diff options
Diffstat (limited to 'src/lseek.c')
| -rw-r--r-- | src/lseek.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/src/lseek.c b/src/lseek.c new file mode 100644 index 000000000..8faa5c8d0 --- /dev/null +++ b/src/lseek.c @@ -0,0 +1,74 @@ +/* + * Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl> + * Copyright (c) 1993 Branko Lankester <branko@hacktic.nl> + * Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jrs@world.std.com> + * Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl> + * Copyright (c) 2002-2005 Roland McGrath <roland@redhat.com> + * Copyright (c) 2009 Andreas Schwab <schwab@redhat.com> + * Copyright (c) 2012 H.J. Lu <hongjiu.lu@intel.com> + * Copyright (c) 2013 Denys Vlasenko <vda.linux@googlemail.com> + * Copyright (c) 2014-2016 Dmitry V. Levin <ldv@strace.io> + * Copyright (c) 2014-2018 The strace developers. + * All rights reserved. + * + * SPDX-License-Identifier: LGPL-2.1-or-later + */ + +#include "defs.h" + +#include "xlat/whence_codes.h" + +/* Linux kernel has exactly one version of lseek: + * fs/read_write.c::SYSCALL_DEFINE3(lseek, unsigned, fd, off_t, offset, unsigned, origin) + * In kernel, off_t is always the same as (kernel's) long + * (see include/uapi/asm-generic/posix_types.h). + * Use test/x32_lseek.c to test lseek decoding. + */ +SYS_FUNC(lseek) +{ + printfd(tcp, tcp->u_arg[0]); + + kernel_long_t offset; + +#ifndef current_klongsize + if (current_klongsize < sizeof(kernel_long_t)) { + offset = (int) tcp->u_arg[1]; + } else +#endif /* !current_klongsize */ + { + offset = tcp->u_arg[1]; + } + + tprintf(", %" PRI_kld ", ", offset); + + printxval(whence_codes, tcp->u_arg[2], "SEEK_???"); + + return RVAL_DECODED; +} + +/* llseek syscall takes explicitly two ulong arguments hi, lo, + * rather than one 64-bit argument for which ULONG_LONG works + * appropriate for the native byte order. + * + * See kernel's fs/read_write.c::SYSCALL_DEFINE5(llseek, ...) + * + * hi,lo are "unsigned longs" and combined exactly this way in kernel: + * ((loff_t) hi << 32) | lo + * Note that for architectures with kernel's long wider than userspace long + * (such as x32), combining code will use *kernel's*, i.e. *wide* longs + * for hi and lo. + */ +SYS_FUNC(llseek) +{ + if (entering(tcp)) { + printfd(tcp, tcp->u_arg[0]); + tprintf(", %lld, ", + ((long long) tcp->u_arg[1] << 32) + | ((long long) tcp->u_arg[2])); + } else { + printnum_int64(tcp, tcp->u_arg[3], "%" PRIu64); + tprints(", "); + printxval(whence_codes, tcp->u_arg[4], "SEEK_???"); + } + return 0; +} |