Re: [PATCH 1/1] change contract between system_path and it's callers

[Alexander Kuleshov <kuleshovmail@gmail.com>]

What do you think if we create int variable, something like
given_config_must_free = 0; and will set up it to 1 in cases where it
will be allocated, and than we can free it in the end of cmd_config?
I'm reading git source code to understanding git internals and found
little memory leak in cat-file, so i fixed it as i described above.

2014-11-26 15:42 GMT+06:00 Alexander Kuleshov <kuleshovmail@gmail.com>:
> Maybe we will discard this patch, because i looked on it and tested
> with different places, it brings more leaks than before?
>
> 2014-11-26 9:53 GMT+06:00 Alexander Kuleshov <kuleshovmail@gmail.com>:
>>>
>>> Comparing this with what I sent out...
>>>
>>> >  builtin/help.c | 10 +++++++---
>>> >  exec_cmd.c     | 17 +++++++++--------
>>> >  exec_cmd.h     |  4 ++--
>>> >  git.c          | 16 ++++++++++++----
>>> >  4 files changed, 30 insertions(+), 17 deletions(-)
>>> >
>>> > @@ -372,7 +373,9 @@ static void show_man_page(const char *git_cmd)
>>> >  static void show_info_page(const char *git_cmd)
>>> >  {
>>> >       const char *page = cmd_to_page(git_cmd);
>>> > -     setenv("INFOPATH", system_path(GIT_INFO_PATH), 1);
>>> > +     char *git_info_path = system_path(GIT_INFO_PATH);
>>> > +     setenv("INFOPATH", git_info_path, 1);
>>> > +     free(git_info_path);
>>>
>>> We are just about to exec; does this warrant the code churn?
>>
>> hmm... Can't understand what's the problem here? We get git_info_path
>> from system_path which returns pointer which will need to free, set it in
>> environment var and than free it...
>>
>>>
>>> >       execlp("info", "info", "gitman", page, (char *)NULL);
>>> >       die(_("no info viewer handled the request"));
>>>
>>> > @@ -34,8 +34,7 @@ const char *system_path(const char *path)
>>> >  #endif
>>> >
>>> >       strbuf_addf(&d, "%s/%s", prefix, path);
>>> > -     path = strbuf_detach(&d, NULL);
>>> > -     return path;
>>> > +     return d.buf;
>>>
>>> These happens to be the same with the current strbuf implementation,
>>> but it is a good manner to use strbuf_detach(&d, NULL) here.  We
>>> don't know what other de-initialization tomorrow's implementation of
>>> the strbuf API may have to do in strbuf_detach().
>>
>> How to do it in correct way?
>>
>>
>>     strbuf_addf(&d, "%s/%s", prefix, path);
>>     path = strbuf_detach(&d, NULL);
>>     return (char*)path;
>>
>> Or something else?
>>
>>>
>>> > @@ -68,16 +67,16 @@ void git_set_argv_exec_path(const char *exec_path)
>>> >
>>> >
>>> >  /* Returns the highest-priority, location to look for git programs. */
>>> > -const char *git_exec_path(void)
>>> > +char *git_exec_path(void)
>>> >  {
>>> >       const char *env;
>>> >
>>> >       if (argv_exec_path)
>>> > -             return argv_exec_path;
>>> > +             return strdup(argv_exec_path);
>>> >
>>> >       env = getenv(EXEC_PATH_ENVIRONMENT);
>>> >       if (env && *env) {
>>> > -             return env;
>>> > +             return strdup(env);
>>> >       }
>>>
>>> Now you are making callers of git_exec_path() responsible for
>>> freeing the result they receive.
>>>
>>> git_exec_path() may be called quite a lot, which means we may end up
>>> calling system_path() many times during the life of a process
>>> without freeing its return value, so this change may be worth doing,
>>> but this patch is insufficient, isn't it?
>>>
>>> You just added load_command_list() in help.c a new leak or two, for
>>> example.  There probably are other callers of this function but I
>>> don't have time to look at all of them myself right now.
>>
>> Yes, need to do that all git_exec_path() callers free result of git_exec_path.
>>
>>>
>>> > @@ -95,8 +94,10 @@ void setup_path(void)
>>> >  {
>>> >       const char *old_path = getenv("PATH");
>>> >       struct strbuf new_path = STRBUF_INIT;
>>> > +     char* exec_path = git_exec_path();
>>> >
>>> > -     add_path(&new_path, git_exec_path());
>>> > +     add_path(&new_path, exec_path);
>>> > +     free(exec_path);
>>> >       add_path(&new_path, argv0_path);
>>>
>>> This part by itself is good, provided if we make it the caller's
>>> responsiblity to free string returned by git_exec_path().
>>>
>>> > diff --git a/git.c b/git.c
>>> > index 82d7a1c..d01c4f1 100644
>>> > --- a/git.c
>>> > +++ b/git.c
>>> > @@ -95,17 +95,25 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
>>> >                       if (*cmd == '=')
>>> >                               git_set_argv_exec_path(cmd + 1);
>>> >                       else {
>>> > -                             puts(git_exec_path());
>>> > +                             char *exec_path = git_exec_path();
>>> > +                             puts(exec_path);
>>> > +                             free(exec_path);
>>> >                               exit(0);
>>> >                       }
>>> >               } else if (!strcmp(cmd, "--html-path")) {
>>> > -                     puts(system_path(GIT_HTML_PATH));
>>> > +                     char *git_html_path = system_path(GIT_HTML_PATH);
>>> > +                     puts(git_html_path);
>>> > +                     free(git_html_path);
>>> >                       exit(0);
>>> >               } else if (!strcmp(cmd, "--man-path")) {
>>> > -                     puts(system_path(GIT_MAN_PATH));
>>> > +                     char *git_man_path = system_path(GIT_MAN_PATH);
>>> > +                     puts(git_man_path);
>>> > +                     free(git_man_path);
>>> >                       exit(0);
>>> >               } else if (!strcmp(cmd, "--info-path")) {
>>> > -                     puts(system_path(GIT_INFO_PATH));
>>> > +                     char *git_info_path = system_path(GIT_INFO_PATH);
>>> > +                     puts(git_info_path);
>>> > +                     free(git_info_path);
>>> >                       exit(0);
>>> >               } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
>>> >                       use_pager = 1;
>>>
>>> None of these warrant the code churn, I would say.
>>
>> Sorry, english is not my first language, what did you mean when saying:
>> "code churn"? Code duplication or something else?
>
>
>
> --
> _________________________
> 0xAX



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