Messages in this thread | | | Date | Sat, 8 Dec 2001 13:17:04 -0500 | From | James Moss <> | Subject | fstat issues |
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I noticed recently that the following no longer works. I was wondering if this is internal to the kernel or if perhaps this is a glibc issue. Also wondering if this was an intential change. It did 'used to work' but I realize that may hold little to no ground since it does seem to be on a per implementation basis. Anyway looking forward to hearing back, feel free to show a better way to go about doing what I'm attempting to do. -James Moss
-------foo.c------------ #include <stdio.h> #include <sys/types.h> #include <sys/file.h> #include <sys/stat.h> #include <sys/errno.h> #include <fcntl.h>
main(argc, argv) int argc; char **argv; { struct stat sb; if (0 == fstat( fileno(stdin), &sb )) { printf( "size %d\n", sb.st_size ); } else { printf( "size %d\n", sb.st_size ); } exit( 0 ); }
------------------- On HP, Solaris, etc... cc foo.c echo "abc" > ftext.txt ./a.out < ftext.txt size 4 cat ftext.txt | ./a.out size 4 On Debian Unstable, latest release of Suse, and latest release of Redhat... gcc foo.c echo "abc" > ftext.txt ./a.out < ftext.txt size 4 cat ftext.txt | ./a.out size 0
Page 90, 4.12 "File Size" Advanced Programming in the UNIX Environment states that it's posix compliant in SVR4 to have the ability to read file size from a pipe and the st_size of the sb struct is defined.... does Linux break SVR4 compliance? Is there a better or new way to do this?
SVID Vol: 1a Version 4
Since a pipe is bi-directional, there are two separate flows of data. Therefore, the size (st_size) returned by a call to fstat with argument fildes[0] or fildes[1] is the number of bytes available for reading from fildes[0] or fildes[1] respectively.
FINAL COPY June 15, 1995 File: ba_os/pipe svid Page: 219 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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