Re: fcntl for mingw
From: Michael Kerrisk (man-pages) <hidden>
Date: 2012-03-24 03:49:36
Subsystem:
the rest · Maintainer:
Linus Torvalds
Possibly related (same subject, not in this thread)
- 2009-12-15 · Re: fcntl for mingw · Eric Blake <hidden>
Hello, On Tue, Dec 15, 2009 at 6:16 PM, Eric Blake [off-list ref] wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 According to Bruno Haible on 12/11/2009 8:38 AM:quoted
quoted
+ switch (action) + { + case F_DUPFD_CLOEXEC: + { + int target = va_arg (arg, int);Is the arg of type 'int' or 'long'? POSIX says it's an 'int'. But the Linux man page <http://www.kernel.org/doc/man-pages/online/pages/man2/fcntl.2.html> says it's 'long' "in most cases", and indeed glibc's fcntl.c implementation uses a 'void *', that is, the same as a 'long'.That's (hopefully) a bug in the Linux man page. The return type is int, and since the arg is an fd and the return type an fd, they had better be the same type. But all the same, I'm cc'ing the man page maintainer.
Who is finally responding.
quoted
It makes a difference on big-endian 64-bit platforms (SPARC64, PPC64),No one writes fcntl(fd,F_DUPFD,1L), since that is contrary to POSIX; and if fcntl(fd,F_DUPFD,1) doesn't work, then that is a bug in the kernel.
Agreed. And POSIX explicitly says "int" for various other F_* commands as well. I think in every case, where the man page says "long" it should probably say "int". (I think the man page was written from the kernel-source perspective, where everything really is "long", but I would likewise consider this a bug if the user needed to specify "1L" and so on.) I have applied the patch below for man-pages-3.38. Comments welcome. Thanks, Michael
diff --git a/man2/fcntl.2 b/man2/fcntl.2
index b2a985a..4b1b14f 100644
--- a/man2/fcntl.2
+++ b/man2/fcntl.2@@ -82,7 +82,7 @@ Whether or not this argument is required is determined by The required argument type is indicated in parentheses after each .I cmd name (in most cases, the required type is -.IR long , +.IR int , and we identify the argument using the name .IR arg ), or
@@ -90,7 +90,7 @@ or is specified if the argument is not required. .SS "Duplicating a file descriptor" .TP -.BR F_DUPFD " (\fIlong\fP)" +.BR F_DUPFD " (\fIint\fP)" Find the lowest numbered available file descriptor greater than or equal to .I arg
@@ -106,7 +106,7 @@ See .BR dup (2) for further details. .TP -.BR F_DUPFD_CLOEXEC " (\fIlong\fP; since Linux 2.6.24)" +.BR F_DUPFD_CLOEXEC " (\fIint\fP; since Linux 2.6.24)" As for .BR F_DUPFD , but additionally set the
@@ -139,7 +139,7 @@ Read the file descriptor flags; .I arg is ignored. .TP -.BR F_SETFD " (\fIlong\fP)" +.BR F_SETFD " (\fIint\fP)" Set the file descriptor flags to the value specified by .IR arg . .SS "File status flags"
@@ -166,7 +166,7 @@ Get the file access mode and the file status flags; .I arg is ignored. .TP -.BR F_SETFL " (\fIlong\fP)" +.BR F_SETFL " (\fIint\fP)" Set the file status flags to the value specified by .IR arg . File access mode
@@ -455,7 +455,7 @@ process group IDs are returned as negative values(but see BUGS below). .I arg is ignored. .TP -.BR F_SETOWN " (\fIlong\fP)" +.BR F_SETOWN " (\fIint\fP)" Set the process ID or process group ID that will receive .B SIGIO and
@@ -663,7 +663,7 @@ the signal handler if installed with .I arg is ignored. .TP -.BR F_SETSIG " (\fIlong\fP)" +.BR F_SETSIG " (\fIint\fP)" Set the signal sent when input or output becomes possible to the value given in .IR arg .
@@ -774,7 +774,7 @@ or .BR truncate (2) the file referred to by that file descriptor. .TP -.BR F_SETLEASE " (\fIlong\fP)" +.BR F_SETLEASE " (\fIint\fP)" Set or remove a file lease according to which of the following values is specified in the integer .IR arg :
@@ -912,7 +912,7 @@ that has been accessed by another process. (This is useful if the caller holds leases against multiple files). .SS "File and directory change notification (dnotify)" .TP -.BR F_NOTIFY " (\fIlong\fP)" +.BR F_NOTIFY " (\fIint\fP)" (Linux 2.4 onward) Provide notification when the directory referred to by .I fd
@@ -1004,7 +1004,7 @@ See .BR inotify (7). .SS "Changing the capacity of a pipe" .TP -.BR F_SETPIPE_SZ " (\fIlong\fP; since Linux 2.6.35)" +.BR F_SETPIPE_SZ " (\fIint\fP; since Linux 2.6.35)" Change the capacity of the pipe referred to by .I fd to be at least
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface"; http://man7.org/tlpi/
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