select(2) ignoring timeval argument

select(2) ignoring timeval argument (Full Version)

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breiter -> select(2) ignoring timeval argument (Mar. 11, '06, 9:37:02 PM)
When I upgraded to SUA/Interix 5.2, I installed xgalaga. Which is frivolous, I know. The thing is that it works fine on SFU/Interix 3.5 but runs crazy-fast on SUA/Interix 5.2. The entire thing is a blur. I pinged Rodney on this and he mentioned that xgalaga uses select(2) to throttle its speed. Thinking maybe I just needed to change the timing, I downloaded grabbed the xgalaga source code. Building it myself didn't help. I looked at documentation of select(2). From man 2 select: If timeout is a non-nil pointer, it specifies a maximum interval to wait for the selection to complete. If timeout is a nil pointer, the select blocks indefinitely. To effect a poll, the timeout argument should be non- nil, pointing to a zero-valued timeval structure. I injected this code at the end of the while(1) loop. //insert a 10 second pause on every loop to test select(). struct timeval pause; gettimeofday(&pause, 0); printf("Get pause time: %d\n", pause.tv_sec); pause.tv_sec += 10L; printf("Add 10 seconds: %d\n", pause.tv_sec); (void) select(0, 0, 0, 0, &pause); This is the kind of output I get while xgalaga is running. Get pause time: 1142130333 Add 10 seconds: 1142130343 Get pause time: 1142130333 Add 10 seconds: 1142130343 Get pause time: 1142130333 Add 10 seconds: 1142130343 Get pause time: 1142130333 Add 10 seconds: 1142130343 Get pause time: 1142130333 Add 10 seconds: 1142130343 Get pause time: 1142130333 Add 10 seconds: 1142130343 Get pause time: 1142130333 Add 10 seconds: 1142130343 Get pause time: 1142130333 Add 10 seconds: 1142130343 Get pause time: 1142130333 Add 10 seconds: 1142130343 Get pause time: 1142130333 Add 10 seconds: 1142130343 No pause happened when select was called, so we're on the same second when the next loop iteration comes around. I think there is something very wrong here. Select(2) seems to be ignoring the timeval pause.

Rodney -> RE: select(2) ignoring timeval argument (Mar. 12, '06, 2:57:57 PM)
mmmm, we're starting to build up quite a selection of things with SUA. 1) Select timer ignored (mentioned above) 2) The SetUid problem (mentioned by Brian in another thread) 3) The AF_UNIX sockets have had the namespace shrunk from 104 to 14 characters.

breiter -> RE: select(2) ignoring timeval argument (Mar. 15, '06, 10:00:57 AM)
Here's a very simple test program that demonstrates the select(2) timeout problem in isolation: #include <stdio.h> #include <sys/time.h> int main() { struct timeval time; int i=0; printf("Testing select(2). Each pass through the loop should pause 10 seconds.\n\n"); for( i; i<10; i++ ) { //insert a 10 second pause on every loop to test select(). gettimeofday(&time, 0); printf("Current time: %d\n", time.tv_sec); time.tv_sec += 10L; printf("Add 10 seconds: %d... And pause by calling select(2).\n", time.tv_sec); (void) select(0, 0, 0, 0, &time); } return 0; } % gcc selecttest.c -o selecttest % ./selecttest Testing select(2). Each pass through the loop should pause 10 seconds. Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2). Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2). Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2). Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2). Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2). Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2). Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2). Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2). Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2). Current time: 1142434664 Add 10 seconds: 1142434674... And pause by calling select(2).

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