   // read mini symbols
   PTR minisyms;
   unsigned int size;
   long symcount = 0;
   if (symbolFile) {
     symcount = bfd_read_minisymbols(symbolFile, kDynamic, &minisyms, &size);
     if (symcount == 0) {
       bfd_close(symbolFile);
     } else {
       bfd_close(lib);
     }
   }
   if (symcount == 0) {
     symcount = bfd_read_minisymbols(lib, kDynamic, &minisyms, &size);
     if (symcount == 0) {
       // symtab is empty; try dynamic symbols
       kDynamic = (bfd_boolean) true;
       symcount = bfd_read_minisymbols(lib, kDynamic, &minisyms, &size);
     }
     symbolFile = lib;
   }
   asymbol* store;
   store = bfd_make_empty_symbol(symbolFile);
   // Scan symbols
   size_t demangle_buffer_size = 128;
   char *demangle_buffer = (char*) malloc(demangle_buffer_size);
   bfd_byte* from = (bfd_byte *) minisyms;
   bfd_byte* fromend = from + symcount * size;
   for (; from < fromend; from += size) {
     asymbol *sym;
     sym = bfd_minisymbol_to_symbol(symbolFile, kDynamic, (const PTR) from, store);
     symbol_info syminfo;
     bfd_get_symbol_info (symbolFile, sym, &syminfo);
 //    if ((syminfo.type == 'T') || (syminfo.type == 't')) {
       const char* nm = bfd_asymbol_name(sym);
       if (nm && nm[0]) {
         char* dnm = nullptr;
         if (strncmp("__thunk", nm, 7)) {
           dnm =
             abi::__cxa_demangle(nm, demangle_buffer, &demangle_buffer_size, 0);
           if (dnm) {
             demangle_buffer = dnm;
           }
         }
         (*sp)->Init(dnm ? dnm : nm, syminfo.value + aBaseAddress);
         NEXT_SYMBOL;
       }
 //    }
   }
   free(demangle_buffer);
   demangle_buffer = nullptr;
   bfd_close(symbolFile);
   int interesting = sp - externalSymbols;
   if (!quiet) {
     printf("%s provided %d symbols\n", aFileName,
            interesting - initialSymbols);
   }
   usefulSymbols = interesting;
 }
 #endif /* USE_BFD */

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tools/jprof/bfd.cpp@97036ab72558 (annotated)

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