Add a new library for collecting stack traces.

Supports collecting the stack trace of the current thread,
another thread in the same process, or a thread in a
different process (using ptrace).

Change-Id: Ica2594e4436edde4ceb7bcc3d78e6c31a7902cbf

5 files changed, 353 insertions, 0 deletions

diff --git a/include/corkscrew/backtrace.h b/include/corkscrew/backtrace.h
new file mode 100644
index 0000000..cecb13d
--- /dev/null
+++ b/include/corkscrew/backtrace.h
@@ -0,0 +1,102 @@
+/*
+ * 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.
+ */
+
+/* A stack unwinder. */
+
+#ifndef _CORKSCREW_BACKTRACE_H
+#define _CORKSCREW_BACKTRACE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <sys/types.h>
+#include <corkscrew/ptrace.h>
+#include <corkscrew/map_info.h>
+#include <corkscrew/symbol_table.h>
+
+/*
+ * Describes a single frame of a backtrace.
+ */
+typedef struct {
+    uintptr_t absolute_pc;     /* absolute PC offset */
+    uintptr_t stack_top;       /* top of stack for this frame */
+    size_t stack_size;         /* size of this stack frame */
+} backtrace_frame_t;
+
+/*
+ * Describes the symbols associated with a backtrace frame.
+ */
+typedef struct {
+    uintptr_t relative_pc;       /* relative PC offset from the start of the library,
+                                    or the absolute PC if the library is unknown */
+    const map_info_t* map_info;  /* memory map of the library, or NULL if unknown */
+    const char* name;            /* symbol name, or NULL if unknown */
+    char* demangled_name;        /* demangled symbol name, or NULL if unknown */
+} backtrace_symbol_t;
+
+/*
+ * Unwinds the call stack for the current thread of execution.
+ * Populates the backtrace array with the program counters from the call stack.
+ * Returns the number of frames collected, or -1 if an error occurred.
+ */
+ssize_t unwind_backtrace(backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth);
+
+/*
+ * Unwinds the call stack for a thread within this process.
+ * Populates the backtrace array with the program counters from the call stack.
+ * Returns the number of frames collected, or -1 if an error occurred.
+ *
+ * The task is briefly suspended while the backtrace is being collected.
+ */
+ssize_t unwind_backtrace_thread(pid_t tid, backtrace_frame_t* backtrace,
+        size_t ignore_depth, size_t max_depth);
+
+/*
+ * Unwinds the call stack of a task within a remote process using ptrace().
+ * Populates the backtrace array with the program counters from the call stack.
+ * Returns the number of frames collected, or -1 if an error occurred.
+ */
+ssize_t unwind_backtrace_ptrace(pid_t tid, const ptrace_context_t* context,
+        backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth);
+
+/*
+ * Gets the symbols for each frame of a backtrace.
+ * The symbols array must be big enough to hold one symbol record per frame.
+ * The symbols must later be freed using free_backtrace_symbols.
+ */
+void get_backtrace_symbols(const backtrace_frame_t* backtrace, size_t frames,
+        backtrace_symbol_t* backtrace_symbols);
+
+/*
+ * Gets the symbols for each frame of a backtrace from a remote process.
+ * The symbols array must be big enough to hold one symbol record per frame.
+ * The symbols must later be freed using free_backtrace_symbols.
+ */
+void get_backtrace_symbols_ptrace(const ptrace_context_t* context,
+        const backtrace_frame_t* backtrace, size_t frames,
+        backtrace_symbol_t* backtrace_symbols);
+
+/*
+ * Frees the storage associated with backtrace symbols.
+ */
+void free_backtrace_symbols(backtrace_symbol_t* backtrace_symbols, size_t frames);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _CORKSCREW_BACKTRACE_H
diff --git a/include/corkscrew/demangle.h b/include/corkscrew/demangle.h
new file mode 100644
index 0000000..04b0225
--- /dev/null
+++ b/include/corkscrew/demangle.h
@@ -0,0 +1,42 @@
+/*
+ * 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.
+ */
+
+/* C++ symbol name demangling. */
+
+#ifndef _CORKSCREW_DEMANGLE_H
+#define _CORKSCREW_DEMANGLE_H
+
+#include <sys/types.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Demangles a C++ symbol name.
+ * If name is NULL or if the name cannot be demangled, returns NULL.
+ * Otherwise, returns a newly allocated string that contains the demangled name.
+ *
+ * The caller must free the returned string using free().
+ */
+char* demangle_symbol_name(const char* name);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _CORKSCREW_DEMANGLE_H
