IO.OIWOP : Output After Input Without Positioning

JavaScript is not currently enabled, but is required for full CodeSonar manual search and browse functionality.

If you are viewing this file in your hub's Web GUI, enable JavaScript in your browser: you will also need it for GUI functionality.

If you opened this file directly from disk, your browser may be directly suppressing JavaScript functionality: certain browsers perform this suppression on local files (but not files delivered by web servers) for security reasons.

If you access the manual through the hub's Web GUI, the functionality will not be suppressed because the hub is a web server.
Alternatively, your browser may allow you to explicitly disable the security setting that suppresses functionality. See the CodeSonar FAQ for more information.

CodeSonar^® 9.2p0

CONFIDENTIAL

CodeSecure Inc

IO.OIWOP : Output After Input Without Positioning

Summary

Output is written to a stream, and input is subsequently read from the same stream without an intervening positioning operation.

Properties

AUTOSARC++14

AUTOSARC++14:A27-0-3

Alternate input and output operations on a file stream shall not be used without an intervening flush or positioning call.

MisraC++2023

MisraC++2023:0.3.2

A function call shall not violate the function's preconditions

MisraC++2023:30.0.2

Reads and writes on the same file stream shall be separated by a positioning operation

CERT-C

CERT-C:FIO39-C

Do not alternately input and output from a stream without an intervening flush or positioning call

CERT-CPP

CERT-CPP:FIO50-CPP

Do not alternately input and output from a file stream without an intervening positioning call

Example

#include <stdio.h>

void in_out(FILE * f){
    (void)fgetc(f);
    (void)fputc('b', f); /* 'Output after Input without Positioning' warning issued here */
}

int in_other_out(FILE * f){
    int x = 1;
    int y = 2;
    (void)fgetc(f);
    x += y;
    (void)fputc('b', f); /* 'Output after Input without Positioning' warning issued here
                          * - output operation does not need to immediately follow input operation
                          */
    return x;
}

void callee_with_out(FILE *f);
void in_then_call(FILE *f){
    (void)fgetc(f);
    callee_with_out(f);
}

void callee_with_out(FILE *f){
    (void)fputc('b', f); /* 'Output after Input without Positioning' warning issued here
                          * - no intervening positioning operation when callee_with_out() is called from in_then_call()
                          */
}

void in_position_out(FILE * f){
    (void)fgetc(f);
    (void)fseek(f, 0, SEEK_SET);
    (void)fputc('b', f);                  /* ok: intervening call to fseek() */
}

Relevant Configuration File Parameters

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