Hi, Pino

在 2015年06月17日 23:37, Pino Toscano 写道:
Hi,

On Wednesday 17 June 2015 10:12:59 Cao jin wrote:
@@ -2083,3 +2083,72 @@ do_btrfs_image (char *const *sources, const char *image,

     return 0;
   }
+
+char **
+do_btrfs_device_stats (const char *path, int zero)
+{
+  const size_t MAX_ARGS = 64;
+  const char *argv[MAX_ARGS];
+  size_t i = 0;
+  CLEANUP_FREE char *buf = NULL;
+  CLEANUP_FREE char *err = NULL;
+  CLEANUP_FREE char *out = NULL;
+  char *p, *key = NULL, *value = NULL;
+  DECLARE_STRINGSBUF (ret);

'ret' is leaked if returning before "return ret.argv".


yup...will fix this. see some other APIs have the same problem.

I will send something to help with these issues, so no need to change
this for now.

OK
+    if (add_string (&ret, key) == -1)
+      return NULL;
+
+    if (add_string (&ret, value) == -1)
+      return NULL;
+
+    p = analyze_line(p, &key, &value, ' ');
+  }

This means that the return "hash" will have keys like:
    [/dev/sda].write_io_errs
? Wouldn't it better to just return the name of the attribute, i.e.
    write_io_errs
?

In the condition that the btrfs have multi devices, its original output
is going to this way:
    [/dev/sda].write_io_errs   0
    [/dev/sda].read_io_errs    0
    [/dev/sda].flush_io_errs   0
    [/dev/sda].corruption_errs 0
    [/dev/sda].generation_errs 0
    [/dev/sdb].write_io_errs   0
    [/dev/sdb].read_io_errs    0
    [/dev/sdb].flush_io_errs   0
    [/dev/sdb].corruption_errs 0
    [/dev/sdb].generation_errs 0
    [/dev/sdc]...
    [/dev/sdc]...
    [/dev/sdc]...
    [/dev/sdc]...
    ...
So. I think the [/dev/sd..] is necessary, how to think?

Possibly, but the user (as in caller for this API) still need to do
some kind of parsing; given that you are basically copying bits from
the btrfs output, they might change breaking users.

Speaking of this: you said that you have a colleague working on
btrfs-progs? What about suggesting to create some machine-parseable
output (csv, xml, yaml, json, whatever) so extracting the results of
btrfs tools is a lot more easy?


Yes, I forward your suggestion and consult him, the result is not surprised:( Here is what I learned from him: For the btrfs-progs cmds who output strings, the output are plain, don`t have patterns. Seen some guys who want a formatted output, they do a filter by themself, it not reasonable to ask btrfs-progs to output formatted strings.

What`s your opinion about the output pattern? I can try to implement it.

Thanks,


--
Yours Sincerely,

Cao Jin

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