From dfd218d5fe18569de44bbd00f75773c4f2fe8316 Mon Sep 17 00:00:00 2001 From: Joel Sherrill Date: Thu, 16 Aug 2001 22:20:06 +0000 Subject: 2001-08-16 Joel Sherrill * libc/lseek.c: Modified after discussion with Eugeny S. Mints to correct the behavior. There were two mistakes. First, iop->offset was incorrectly set for SEEK_END. Second, iop->offset should be left unmodified if there are errors. This modification attempts to fix both situations. --- cpukit/libcsupport/src/lseek.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) (limited to 'cpukit/libcsupport/src/lseek.c') diff --git a/cpukit/libcsupport/src/lseek.c b/cpukit/libcsupport/src/lseek.c index 069952ff8e..910b81d231 100644 --- a/cpukit/libcsupport/src/lseek.c +++ b/cpukit/libcsupport/src/lseek.c @@ -26,15 +26,25 @@ off_t lseek( ) { rtems_libio_t *iop; + off_t old_offset; + off_t status; rtems_libio_check_fd( fd ); iop = rtems_libio_iop( fd ); rtems_libio_check_is_open(iop); + /* + * Check as many errors as possible before touching iop->offset. + */ + + if ( !iop->handlers->lseek_h ) + set_errno_and_return_minus_one( ENOTSUP ); + /* * Now process the lseek(). */ + old_offset = iop->offset; switch ( whence ) { case SEEK_SET: iop->offset = offset; @@ -45,18 +55,28 @@ off_t lseek( break; case SEEK_END: - iop->offset = iop->size - offset; + iop->offset = iop->size + offset; break; default: - errno = EINVAL; - return -1; + set_errno_and_return_minus_one( EINVAL ); } - if ( !iop->handlers->lseek_h ) - set_errno_and_return_minus_one( ENOTSUP ); + /* + * At this time, handlers assume iop->offset has the desired + * new offset. + */ + + status = (*iop->handlers->lseek_h)( iop, offset, whence ); + if ( !status ) + return 0; + + /* + * So if the operation failed, we have to restore iop->offset. + */ - return (*iop->handlers->lseek_h)( iop, offset, whence ); + iop->offset = old_offset; + return status; } /* -- cgit v1.2.3