summaryrefslogtreecommitdiffstats
path: root/man2/readv.2
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--man2/readv.248
1 files changed, 24 insertions, 24 deletions
diff --git a/man2/readv.2 b/man2/readv.2
index db6abbc..c1295cd 100644
--- a/man2/readv.2
+++ b/man2/readv.2
@@ -9,7 +9,7 @@
.\" add more details.
.\" 2010-11-16, mtk, Added documentation of preadv() and pwritev()
.\"
-.TH readv 2 2023-05-03 "Linux man-pages 6.05.01"
+.TH readv 2 2023-10-31 "Linux man-pages 6.7"
.SH NAME
readv, writev, preadv, pwritev, preadv2, pwritev2 \-
read or write data into multiple buffers
@@ -19,26 +19,26 @@ Standard C library
.SH SYNOPSIS
.nf
.B #include <sys/uio.h>
-.PP
+.P
.BI "ssize_t readv(int " fd ", const struct iovec *" iov ", int " iovcnt );
.BI "ssize_t writev(int " fd ", const struct iovec *" iov ", int " iovcnt );
-.PP
+.P
.BI "ssize_t preadv(int " fd ", const struct iovec *" iov ", int " iovcnt ,
.BI " off_t " offset );
.BI "ssize_t pwritev(int " fd ", const struct iovec *" iov ", int " iovcnt ,
.BI " off_t " offset );
-.PP
+.P
.BI "ssize_t preadv2(int " fd ", const struct iovec *" iov ", int " iovcnt ,
.BI " off_t " offset ", int " flags );
.BI "ssize_t pwritev2(int " fd ", const struct iovec *" iov ", int " iovcnt ,
.BI " off_t " offset ", int " flags );
.fi
-.PP
+.P
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
-.PP
+.P
.BR preadv (),
.BR pwritev ():
.nf
@@ -57,7 +57,7 @@ buffers from the file associated with the file descriptor
into the buffers described by
.I iov
("scatter input").
-.PP
+.P
The
.BR writev ()
system call writes
@@ -67,7 +67,7 @@ buffers of data described by
to the file associated with the file descriptor
.I fd
("gather output").
-.PP
+.P
The pointer
.I iov
points to an array of
@@ -75,19 +75,19 @@ points to an array of
structures,
described in
.BR iovec (3type).
-.PP
+.P
The
.BR readv ()
system call works just like
.BR read (2)
except that multiple buffers are filled.
-.PP
+.P
The
.BR writev ()
system call works just like
.BR write (2)
except that multiple buffers are written out.
-.PP
+.P
Buffers are processed in array order.
This means that
.BR readv ()
@@ -106,7 +106,7 @@ writes out the entire contents of
before proceeding to
.IR iov[1] ,
and so on.
-.PP
+.P
The data transfers performed by
.BR readv ()
and
@@ -136,7 +136,7 @@ but adds a fourth argument,
.IR offset ,
which specifies the file offset at which the input operation
is to be performed.
-.PP
+.P
The
.BR pwritev ()
system call combines the functionality of
@@ -149,7 +149,7 @@ but adds a fourth argument,
.IR offset ,
which specifies the file offset at which the output operation
is to be performed.
-.PP
+.P
The file offset is not changed by these system calls.
The file referred to by
.I fd
@@ -162,7 +162,7 @@ and
calls, but add a fifth argument,
.IR flags ,
which modifies the behavior on a per-call basis.
-.PP
+.P
Unlike
.BR preadv ()
and
@@ -170,7 +170,7 @@ and
if the
.I offset
argument is \-1, then the current file offset is used and updated.
-.PP
+.P
The
.I flags
argument contains a bitwise OR of zero or more of the following flags:
@@ -249,13 +249,13 @@ return the number of bytes read;
and
.BR pwritev2 ()
return the number of bytes written.
-.PP
+.P
Note that it is not an error for a successful call to transfer fewer bytes
than requested (see
.BR read (2)
and
.BR write (2)).
-.PP
+.P
On error, \-1 is returned, and \fIerrno\fP is set to indicate the error.
.SH ERRORS
The errors are as given for
@@ -297,9 +297,9 @@ corresponding GNU C library wrapper functions shown in the SYNOPSIS.
The final argument,
.IR offset ,
is unpacked by the wrapper functions into two arguments in the system calls:
-.PP
+.P
.BI " unsigned long " pos_l ", unsigned long " pos
-.PP
+.P
These arguments contain, respectively, the low order and high order 32 bits of
.IR offset .
.SH STANDARDS
@@ -329,12 +329,12 @@ POSIX.1-2001,
.\" and \fIint\fP as the return type.
.\" The readv/writev system calls were buggy before Linux 1.3.40.
.\" (Says release.libc.)
-.PP
+.P
.BR preadv (),
.BR pwritev ():
Linux 2.6.30,
glibc 2.10.
-.PP
+.P
.BR preadv2 (),
.BR pwritev2 ():
Linux 4.6,
@@ -365,7 +365,7 @@ The wrapper function for
.BR writev ()
performed the analogous task using a temporary buffer and a call to
.BR write (2).
-.PP
+.P
The need for this extra effort in the glibc wrapper functions
went away with Linux 2.2 and later.
However, glibc continued to provide this behavior until glibc 2.10.
@@ -405,7 +405,7 @@ flag may return 0 even when not at end of file.
.SH EXAMPLES
The following code sample demonstrates the use of
.BR writev ():
-.PP
+.P
.in +4n
.EX
char *str0 = "hello ";