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Emulate PTRACE_GETREGSET in ptrace wrapper

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Newer versions of libunwind use `PTRACE_GETREGSET` to obtain register data.
This change should make it easier to upgrade the libunwind dependency.

PiperOrigin-RevId: 420057842
Change-Id: Ib9abbeff574e457009709715f912ba5962033c5d
This commit is contained in:
Christian Blichmann 2022-01-06 07:32:40 -08:00 committed by Copybara-Service
parent 0598ea4687
commit 21847a1ef1
1 changed files with 17 additions and 9 deletions
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26
sandboxed_api/sandbox2/unwind/ptrace_hook.cc
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@ -14,12 +14,14 @@
#include "sandboxed_api/sandbox2/unwind/ptrace_hook.h"
#include <elf.h> // For NT_PRSTATUS
#include <sys/ptrace.h>
#include <sys/uio.h>
#include <unistd.h>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <vector>
@ -68,14 +70,8 @@ extern "C" long int ptrace_wrapped( // NOLINT
switch (request) {
case PTRACE_PEEKDATA: {
long int read_data; // NOLINT
struct iovec local = {
.iov_base = &read_data,
.iov_len = sizeof(long int), // NOLINT
};
struct iovec remote = {
.iov_base = addr,
.iov_len = sizeof(long int), // NOLINT
};
iovec local = {.iov_base = &read_data, .iov_len = sizeof(read_data)};
iovec remote = {.iov_base = addr, .iov_len = sizeof(read_data)};
if (process_vm_readv(pid, &local, 1, &remote, 1, 0) <= 0) {
return -1;
@ -91,10 +87,22 @@ extern "C" long int ptrace_wrapped( // NOLINT
}
return (*g_registers)[offset / kRegSize];
}
case PTRACE_GETREGSET: {
// Only return general-purpose registers.
if (auto kind = reinterpret_cast<uintptr_t>(addr); kind != NT_PRSTATUS) {
return -1;
}
auto reg_set = reinterpret_cast<iovec*>(data);
if (reg_set->iov_len > g_registers->size() * kRegSize) {
return -1;
}
memcpy(reg_set->iov_base, g_registers->data(), reg_set->iov_len);
break;
}
default:
fprintf(stderr, "ptrace_wrapped(): operation not permitted: %d\n",
request);
_exit(1);
abort();
}
return 0;
}