1 files changed, 134 insertions, 0 deletions
diff --git a/libcorkscrew/ptrace.c b/libcorkscrew/ptrace.c
new file mode 100644
index 000000000..6ed77c45b
--- /dev/null
+++ b/libcorkscrew/ptrace.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2011 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 "Corkscrew"
+//#define LOG_NDEBUG 0
+
+#include "ptrace-arch.h"
+#include <corkscrew/ptrace.h>
+
+#include <errno.h>
+#include <sys/ptrace.h>
+#include <cutils/log.h>
+
+static const uint32_t ELF_MAGIC = 0x464C457f; // "ELF\0177"
+
+#ifndef PAGE_SIZE
+#define PAGE_SIZE 4096
+#endif
+
+#ifndef PAGE_MASK
+#define PAGE_MASK (~(PAGE_SIZE - 1))
+#endif
+
+bool try_get_word(pid_t tid, uintptr_t ptr, uint32_t* out_value) {
+    if (ptr & 3) {
+        LOGV("try_get_word: invalid pointer 0x%08x", ptr);
+        *out_value = 0;
+        return false;
+    }
+    if (tid < 0) {
+#if 0 /*unreliable, unclear whether this is safe from a signal handler context*/
+        // Determine whether the pointer is likely to be valid before dereferencing it.
+        unsigned char vec[1];
+        while (mincore((void*)(ptr & PAGE_MASK), sizeof(uint32_t), vec)) {
+            if (errno != EAGAIN && errno != EINTR) {
+                LOGV("try_get_word: invalid pointer 0x%08x, mincore() errno=%d", ptr, errno);
+                *out_value = 0;
+                return false;
+            }
+        }
+#endif
+        *out_value = *(uint32_t*)ptr;
+        return true;
+    } 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, tid, (void*)ptr, NULL);
+        if (*out_value == 0xffffffffL && errno) {
+            LOGV("try_get_word: invalid pointer 0x%08x, ptrace() errno=%d", ptr, errno);
+            *out_value = 0;
+            return false;
+        }
+        return true;
+    }
+}
+
+static void load_ptrace_map_info_data(pid_t pid, map_info_t* mi) {
+    if (mi->is_executable) {
+        uint32_t elf_magic;
+        if (try_get_word(pid, mi->start, &elf_magic) && elf_magic == ELF_MAGIC) {
+            map_info_data_t* data = (map_info_data_t*)calloc(1, sizeof(map_info_data_t));
+            if (data) {
+                mi->data = data;
+                if (mi->name[0]) {
+                    data->symbol_table = load_symbol_table(mi->name);
+                }
+#ifdef CORKSCREW_HAVE_ARCH
+                load_ptrace_map_info_data_arch(pid, mi, data);
+#endif
+            }
+        }
+    }
+}
+
+ptrace_context_t* load_ptrace_context(pid_t pid) {
+    ptrace_context_t* context =
+            (ptrace_context_t*)calloc(1, sizeof(ptrace_context_t));
+    if (context) {
+        context->map_info_list = load_map_info_list(pid);
+        for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) {
+            load_ptrace_map_info_data(pid, mi);
+        }
+    }
+    return context;
+}
+
+static void free_ptrace_map_info_data(map_info_t* mi) {
+    map_info_data_t* data = (map_info_data_t*)mi->data;
+    if (data) {
+        if (data->symbol_table) {
+            free_symbol_table(data->symbol_table);
+        }
+#ifdef CORKSCREW_HAVE_ARCH
+        free_ptrace_map_info_data_arch(mi, data);
+#endif
+        free(data);
+        mi->data = NULL;
+    }
+}
+
+void free_ptrace_context(ptrace_context_t* context) {
+    for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) {
+        free_ptrace_map_info_data(mi);
+    }
+    free_map_info_list(context->map_info_list);
+}
+
+void find_symbol_ptrace(const ptrace_context_t* context,
+        uintptr_t addr, const map_info_t** out_map_info, const symbol_t** out_symbol) {
+    const map_info_t* mi = find_map_info(context->map_info_list, addr);
+    const symbol_t* symbol = NULL;
+    if (mi) {
+        const map_info_data_t* data = (const map_info_data_t*)mi->data;
+        if (data && data->symbol_table) {
+            symbol = find_symbol(data->symbol_table, addr - mi->start);
+        }
+    }
+    *out_map_info = mi;
+    *out_symbol = symbol;
+}