Support BSDs by special-casing Linux and Android specifically

[ryanavella]

This is kind of gross, but at least gets the crate compiling on the BSDs that don't have an ioctl for querying block size. Solves #157.

To be honest I don't understand this code-base enough to know the "proper" fix. I'd like to understand why the ioctl is needed in the first place, instead of relying exclusively on std::fs::MetaData::len when that is present. This understand could help me to craft the "proper" patch for FreeBSD support.

[nabijaczleweli]

Why: struct stat::st_size is 0 for devices, natch
How: this should probably use the same methodology as I do in voreutils (https://git.sr.ht/~nabijaczleweli/voreutils/tree/02bcd701febb555147b67e0fa7fdc1504fe3cca2/item/cmd/wc.cpp#L155-177), which includes Linux, {Free,Net}BSD, OpenBSD, and the illumos gate. maybe drop the illumos gate. I'll probably do this in a bit but this is incredibly annoying to do in Rust

[ryanavella]

Interesting, I didn't realize std::fs::Metadata was just a wrapper around struct stat on linux/bsd. I'll close this in favor of a less gross, more correct fix.

[nabijaczleweli]

unsurprisingly, that works:

root@freebsd:/mnt/http # curl localhost:8000 | grep '<abbr title="[1-9]'
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0[2023-12-28 16:03:38] 127.0.0.1:47876 was served directory listing for /dev
len 8 vecnum: 129 sizeof (zfs_cmd_t) 4528
100 51684  100 51684    0     0   137k  <tr><td><a href="/bpf0" id="bpf0" class="file_icon"></a></td> <td><a href="/bpf0">bpf0</a></td> <td><a href="/bpf0" class="datetime">2023-12-28 15:51:54</a></td> <td><a href="/bpf0"><abbr title="3 B">3 B</abbr></a></td> </tr>
100 51684  100 51684    0   <tr><td><a href="/kbd0" id="kbd0" class="file_icon"></a></td> <td><a href="/kbd0">kbd0</a></td> <td><a href="/kbd0" class="datetime">2023-12-28
15:51:54</a></td> <td><a href="/kbd0"><abbr title="6 B">6 B</abbr></a></td> </tr>
  0<tr><td><a href="/kbd1" id="kbd1" class="file_icon"></a></td> <td><a href="/kbd1">kbd1</a></td> <td><a href="/kbd1" class="datetime">2023-12-28 15:51:54</a></td> <td><a
href="/kbd1"><abbr title="7 B">7 B</abbr></a></td> </tr>
   137k      0 --:--:--<tr><td><a href="/log" id="log" class="file_icon"></a></td> <td><a href="/log">log</a></td> <td><a href="/log" class="datetime">2023-12-28 15:52:08</a></td> <td><a href="/log"><abbr title="12 B">12 B</abbr></a></td> </tr>
 --:--:-- --:--:--  137k
<tr><td><a href="/md0" id="md0" class="file_icon"></a></td> <td><a href="/md0">md0</a></td> <td><a href="/md0" class="datetime">2023-12-28 15:52:08</a></td> <td><a href="/md0"><abbr title="6442450944 B">6 GiB</abbr></a></td> </tr>
<tr><td><a href="/stderr" id="stderr" class="file_icon"></a></td> <td><a href="/stderr">stderr</a></td> <td><a href="/stderr" class="datetime">2023-12-28 15:51:54</a></td>
<td><a href="/stderr"><abbr title="4 B">4 B</abbr></a></td> </tr>
<tr><td><a href="/stdin" id="stdin" class="file_icon"></a></td> <td><a href="/stdin">stdin</a></td> <td><a href="/stdin" class="datetime">2023-12-28 15:51:54</a></td> <td><a href="/stdin"><abbr title="4 B">4 B</abbr></a></td> </tr>
<tr><td><a href="/stdout" id="stdout" class="file_icon"></a></td> <td><a href="/stdout">stdout</a></td> <td><a href="/stdout" class="datetime">2023-12-28 15:51:54</a></td>
<td><a href="/stdout"><abbr title="4 B">4 B</abbr></a></td> </tr>
<tr><td><a href="/urandom" id="urandom" class="file_icon"></a></td> <td><a href="/urandom">urandom</a></td> <td><a href="/urandom" class="datetime">2023-12-28 15:51:54</a></td> <td><a href="/urandom"><abbr title="6 B">6 B</abbr></a></td> </tr>
<tr><td><a href="/vtbd0" id="vtbd0" class="file_icon"></a></td> <td><a href="/vtbd0">vtbd0</a></td> <td><a href="/vtbd0" class="datetime">2023-12-28 15:51:54</a></td> <td><a href="/vtbd0"><abbr title="107374182400 B">100 GiB</abbr></a></td> </tr>
<tr><td><a href="/vtbd0p1" id="vtbd0p1" class="file_icon"></a></td> <td><a href="/vtbd0p1">vtbd0p1</a></td> <td><a href="/vtbd0p1" class="datetime">2023-12-28 15:51:54</a></td> <td><a href="/vtbd0p1"><abbr title="65024 B">63.5 KiB</abbr></a></td> </tr>
<tr><td><a href="/vtbd0p2" id="vtbd0p2" class="file_icon"></a></td> <td><a href="/vtbd0p2">vtbd0p2</a></td> <td><a href="/vtbd0p2" class="datetime">2023-12-28 15:51:54</a></td> <td><a href="/vtbd0p2"><abbr title="34091008 B">32.5 MiB</abbr></a></td> </tr>
<tr><td><a href="/vtbd0p3" id="vtbd0p3" class="file_icon"></a></td> <td><a href="/vtbd0p3">vtbd0p3</a></td> <td><a href="/vtbd0p3" class="datetime">2023-12-28 15:51:54</a></td> <td><a href="/vtbd0p3"><abbr title="5368709120 B">5 GiB</abbr></a></td> </tr>
<tr><td><a href="/vtbd0p4" id="vtbd0p4" class="file_icon"></a></td> <td><a href="/vtbd0p4">vtbd0p4</a></td> <td><a href="/vtbd0p4" class="datetime">2023-12-28 15:51:54</a></td> <td><a href="/vtbd0p4"><abbr title="101970869248 B">95 GiB</abbr></a></td> </tr>

[nabijaczleweli]

Released in v2.0.0.