diff --git a/include/corkscrew/map_info.h b/include/corkscrew/map_info.h
new file mode 100644
index 0000000..a1c344f
--- /dev/null
+++ b/include/corkscrew/map_info.h
@@ -0,0 +1,54 @@
+/*
+ * 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.
+ */
+
+/* Process memory map. */
+
+#ifndef _CORKSCREW_MAP_INFO_H
+#define _CORKSCREW_MAP_INFO_H
+
+#include <sys/types.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct map_info {
+    struct map_info* next;
+    uintptr_t start;
+    uintptr_t end;
+    bool is_executable;
+    void* data; // arbitrary data associated with the map by the user, initially NULL
+    char name[];
+} map_info_t;
+
+/* Loads memory map from /proc/<tid>/maps. */
+map_info_t* load_map_info_list(pid_t tid);
+
+/* Frees memory map. */
+void free_map_info_list(map_info_t* milist);
+
+/* Finds the memory map that contains the specified address. */
+const map_info_t* find_map_info(const map_info_t* milist, uintptr_t addr);
+
+/* Gets the memory map for this process.  (result is cached) */
+const map_info_t* my_map_info_list();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _CORKSCREW_MAP_INFO_H
diff --git a/include/corkscrew/ptrace.h b/include/corkscrew/ptrace.h
new file mode 100644
index 0000000..6acf9eb
--- /dev/null
+++ b/include/corkscrew/ptrace.h
@@ -0,0 +1,97 @@
+/*
+ * 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.
+ */
+
+/* Useful ptrace() utility functions. */
+
+#ifndef _CORKSCREW_PTRACE_H
+#define _CORKSCREW_PTRACE_H
+
+#include <corkscrew/map_info.h>
+#include <corkscrew/symbol_table.h>
+
+#include <sys/types.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Stores information about a process that is used for several different
+ * ptrace() based operations. */
+typedef struct {
+    map_info_t* map_info_list;
+} ptrace_context_t;
+
+#if __i386__
+/* ptrace() register context. */
+typedef struct pt_regs_x86 {
+    uint32_t ebx;
+    uint32_t ecx;
+    uint32_t edx;
+    uint32_t esi;
+    uint32_t edi;
+    uint32_t ebp;
+    uint32_t eax;
+    uint32_t xds;
+    uint32_t xes;
+    uint32_t xfs;
+    uint32_t xgs;
+    uint32_t orig_eax;
+    uint32_t eip;
+    uint32_t xcs;
+    uint32_t eflags;
+    uint32_t esp;
+    uint32_t xss;
+} pt_regs_x86_t;
+#endif
+
+/*
+ * Reads a word of memory safely.
+ * Uses ptrace() if tid >= 0, local memory otherwise.
+ * Returns false if the word could not be read.
+ */
+bool try_get_word(pid_t tid, uintptr_t ptr, uint32_t* out_value);
+
+/*
+ * Loads information needed for examining a remote process using ptrace().
+ * The caller must already have successfully attached to the process
+ * using ptrace().
+ *
+ * The context can be used for any threads belonging to that process
+ * assuming ptrace() is attached to them before performing the actual
+ * unwinding.  The context can continue to be used to decode backtraces
+ * even after ptrace() has been detached from the process.
+ */
+ptrace_context_t* load_ptrace_context(pid_t pid);
+
+/*
+ * Frees a ptrace context.
+ */
+void free_ptrace_context(ptrace_context_t* context);
+
+/*
+ * Finds a symbol using ptrace.
+ * Returns the containing map and information about the symbol, or
+ * NULL if one or the other is not available.
+ */
+void find_symbol_ptrace(const ptrace_context_t* context,
+        uintptr_t addr, const map_info_t** out_map_info, const symbol_t** out_symbol);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _CORKSCREW_PTRACE_H
diff --git a/include/corkscrew/symbol_table.h b/include/corkscrew/symbol_table.h
new file mode 100644
index 0000000..020c8b8
--- /dev/null
+++ b/include/corkscrew/symbol_table.h
@@ -0,0 +1,58 @@
+/*
+ * 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.
+ */
+
+#ifndef _CORKSCREW_SYMBOL_TABLE_H
+#define _CORKSCREW_SYMBOL_TABLE_H
+
+#include <sys/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct {
+    uintptr_t start;
+    uintptr_t end;
+    char* name;
+} symbol_t;
+
+typedef struct {
+    symbol_t* symbols;
+    size_t num_symbols;
+} symbol_table_t;
+
+/*
+ * Loads a symbol table from a given file.
+ * Returns NULL on error.
+ */
+symbol_table_t* load_symbol_table(const char* filename);
+
+/*
+ * Frees a symbol table.
+ */
+void free_symbol_table(symbol_table_t* table);
+
+/*
+ * Finds a symbol associated with an address in the symbol table.
+ * Returns NULL if not found.
+ */
+const symbol_t* find_symbol(const symbol_table_t* table, uintptr_t addr);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _CORKSCREW_SYMBOL_TABLE_H