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Full Discussion: Problem with lseek call.
Top Forums Programming Problem with lseek call. Post 302916915 by Corona688 on Friday 12th of September 2014 01:23:01 PM
Old 09-12-2014
Try perror("error message prefix"), much simpler.

C is grouping your open statement like this:

Code:
if (fd = (open("mem", O_RDONLY) == -1) )

So fd becomes 1 if the file fails to open, or 0 if the file is there. It must be failing, since if it opened, == -1 it would evaluate false and quit.

By unfortunate coincidence, 1 is a valid file descriptor -- standard output. It's probably a terminal or pipe, which of course can't seek.

So either parenthesize defensively, or put the assignment outside the if-statement (usually preferred).
Last edited by Corona688; 09-12-2014 at 02:28 PM..
This User Gave Thanks to Corona688 For This Post:
Sir_Tomasz
 

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LEARN ABOUT HPUX

posix_openpt

posix_openpt(3C)														  posix_openpt(3C)

NAME

       posix_openpt() - open a pseudo-terminal master device

SYNOPSIS

   Parameters
       oflag	 indicates  the  file  status flags and file access modes of the open file description. Values for oflag are constructed by a bit-
		 wise-inclusive OR of flags from the following list, defined in

		 Open for reading and writing.

		 If set    will not cause the terminal device to become the controlling terminal for the process.

DESCRIPTION

       The function establishes a connection between a master device for a pseudo-terminal and a file descriptor. This file descriptor can be used
       to  refer  that	device.   The  file status flags and file access modes of the opened file descriptor will be set according to the value of
       oflag.

RETURN VALUE

       Upon successful completion opens a master pseudo-terminal device and returns a non-negative integer representing the lowest numbered unused
       file descriptor. Otherwise, returns -1 and is set to indicate the error.

ERRORS

       On failure sets one of the following values for

       OPEN_MAX       file descriptors are currently open in the calling process.

       The maximum allowable number of files are currently open on the system.

       The value of   oflag is not valid.

       Out of pseudo-terminal resources.

       Out of STREAMS resources.

AUTHOR

       was developed by HP.

SEE ALSO

       open(2), grantpt(3C), ptsname(3C), unlockpt(3C), ptm(7), pts(7).

																  posix_openpt(3C)
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