ESP_LOGD crashes when a %s parameter is NULL

[ataweg]

The following code snipplet results in a program crash:

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 char *string = NULL;
 ESP_LOGD( TAG, "*** crash here %s", string );

Since the ESP_LOG * functions are often used for debugging, it is more than annoying when these functions themselves crash, because the parameters are not well defined.

[JimmyPedersen]

The following code snipplet results in a program crash:

Code: Select all

 char *string = NULL;
 ESP_LOGD( TAG, "*** crash here %s", string );

Since the ESP_LOG * functions are often used for debugging, it is more than annoying when these functions themselves crash, because the parameters are not well defined.

I would hazard to guess that the the esp_log_write function (used by the ESP_LOG macro) uses the standard vsnprintf and unless they change that any other solution would be non-trivial.
While the NULL string issue is irritating, it has bitten me more than once, it seems to be the standard for printf-like funtions to act like this (How ever annoying).

The C standard from 1999 says:

7.1.4 Use of library functions

1 Each of the following statements applies unless explicitly stated otherwise in the detailed descriptions that follow: If an argument to a function has an invalid value (such as a value outside the domain of the function, or a pointer outside the address space of the program, or a null pointer,or a pointer to non-modifiable storage when the corresponding parameter is not const-qualified) or a type (after promotion) not expected by a function with variable number of arguments, the behavior is undefined.

To wrap it up, it's to save space.


Maybe you can use something like:

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#define SS(s) (s!=NULL?s:"")	// Safe strings. Check string for NULL

or if you prefer

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#define SS(s) (s!=NULL?s:"<NULL>")	// Safe strings. Check string for NULL

and then wrap strings in ESP_LOGD outputs like so:

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 char *string = NULL;
 ESP_LOGD( TAG, "*** crash here %s", SS(string) );