Merge "Revert "Use process_vm_readv to read memory.""
diff --git a/libbacktrace/BacktracePtrace.cpp b/libbacktrace/BacktracePtrace.cpp
index 148c418..fd8b713 100644
--- a/libbacktrace/BacktracePtrace.cpp
+++ b/libbacktrace/BacktracePtrace.cpp
@@ -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 @@
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;
-
- struct iovec remote_io;
- remote_io.iov_base = reinterpret_cast<void*>(addr);
- remote_io.iov_len = bytes;
-
- ssize_t bytes_read = process_vm_readv(Tid(), &local_io, 1, &remote_io, 1, 0);
- if (bytes_read == -1) {
- return 0;
+ 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;
}
- return static_cast<size_t>(bytes_read);
+
+ 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
}