php调试方法总结
這幾天看完了php的虛擬機和詞法解析，寫下這篇日志來將php的調試方法做一個總結，像一些最簡單的var_dump,die這種入門級調試技巧就不說了，這種var_dump die的方法在fpm上還好說，但是如果是守護進程就需要破壞現場，重啟服務。寫日志有的時候也很難命中進程現場的運行情況。
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如果我們運行了一個守護進程陷入了死循環或者阻塞希望知道這個程序的運行位置，或者希望知道程序里發生了什么我們應該怎么辦呢？我們可以使用gdb和strace去調試程序
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1、strace
strace 這個東西主要是用來觀察進程的網絡通訊方面的執行問題，好多次我都是通過strace排查出了問題所在！！！
strace -p 進程號
strace 可以觀察進程的函數運行過程以及信號執行情況，好多次我都是使用strace去排查出程序出現的問題，比如curl沒有設置timeout，當出現網絡波動的時候，導致出現了大量的SIGPIPE信號我們就可以使用strace觀察出來，包括子進程頻繁掛掉的信號SIGCHILD信號我們也可以通過strace看出來，還有是否有收到數據啊等等。
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2、gdbinit
我們使用gdb -p 進程號
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進入之后 source + gdbinit的路徑
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使用zbacktrace 就可以看到php的調用棧了
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3.使用gdb
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如果從gdb上我們需要了解zend的虛擬機
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主要從execute_data 這個數據結構上去查看運行過程
struct _zend_execute_data {const zend_op *opline; /* executed opline */zend_execute_data *call; /* current call */zval *return_value;zend_function *func; /* executed function */zval This; /* this + call_info + num_args */zend_execute_data *prev_execute_data;zend_array *symbol_table; #if ZEND_EX_USE_RUN_TIME_CACHEvoid **run_time_cache; /* cache op_array->run_time_cache */ #endif };union _zend_function {zend_uchar type; /* MUST be the first element of this struct! */uint32_t quick_arg_flags;struct {zend_uchar type; /* never used */zend_uchar arg_flags[3]; /* bitset of arg_info.pass_by_reference */uint32_t fn_flags;zend_string *function_name;zend_class_entry *scope;union _zend_function *prototype;uint32_t num_args;uint32_t required_num_args;zend_arg_info *arg_info;} common;zend_op_array op_array;zend_internal_function internal_function; };我們可以通過execute_data中的func這個成員里的common 成員中的function_name里去看到函數名字，filename可以看到文件敏子等等，當然如果我們想知道之前的調用過程可通過prev_execute_data 繼續向上查看，當然我們可以通過
EG(current_execute_data)去查看運行棧，里面也是有prev_execute_data的
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如一個簡單的gdb例子
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(gdb) p *executor_globals.current_execute_data->func->common.function_name->val@10 $1 = {116 't', 114 'r', 97 'a', 99 'c', 107 'k', 101 'e', 114 'r', 95 '_', 116 't', 101 'e'} (gdb) p *executor_globals.current_execute_data->prev_execute_data->func->common.function_name->val@10 $2 = {116 't', 101 'e', 115 's', 116 't', 0 '\000', 110 'n', 103 'g', 0 '\000', 1 '\001', 0 '\000'} (gdb) p execute_data $3 = (zend_execute_data *) 0x7fa8c0e1d150 (gdb) p *execute_data $4 = {opline = 0x0, call = 0x0, return_value = 0x0, func = 0x563525130dc0, This = {value = {lval = 0, dval = 0, counted = 0x0, str = 0x0, arr = 0x0, obj = 0x0, res = 0x0, ref = 0x0, ast = 0x0, zv = 0x0, ptr = 0x0, ce = 0x0, func = 0x0, ww = {w1 = 0, w2 = 0}}, u1 = {v = {type = 0 '\000', type_flags = 0 '\000', u = {call_info = 0, extra = 0}}, type_info = 0}, u2 = {next = 1, cache_slot = 1, opline_num = 1, lineno = 1, num_args = 1, fe_pos = 1, fe_iter_idx = 1, access_flags = 1, property_guard = 1, constant_flags = 1, extra = 1}}, prev_execute_data = 0x7fa8c0e1d0b0, symbol_table = 0x0, run_time_cache = 0x0} (gdb) p *execute_data.prev_execute_data $5 = {opline = 0x7fa8c0ed0ee0, call = 0x0, return_value = 0x0, func = 0x7fa8c0e18d58, This = {value = {lval = 0, dval = 0, counted = 0x0, str = 0x0, arr = 0x0, obj = 0x0, res = 0x0, ref = 0x0, ast = 0x0, zv = 0x0, ptr = 0x0, ce = 0x0, func = 0x0, ww = {w1 = 0, w2 = 0}}, u1 = {v = {type = 0 '\000', type_flags = 0 '\000', u = {call_info = 0, extra = 0}}, type_info = 0}, u2 = {next = 0, cache_slot = 0, opline_num = 0, lineno = 0, num_args = 0, fe_pos = 0, fe_iter_idx = 0, access_flags = 0, property_guard = 0, constant_flags = 0, extra = 0}}, prev_execute_data = 0x7fa8c0e1d030, symbol_table = 0x300000000, run_time_cache = 0x7fa8c0e18e30} (gdb) p *execute_data.prev_execute_data.common There is no member named common. (gdb) p *execute_data.prev_execute_data.func $6 = {type = 2 '\002', quick_arg_flags = 2, common = {type = 2 '\002', arg_flags = {0 '\000', 0 '\000', 0 '\000'}, fn_flags = 134217728, function_name = 0x7fa8c0e80540, scope = 0x0, prototype = 0x0, num_args = 0, required_num_args = 0, arg_info = 0x0}, op_array = {type = 2 '\002', arg_flags = {0 '\000', 0 '\000', 0 '\000'}, fn_flags = 134217728, function_name = 0x7fa8c0e80540, scope = 0x0, prototype = 0x0, num_args = 0, required_num_args = 0, arg_info = 0x0, cache_size = 24, last_var = 1, T = 4, last = 11, opcodes = 0x7fa8c0ed0e00, run_time_cache = 0x7fa8c0e18e30, static_variables = 0x0, vars = 0x7fa8c0e79620, refcount = 0x7fa8c0e79618, last_live_range = 0, last_try_catch = 0, live_range = 0x0, try_catch_array = 0x0, filename = 0x7fa8c0e92600, line_start = 2, line_end = 7, doc_comment = 0x0, last_literal = 5, literals = 0x7fa8c0ed0f60, reserved = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}}, internal_function = {type = 2 '\002', arg_flags = {0 '\000', 0 '\000', 0 '\000'}, fn_flags = 134217728, function_name = 0x7fa8c0e80540, scope = 0x0, prototype = 0x0, num_args = 0, required_num_args = 0, arg_info = 0x0, handler = 0x100000018, module = 0xb00000004, reserved = {0x7fa8c0ed0e00, 0x7fa8c0e18e30, 0x0, 0x7fa8c0e79620, 0x7fa8c0e79618, 0x0}}} (gdb) p *execute_data.prev_execute_data.func.common Structure has no component named operator*. (gdb) p *execute_data.prev_execute_data.func $7 = {type = 2 '\002', quick_arg_flags = 2, common = {type = 2 '\002', arg_flags = {0 '\000', 0 '\000', 0 '\000'}, fn_flags = 134217728, function_name = 0x7fa8c0e80540, scope = 0x0, prototype = 0x0, num_args = 0, required_num_args = 0, arg_info = 0x0}, op_array = {type = 2 '\002', arg_flags = {0 '\000', 0 '\000', 0 '\000'}, fn_flags = 134217728, function_name = 0x7fa8c0e80540, scope = 0x0, prototype = 0x0, num_args = 0, required_num_args = 0, arg_info = 0x0, cache_size = 24, last_var = 1, T = 4, last = 11, opcodes = 0x7fa8c0ed0e00, run_time_cache = 0x7fa8c0e18e30, static_variables = 0x0, vars = 0x7fa8c0e79620, refcount = 0x7fa8c0e79618, last_live_range = 0, last_try_catch = 0, live_range = 0x0, try_catch_array = 0x0, filename = 0x7fa8c0e92600, line_start = 2, line_end = 7, doc_comment = 0x0, last_literal = 5, literals = 0x7fa8c0ed0f60, reserved = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}}, internal_function = {type = 2 '\002', arg_flags = {0 '\000', 0 '\000', 0 '\000'}, fn_flags = 134217728, function_name = 0x7fa8c0e80540, scope = 0x0, prototype = 0x0, num_args = 0, required_num_args = 0, arg_info = 0x0, handler = 0x100000018, module = 0xb00000004, reserved = {0x7fa8c0ed0e00, 0x7fa8c0e18e30, 0x0, 0x7fa8c0e79620, 0x7fa8c0e79618, 0x0}}} (gdb) p *execute_data.prev_execute_data.func.common Structure has no component named operator*. (gdb) p *execute_data.prev_execute_data.func.common.function_name $8 = {gc = {refcount = 1, u = {type_info = 6}}, h = 9223372043240499301, len = 4, val = {116 't'}} (gdb) p *execute_data.prev_execute_data.func.common.function_name.val@10 $9 = {116 't', 101 'e', 115 's', 116 't', 0 '\000', 110 'n', 103 'g', 0 '\000', 1 '\001', 0 '\000'}當然在條件允許可以直接var_dump的情況下可以不用gdb直接用debug_backtrace做這件事
