svn commit: r366207 - head/lib/libc/gen

[Konstantin Belousov]

On Sun, Sep 27, 2020 at 10:26:41PM +0000, Alan Somers wrote:
> Author: asomers
> Date: Sun Sep 27 22:26:41 2020
> New Revision: 366207
> URL: https://svnweb.freebsd.org/changeset/base/366207
> 
> Log:
>   Misc compiler warning fixes in lib/libc
>   
>   Reviewed by:	kevans, imp
>   MFC after:	2 weeks
>   Differential Revision:	https://reviews.freebsd.org/D26534
> 
> Modified:
>   head/lib/libc/gen/auxv.c
>   head/lib/libc/gen/basename_compat.c
>   head/lib/libc/gen/crypt.c
>   head/lib/libc/gen/dirname_compat.c
>   head/lib/libc/gen/fts-compat.c
>   head/lib/libc/gen/ftw-compat11.c
>   head/lib/libc/gen/getentropy.c
> 
> Modified: head/lib/libc/gen/auxv.c
> ==============================================================================
> --- head/lib/libc/gen/auxv.c	Sun Sep 27 21:43:19 2020	(r366206)
> +++ head/lib/libc/gen/auxv.c	Sun Sep 27 22:26:41 2020	(r366207)
> @@ -67,7 +67,8 @@ __init_elf_aux_vector(void)
>  }
>  
>  static pthread_once_t aux_once = PTHREAD_ONCE_INIT;
> -static int pagesize, osreldate, canary_len, ncpus, pagesizes_len, bsdflags;
> +static int pagesize, osreldate, ncpus, bsdflags;
> +static size_t canary_len, pagesizes_len;
>  static int hwcap_present, hwcap2_present;
>  static char *canary, *pagesizes, *execpath;
>  static void *ps_strings, *timekeep;
> @@ -245,16 +246,21 @@ int
>  _elf_aux_info(int aux, void *buf, int buflen)
>  {
>  	int res;
> +	size_t buflen_;
>  
>  	__init_elf_aux_vector();
>  	if (__elf_aux_vector == NULL)
>  		return (ENOSYS);
>  	_once(&aux_once, init_aux);
>  
> +	if (buflen < 0)
> +		return (EINVAL);
> +	buflen_ = (size_t)buflen;
> +
>  	switch (aux) {
>  	case AT_CANARY:
> -		if (canary != NULL && canary_len >= buflen) {
> -			memcpy(buf, canary, buflen);
> +		if (canary != NULL && canary_len >= buflen_) {
> +			memcpy(buf, canary, buflen_);
>  			memset(canary, 0, canary_len);
>  			canary = NULL;
>  			res = 0;
> @@ -267,35 +273,35 @@ _elf_aux_info(int aux, void *buf, int buflen)
>  		else if (buf == NULL)
>  			res = EINVAL;
>  		else {
> -			if (strlcpy(buf, execpath, buflen) >= buflen)
> +			if (strlcpy(buf, execpath, buflen_) >= buflen_)
>  				res = EINVAL;
>  			else
>  				res = 0;
>  		}
>  		break;
>  	case AT_HWCAP:
> -		if (hwcap_present && buflen == sizeof(u_long)) {
> +		if (hwcap_present && buflen_ == sizeof(u_long)) {
>  			*(u_long *)buf = hwcap;
>  			res = 0;
>  		} else
>  			res = ENOENT;
>  		break;
>  	case AT_HWCAP2:
> -		if (hwcap2_present && buflen == sizeof(u_long)) {
> +		if (hwcap2_present && buflen_ == sizeof(u_long)) {
>  			*(u_long *)buf = hwcap2;
>  			res = 0;
>  		} else
>  			res = ENOENT;
>  		break;
>  	case AT_PAGESIZES:
> -		if (pagesizes != NULL && pagesizes_len >= buflen) {
> -			memcpy(buf, pagesizes, buflen);
> +		if (pagesizes != NULL && pagesizes_len >= buflen_) {
> +			memcpy(buf, pagesizes, buflen_);
>  			res = 0;
>  		} else
>  			res = ENOENT;
>  		break;
>  	case AT_PAGESZ:
> -		if (buflen == sizeof(int)) {
> +		if (buflen_ == sizeof(int)) {
>  			if (pagesize != 0) {
>  				*(int *)buf = pagesize;
>  				res = 0;
> @@ -305,7 +311,7 @@ _elf_aux_info(int aux, void *buf, int buflen)
>  			res = EINVAL;
>  		break;
>  	case AT_OSRELDATE:
> -		if (buflen == sizeof(int)) {
> +		if (buflen_ == sizeof(int)) {
>  			if (osreldate != 0) {
>  				*(int *)buf = osreldate;
>  				res = 0;
> @@ -315,7 +321,7 @@ _elf_aux_info(int aux, void *buf, int buflen)
>  			res = EINVAL;
>  		break;
>  	case AT_NCPUS:
> -		if (buflen == sizeof(int)) {
> +		if (buflen_ == sizeof(int)) {
>  			if (ncpus != 0) {
>  				*(int *)buf = ncpus;
>  				res = 0;
> @@ -325,7 +331,7 @@ _elf_aux_info(int aux, void *buf, int buflen)
>  			res = EINVAL;
>  		break;
>  	case AT_TIMEKEEP:
> -		if (buflen == sizeof(void *)) {
> +		if (buflen_ == sizeof(void *)) {
>  			if (timekeep != NULL) {
>  				*(void **)buf = timekeep;
>  				res = 0;
> @@ -335,14 +341,14 @@ _elf_aux_info(int aux, void *buf, int buflen)
>  			res = EINVAL;
>  		break;
>  	case AT_BSDFLAGS:
> -		if (buflen == sizeof(int)) {
> +		if (buflen_ == sizeof(int)) {
>  			*(int *)buf = bsdflags;
>  			res = 0;
>  		} else
>  			res = EINVAL;
>  		break;
>  	case AT_PS_STRINGS:
> -		if (buflen == sizeof(void *)) {
> +		if (buflen_ == sizeof(void *)) {
>  			if (ps_strings != NULL) {
>  				*(void **)buf = ps_strings;
>  				res = 0;

This is significant uglification of the code in the name of fixing pointless
warnings.

I suspect that you tried to shut down warning about comparision of integers
of different size, int vs. sizeof() which has size_t result.  Is there
anything else ?

All these values should be small integers, which is quite vividly
illustrated by comparision with sizeof() of built-in types.  If compiler
cannot deduce that itself the warning should be forcibly disabled by
flag instead of doing 'buflen_'.

And canary_len/pagesizes_len do not need to take 8 bytes, their values
never become greater than one hundred.