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Re: [Libguestfs] [PATCH 1/2] New API: list_md_devices

On 10/11/11 14:53, Richard W.M. Jones wrote:
On Thu, Nov 10, 2011 at 02:19:11PM +0000, Matthew Booth wrote:
+    /* Look for directories under /sys/block matching md[0-9]*
+     * As an additional check, we also make sure they have a md subdirectory */
+    int err = glob(PREFIX "[0-9]*" SUFFIX, GLOB_ERR, NULL,&mds);
+    if (err == GLOB_NOSPACE) {
+        reply_with_error("OOM searching for md devices");
+        goto error;
+    } else if (err == GLOB_ABORTED) {
+        reply_with_error("Read error searching for md devices");
+        goto error;

Since glob is supposed to set errno on error, I'd prefer:

   reply_with_perror ("glob");

for both of the branches above (combine them into a single branch
if you like).

glob has a callback (which I'm not using) for returning an error for each individual failure it hits. It's not actually documented to set errno at all. A glob failure here is pretty unlikely, so writing a bunch of code to collate errors and report them all nicely seems a waste. Simply catching an error seems good enough.

+    } else if (err == GLOB_NOMATCH) {
+        /* This is fine */
+    }

I think this branch should just be dropped.

Heh, yeah. It used to have code in it :)

+    for (size_t i = 0; i<  mds.gl_pathc; i++) {
+        size_t len = strlen(mds.gl_pathv[i]) - strlen(PREFIX) - strlen(SUFFIX);
+#define DEV "/dev/md"
+        char *dev = malloc(strlen(DEV) + len  + 1);

Need to check the return value from malloc and reply_with_perror /
goto error on failure.


+# Create a raid1 based on the 2 disks
+debug sh "/usr/bin/yes | mdadm -C /dev/md/test --level=1 --raid-devices=2 /dev/vda /dev/vdb>/dev/null 2>&1"

I guessed we'd be running the debug backdoor here to create devices.
Is it not worth binding this call too?

Maybe another day :)

+# Ensure list-md-devices now returns the newly create md device


Generally looking good.

Updated patch to follow.

Matthew Booth, RHCA, RHCSS
Red Hat Engineering, Virtualisation Team

GPG ID:  D33C3490
GPG FPR: 3733 612D 2D05 5458 8A8A 1600 3441 EA19 D33C 3490

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