1 files changed, 113 insertions, 0 deletions
diff --git a/libbacktrace/common.c b/libbacktrace/common.c
new file mode 100644
index 0000000..20786f4
--- /dev/null
+++ b/libbacktrace/common.c
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2013 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 "libbacktrace"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/ptrace.h>
+#include <inttypes.h>
+
+#include <cutils/log.h>
+#include <backtrace/backtrace.h>
+
+#include "common.h"
+
+bool backtrace_read_word(const backtrace_t* backtrace, uintptr_t ptr,
+                         uint32_t* out_value) {
+  if (ptr & 3) {
+    ALOGW("backtrace_read_word: invalid pointer %p", (void*)ptr);
+    *out_value = (uint32_t)-1;
+    return false;
+  }
+
+  // Check if reading from the current process, or a different process.
+  if (backtrace->tid < 0) {
+    const backtrace_map_info_t* map_info = backtrace_find_map_info(backtrace->map_info_list, ptr);
+    if (map_info && map_info->is_readable) {
+      *out_value = *(uint32_t*)ptr;
+      return true;
+    } else {
+      ALOGW("backtrace_read_word: pointer %p not in a readbale map", (void*)ptr);
+      *out_value = (uint32_t)-1;
+      return false;
+    }
+  } else {
+#if defined(__APPLE__)
+    ALOGW("read_word: MacOS does not support reading from another pid.\n");
+    return false;
+#else
+    // ptrace() returns -1 and sets errno when the operation fails.
+    // To disambiguate -1 from a valid result, we clear errno beforehand.
+    errno = 0;
+    *out_value = ptrace(PTRACE_PEEKTEXT, backtrace->tid, (void*)ptr, NULL);
+    if (*out_value == (uint32_t)-1 && errno) {
+      ALOGW("try_get_word: invalid pointer 0x%08x reading from tid %d, "
+            "ptrace() errno=%d", ptr, backtrace->tid, errno);
+      return false;
+    }
+    return true;
+  }
+#endif
+}
+
+const char *backtrace_get_map_info(
+    const backtrace_t* backtrace, uintptr_t pc, uintptr_t* start_pc) {
+  const backtrace_map_info_t* map_info = backtrace_find_map_info(backtrace->map_info_list, pc);
+  if (map_info) {
+    if (start_pc) {
+      *start_pc = map_info->start;
+    }
+    return map_info->name;
+  }
+  return NULL;
+}
+
+void backtrace_format_frame_data(
+    const backtrace_frame_data_t* frame, size_t frame_num, char *buf, size_t buf_size) {
+  uintptr_t relative_pc;
+  const char* map_name;
+  if (frame->map_name) {
+    map_name = frame->map_name;
+  } else {
+    map_name = "<unknown>";
+  }
+  if (frame->map_offset) {
+    relative_pc = frame->map_offset;
+  } else {
+    relative_pc = frame->pc;
+  }
+  if (frame->proc_name && frame->proc_offset) {
+    snprintf(buf, buf_size, "#%02zu pc %0*" PRIxPTR "  %s (%s+%" PRIuPTR ")",
+             frame_num, (int)sizeof(uintptr_t)*2, relative_pc, map_name,
+             frame->proc_name, frame->proc_offset);
+  } else if (frame->proc_name) {
+    snprintf(buf, buf_size, "#%02zu pc %0*" PRIxPTR "  %s (%s)", frame_num,
+             (int)sizeof(uintptr_t)*2, relative_pc, map_name, frame->proc_name);
+  } else {
+    snprintf(buf, buf_size, "#%02zu pc %0*" PRIxPTR "  %s", frame_num,
+             (int)sizeof(uintptr_t)*2, relative_pc, map_name);
+  }
+}
+
+void free_frame_data(backtrace_t* backtrace) {
+  for (size_t i = 0; i < backtrace->num_frames; i++) {
+    if (backtrace->frames[i].proc_name) {
+      free(backtrace->frames[i].proc_name);
+    }
+  }
+  backtrace->num_frames = 0;
+}