Syslinux - Apr 2013 - Confusing error message when pointing the linux installer at a missing directory.

Last night, I was trying to install syslinux (5.01) to a SD card of
mine, writing to a subdirectory to keep the layout neat:

syslinux-5.01/linux# ./syslinux -i -d /boot /dev/mmcblk0p1
/dev/mmcblk0p1: No such file or directory

The message is coming from do_open_file() in syslinux.c: the call to
open() fails because the containing directory isn't present, and then it
calls perror(opt.device).

If the directory is present, syslinux installs and will boot. It's just
a matter of either improving the error message or trying to make the
directory before populating it.

-- Jack

On Thu, Apr 18, 2013 at 06:37:49AM +1000, Jack Kelly
wrote:
> Last night, I was trying to install syslinux (5.01) to a SD card of
> mine, writing to a subdirectory to keep the layout neat:
> 
> syslinux-5.01/linux# ./syslinux -i -d /boot /dev/mmcblk0p1
> /dev/mmcblk0p1: No such file or directory
> 
> The message is coming from do_open_file() in syslinux.c: the call to
> open() fails because the containing directory isn't present, and then
it
> calls perror(opt.device).
> 
> If the directory is present, syslinux installs and will boot. It's just
> a matter of either improving the error message or trying to make the
> directory before populating it.
> 

Package: extlinux
Version: 2:4.05+dfsg-6+deb7u1

  I think the same error message is printed when extlinux is trying
to use a read only file system.  Maybe that message should also be
improved.  2:4.05+dfsg-6+deb7u1 is from debian.  Even though debian
seem to change the source code, I think the relevant code is not
different from upstream.

On 04/17/2013 09:37 PM, Jack Kelly wrote:
> Last night, I was trying to install syslinux (5.01) to a SD card of
> mine, writing to a subdirectory to keep the layout neat:
> 
> syslinux-5.01/linux# ./syslinux -i -d /boot /dev/mmcblk0p1
> /dev/mmcblk0p1: No such file or directory
> 
> The message is coming from do_open_file() in syslinux.c: the call to
> open() fails because the containing directory isn't present, and then
it
> calls perror(opt.device).
> 
> If the directory is present, syslinux installs and will boot. It's just
> a matter of either improving the error message or trying to make the
> directory before populating it.
Thanks for the report, I queued up the following patch. Note it will
print something like,

    /tmp/syslinux.XXX/boot/ldlinux.sys: No such file or directory

which still isn't entirely clear, but is at least more helpful than what
we have currently.

---
>From faff52ef2bd3dca503a6fef3129f02284e9b6ca4 Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming at intel.com>
Date: Thu, 25 Apr 2013 15:14:18 +0100
Subject: [PATCH] linux: Clear up error message

Passing opt.device to perror() in do_open_file() results in confusing
error messages, as Jack reports,

  Last night, I was trying to install syslinux (5.01) to a SD card of
  mine, writing to a subdirectory to keep the layout neat:

  syslinux-5.01/linux# ./syslinux -i -d /boot /dev/mmcblk0p1
  /dev/mmcblk0p1: No such file or directory

  The message is coming from do_open_file() in syslinux.c: the call to
  open() fails because the containing directory isn't present, and then it
  calls perror(opt.device).

We should instead be passing 'name' to perror() so that we know _which_
file doesn't exist.

Reported-by: Jack Kelly <jack at jackkelly.name>
Signed-off-by: Matt Fleming <matt.fleming at intel.com>
---
 linux/syslinux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linux/syslinux.c b/linux/syslinux.c
index f4749ea..f64834b 100755
--- a/linux/syslinux.c
+++ b/linux/syslinux.c
@@ -251,7 +251,7 @@ int do_open_file(char *name)
     unlink(name);
     fd = open(name, O_WRONLY | O_CREAT | O_TRUNC, 0444);
     if (fd < 0)
-	perror(opt.device);
+	perror(name);
 
     return fd;
 }
-- 
1.8.1.4



-- 
Matt Fleming, Intel Open Source Technology Center