LANG.ERRCODE.NZ : Non-zero Error Code

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The code calls a function f() that will set an error code (such as errno) on failure, but the error code is not set to zero (0) before the call. This means that if the error code is non-zero after calling f(), it may have been set by some earlier function call and not by f().

Class Name

Non-zero Error Code

Significance

style

Mnemonic

LANG.ERRCODE.NZ

Categories

MisraC2023	MisraC2023:22.8	The value of errno shall be set to zero prior to a call to an errno-setting-function
	MisraC2023:D.4.7	If a function returns error information, then that error information shall be tested
Misra2012	Misra2012:22.8	The value of errno shall be set to zero prior to a call to an errno-setting-function
	Misra2012:D.4.7	If a function returns error information, then that error information shall be tested
Misra2004	Misra2004:16.10	If a function returns error information, then that error information shall be tested
	Misra2004:20.5	The error indicator errno shall not be used
AUTOSARC++14	AUTOSARC++14:M0-3-2	If a function generates error information, then that error information shall be tested.
	AUTOSARC++14:M19-3-1	The error indicator errno shall not be used.
MisraC++2008	MisraC++2008:0-3-2	If a function generates error information, then that error information shall be tested.
	MisraC++2008:19-3-1	The error indicator errno shall not be used.
TS17961	TS17961:5.24-inverrno	5.24. Incorrectly setting and using errno
CERT-C	CERT-C:ERR33-C	Detect and handle standard library errors
	CERT-C:POS54-C	Detect and handle POSIX library errors
JSF++	JSF++:17	The error indicator errno shall not be used.
	JSF++:115	If a function returns error information, then that error information will be tested.

Availability

Available for C and C++.

Enabling

Checks for this warning class are disabled by default. To enable them, add the following WARNING_FILTER rule to the project configuration file.

WARNING_FILTER += allow class="Non-zero Error Code"

#include <errno.h>
#include <stdio.h>

void errno_nonzero(FILE *fp1, FILE *fp2){
    errno=0;
    (void) fseek(fp1, 0L, 0);              /* ok: errno set to 0 immediately before call */
    (void) ftell(fp1);       /* 'Non-zero Error Code' warning issued here
                              * - errno not set to 0 before call to ftell()
                              * - if errno was set by the fseek() call, this value is not cleared
                              */
    if (errno==0){
        (void) ftell(fp2);                 /* ok: call only occurs on path where errno==0 */
    }
    else {
        /* handle error */                 /* errno!=0 may have been caused by the ftell(fp1) call, but it may
                                            * also have been caused by the fseek() call. */
    }
}

The following configuration file parameters affect checks for this warning class.

LANG.ERRCODE.NZ : Non-zero Error Code

Summary

Properties

Example

Relevant Configuration File Parameters