am 38f125b8: am 837a6739: Merge "Add variable length read to Backtrace." (4f1bb82b) · Commits · e / os / android_system_core

include/backtrace/Backtrace.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -84,6 +84,12 @@ public:
		// Read the data at a specific address.
		virtual bool ReadWord(uintptr_t ptr, word_t* out_value) = 0;

		// Read arbitrary data from a specific address. If a read request would
		// span from one map to another, this call only reads up until the end
		// of the current map.
		// Returns the total number of bytes actually read.
		virtual size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes) = 0;

		// Create a string representing the formatted line of backtrace information
		// for a single frame.
		virtual std::string FormatFrameData(size_t frame_num);

libbacktrace/BacktraceImpl.cpp

+85 −10

Original line number	Diff line number	Diff line
		@@ -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 @@ bool BacktraceCurrent::ReadWord(uintptr_t ptr, word_t* out_value) {
		}
		}

		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(
		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
		}

libbacktrace/BacktraceImpl.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -56,6 +56,8 @@ public:
		BacktraceCurrent(BacktraceImpl* impl, BacktraceMap* map);
		virtual ~BacktraceCurrent();

		size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes);

		bool ReadWord(uintptr_t ptr, word_t* out_value);
		};

		@@ -64,6 +66,8 @@ public:
		BacktracePtrace(BacktraceImpl* impl, pid_t pid, pid_t tid, BacktraceMap* map);
		virtual ~BacktracePtrace();

		size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes);

		bool ReadWord(uintptr_t ptr, word_t* out_value);
		};