Re: Review: psql include file using relative path

On Fri, May 20, 2011 at 2:35 PM, Gurjeet Singh <singh.gurjeet@gmail.com> wrote:
> On Sat, May 14, 2011 at 5:03 PM, Josh Kupershmidt <schmiddy@gmail.com>
> wrote:
> Thanks a lot for the review. My responses are inline below.

Thanks for the fixes. Your updated patch is sent as a
patch-upon-a-patch, it'll probably be easier for everyone
(particularly the final committer) if you send inclusive patches
instead.

>> == Documentation ==
>> The patch includes the standard psql help output description for the
>> new \ir command. I think ./doc/src/sgml/ref/psql-ref.sgml needs to be
>> patched as well, though.
>
> Done.

This is a decent description from a technical standpoint:

       <para>
       When used within a script, if the <replaceable
class="parameter">filename</replaceable>
       uses relative path notation, then the file will be looked up
relative to currently
       executing file's location.

       If the <replaceable class="parameter">filename</replaceable>
uses an absolute path
       notation, or if this command is being used in interactive
mode, then it behaves the
       same as <literal>\i</> command.
       </para>

but I think these paragraphs could be made a little more clear, by
making a suggestion about why someone would be interested in \ir. How
about this:

       <para>
       The <literal>\ir</> command is similar to <literal>\i</>, but
is useful for files which
       load in other files.

       When used within a file loaded via <literal>\i</literal>,
<literal>\ir</literal>, or
       <option>-f</option>, if the <replaceable
class="parameter">filename</replaceable>
       is specified with a relative path, then the location of the
file will be determined
       relative to the currently executing file's location.
       </para>

       <para>
       If <replaceable class="parameter">filename</replaceable> is given as an
       absolute path, or if this command is used in interactive mode, then
       <literal>\ir</> behaves the same as the <literal>\i</> command.
       </para>

The sentence "When used within a file ..." is now a little
clunky/verbose, but I was trying to avoid potential confusion from
someone trying \ir via 'cat ../filename.sql | psql', which would be
"used within a script", but \ir wouldn't know that.

>> == Code ==
>> 1.) I have some doubts about whether the memory allocated here:
>>    char *relative_file = pg_malloc(dir_len + 1 + file_len + 1);
>> is always free()'d, particularly if this condition is hit:
>>
>>    if (!fd)
>>    {
>>        psql_error("%s: %s\n", filename, strerror(errno));
>>        return EXIT_FAILURE;
>>    }
>
> Fixed.

Well, this fix:

       if (!fd)
       {
+               if (relative_path != NULL)
+                       free(relative_path);

+
               psql_error("%s: %s\n", filename, strerror(errno));

uses the wrong variable name (relative_path instead of relative_file),
and the subsequent psql_error() call will then reference freed memory,
since relative_file was assigned to filename.

But even after fixing this snippet to get it to compile, like so:

   if (!fd)
   {
       psql_error("%s: %s\n", filename, strerror(errno));

       if (relative_file != NULL)
           free(relative_file);

       return EXIT_FAILURE;
   }

I was still seeing memory leaks in valgrind growing with the number of
\ir calls between files (see valgrind_bad_report.txt attached). I
think that relative_file needs to be freed even in the non-error case,
like so:

error:
   if (fd != stdin)
       fclose(fd);

   if (relative_file != NULL)
       free(relative_file);

   pset.inputfile = oldfilename;
   return result;

At least, that fix seemed to get rid of the ballooning valgrind
reports for me. I then see a constant-sized < 500 byte leak complaint
from valgrind, the same as with unpatched psql.

>> 4.) I think the changes to process_file() merit another comment or
>> two, e.g. describing what relative_file is supposed to be.

> Added.

Some cleanup for this comment:

+               /*
+                * If the currently processing file uses \ir command, and the parameter
+                * to the command is a relative file path, then we resolve this path
+                * relative to currently processing file.

suggested tweak:

   If the currently processing file uses the \ir command, and the filename
   parameter is given as a relative path, then we resolve this path relative
   to the currently processing file (pset.inputfile).

+                *
+                * If the \ir command was executed in interactive mode (i.e. not in a
+                * script) the we treat it the same as \i command.
+                */

suggested tweak:

   If the \ir command was executed in interactive mode (i.e. not in a
   script, and pset.inputfile will be NULL) then we treat the filename
   the same as the \i command does.