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Add offset to backtrace_string printing.

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The libmemunreachable code uses backtrace_string to print out the backtrace
information. However, when the offset of the map that a frame is in is
non-zero, no information is printed. This means that when a frame comes from
a shared library loaded from an apk, it's impossible to tell which
shared library the frame is really coming from.

Add the offset display when it's non-zero. This means this can now be fed
to development/scripts/stack to decode the frame.

Bug: 37276041

Test: Ran dumpsys meminfo --unreachable on an app that leaks from a
Test: shared library and verified the offset output is present.
Change-Id: I61d34ae3f617622d354cc099eff520a64782b6e2
This commit is contained in:
Christopher Ferris 2017-05-25 18:26:37 -07:00
parent a559cff654
commit c0352bbd5f
1 changed files with 12 additions and 3 deletions
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15
libc/malloc_debug/backtrace.cpp
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@ -153,18 +153,27 @@ std::string backtrace_string(const uintptr_t* frames, size_t frame_count) {
if (soname == nullptr) {
soname = "<unknown>";
}
char offset_buf[128];
if (entry != nullptr && entry->offset != 0) {
snprintf(offset_buf, sizeof(offset_buf), " (offset 0x%" PRIxPTR ")", entry->offset);
} else {
offset_buf[0] = '\0';
}
char buf[1024];
if (symbol != nullptr) {
char* demangled_symbol = __cxa_demangle(symbol, nullptr, nullptr, nullptr);
const char* best_name = (demangled_symbol != nullptr) ? demangled_symbol : symbol;
async_safe_format_buffer(
buf, sizeof(buf), " #%02zd pc %" PAD_PTR " %s (%s+%" PRIuPTR ")\n", frame_num,
rel_pc, soname, best_name, frames[frame_num] - offset);
buf, sizeof(buf), " #%02zd pc %" PAD_PTR " %s%s (%s+%" PRIuPTR ")\n", frame_num,
rel_pc, soname, offset_buf, best_name, frames[frame_num] - offset);
free(demangled_symbol);
} else {
async_safe_format_buffer(
buf, sizeof(buf), " #%02zd pc %" PAD_PTR " %s\n", frame_num, rel_pc, soname);
buf, sizeof(buf), " #%02zd pc %" PAD_PTR " %s%s\n", frame_num, rel_pc, soname,
offset_buf);
}
str += buf;
}