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貼出他的核心源碼看到也是這么做的
ZEND_API void zend_fetch_debug_backtrace(zval *return_value, int skip_last, int options, int limit) /* {{{ */ {zend_execute_data *ptr, *skip, *call = NULL;zend_object *object;int lineno, frameno = 0;zend_function *func;zend_string *function_name;zend_string *filename;zend_string *include_filename = NULL;zval stack_frame, tmp;array_init(return_value);if (!(ptr = EG(current_execute_data))) {return;}if (!ptr->func || !ZEND_USER_CODE(ptr->func->common.type)) {call = ptr;ptr = ptr->prev_execute_data;}if (ptr) {if (skip_last) {/* skip debug_backtrace() */call = ptr;ptr = ptr->prev_execute_data;} else {/* skip "new Exception()" */if (ptr->func && ZEND_USER_CODE(ptr->func->common.type) && (ptr->opline->opcode == ZEND_NEW)) {call = ptr;ptr = ptr->prev_execute_data;}}if (!call) {call = ptr;ptr = ptr->prev_execute_data;}}while (ptr && (limit == 0 || frameno < limit)) {frameno++;array_init(&stack_frame);ptr = zend_generator_check_placeholder_frame(ptr);skip = ptr;/* skip internal handler */if ((!skip->func || !ZEND_USER_CODE(skip->func->common.type)) &&skip->prev_execute_data &&skip->prev_execute_data->func &&ZEND_USER_CODE(skip->prev_execute_data->func->common.type) &&skip->prev_execute_data->opline->opcode != ZEND_DO_FCALL &&skip->prev_execute_data->opline->opcode != ZEND_DO_ICALL &&skip->prev_execute_data->opline->opcode != ZEND_DO_UCALL &&skip->prev_execute_data->opline->opcode != ZEND_DO_FCALL_BY_NAME &&skip->prev_execute_data->opline->opcode != ZEND_INCLUDE_OR_EVAL) {skip = skip->prev_execute_data;}if (skip->func && ZEND_USER_CODE(skip->func->common.type)) {filename = skip->func->op_array.filename;if (skip->opline->opcode == ZEND_HANDLE_EXCEPTION) {if (EG(opline_before_exception)) {lineno = EG(opline_before_exception)->lineno;} else {lineno = skip->func->op_array.line_end;}} else {lineno = skip->opline->lineno;}ZVAL_STR_COPY(&tmp, filename);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_FILE), &tmp);ZVAL_LONG(&tmp, lineno);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_LINE), &tmp);/* try to fetch args only if an FCALL was just made - elsewise we're in the middle of a function* and debug_baktrace() might have been called by the error_handler. in this case we don't* want to pop anything of the argument-stack */} else {zend_execute_data *prev_call = skip;zend_execute_data *prev = skip->prev_execute_data;while (prev) {if (prev_call &&prev_call->func &&!ZEND_USER_CODE(prev_call->func->common.type) &&!