Differences between version 2 and predecessor to the previous major change of lseek(2).
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| Newer page: | version 2 | Last edited on Monday, March 10, 2003 2:34:17 pm | by PerryLorier | Revert |
| Older page: | version 1 | Last edited on Tuesday, June 4, 2002 12:23:42 am | by perry | Revert |
@@ -1,122 +1,45 @@
-LSEEK
-!!!LSEEK
-NAME
-SYNOPSIS
-DESCRIPTION
-RETURN VALUE
-ERRORS
-CONFORMING TO
-RESTRICTIONS
-NOTES
-SEE ALSO
-----
!!NAME
+lseek - reposition read/write file offset
-
-lseek - reposition read/write file offset
!!SYNOPSIS
+ #include <sys/types.h>
+ #include <unistd.h>
-__#include
__
-#include
__
+
__off
_t lseek(int
__ ''fildes''__, off_t__ ''offset''__, int__ ''whence''__);
__
-
-__off_t lseek(int__ ''fildes''__, off_t__
-''offset''__, int__
-''whence''__);__
!!DESCRIPTION
+The lseek(2) function repositions the offset of the file descriptor ''fildes'' to the argument ''offset'' according to the directive ''whence'' as follows:
+;[SEEK_SET]: The offset is set to ''offset'' bytes.
+;[SEEK_CUR]: The offset is set to its current location plus ''offset'' bytes.
+;[SEEK_END]: The offset is set to the size of the file plus ''offset'' bytes.
-The __
lseek__
function repositions
the offset of the file
-descriptor ''fildes'' to
the argument ''offset''
-according to
the directive ''whence'' as
-follows:
+The lseek(2)
function allows
the file
offset to be set beyond the end
of the existing end-of-
file of
the file. If data is later written at this point, subsequent reads of the data in the gap return bytes of zeros (until data is actually written into
the gap).
-
-__SEEK_SET__
-
-
-The offset is set to ''offset'' bytes.
-
-
-__SEEK_CUR__
-
-
-The offset is set to its current location plus ''offset''
-bytes.
-
-
-__SEEK_END__
-
-
-The offset is set to the size of the file plus ''offset''
-bytes.
-
-
-The __lseek__ function allows the file offset to be set
-beyond the end of the existing end-of-file of the file. If
-data is later written at this point, subsequent reads of the
-data in the gap return bytes of zeros (until data is
-actually written into the gap).
!!RETURN VALUE
-
-
-
-
-
-returned and ''errno'' is set to indicate the
-
+Upon successful completion, __lseek__ returns the resulting offset location as measured in bytes from the beginning of the file. Otherwise, a value of (off_t)-1 is
+returned and ''errno'' is set to indicate the error.
!!ERRORS
+;[EBADF]: ''Fildes'' is not an open file descriptor.
+;[ESPIPE]: ''Fildes'' is associated with a pipe, socket, or FIFO.
+;[EINVAL]: ''Whence'' is not a proper value.
-
-__EBADF__
-
-
-''Fildes'' is not an open file descriptor.
-
-
-__ESPIPE__
-
-
-''Fildes'' is associated with a pipe, socket, or
-FIFO.
-
-
-__EINVAL__
-
-
-''Whence'' is not a proper value.
!!CONFORMING TO
+SVr4, POSIX, BSD 4.3
-
-SVr4, POSIX, BSD 4.3
!!RESTRICTIONS
+Some devices are incapable of seeking and POSIX does not specify which devices must support it.
+Linux specific restrictions: using lseek(2) on a tty device returns [ESPIPE]. Other systems return the number of written characters, using SEEK_SET to set the
+counter. Some devices, e.g. __/dev/null__ do not cause the error [ESPIPE], but return a pointer which value is undefined.
-Some devices are incapable of seeking and POSIX does not
-specify which devices must support it.
-
-
-Linux specific restrictions: using __lseek__ on a tty
-device returns __ESPIPE__. Other systems return the
-number of written characters, using SEEK_SET to set the
-counter. Some devices, e.g. __/dev/null__ do not cause
-the error __ESPIPE__, but return a pointer which value is
-undefined.
!!NOTES
+This document's use of ''whence'' is incorrect English, but maintained for historical (hysterical?) reasons.
+When converting old code, substitute values for ''whence'' with the following macros:
-This document's use
of ''whence'' is incorrect English
,
-but maintained for historical reasons
.
+SVR1-3 returns __long__ instead
of __off_t__
, BSD returns __int__
.
-
-When converting old code, substitute values for
-''whence'' with the following macros:
-
-
-SVR1-3 returns __long__ instead of __off_t__, BSD returns __int__.
!!SEE ALSO
-
-
dup(2), open(2), fseek(3)
-----
