Created attachment 221499 [details]
patch to fix diff bug
When diff hits certain access errors, function diffreg() shows the error message, and then returns to the calling function, which calls print_status() with the return value.
However, in these cases, the return value isn't changed from the initial default value of D_SAME.
Normally, print_status() with a value of D_SAME does nothing, so this works out ok, however, if the "-s" flag is set, a message is displayed showing identicality:
printf("Files %s%s and %s%s are identical\n", path1, entry, path2, entry);
This then produces such results as:
% diff -s /COPYRIGHT /var/run/rpcbind.sock
diff: /var/run/rpcbind.sock: Operation not supported
Files /COPYRIGHT and /var/run/rpcbind.sock are identical
% diff -s /COPYRIGHT /etc/master.passwd
diff: /etc/master.passwd: Permission denied
Files /COPYRIGHT and /etc/master.passwd are identical
A quick fix would be to alter the above line:
if (sflag && status & 2)
A less hacky fix is attached as a patch. It creates a D_ERROR status which is returned in such cases, and print_status() then deals with that status seperately from D_SAME.
Adding bapt@ and kevans@ in case they want to look as they've hacked on diff(1) recently.