CERT C++: MSC33-C

Do not pass invalid data to the asctime() function

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Description

Rule Definition

Do not pass invalid data to the asctime() function.¹

Polyspace Implementation

The rule checker checks for Use of obsolete standard function.

Examples

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Use of obsolete standard function

Issue

Use of obsolete standard function detects calls to standard function routines that are considered legacy, removed, deprecated, or obsolete by C/C++ coding standards.

Obsolete Function	Standards	Risk	Replacement Function
`asctime`	Deprecated in POSIX.1-2008	Not thread-safe.	`strftime` or `asctime_s`
`asctime_r`	Deprecated in POSIX.1-2008	Implementation based on unsafe function `sprintf`.	`strftime` or `asctime_s`
`bcmp`	Deprecated in 4.3BSD Marked as legacy in POSIX.1-2001.	Returns from function after finding the first differing byte, making it vulnerable to timing attacks.	`memcmp`
`bcopy`	Deprecated in 4.3BSD Marked as legacy in POSIX.1-2001.	Returns from function after finding the first differing byte, making it vulnerable to timing attacks.	`memcpy` or `memmove`
`brk` and `sbrk`	Marked as legacy in SUSv2 and POSIX.1-2001.		`malloc`
`bsd_signal`	Removed in POSIX.1-2008		`sigaction`
`bzero`	Marked as legacy in POSIX.1-2001. Removed in POSIX.1-2008.		`memset`
`ctime`	Deprecated in POSIX.1-2008	Not thread-safe.	`strftime` or `asctime_s`
`ctime_r`	Deprecated in POSIX.1-2008	Implementation based on unsafe function `sprintf`.	`strftime` or `asctime_s`
`cuserid`	Removed in POSIX.1-2001.	Not reentrant. Precise functionality not standardized causing portability issues.	`getpwuid`
`ecvt` and `fcvt`	Marked as legacy in POSIX.1-2001. Removed in POSIX.1-2008	Not reentrant	`snprintf`
`ecvt_r` and `fcvt_r`	Marked as legacy in POSIX.1-2001. Removed in POSIX.1-2008		`snprintf`
`ftime`	Removed in POSIX.1-2008		`time`, `gettimeofday`, `clock_gettime`
`gamma`, `gammaf`, `gammal`	Function not specified in any standard because of historical variations	Portability issues.	`tgamma`, `lgamma`
`gcvt`	Marked as legacy in POSIX.1-2001. Removed in POSIX.1-2008.		`snprintf`
`getcontext`	Removed in POSIX.1-2008.	Portability issues.	Use POSIX thread instead.
`getdtablesize`	BSD API function not included in POSIX.1-2001	Portability issues.	`sysconf( _SC_OPEN_MAX )`
`gethostbyaddr`	Removed in POSIX.1-2008	Not reentrant	`getaddrinfo`
`gethostbyname`	Removed in POSIX.1-2008	Not reentrant	`getnameinfo`
`getpagesize`	BSD API function not included in POSIX.1-2001	Portability issues.	`sysconf( _SC_PAGESIZE )`
`getpass`	Removed in POSIX.1-2001.	Not reentrant.	`getpwuid`
`getw`	Not present in POSIX.1-2001.		`fread`
`getwd`	Marked legacy in POSIX.1-2001. Removed in POSIX.1-2008.		`getcwd`
`index`	Marked as legacy in POSIX.1-2001. Removed in POSIX.1-2008.		`strchr`
`makecontext`	Removed in POSIX.1-2008.	Portability issues.	Use POSIX thread instead.
`memalign`	Appears in SunOS 4.1.3. Not in 4.4 BSD or POSIX.1-2001		`posix_memalign`
`mktemp`	Removed in POSIX.1-2008.	Generated names are predictable and can cause a race condition.	`mkstemp` removes race risk
`pthread_attr_getstackaddr` and `pthread_attr_setstackaddr`		Ambiguities in the specification of the `stackaddr` attribute cause portability issues	`pthread_attr_getstack` and `pthread_attr_setstack`
`putw`	Not present in POSIX.1-2001.	Portability issues.	`fwrite`
`qecvt` and `qfcvt`	Marked as legacy in POSIX.1-2001, removed in POSIX.1-2008		`snprintf`
`qecvt_r` and `qfcvt_r`	Marked as legacy in POSIX.1-2001, removed in POSIX.1-2008		`snprintf`
`rand_r`	Marked as obsolete in POSIX.1-2008
`re_comp`	BSD API function	Portability issues	`regcomp`
`re_exes`	BSD API function	Portability issues	`regexec`
`rindex`	Marked as legacy in POSIX.1-2001. Removed in POSIX.1-2008.		`strrchr`
`scalb`	Removed in POSIX.1-2008		`scalbln`, `scalblnf`, or `scalblnl`
`sigblock`	4.3BSD signal API whose origin is unclear		`sigprocmask`
`sigmask`	4.3BSD signal API whose origin is unclear		`sigprocmask`
`sigsetmask`	4.3BSD signal API whose origin is unclear		`sigprocmask`
`sigstack`	Interface is obsolete and not implemented on most platforms.	Portability issues.	`sigaltstack`
`sigvec`	4.3BSD signal API whose origin is unclear		`sigaction`
`swapcontext`	Removed in POSIX.1-2008	Portability issues.	Use POSIX threads.
`tmpnam` and `tmpnam_r`	Marked as obsolete in POSIX.1-2008.	This function generates a different string each time it is called, up to TMP_MAX times. If it is called more than TMP_MAX times, the behavior is implementation-defined.	`mkstemp`, `tmpfile`
`ttyslot`	Removed in POSIX.1-2001.
`ualarm`	Marked as legacy in POSIX.1-2001. Removed in POSIX.1-2008.	Errors are under-specified	`setitimer` or POSIX `timer_create`
`usleep`	Removed in POSIX.1-2008.		`nanosleep`
`utime`	SVr4, POSIX.1-2001. POSIX.1-2008 marks as obsolete.
`valloc`	Marked as obsolete in 4.3BSD. Marked as legacy in SUSv2. Removed from POSIX.1-2001		`posix_memalign`
`vfork`	Removed from POSIX.1-2008	Under-specified in previous standards.	`fork`
`wcswcs`	This function was not included in the final ISO/IEC 9899:1990/Amendment 1:1995 (E).		`wcsstr`
`WinExec`	WinAPI provides this function only for 16-bit Windows compatibility.		`CreateProcess`
`LoadModule`	WinAPI provides this function only for 16-bit Windows compatibility.		`CreateProcess`

