svn commit: r366207 - head/lib/libc/gen
Alan Somers
asomers at freebsd.org
Mon Sep 28 04:09:02 UTC 2020
On Sun, Sep 27, 2020 at 5:15 PM Konstantin Belousov <kostikbel at gmail.com>
wrote:
> 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.
>
Warnings are NOT pointless. 99% of them are. But the only way to find the
1% that aren't is to quell the 99% that are. Last week I wrote a bug that
fortunately got caught in code review. But it shouldn't have made it that
far. It should've been caught by the compiler, but libc is only built with
WARNS=2. This commit is one step towards raising libc's WARNs level to 3.
Only 334 files left to go.
>
> 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 ?
>
Mostly the warnings were about comparisons of integers with different
signedness. Also there were some warnings about missing prototypes.
>
> 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.
>
Better to give it enough space that the compiler can check it statically,
rather than require runtime checks.
-Alan
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