Re: [PATCH] Rewrite bulk-checkin.c:finish_bulk_checkin() to use a strbuf for handling packname

[Eric Sunshine <sunshine@sunshineco.com>]

On Fri, Feb 28, 2014 at 3:28 AM, Sun He <sunheehnus@gmail.com> wrote:
> Signed-off-by: Sun He <sunheehnus@gmail.com>
> ---

Nicely done.

Due to the necessary changes to finish_tmp_packfile(), the focus of
this patch has changed slightly from that suggested by the
microproject. It's really now about finish_tmp_packfile() rather than
finish_bulk_checkin(). As such, it may make sense to adjust the patch
subject to reflect this. For instance:

  Subject: finish_tmp_packfile(): use strbuf for pathname construction

More comments below.

]> diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
> index c733379..72fb82b 100644
> --- a/builtin/pack-objects.c
> +++ b/builtin/pack-objects.c
> @@ -803,7 +803,7 @@ static void write_pack_file(void)
>
>                 if (!pack_to_stdout) {
>                         struct stat st;
> -                       char tmpname[PATH_MAX];
> +                       struct strbuf tmpname = STRBUF_INIT;
>
>                         /*
>                          * Packs are runtime accessed in their mtime
> @@ -823,26 +823,22 @@ static void write_pack_file(void)
>                                 utb.modtime = --last_mtime;
>                                 if (utime(pack_tmp_name, &utb) < 0)
>                                         warning("failed utime() on %s: %s",
> -                                               tmpname, strerror(errno));
> +                                               pack_tmp_name, strerror(errno));

Good catch finding this bug (as your commentary below states).
Ideally, each conceptual change should be presented distinctly from
others, so this bug should have its own patch (even though it's just a
one-liner).

>                         }
>
> -                       /* Enough space for "-<sha-1>.pack"? */
> -                       if (sizeof(tmpname) <= strlen(base_name) + 50)
> -                               die("pack base name '%s' too long", base_name);
> -                       snprintf(tmpname, sizeof(tmpname), "%s-", base_name);
> +                       strbuf_addf(&tmpname, "%s-", base_name);
>
>                         if (write_bitmap_index) {
>                                 bitmap_writer_set_checksum(sha1);
>                                 bitmap_writer_build_type_index(written_list, nr_written);
>                         }
>
> -                       finish_tmp_packfile(tmpname, pack_tmp_name,
> +                       finish_tmp_packfile(&tmpname, pack_tmp_name,
>                                             written_list, nr_written,
>                                             &pack_idx_opts, sha1);
>
>                         if (write_bitmap_index) {
> -                               char *end_of_name_prefix = strrchr(tmpname, 0);
> -                               sprintf(end_of_name_prefix, "%s.bitmap", sha1_to_hex(sha1));
> +                               strbuf_addf(&tmpname, "%s.bitmap" ,sha1_to_hex(sha1));
>
>                                 stop_progress(&progress_state);
>
> diff --git a/pack-write.c b/pack-write.c
> index 9b8308b..2204aa9 100644
> --- a/pack-write.c
> +++ b/pack-write.c
> @@ -336,7 +336,7 @@ struct sha1file *create_tmp_packfile(char **pack_tmp_name)
>         return sha1fd(fd, *pack_tmp_name);
>  }
>
> -void finish_tmp_packfile(char *name_buffer,
> +void finish_tmp_packfile(struct strbuf *name_buffer,
>                          const char *pack_tmp_name,
>                          struct pack_idx_entry **written_list,
>                          uint32_t nr_written,
> @@ -344,7 +344,7 @@ void finish_tmp_packfile(char *name_buffer,
>                          unsigned char sha1[])
>  {
>         const char *idx_tmp_name;
> -       char *end_of_name_prefix = strrchr(name_buffer, 0);
> +       int pre_len = name_buffer->len;

Minor: Perhaps basename_len (or some such) would convey a bit more
meaning than pre_len.

>         if (adjust_shared_perm(pack_tmp_name))
>                 die_errno("unable to make temporary pack file readable");
> @@ -354,17 +354,21 @@ void finish_tmp_packfile(char *name_buffer,
>         if (adjust_shared_perm(idx_tmp_name))
>                 die_errno("unable to make temporary index file readable");
>
> -       sprintf(end_of_name_prefix, "%s.pack", sha1_to_hex(sha1));
> -       free_pack_by_name(name_buffer);
> +       strbuf_addf(name_buffer, "%s.pack", sha1_to_hex(sha1));
> +       free_pack_by_name(name_buffer->buf);
>
> -       if (rename(pack_tmp_name, name_buffer))
> +       if (rename(pack_tmp_name, name_buffer->buf))
>                 die_errno("unable to rename temporary pack file");
>
> -       sprintf(end_of_name_prefix, "%s.idx", sha1_to_hex(sha1));
> -       if (rename(idx_tmp_name, name_buffer))
> +       /* remove added suffix string(sha1.pack) */
> +       strbuf_remove(name_buffer, pre_len, name_buffer->len - pre_len);

Since you are merely truncating the buffer back to pre_len, perhaps

    strbuf_setlen(name_buffer, pre_len)

would be more idiomatic and easier to read (and would allow you to
drop the comment).

> +
> +       strbuf_addf(name_buffer, "%s.idx", sha1_to_hex(sha1));
> +       if (rename(idx_tmp_name, name_buffer->buf))
>                 die_errno("unable to rename temporary index file");
>
> -       *end_of_name_prefix = '\0';
> +       /* remove added suffix string(sha1.idx) */
> +       strbuf_remove(name_buffer, pre_len, name_buffer->len - pre_len);

Ditto.

>         free((void *)idx_tmp_name);
>  }
> --
> 1.9.0.138.g2de3478.dirty
>
> Hello,
> This is my patch for the GSoC microproject #2
>
> I follow the suggestion of Junio to use the strbuf_addf to deal with this thing.
> And the usage of strbuf_addf needs to change the function finish_tmp_packfile, I search all over the source code ($ find .| xargs grep "finish_tmp_packfile")
> The following files contains finish_tmp_packfile:
>         bulk-checkin.c
>         builtin/pack-object.c
>         pack-write.c
>         pack.h
> And I do some change to fix them.
> I changed my vimrc so that tabs will not be changed into spaces automatically.
>
> And I came across a bug when I was doing my microproject.
> position:  builtin/pack-objects.c: write_pack_file: if(!pack_to_stdout): first else in it
>  warning() function used an uninitialized array, and I changed it to pack_tmp_name.
>
> Thank you all for all your suggestions.

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