I'm writing a multithreaded server in C for a uni project and I'm having a hard time figuring out how to do error handling in a nice, readable and standard way.
Right now, if the program terminates successfully, I free every bit of allocated memory at the end of it. But what if a fatal error occurs during the execution (e.g. malloc returns NULL)?
For example, let's say I have a custom data type mydata_t and a constructor function mydata_t *mydata_init() that is used by several modules of my program. After seeing some code on the internet, this is how I would have written it:
mydata_t *mydata_init() {
mydata_t *mydata = malloc(sizeof(mydata_t));
if (!mydata) return NULL;
mydata->field1 = malloc(sizeof(mydata2_t));
if (!mydata->field1) return NULL;
mydata->field2 = malloc(sizeof(mydata3_t));
if (!mydata->field2) return NULL;
/*
Initialization of other fields
*/
return mydata;
}
It does seem nice and clean, but is this the "standard" way to do it?
In particular, what if one of the mallocs returns NULL? Is it necessary to free all the previously allocated memory? Is it reasonable to change the code to something like this?
mydata_t *mydata_init() {
mydata_t *mydata = malloc(sizeof(mydata_t));
if (!mydata) goto err_1;
mydata->field1 = malloc(sizeof(mydata2_t));
if (!mydata->field1) goto err_2;
mydata->field2 = malloc(sizeof(mydata3_t));
if (!mydata->field2) goto err_3;
/*
Initialization of other fields
*/
return mydata;
/*
Other tags
*/
err_3:
free(mydata->field1);
err_2:
free(mydata);
err_1:
return NULL;
}
