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List:       busybox
Subject:    Re: PATCH - mount bugfix - it behaves like util-linux mount
From:       Denys Vlasenko <vda.linux () googlemail ! com>
Date:       2021-08-23 0:37:19
Message-ID: CAK1hOcNo3ODiekaWOo4NfLKE2ukL_pN3M1tpYFhy56jS6WnQ=g () mail ! gmail ! com
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On Tue, Aug 10, 2021 at 6:30 PM Roberto A. Foglietta
<roberto.foglietta@gmail.com> wrote:
> 
> Hi all,
> 
> this is following my message about "Curious bug in remounting read-only cdrom mount \
> point". I have created a patch to fix the behaviour of mount aligning with \
> uitl-linux mount. The main differences are the return codes and warning messages \
> but AFAIK they behave the same way in failures and success cases. 
> I hope this patch will be applied and feel free to improve it.
> 
> You can test with TinyCore Editor Suite v0.4.0 which has a fastlane to test busybox \
> changes 
> busybox/busybox.sh update suid  (because mount belongs to suid exec in TC)
> 
> For other changes use nosuid (or nothing which is the same).
> 
> https://github.com/robang74/tinycore-editor/archive/refs/tags/v0.4.0.tar.gz
> 
> 
> ###### mount by util-linux ######
> 
> root@box:~# mount -o rw /dev/sr0 /mnt/sda2; echo $?
> mount: /mnt/sda2: WARNING: source write-protected, mounted read-only.
> 0

So, unit-linux _does_ fall back to RO if -o rw is specified?
Then this is wrong:

+            if(!explicit_rw) {
+                if (!strncasecmp("rw", newopts, 2)) {
+                    explicit_rw = 1;
+                }
+            }

(as well as buggy, it would think that "-o rwqwerty" is "rw").



+static bool explicit_rw = 0;
...
+    if (opt & OPT_w) {
+        explicit_rw = 1;
+        append_mount_options(&cmdopts, "rw"); // -w
+    }

Global variable option_mask32 already exists, and already has
the flag bit set for you. Let's just use it.

Fixed in git. Thank you for the bug report.
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