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// 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 */