[PATCH v2] close_range.2: Add _GNU_SOURCE and unistd.h to SYNOPSIS

Mark Wielaard
2024-02-11T23:30:43Z

close_range is defined in unistd.h when _GNU_SOURCE is defined.
The linux/close_range.h include file only defines the (linux specific)
flags constants. The flags argument is an int, not an unsigned int, in
the glibc wrapper. Use the close_range library call in the example code
instead of syscall.

Fixes: 71a62d6c3c56 ("close_range.2: Glibc added a wrapper recently")
Fixes: c2356ba085ed ("close_range.2: Glibc 2.34 has added a close_range() wrapper")

Reported-by: Alexandra Hájková <ahajkova@redhat.com>
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
man2/close_range.2 | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/man2/close_range.2 b/man2/close_range.2
index 380a47365..62b728e96 100644
--- a/man2/close_range.2
+++ b/man2/close_range.2
@@ -11,10 +11,13 @@ Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
-.B #include <linux/close_range.h>
+.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
+.B #include <unistd.h>
+.P
+.BR "#include <linux/close_range.h>" " /* For the flags constants */"
.P
.BI "int close_range(unsigned int " first ", unsigned int " last ,
-.BI " unsigned int " flags );
+.BI " int " flags );
.fi
.SH DESCRIPTION
The
@@ -205,7 +208,6 @@ result from the calls to
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
-#include <sys/syscall.h>
#include <unistd.h>
\&
/* Show the contents of the symbolic links in /proc/self/fd */
@@ -259,7 +261,7 @@ main(int argc, char *argv[])
\&
printf("========= About to call close_range() =======\en");
\&
- if (syscall(SYS_close_range, 3, \[ti]0U, 0) == \-1) {
+ if (close_range(3, \[ti]0U, 0) == \-1) {
perror("close_range");
exit(EXIT_FAILURE);
}
--
2.39.3