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alarm signal processing
Post 302322931 by liaobert on Friday 5th of June 2009 01:39:05 AM
06-05-2009
alarm signal processing
I'm writing a function right now, and I want to set an alarm to avoid a timeout, here's the general idea of my code:
int amt = -2;
alarm(10);
amt = read(fd, &t->buf[tailpos], TASKBUFSIZ - tailpos); //do a read
when the alarm goes off, i want to check the value of "amt"
basically, i want to check to see that the read call was completed in under 10 seconds, however in a signal handler, i dont think you can pass in the value of amt. so is my approach possible to implement? or would i need to a fork a process and do it that way? I'd prefer not to do that, I ran into some problems with that approach..
here's the entirety of the function as well:
taskbufresult_t read_to_taskbuf(int fd, task_t *t)
{
unsigned headpos = (t->head % TASKBUFSIZ);
unsigned tailpos = (t->tail % TASKBUFSIZ);
ssize_t amt;
if (t->head == t->tail || headpos < tailpos)
amt = read(fd, &t->buf[tailpos], TASKBUFSIZ - tailpos);
else
amt = read(fd, &t->buf[tailpos], headpos - tailpos);
if (amt == -1 && (errno == EINTR || errno == EAGAIN
|| errno == EWOULDBLOCK))
return TBUF_AGAIN;
else if (amt == -1)
return TBUF_ERROR;
else if (amt == 0)
return TBUF_END;
else {
t->tail += amt;
return TBUF_OK;
}
}
help would be much appreciated, my TAs suck...
int amt = -2;
alarm(10);
amt = read(fd, &t->buf[tailpos], TASKBUFSIZ - tailpos); //do a read
when the alarm goes off, i want to check the value of "amt"
basically, i want to check to see that the read call was completed in under 10 seconds, however in a signal handler, i dont think you can pass in the value of amt. so is my approach possible to implement? or would i need to a fork a process and do it that way? I'd prefer not to do that, I ran into some problems with that approach..
here's the entirety of the function as well:
taskbufresult_t read_to_taskbuf(int fd, task_t *t)
{
unsigned headpos = (t->head % TASKBUFSIZ);
unsigned tailpos = (t->tail % TASKBUFSIZ);
ssize_t amt;
if (t->head == t->tail || headpos < tailpos)
amt = read(fd, &t->buf[tailpos], TASKBUFSIZ - tailpos);
else
amt = read(fd, &t->buf[tailpos], headpos - tailpos);
if (amt == -1 && (errno == EINTR || errno == EAGAIN
|| errno == EWOULDBLOCK))
return TBUF_AGAIN;
else if (amt == -1)
return TBUF_ERROR;
else if (amt == 0)
return TBUF_END;
else {
t->tail += amt;
return TBUF_OK;
}
}
help would be much appreciated, my TAs suck...
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LEARN ABOUT SUNOS
amt
amt(1) User Commands amt(1) NAME
amt - run abstract machine test SYNOPSIS
amt [-s] DESCRIPTION
The amt command is for use in a Common Criteria security certified system. The command is used to verify that the low level functions nec- essary to enforce the object reuse requirements of the Controlled Access Protection Profile are working correctly. /usr/bin/amt is a shell script that executes tests specific to your system. For a 32-bit system, the tests run as a 32-bit application. For a 64-bit system, the tests run twice; once as a 32-bit application and once as a 64-bit application. amt lists test results with a "pass" or "fail" for each test it performs, unless output is suppressed with the -s option. OPTIONS
The following option is supported: -s Suppresses output. EXIT STATUS
The following error values are returned: 0 All tests passed. >0 Count of the number of tests that failed. <0 Incorrect command line argument. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ |Interface Stability |Evolving | +-----------------------------+-----------------------------+ SEE ALSO
attributes(5) SunOS 5.10 19 Aug 2003 amt(1)