Re: Why does stat(2) say <unistd.h> is needed?

[Jonathan Wakely <jwakely@redhat.com>]

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On 09/02/21 12:27 +0100, Alejandro Colomar (man-pages) wrote:
>Hello Jonathan,
>
>On 2/9/21 12:09 PM, Jonathan Wakely wrote:
>>The stat(2) man page says:
>>
>>SYNOPSIS
>>        #include <sys/types.h>
>>        #include <sys/stat.h>
>>        #include <unistd.h>
>>
>>        int stat(const char *pathname, struct stat *statbuf);
>>        int fstat(int fd, struct stat *statbuf);
>>        int lstat(const char *pathname, struct stat *statbuf);
>>
>>But I don't see anything there that would require <unistd.h>. POSIX
>>doesn't require it (and since POSIX.1-2001 no longer requires
>><sys/types.h>, saying "Although <sys/types.h> was required for
>>conforming implementations of previous POSIX specifications, it was
>>not required for UNIX applications.")
>>
>>Is the inclusion of <unistd.h> there a mistake?
>>
>>I've been trying to track down why a libstdc++ header includes
>><unistd.h> for no apparent reason, and my best guess is that it's a
>>result of this man page saying to do it.
>>
>As far as we can tell, there's no reason to include it.  See <https://lore.kernel.org/linux-man/97457bf2-2b29-af4b-c910-2391c69c4134@gmail.com/>.
>
>We haven't fixed it yet, because I'd like to fix all of the pages, and 
>that's likely to take months (reading through every manual page in 
>senctions 2 & 3, reading thorugh every included header, checking POSIX 
>requirements, asking Michael if there may be historical reasons for a 
>specific case, ...), but I'll do it some day.
>
>For now, if you submit a patch, I'll merge it.

Attached, thanks.



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From d5b66a6b83302bd4070e3c83fb1dab341b76b728 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Tue, 9 Feb 2021 11:46:02 +0000
Subject: [PATCH] stat.2: Remove <unistd.h> from synopsis

There seems to be no reason <unistd.h> is shown here, so remove it.

Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
---
 man2/stat.2 | 1 -
 1 file changed, 1 deletion(-)

diff --git a/man2/stat.2 b/man2/stat.2
index 734c74b04..fed926715 100644
--- a/man2/stat.2
+++ b/man2/stat.2
@@ -43,7 +43,6 @@ stat, fstat, lstat, fstatat \- get file status
 .nf
 .B #include <sys/types.h>
 .B #include <sys/stat.h>
-.B #include <unistd.h>
 .PP
 .BI "int stat(const char *" pathname ", struct stat *" statbuf );
 .BI "int fstat(int " fd ", struct stat *" statbuf );
-- 
2.29.2