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Checkpoint: Assure proper buffer alignment

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We have a char buffer on the stack, which we then cast to a
struct, and then proceed to access elements in the struct.
This is not safe across all platforms, as some platforms
may require a certain alignment for members of the struct.
We fix this by assuring an appropriate alignment for our
char buffer.

We also use C++ casting, and rename our buffer to differenciate
it from the other 'buffer' variable in this function.

Test: TreeHugger
Change-Id: I8254cb6b8124e394bd805afd1ccca0faedb27ffa
This commit is contained in:
Greg Kaiser 2018-12-18 12:22:29 -08:00
parent 8ae16db72a
commit 8859c9c9e7
1 changed files with 5 additions and 6 deletions
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11
Checkpoint.cpp
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@ -296,9 +296,9 @@ Status cp_restoreCheckpoint(const std::string& blockDevice) {
PLOG(ERROR) << "Cannot open " << blockDevice;
return Status::fromExceptionCode(errno, ("Cannot open " + blockDevice).c_str());
}
char buffer[kBlockSize];
device.read(buffer, kBlockSize);
log_sector& ls = *(log_sector*)buffer;
alignas(alignof(log_sector)) char ls_buffer[kBlockSize];
device.read(ls_buffer, kBlockSize);
log_sector& ls = *reinterpret_cast<log_sector*>(ls_buffer);
if (ls.magic != kMagic) {
LOG(ERROR) << "No magic";
return Status::fromExceptionCode(EINVAL, "No magic");
@ -307,10 +307,9 @@ Status cp_restoreCheckpoint(const std::string& blockDevice) {
LOG(INFO) << "Restoring " << ls.sequence << " log sectors";
for (int sequence = ls.sequence; sequence >= 0; sequence--) {
char buffer[kBlockSize];
device.seekg(0);
device.read(buffer, kBlockSize);
log_sector& ls = *(log_sector*)buffer;
device.read(ls_buffer, kBlockSize);
ls = *reinterpret_cast<log_sector*>(ls_buffer);
if (ls.magic != kMagic) {
LOG(ERROR) << "No magic!";
return Status::fromExceptionCode(EINVAL, "No magic");