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mysqlnd php,php mysqlnd

赏育
2023-12-01

# mysql pod

介绍 mysqlnd

首先mysqlnd 是php 自带的mysql 扩展,mysqlnd是mysql native driver 的简称

在文件 /ext/mysqlnd/mysqlnd_ps.c

mysqlnd_stmt_read_prepare_response(MYSQLND_STMT * s)

{

MYSQLND_PACKET_PREPARE_RESPONSE * prepare_resp;

...

if (FAIL == PACKET_READ(prepare_resp)) {

goto done;

}

...

}

先看宏MYSQLND_PACKET_PREPARE_RESPONSE

/* COM_PREPARE response packet */

typedef struct st_mysqlnd_packet_prepare_response {

MYSQLND_PACKET_HEADER header;

/* also known as field_count 0x00=OK , 0xFF=error */

unsigned char error_code;

zend_ulong stmt_id;

unsigned int field_count;

unsigned int param_count;

unsigned int warning_count;

/* present in case of error */

MYSQLND_ERROR_INFO error_info;

} MYSQLND_PACKET_PREPARE_RESPONSE;

看到define 部分 其实调用了 read_from_net 这个方法

而read_from_net 就是php_mysqlnd_prepare_read

首先看到宏 PACKET_READ

/ext/mysqlnd/mysqlnd_wireprotocol.c

#define PACKET_READ(packet) ((packet)->header.m->read_from_net((packet)))

由于 packet 的类型是MYSQLND_PACKET_PREPARE_RESPONSE ,所以packet->header即

MYSQLND_PACKET_HEADER 类型。

我们来看一下这个结构图的定义:

typedef struct st_mysqlnd_packet_header {

...

mysqlnd_packet_methods *m;

...

MYSQLND_CONN_DATA * conn;

...

} MYSQLND_PACKET_HEADER;

好了,我们现在到了最后一步

// 注意这个静态全局变量

/* {{{ packet_methods */

static mysqlnd_packet_methods packet_methods[PROT_LAST] =

{

...

{

sizeof(MYSQLND_PACKET_PREPARE_RESPONSE),

php_mysqlnd_prepare_read, /* read */

NULL, /* write */

php_mysqlnd_prepare_free_mem,

}, /* PROT_PREPARE_RESP_PACKET */

...

};

/* }}} */

接下来我们只需要往下找php_mysqlnd_prepare_read 即可。

/* {{{ php_mysqlnd_prepare_read */

static enum_func_status

php_mysqlnd_prepare_read(void * _packet)

{

MYSQLND_PACKET_PREPARE_RESPONSE *packet= (MYSQLND_PACKET_PREPARE_RESPONSE *) _packet;

MYSQLND_ERROR_INFO * error_info = packet->header.error_info;

MYSQLND_PFC * pfc = packet->header.protocol_frame_codec;

MYSQLND_VIO * vio = packet->header.vio;

MYSQLND_STATS * stats = packet->header.stats;

MYSQLND_CONNECTION_STATE * connection_state = packet->header.connection_state;

/* In case of an error, we should have place to put it */

size_t buf_len = pfc->cmd_buffer.length;

zend_uchar *buf = (zend_uchar *) pfc->cmd_buffer.buffer;

zend_uchar *p = buf;

const zend_uchar * const begin = buf;

unsigned int data_size;

DBG_ENTER("php_mysqlnd_prepare_read");

if (FAIL == mysqlnd_read_packet_header_and_body(&(packet->header), pfc, vio, stats, error_info, connection_state, buf, buf_len, "prepare", PROT_PREPARE_RESP_PACKET)) {

DBG_RETURN(FAIL);

}

BAIL_IF_NO_MORE_DATA;

data_size = packet->header.size;

packet->error_code = uint1korr(p);

p++;

BAIL_IF_NO_MORE_DATA;

if (ERROR_MARKER == packet->error_code) {

php_mysqlnd_read_error_from_line(p, data_size - 1,

packet->error_info.error,

sizeof(packet->error_info.error),

&packet->error_info.error_no,

packet->error_info.sqlstate

);

DBG_RETURN(PASS);

}

if (data_size != PREPARE_RESPONSE_SIZE_41 &&

data_size != PREPARE_RESPONSE_SIZE_50 &&

!(data_size > PREPARE_RESPONSE_SIZE_50)) {

DBG_ERR_FMT("Wrong COM_STMT_PREPARE response size. Received %u", data_size);

php_error(E_WARNING, "Wrong COM_STMT_PREPARE response size. Received %u", data_size);

DBG_RETURN(FAIL);

}

packet->stmt_id = uint4korr(p);

p += 4;

BAIL_IF_NO_MORE_DATA;

/* Number of columns in result set */

packet->field_count = uint2korr(p);

p += 2;

BAIL_IF_NO_MORE_DATA;

packet->param_count = uint2korr(p);

p += 2;

BAIL_IF_NO_MORE_DATA;

if (data_size > 9) {

/* 0x0 filler sent by the server for 5.0+ clients */

p++;

BAIL_IF_NO_MORE_DATA;

packet->warning_count = uint2korr(p);

}

DBG_INF_FMT("Prepare packet read: stmt_id=%u fields=%u params=%u",

packet->stmt_id, packet->field_count, packet->param_count);

BAIL_IF_NO_MORE_DATA;

DBG_RETURN(PASS);

premature_end:

DBG_ERR_FMT("PREPARE packet %d bytes shorter than expected", p - begin - packet->header.size);

php_error_docref(NULL, E_WARNING, "PREPARE packet "MYSQLND_SZ_T_SPEC" bytes shorter than expected",

p - begin - packet->header.size);

DBG_RETURN(FAIL);

}

/* }}} */

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