Add variable length read to Backtrace.
Included tests for this new feature.
Changed the NULLs to nullptr in backtrace_test.
Changed UniquePtr to std::unique_ptr in backtrace_test.
Change-Id: I92375465b8f8ba84589834cc162db5915bf1be81
diff --git a/libbacktrace/BacktraceImpl.cpp b/libbacktrace/BacktraceImpl.cpp
index fb8a725..4650b6a 100644
--- a/libbacktrace/BacktraceImpl.cpp
+++ b/libbacktrace/BacktraceImpl.cpp
@@ -17,6 +17,7 @@
#include <errno.h>
#include <stdlib.h>
#include <string.h>
+#include <sys/param.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <ucontext.h>
@@ -159,6 +160,17 @@
}
}
+size_t BacktraceCurrent::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
+ backtrace_map_t map;
+ FillInMap(addr, &map);
+ if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
+ return 0;
+ }
+ bytes = MIN(map.end - addr, bytes);
+ memcpy(buffer, reinterpret_cast<uint8_t*>(addr), bytes);
+ return bytes;
+}
+
//-------------------------------------------------------------------------
// BacktracePtrace functions.
//-------------------------------------------------------------------------
@@ -171,25 +183,88 @@
BacktracePtrace::~BacktracePtrace() {
}
-bool BacktracePtrace::ReadWord(uintptr_t ptr, word_t* out_value) {
- if (!VerifyReadWordArgs(ptr, out_value)) {
+#if !defined(__APPLE__)
+static bool PtraceRead(pid_t tid, uintptr_t addr, word_t* out_value) {
+ // ptrace() returns -1 and sets errno when the operation fails.
+ // To disambiguate -1 from a valid result, we clear errno beforehand.
+ errno = 0;
+ *out_value = ptrace(PTRACE_PEEKTEXT, tid, reinterpret_cast<void*>(addr), NULL);
+ if (*out_value == static_cast<word_t>(-1) && errno) {
+ BACK_LOGW("invalid pointer %p reading from tid %d, ptrace() strerror(errno)=%s",
+ reinterpret_cast<void*>(addr), tid, strerror(errno));
return false;
}
+ return true;
+}
+#endif
+bool BacktracePtrace::ReadWord(uintptr_t ptr, word_t* out_value) {
#if defined(__APPLE__)
BACK_LOGW("MacOS does not support reading from another pid.");
return false;
#else
- // ptrace() returns -1 and sets errno when the operation fails.
- // To disambiguate -1 from a valid result, we clear errno beforehand.
- errno = 0;
- *out_value = ptrace(PTRACE_PEEKTEXT, Tid(), reinterpret_cast<void*>(ptr), NULL);
- if (*out_value == static_cast<word_t>(-1) && errno) {
- BACK_LOGW("invalid pointer %p reading from tid %d, ptrace() strerror(errno)=%s",
- reinterpret_cast<void*>(ptr), Tid(), strerror(errno));
+ if (!VerifyReadWordArgs(ptr, out_value)) {
return false;
}
- return true;
+
+ backtrace_map_t map;
+ FillInMap(ptr, &map);
+ if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
+ return false;
+ }
+
+ return PtraceRead(Tid(), ptr, out_value);
+#endif
+}
+
+size_t BacktracePtrace::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
+#if defined(__APPLE__)
+ BACK_LOGW("MacOS does not support reading from another pid.");
+ return 0;
+#else
+ backtrace_map_t map;
+ FillInMap(addr, &map);
+ if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
+ return 0;
+ }
+
+ bytes = MIN(map.end - addr, bytes);
+ size_t bytes_read = 0;
+ word_t data_word;
+ size_t align_bytes = addr & (sizeof(word_t) - 1);
+ if (align_bytes != 0) {
+ if (!PtraceRead(Tid(), addr & ~(sizeof(word_t) - 1), &data_word)) {
+ return 0;
+ }
+ align_bytes = sizeof(word_t) - align_bytes;
+ memcpy(buffer, reinterpret_cast<uint8_t*>(&data_word) + sizeof(word_t) - align_bytes,
+ align_bytes);
+ addr += align_bytes;
+ buffer += align_bytes;
+ bytes -= align_bytes;
+ bytes_read += align_bytes;
+ }
+
+ size_t num_words = bytes / sizeof(word_t);
+ for (size_t i = 0; i < num_words; i++) {
+ if (!PtraceRead(Tid(), addr, &data_word)) {
+ return bytes_read;
+ }
+ memcpy(buffer, &data_word, sizeof(word_t));
+ buffer += sizeof(word_t);
+ addr += sizeof(word_t);
+ bytes_read += sizeof(word_t);
+ }
+
+ size_t left_over = bytes & (sizeof(word_t) - 1);
+ if (left_over) {
+ if (!PtraceRead(Tid(), addr, &data_word)) {
+ return bytes_read;
+ }
+ memcpy(buffer, &data_word, left_over);
+ bytes_read += left_over;
+ }
+ return bytes_read;
#endif
}