debuggerd: advance our amazing bet.

Remove debuggerd in favor of a helper process that gets execed by
crashing processes.

Bug: http://b/30705528
Test: debuggerd_test
Change-Id: I9906c69473989cbf7fe5ea6cccf9a9c563d75906

1 files changed, 203 insertions, 0 deletions

diff --git a/debuggerd/libdebuggerd/utility.cpp b/debuggerd/libdebuggerd/utility.cpp
new file mode 100644
index 000000000..57209aaef
--- /dev/null
+++ b/debuggerd/libdebuggerd/utility.cpp
@@ -0,0 +1,203 @@
+/*
+ * Copyright 2008, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "DEBUG"
+
+#include "utility.h"
+
+#include <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <string>
+
+#include <android-base/stringprintf.h>
+#include <backtrace/Backtrace.h>
+#include <log/log.h>
+
+// Whitelist output desired in the logcat output.
+bool is_allowed_in_logcat(enum logtype ltype) {
+  if ((ltype == HEADER)
+   || (ltype == REGISTERS)
+   || (ltype == BACKTRACE)) {
+    return true;
+  }
+  return false;
+}
+
+void _LOG(log_t* log, enum logtype ltype, const char* fmt, ...) {
+  bool write_to_tombstone = (log->tfd != -1);
+  bool write_to_logcat = is_allowed_in_logcat(ltype)
+                      && log->crashed_tid != -1
+                      && log->current_tid != -1
+                      && (log->crashed_tid == log->current_tid);
+
+  char buf[512];
+  va_list ap;
+  va_start(ap, fmt);
+  vsnprintf(buf, sizeof(buf), fmt, ap);
+  va_end(ap);
+
+  size_t len = strlen(buf);
+  if (len <= 0) {
+    return;
+  }
+
+  if (write_to_tombstone) {
+    TEMP_FAILURE_RETRY(write(log->tfd, buf, len));
+  }
+
+  if (write_to_logcat) {
+    __android_log_buf_write(LOG_ID_CRASH, ANDROID_LOG_FATAL, LOG_TAG, buf);
+    if (log->amfd_data != nullptr) {
+      *log->amfd_data += buf;
+    }
+  }
+}
+
+bool wait_for_signal(pid_t tid, siginfo_t* siginfo) {
+  while (true) {
+    int status;
+    pid_t n = TEMP_FAILURE_RETRY(waitpid(tid, &status, __WALL));
+    if (n == -1) {
+      ALOGE("waitpid failed: tid %d, %s", tid, strerror(errno));
+      return false;
+    } else if (n == tid) {
+      if (WIFSTOPPED(status)) {
+        if (ptrace(PTRACE_GETSIGINFO, tid, nullptr, siginfo) != 0) {
+          ALOGE("PTRACE_GETSIGINFO failed: %s", strerror(errno));
+          return false;
+        }
+        return true;
+      } else {
+        ALOGE("unexpected waitpid response: n=%d, status=%08x\n", n, status);
+        // This is the only circumstance under which we can allow a detach
+        // to fail with ESRCH, which indicates the tid has exited.
+        return false;
+      }
+    }
+  }
+}
+
+#define MEMORY_BYTES_TO_DUMP 256
+#define MEMORY_BYTES_PER_LINE 16
+
+void dump_memory(log_t* log, Backtrace* backtrace, uintptr_t addr, const char* fmt, ...) {
+  std::string log_msg;
+  va_list ap;
+  va_start(ap, fmt);
+  android::base::StringAppendV(&log_msg, fmt, ap);
+  va_end(ap);
+
+  // Align the address to sizeof(long) and start 32 bytes before the address.
+  addr &= ~(sizeof(long) - 1);
+  if (addr >= 4128) {
+    addr -= 32;
+  }
+
+  // Don't bother if the address looks too low, or looks too high.
+  if (addr < 4096 ||
+#if defined(__LP64__)
+      addr > 0x4000000000000000UL - MEMORY_BYTES_TO_DUMP) {
+#else
+      addr > 0xffff0000 - MEMORY_BYTES_TO_DUMP) {
+#endif
+    return;
+  }
+
+  _LOG(log, logtype::MEMORY, "\n%s\n", log_msg.c_str());
+
+  // Dump 256 bytes
