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Adding a section explaining how to fake variadic functions

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Rubio R. C. Terra
2017-02-06 18:10:45 -02:00
committed by Rubio Ribeiro Canario Terra
parent 74c07a8f66
commit 7cb667102d
1 changed files with 17 additions and 0 deletions
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README.md
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@@ -329,6 +329,23 @@ The fake will call your custom functions in the order specified by the SET_CUSTO
macro. When the last custom fake is reached the fake will keep calling the last custom macro. When the last custom fake is reached the fake will keep calling the last custom
fake in the sequence. This macro works much like the SET_RETURN_SEQ macro. fake in the sequence. This macro works much like the SET_RETURN_SEQ macro.
## Variadic Functions
You can fake variadic functions using the macros <tt>FAKE_VALUE_FUNC_VARARG</tt>
and <tt>FAKE_VOID_FUNC_VARARG</tt>. For instance:
FAKE_VALUE_FUNC_VARARG(int, fprintf, FILE *, const char*, ...);
In order to access the variadic parameters from a custom fake function, declare a
<tt>va_list</tt> parameter. For instance, a custom fake for <tt>fprintf()</tt>
could call the real <tt>fprintf()</tt> like this:
int fprintf_custom(FILE *stream, const char *format, va_list ap) {
if (fprintf0_fake.return_val < 0) // should we fail?
return fprintf0_fake.return_val;
return vfprintf(stream, format, ap);
}
## How do I fake a function that returns a value by reference? ## How do I fake a function that returns a value by reference?
The basic mechanism that FFF provides you in this case is the custom_fake field described in the *Custom Return Value Delegate* example above. The basic mechanism that FFF provides you in this case is the custom_fake field described in the *Custom Return Value Delegate* example above.