bug#70411: [bug] install(1) fails to read /dev/stdin on Darwin

[Pádraig Brady]

On 16/04/2024 12:33, Pádraig Brady wrote:
> On 16/04/2024 01:19, Alejandro Colomar wrote:
> > Hi!
> >
> > I don't own a Darwin system, so I can't help much reproduce.  However,
> > I've received a bug report to the Linux man-pages, that our build
> > system (GNUmakefile-based), which ends up calling
> >
> >         ... | install /dev/stdin $@
> >
> > doesn't work on Darwin.  Here's the original bug report:
> > <https://github.com/NixOS/nixpkgs/pull/300797>.
> >
> > Here are the reported error messages:
> >
> > ...
> > INSTALL         
> > /nix/store/3s28l9ijlkmsq8256zdxjvl173gkn37c-man-pages-6.7/share/man/man3/addseverity.3
> > INSTALL         
> > /nix/store/3s28l9ijlkmsq8256zdxjvl173gkn37c-man-pages-6.7/share/man/man3/adjtime.3
> > install: skipping file '/dev/stdin', as it was replaced while being copied
> > make: *** [share/mk/install/man.mk:54: 
> > /nix/store/3s28l9ijlkmsq8256zdxjvl173gkn37c-man-pages-6.7/share/man/man3/addmntent.3]
> >  Error 1
> > make: *** Waiting for unfinished jobs....
> > install: skipping file '/dev/stdin', as it was replaced while being copied
> > make: *** [share/mk/install/man.mk:54: 
> > /nix/store/3s28l9ijlkmsq8256zdxjvl173gkn37c-man-pages-6.7/share/man/man3/acosh.3]
> >  Error 1
> > install: skipping file '/dev/stdin', as it was replaced while being copied
> > install: skipping file '/dev/stdin', as it was replaced while being copied
> > install: skipping file '/dev/stdin', as it was replaced while being copied
> > ...
> >
> > I don't see why install(1) should fail to read /dev/stdin under any
> > POSIX system
>
> What version of darwin is this? I can't repro on Darwin 21.6.0 (MacOSX 12.6).
> The issue seems to be that /dev/stdin returns a varying inode which install(1) 
> doesn't like currently

Note that check originally came from:
https://github.com/coreutils/coreutils/commit/dea4262fa

I suppose we could relax the check as follows, for files of apparent size 0
which would cater for this, and others that may also have unstable inodes.

cheers,
Pádraig.

diff --git a/src/copy.c b/src/copy.c
index 2145d89d5..fb5f0a1a0 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -1263,8 +1263,11 @@ copy_reg (char const *src_name, char const *dst_name,
     }

   /* Compare the source dev/ino from the open file to the incoming,
-     saved ones obtained via a previous call to stat.  */
-  if (! psame_inode (src_sb, &src_open_sb))
+     saved ones obtained via a previous call to stat.  Restrict
+     the check to files with an apparent size, to support "files"
+     with unstable inodes, like /dev/stdin on macOS.  */
+  if (! psame_inode (src_sb, &src_open_sb)
+      && (src_sb->st_size || src_open_sb.st_size))
     {
       error (0, 0,
              _("skipping file %s, as it was replaced while being copied"),