TPM 2.0中的tpm2_load命令对应的源文件就是tpm2_load.c，该文件位于tpm2-tools/tools/下，一共有364行（版本5.5）。

下边对该文件结合tpm2_load进行深入的、完全的解析。

tpm2-tools代码链接：GitHub - tpm2-software/tpm2-tools: The source repository for the Trusted Platform Module (TPM2.0) tools

先来看第一段代码：

// Register this tool with tpm2_tool.c
TPM2_TOOL_REGISTER("load", tpm2_tool_onstart, tpm2_tool_onrun,tpm2_tool_onstop, 0)

TPM2_TOOL_REGISTER是一个宏定义，在tpm2-tools/tools/tpm2_tool.h中，代码如下：

#define TPM2_TOOL_REGISTER(tool_name,tool_onstart,tool_onrun,tool_onstop,tool_onexit) \static const tpm2_tool tool = { \.name		= tool_name, \.onstart	= tool_onstart, \.onrun		= tool_onrun, \.onstop		= tool_onstop, \.onexit		= tool_onexit, \}; \static void \__attribute__((__constructor__)) \__attribute__((__used__)) \_tpm2_tool_init(void) \{ \tpm2_tool_register(&tool); \}

TPM2_TOOLS_REGISTER宏定义是整个tpm2-tools中的命令所共用的，是一个框架性质的代码。

在本文件tpm2_load.c也可以说tpm2_load命令中，宏展开后为：

static const tpm2_tool tool = { .name		= load, .onstart	= tpm2_tool_onstart, .onrun		= tpm2_tool_onrun, .onstop		= tpm2_tool_onstop, .onexit		= 0, }; 
static void 
__attribute__((__constructor__)) 
__attribute__((__used__)) 
_tpm2_tool_init(void) 
{ tpm2_tool_register(&tool); 
}

tpm2_tool结构的定义也在tpm2-tools/tools/tpm2_tool.h中，代码如下：

typedef struct {const char * name;tpm2_tool_onstart_t onstart;tpm2_tool_onrun_t onrun;tpm2_tool_onstop_t onstop;tpm2_tool_onexit_t onexit;
} tpm2_tool;

其中包含的相关函数指针如下（同文件中，就在上边）：

/*** An optional interface for tools to specify what options they support.* They are concatenated with main's options and passed to getopt_long.* @param opts*  The callee can choose to set *opts to a tpm_options pointer allocated*  via tpm2_options_new(). Setting *opts to NULL is not an error, and*  Indicates that no options are specified by the tool.** @return*  True on success, false on error.*/
typedef bool (*tpm2_tool_onstart_t)(tpm2_options **opts);/*** This is the main interface for tools, after tcti and sapi/esapi initialization* are performed.* @param ectx*  The system/esapi api context.* @param flags*  Flags that tools may wish to respect.* @return*  A tool_rc indicating status.*/
typedef tool_rc (*tpm2_tool_onrun_t)(ESYS_CONTEXT *ectx, tpm2_option_flags flags);/*** Called after tpm2_tool_onrun() is invoked. ESAPI context is still valid during this call.* @param ectx*  The system/esapi api context.* @return*  A tool_rc indicating status.*/
typedef tool_rc (*tpm2_tool_onstop_t)(ESYS_CONTEXT *ectx);/*** Called when the tool is exiting, useful for cleanup.*/
typedef void (*tpm2_tool_onexit_t)(void);

tpm2_tool_register函数在tpm2-tools/tools/tpm2_tools.c中实现，代码如下：

/** Build a list of the TPM2 tools linked into this executable*/
#ifndef TPM2_TOOLS_MAX
#define TPM2_TOOLS_MAX 1024
#endif
static const tpm2_tool *tools[TPM2_TOOLS_MAX];
static unsigned tool_count;void tpm2_tool_register(const tpm2_tool *tool) {if (tool_count < TPM2_TOOLS_MAX) {tools[tool_count++] = tool;} else {LOG_ERR("Over tool count");abort();}
}

回到tpm2_load.c，来看具体的几个函数。

（1）tpm2_tool_onstart

tpm2_tool_onstart函数代码如下：

static bool tpm2_tool_onstart(tpm2_options **opts) {const struct option topts[] = {{ "auth",           required_argument, 0, 'P' },{ "public",         required_argument, 0, 'u' },{ "private",        required_argument, 0, 'r' },{ "name",           required_argument, 0, 'n' },{ "key-context",    required_argument, 0, 'c' },{ "parent-context", required_argument, 0, 'C' },{ "cphash",         required_argument, 0,  0  },};*opts = tpm2_options_new("P:u:r:n:C:c:", ARRAY_LEN(topts), topts, on_option,0, 0);return *opts != 0;
}

（2）tpm2_tool_onrun

tpm2_tool_onrun函数代码如下：

static tool_rc tpm2_tool_onrun(ESYS_CONTEXT *ectx, tpm2_option_flags flags) {UNUSED(flags);/** 1. Process options*/tool_rc rc = check_options(ectx);if (rc != tool_rc_success) {return rc;}/** 2. Process inputs*/rc = process_inputs(ectx);if (rc != tool_rc_success) {return rc;}/** 3. TPM2_CC_ call*/rc = load(ectx);if (rc != tool_rc_success) {return rc;}/** 4. Process outputs*/return process_output(ectx);
}

（3）tpm2_tool_onstop

tpm2_tool_onstop函数代码如下：

static tool_rc tpm2_tool_onstop(ESYS_CONTEXT *ectx) {UNUSED(ectx);/** 1. Free objects*//** 2. Close authorization sessions*/tool_rc rc = tpm2_session_close(&ctx.parent.object.session);/** 3. Close auxiliary sessions*/return rc;
}