Since /sys is unavailable in build environments, the list of available
TCP network interfaces cannot be obtained via /sys/class/net.  This patch
provides alternative code that uses the SIOCGIFCONF ioctl to get the
names of the available TCP network interfaces.

diff --git a/src/uct/tcp/tcp_iface.c b/src/uct/tcp/tcp_iface.c
index cad4a2709..7c1d2c9de 100644
--- a/src/uct/tcp/tcp_iface.c
+++ b/src/uct/tcp/tcp_iface.c
@@ -17,6 +17,8 @@
 #include <sys/poll.h>
 #include <netinet/tcp.h>
 #include <dirent.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
 
 
 extern ucs_class_t UCS_CLASS_DECL_NAME(uct_tcp_iface_t);
@@ -586,6 +588,68 @@ static UCS_CLASS_DEFINE_NEW_FUNC(uct_tcp_iface_t, uct_iface_t, uct_md_h,
                                  uct_worker_h, const uct_iface_params_t*,
                                  const uct_iface_config_t*);
 
+/* Fetch information about available network devices through an ioctl.  */
+static ucs_status_t query_devices_ioctl(uct_md_h md,
+					uct_tl_device_resource_t **tl_devices_p,
+					unsigned *num_tl_devices_p)
+{
+    int sock, err, i;
+    uct_tl_device_resource_t *resources, *tmp;
+    unsigned num_resources;
+    ucs_status_t status;
+    struct ifconf conf;
+    struct ifreq reqs[10];
+
+    conf.ifc_len = sizeof reqs;
+    conf.ifc_req = reqs;
+
+    sock = socket(SOCK_STREAM, AF_INET, 0);
+    if (sock < 0) {
+	ucs_error("socket(2) failed: %m");
+	status = UCS_ERR_IO_ERROR;
+	goto out;
+    }
+
+    err = ioctl(sock, SIOCGIFCONF, &conf);
+    if (err < 0) {
+	ucs_error("SIOCGIFCONF ioctl failed: %m");
+	status = UCS_ERR_IO_ERROR;
+	goto out;
+    }
+
+    resources     = NULL;
+    num_resources = 0;
+    for (i = 0; i < conf.ifc_len / sizeof(struct ifreq); i++) {
+	const char *name = reqs[i].ifr_name;
+
+        if (!ucs_netif_is_active(name, AF_INET)) {
+            continue;
+        }
+
+        tmp = ucs_realloc(resources, sizeof(*resources) * (num_resources + 1),
+                          "tcp resources");
+        if (tmp == NULL) {
+            ucs_free(resources);
+            status = UCS_ERR_NO_MEMORY;
+            goto out;
+        }
+        resources = tmp;
+
+        ucs_snprintf_zero(resources[i].name, sizeof(resources[i].name),
+                          "%s", name);
+        resources[i].type = UCT_DEVICE_TYPE_NET;
+        ++num_resources;
+    }
+
+    *num_tl_devices_p = num_resources;
+    *tl_devices_p     = resources;
+    status            = UCS_OK;
+
+out:
+    if (sock >= 0) close(sock);
+    return status;
+}
+
 ucs_status_t uct_tcp_query_devices(uct_md_h md,
                                    uct_tl_device_resource_t **devices_p,
                                    unsigned *num_devices_p)
@@ -599,9 +663,9 @@ ucs_status_t uct_tcp_query_devices(uct_md_h md,
 
     dir = opendir(UCT_TCP_IFACE_NETDEV_DIR);
     if (dir == NULL) {
-        ucs_error("opendir(%s) failed: %m", UCT_TCP_IFACE_NETDEV_DIR);
-        status = UCS_ERR_IO_ERROR;
-        goto out;
+	/* When /sys is unavailable, as can be the case in a container,
+	 * resort to a good old 'ioctl'.  */
+	return query_devices_ioctl(md, devices_p, num_devices_p);
     }
 
     devices     = NULL;
@@ -655,7 +719,6 @@ ucs_status_t uct_tcp_query_devices(uct_md_h md,
 
 out_closedir:
     closedir(dir);
-out:
     return status;
 }
 
</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Tobias Geerinckx-Rice &lt;me@tobias.gr&gt;</td><td class='right'>2020-07-26 19:28:23 +0200</td></tr>
<tr><th>committer</th><td>Tobias Geerinckx-Rice &lt;me@tobias.gr&gt;</td><td class='right'>2020-07-26 20:45:00 +0200</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/guix/commit/gnu/packages?id=b2c163cec38f349a8b508edfd022f6255d5d3811'>b2c163cec38f349a8b508edfd022f6255d5d3811</a> (<a href='/guix/patch/gnu/packages?id=b2c163cec38f349a8b508edfd022f6255d5d3811'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/guix/tree/?id=b2c163cec38f349a8b508edfd022f6255d5d3811'>f66940fda772fc7e0a4f9963df96a266743e2c2b</a> /<a href='/guix/tree/gnu/packages?id=b2c163cec38f349a8b508edfd022f6255d5d3811'>gnu/packages</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/guix/commit/gnu/packages?id=310f83497daf05b7500be5efedecbed336fc4f1a'>310f83497daf05b7500be5efedecbed336fc4f1a</a> (<a href='/guix/diff/gnu/packages?id=b2c163cec38f349a8b508edfd022f6255d5d3811&amp;id2=310f83497daf05b7500be5efedecbed336fc4f1a'>diff</a>)</td></tr><tr><th>download</th><td colspan='2' class='oid'><a href='/guix/snapshot/guix-b2c163cec38f349a8b508edfd022f6255d5d3811.tar.gz'>guix-b2c163cec38f349a8b508edfd022f6255d5d3811.tar.gz</a><br/><a href='/guix/snapshot/guix-b2c163cec38f349a8b508edfd022f6255d5d3811.zip'>guix-b2c163cec38f349a8b508edfd022f6255d5d3811.zip</a><br/></td></tr></table>
<div class='commit-subject'>gnu: python-bleach: Update to 3.1.5.</div><div class='commit-msg'>* gnu/packages/python-xyz.scm (python-bleach): Update to 3.1.5.
</div><div class='diffstat-header'><a href='/guix/diff/?id=b2c163cec38f349a8b508edfd022f6255d5d3811'>Diffstat</a> (limited to 'gnu/packages')</div><table summary='diffstat' class='diffstat'>