Merge "Revert "Use process_vm_readv to read memory."" (f96e7446) · Commits · e / os / android_system_core

libbacktrace/BacktracePtrace.cpp

+33 −12

Original line number	Diff line number	Diff line
		@@ -17,7 +17,6 @@
		#include <errno.h>
		#include <stdint.h>
		#include <string.h>
		#include <sys/uio.h>
		#include <sys/param.h>
		#include <sys/ptrace.h>
		#include <sys/types.h>
		@@ -73,20 +72,42 @@ size_t BacktracePtrace::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
		if (!BacktraceMap::IsValid(map) \|\| !(map.flags & PROT_READ)) {
		return 0;
		}
		bytes = MIN(map.end - addr, bytes);

		struct iovec local_io;
		local_io.iov_base = buffer;
		local_io.iov_len = bytes;
		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;
		}
		size_t copy_bytes = MIN(sizeof(word_t) - align_bytes, bytes);
		memcpy(buffer, reinterpret_cast<uint8_t*>(&data_word) + align_bytes, copy_bytes);
		addr += copy_bytes;
		buffer += copy_bytes;
		bytes -= copy_bytes;
		bytes_read += copy_bytes;
		}

		struct iovec remote_io;
		remote_io.iov_base = reinterpret_cast<void*>(addr);
		remote_io.iov_len = 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);
		}

		ssize_t bytes_read = process_vm_readv(Tid(), &local_io, 1, &remote_io, 1, 0);
		if (bytes_read == -1) {
		return 0;
		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 static_cast<size_t>(bytes_read);
		return bytes_read;
		#endif
		}