Hello! On Thu, Dec 21, 2023 at 05:37:02PM +0400, Sergey Kandaurov wrote:
> > On 16 Dec 2023, at 06:57, Maxim Dounin <mdou...@mdounin.ru> wrote: > > > > Hello! > > > > On Sat, Dec 09, 2023 at 08:42:11AM +0000, J Carter wrote: > > > >> On Sat, 09 Dec 2023 07:46:10 +0000 > >> J Carter <jordanc.car...@outlook.com> wrote: > >> > >>> # HG changeset patch > >>> # User J Carter <jordanc.car...@outlook.com> > >>> # Date 1702101635 0 > >>> # Sat Dec 09 06:00:35 2023 +0000 > >>> # Node ID 1a77698f82d2580aa8b8f62ce89b4dbb6d678c5d > >>> # Parent d9275e982a7188a1ea7855295ffa93362ea9830f > >>> Win32: extended ngx_random range to 0x7fffffff > >>> > >>> rand() is used on win32. RAND_MAX is implementation defined. win32's is > >>> 0x7fff. > >>> > >>> Existing uses of ngx_random rely upon 0x7fffffff range provided by > >>> posix implementations of random(). > >>> > >>> diff -r d9275e982a71 -r 1a77698f82d2 src/os/win32/ngx_win32_config.h > >>> --- a/src/os/win32/ngx_win32_config.h Sat Dec 09 05:09:07 2023 +0000 > >>> +++ b/src/os/win32/ngx_win32_config.h Sat Dec 09 06:00:35 2023 +0000 > >>> @@ -280,7 +280,9 @@ > >>> > >>> #define NGX_HAVE_GETADDRINFO 1 > >>> > >>> -#define ngx_random rand > >>> +#define ngx_random > >>> \ > >>> + ((rand() << 16) | (rand() << 1) | (rand() >> 14)) > >>> + > >>> #define ngx_debug_init() > >>> > >>> > >> > >> ^ my mistake - copying error.. > >> > >> # HG changeset patch > >> # User J Carter <jordanc.car...@outlook.com> > >> # Date 1702111094 0 > >> # Sat Dec 09 08:38:14 2023 +0000 > >> # Node ID 10ef59a412a330872fc6d46de64f42e32e997b3a > >> # Parent d9275e982a7188a1ea7855295ffa93362ea9830f > >> Win32: extended ngx_random range to 0x7fffffff > > > > Nitpicking: > > > > Win32: extended ngx_random() range to 0x7fffffff. > > > >> > >> rand() is used on win32. RAND_MAX is implementation defined. win32's is > >> 0x7fff. > >> > >> Existing uses of ngx_random rely upon 0x7fffffff range provided by > >> posix implementations of random(). > > > > Thanks for catching this. > > > > As far as I can see, the only module which actually relies on the > > range is the random index module. Relying on the ngx_random() > > range generally looks wrong to me, and we might want to change the > > code to don't. OTOH, it's the only way to get a completely > > uniform distribution, and that's what the module tries to do. As > > such, it might be good enough to preserve it as is, at least till > > further changes to ngx_random(). > > > > Either way, wider range for ngx_random() should be beneficial in > > other places. > > > >> > >> diff -r d9275e982a71 -r 10ef59a412a3 src/os/win32/ngx_win32_config.h > >> --- a/src/os/win32/ngx_win32_config.h Sat Dec 09 05:09:07 2023 +0000 > >> +++ b/src/os/win32/ngx_win32_config.h Sat Dec 09 08:38:14 2023 +0000 > >> @@ -280,7 +280,9 @@ > >> > >> #define NGX_HAVE_GETADDRINFO 1 > >> > >> -#define ngx_random rand > >> +#define ngx_random() > >> \ > > > > Nitpicking: the "\" character should be at the 79th column (in > > some files at 78th). This ensures that a diff won't wrap on a > > standard 80-column terminal. > > > >> + ((rand() << 16) | (rand() << 1) | (rand() >> 14)) > >> + > >> #define ngx_debug_init() > > > > Using "|" for random numbers looks utterly wrong to me, even if > > ORed values are guaranteed to not interfere. > > > > I would rather use "^", and avoid dependency on the particular > > value of RAND_MAX (other than POSIX-required minimum of 32767) by > > using something like > > > > 0x7fffffff & ((rand() << 16) ^ (rand() << 8) ^ rand()) > > > > with proper typecasts. > > > > Something like this should work: > > > > diff --git a/src/os/win32/ngx_win32_config.h > > b/src/os/win32/ngx_win32_config.h > > --- a/src/os/win32/ngx_win32_config.h > > +++ b/src/os/win32/ngx_win32_config.h > > @@ -280,7 +280,11 @@ typedef int sig_atomic_t > > > > #define NGX_HAVE_GETADDRINFO 1 > > > > -#define ngx_random rand > > +#define ngx_random() > > \ > > + ((long) (0x7fffffff & ( ((uint32_t) rand() << 16) > > \ > > + ^ ((uint32_t) rand() << 8) > > \ > > + ^ ((uint32_t) rand()) ))) > > + > > #define ngx_debug_init() > > > > > > Nitpicking: you might want to re-align the "^" operator to the first > symbol of the left-hand operand (similar to NGX_CONF_TAKE1234, or > even NGX_UNIX_ADDRSTRLEN). Other than that, it looks good. It's intentionally aligned this way to simplify reading. Such style is occasionally used in complex macro definitions, see ngx_mp4_get_32value() or ngx_proxy_protocol_parse_uint32() for some examples. Just for completeness, below is the updated patch. # HG changeset patch # User J Carter <jordanc.car...@outlook.com> # Date 1702111094 0 # Sat Dec 09 08:38:14 2023 +0000 # Node ID 92923ac5ea2a395774b28460f07d0fd2e1a2de24 # Parent cc16989c6d61385027c1ebfd43929f8369fa5f62 Win32: extended ngx_random() range to 0x7fffffff. rand() is used on win32. RAND_MAX is implementation defined. win32's is 0x7fff. Existing uses of ngx_random() rely upon 0x7fffffff range provided by POSIX implementations of random(). diff -r cc16989c6d61 -r 92923ac5ea2a src/os/win32/ngx_win32_config.h --- a/src/os/win32/ngx_win32_config.h Sat Dec 16 03:40:01 2023 +0400 +++ b/src/os/win32/ngx_win32_config.h Sat Dec 09 08:38:14 2023 +0000 @@ -280,7 +280,11 @@ typedef int sig_atomic_t #define NGX_HAVE_GETADDRINFO 1 -#define ngx_random rand +#define ngx_random() \ + ((long) (0x7fffffff & ( ((uint32_t) rand() << 16) \ + ^ ((uint32_t) rand() << 8) \ + ^ ((uint32_t) rand()) ))) + #define ngx_debug_init() -- Maxim Dounin http://mdounin.ru/ _______________________________________________ nginx-devel mailing list nginx-devel@nginx.org https://mailman.nginx.org/mailman/listinfo/nginx-devel
