Merge "Use process_vm_readv to read memory." am: bf0cf4e22d am: 8d7440e13c (afff774b) · Commits · e / os / android_system_core

libbacktrace/BacktracePtrace.cpp

+12 −33

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

	bytes = MIN(map.end - addr, 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;
	}

	size_t num_words = bytes / sizeof(word_t);		struct iovec local_io;
	for (size_t i = 0; i < num_words; i++) {		local_io.iov_base = buffer;
	if (!PtraceRead(Tid(), addr, &data_word)) {		local_io.iov_len = bytes;
	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);		struct iovec remote_io;
	if (left_over) {		remote_io.iov_base = reinterpret_cast<void*>(addr);
	if (!PtraceRead(Tid(), addr, &data_word)) {		remote_io.iov_len = bytes;
	return bytes_read;
	}		ssize_t bytes_read = process_vm_readv(Tid(), &local_io, 1, &remote_io, 1, 0);
	memcpy(buffer, &data_word, left_over);		if (bytes_read == -1) {
	bytes_read += left_over;		return 0;
	}		}
	return bytes_read;		return static_cast<size_t>(bytes_read);
	#endif		#endif
	}		}