Fix

The fix depends on the root cause of the defect. Often the result details show a sequence of events that led to the defect. You can implement the fix on any event in the sequence. If the result details do not show the event history, you can trace back using right-click options in the source code and see previous related events. See also Interpret Bug Finder Results in Polyspace Desktop User Interface.

See examples of fixes below.

If you do not want to fix the issue, add comments to your result or code to avoid another review. See:

Address Results in Polyspace User Interface Through Bug Fixes or Justifications if you review results in the Polyspace user interface.
Address Results in Polyspace Access Through Bug Fixes or Justifications (Polyspace Access) if you review results in a web browser.
Annotate Code and Hide Known or Acceptable Results if you review results in an IDE.

Example - Printing Out Time

#include <stdio.h>
#include <time.h> 

void timecheck_bad(int argc, char *argv[])
{
    time_t ticks; 

    ticks = time(NULL);
    printf("%.24s\r\n", ctime(&ticks)); //Noncompliant
}

In this example, the function ctime formats the current time and prints it out. However, ctime was removed after C99 because it does not work on multithreaded programs.

Correction — Different Time Function

One possible correction is to use strftime instead because this function uses a set buffer size.

#include <stdio.h>
#include <string.h>
#include <time.h> 

void timecheck_good(int argc, char *argv[])
{
    char outBuff[1025];
    time_t ticks; 
    struct tm * timeinfo;
    
    memset(outBuff, 0, sizeof(outBuff)); 
    
    ticks = time(NULL);
    timeinfo = localtime(&ticks);
    strftime(outBuff,sizeof(outBuff),"%I:%M%p.",timeinfo);
    fprintf(stdout, outBuff);
}

Check Information

Group: 49. Miscellaneous (MSC)

Version History

Introduced in R2019a