+  uintptr_t data[MEMORY_BYTES_TO_DUMP/sizeof(uintptr_t)];
+  memset(data, 0, MEMORY_BYTES_TO_DUMP);
+  size_t bytes = backtrace->Read(addr, reinterpret_cast<uint8_t*>(data), sizeof(data));
+  if (bytes % sizeof(uintptr_t) != 0) {
+    // This should never happen, but just in case.
+    ALOGE("Bytes read %zu, is not a multiple of %zu", bytes, sizeof(uintptr_t));
+    bytes &= ~(sizeof(uintptr_t) - 1);
+  }
+
+  uintptr_t start = 0;
+  bool skip_2nd_read = false;
+  if (bytes == 0) {
+    // In this case, we might want to try another read at the beginning of
+    // the next page only if it's within the amount of memory we would have
+    // read.
+    size_t page_size = sysconf(_SC_PAGE_SIZE);
+    start = ((addr + (page_size - 1)) & ~(page_size - 1)) - addr;
+    if (start == 0 || start >= MEMORY_BYTES_TO_DUMP) {
+      skip_2nd_read = true;
+    }
+  }
+
+  if (bytes < MEMORY_BYTES_TO_DUMP && !skip_2nd_read) {
+    // Try to do one more read. This could happen if a read crosses a map,
+    // but the maps do not have any break between them. Or it could happen
+    // if reading from an unreadable map, but the read would cross back
+    // into a readable map. Only requires one extra read because a map has
+    // to contain at least one page, and the total number of bytes to dump
+    // is smaller than a page.
+    size_t bytes2 = backtrace->Read(addr + start + bytes, reinterpret_cast<uint8_t*>(data) + bytes,
+                                    sizeof(data) - bytes - start);
+    bytes += bytes2;
+    if (bytes2 > 0 && bytes % sizeof(uintptr_t) != 0) {
+      // This should never happen, but we'll try and continue any way.
+      ALOGE("Bytes after second read %zu, is not a multiple of %zu", bytes, sizeof(uintptr_t));
+      bytes &= ~(sizeof(uintptr_t) - 1);
+    }
+  }
+
+  // Dump the code around memory as:
+  //  addr             contents                           ascii
+  //  0000000000008d34 ef000000e8bd0090 e1b00000512fff1e  ............../Q
+  //  0000000000008d44 ea00b1f9e92d0090 e3a070fcef000000  ......-..p......
+  // On 32-bit machines, there are still 16 bytes per line but addresses and
+  // words are of course presented differently.
+  uintptr_t* data_ptr = data;
+  size_t current = 0;
+  size_t total_bytes = start + bytes;
+  for (size_t line = 0; line < MEMORY_BYTES_TO_DUMP / MEMORY_BYTES_PER_LINE; line++) {
+    std::string logline;
+    android::base::StringAppendF(&logline, "    %" PRIPTR, addr);
+
+    addr += MEMORY_BYTES_PER_LINE;
+    std::string ascii;
+    for (size_t i = 0; i < MEMORY_BYTES_PER_LINE / sizeof(uintptr_t); i++) {
+      if (current >= start && current + sizeof(uintptr_t) <= total_bytes) {
+        android::base::StringAppendF(&logline, " %" PRIPTR, *data_ptr);
+
+        // Fill out the ascii string from the data.
+        uint8_t* ptr = reinterpret_cast<uint8_t*>(data_ptr);
+        for (size_t val = 0; val < sizeof(uintptr_t); val++, ptr++) {
+          if (*ptr >= 0x20 && *ptr < 0x7f) {
+            ascii += *ptr;
+          } else {
+            ascii += '.';
+          }
+        }
+        data_ptr++;
+      } else {
+        logline += ' ' + std::string(sizeof(uintptr_t) * 2, '-');
+        ascii += std::string(sizeof(uintptr_t), '.');
+      }
+      current += sizeof(uintptr_t);
+    }
+    _LOG(log, logtype::MEMORY, "%s  %s\n", logline.c_str(), ascii.c_str());
+  }
+}