Any good idioms for error handling in straight C programs?

Question

Getting back in to some C work.

Many of my functions look like this:

int err = do_something(arg1, arg2, arg3, &result); 

With the intent the result gets populated by the function, and the return value is the status of the call.

The darkside is you get something naive like this:

int err = func1(...); if (!err) {     err = func2(...);     if (!err) {         err = func3(...);     } } return err; 

I could macro it I suppose:

#define ERR(x) if (!err) { err = (x) } int err = 0; ERR(func1(...)); ERR(func2(...)); ERR(func3(...)); return err; 

But that only works if I'm chaining function calls, vs doing other work.

Obviously Java, C#, C++ have exceptions that work very well for these kinds of things.

I'm just curious what other folks do and how other folks do error handling in their C programs nowadays.

Answer 1

If you have resources that need to be released at the end, then sometimes the old trusty goto can be handy!

int major_func(size_t len) {     int err;     char *buf;      buf = malloc(len);      if (err = minor_func1(buf))         goto major_func_end;     if (err = minor_func2(buf))         goto major_func_end;     if (err = minor_func3(buf))         goto major_func_end;  major_func_end:     free(buf);     return err; } 

Answer 2

Two typical patterns:

int major_func() {     int err = 0;      if (err = minor_func1()) return err;     if (err = minor_func2()) return err;     if (err = minor_func3()) return err;      return 0; }  int other_idea() {     int err = minor_func1();     if (!err)         err = minor_func2();     if (!err)         err = minor_func3();     return err;             }  void main_func() {     int err = major_func();     if (err)     {         show_err();         return;     }     happy_happy_joy_joy();      err = other_idea();     if (err)     {         show_err();         return;     }     happy_happy_joy_joy(); }