(prev_call->func->common.fn_flags & ZEND_ACC_CALL_VIA_TRAMPOLINE)) {break;}if (prev->func && ZEND_USER_CODE(prev->func->common.type)) {ZVAL_STR_COPY(&tmp, prev->func->op_array.filename);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_FILE), &tmp);ZVAL_LONG(&tmp, prev->opline->lineno);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_LINE), &tmp);break;}prev_call = prev;prev = prev->prev_execute_data;}filename = NULL;}/* $this may be passed into regular internal functions */object = (call && (Z_TYPE(call->This) == IS_OBJECT)) ? Z_OBJ(call->This) : NULL;if (call && call->func) {func = call->func;function_name = (func->common.scope &&func->common.scope->trait_aliases) ?zend_resolve_method_name((object ? object->ce : func->common.scope), func) :func->common.function_name;} else {func = NULL;function_name = NULL;}if (function_name) {ZVAL_STR_COPY(&tmp, function_name);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_FUNCTION), &tmp);if (object) {if (func->common.scope) {ZVAL_STR_COPY(&tmp, func->common.scope->name);} else if (object->handlers->get_class_name == zend_std_get_class_name) {ZVAL_STR_COPY(&tmp, object->ce->name);} else {ZVAL_STR(&tmp, object->handlers->get_class_name(object));}zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_CLASS), &tmp);if ((options & DEBUG_BACKTRACE_PROVIDE_OBJECT) != 0) {ZVAL_OBJ(&tmp, object);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_OBJECT), &tmp);Z_ADDREF(tmp);}ZVAL_INTERNED_STR(&tmp, ZSTR_KNOWN(ZEND_STR_OBJECT_OPERATOR));zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_TYPE), &tmp);} else if (func->common.scope) {ZVAL_STR_COPY(&tmp, func->common.scope->name);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_CLASS), &tmp);ZVAL_INTERNED_STR(&tmp, ZSTR_KNOWN(ZEND_STR_PAAMAYIM_NEKUDOTAYIM));zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_TYPE), &tmp);}if ((options & DEBUG_BACKTRACE_IGNORE_ARGS) == 0 &&func->type != ZEND_EVAL_CODE) {debug_backtrace_get_args(call, &tmp);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_ARGS), &tmp);}} else {/* i know this is kinda ugly, but i'm trying to avoid extra cycles in the main execution loop */zend_bool build_filename_arg = 1;zend_string *pseudo_function_name;if (!ptr->func || !ZEND_USER_CODE(ptr->func->common.type) || ptr->opline->opcode != ZEND_INCLUDE_OR_EVAL) {/* can happen when calling eval from a custom sapi */pseudo_function_name = ZSTR_KNOWN(ZEND_STR_UNKNOWN);build_filename_arg = 0;} elseswitch (ptr->opline->extended_value) {case ZEND_EVAL:pseudo_function_name = ZSTR_KNOWN(ZEND_STR_EVAL);build_filename_arg = 0;break;case ZEND_INCLUDE:pseudo_function_name = ZSTR_KNOWN(ZEND_STR_INCLUDE);break;case ZEND_REQUIRE:pseudo_function_name = ZSTR_KNOWN(ZEND_STR_REQUIRE);break;case ZEND_INCLUDE_ONCE:pseudo_function_name = ZSTR_KNOWN(ZEND_STR_INCLUDE_ONCE);break;case ZEND_REQUIRE_ONCE:pseudo_function_name = ZSTR_KNOWN(ZEND_STR_REQUIRE_ONCE);break;default:/* this can actually happen if you use debug_backtrace() in your error_handler and* you're in the top-scope */pseudo_function_name = ZSTR_KNOWN(ZEND_STR_UNKNOWN);build_filename_arg = 0;break;}if (build_filename_arg && include_filename) {zval arg_array;array_init(&arg_array);/* include_filename always points to the last filename of the last last called-function.if we have called include in the frame above - this is the file we have included.*/ZVAL_STR_COPY(&tmp, include_filename);zend_hash_next_index_insert_new(Z_ARRVAL(arg_array), &tmp);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_ARGS), &arg_array);}ZVAL_INTERNED_STR(&tmp, pseudo_function_name);zend_hash_add_new(Z_ARRVAL(stack_frame), ZSTR_KNOWN(ZEND_STR_FUNCTION), &tmp);}zend_hash_next_index_insert_new(Z_ARRVAL_P(return_value), &stack_frame);include_filename = filename;call = skip;ptr = skip->prev_execute_data;} }?
總結
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