machine-id: initialize from $container_uuid if not set otherwise

This is a result of the discussions on

https://bugs.freedesktop.org/show_bug.cgi?id=46894

1 files changed, 67 insertions, 14 deletions

diff --git a/src/machine-id-setup.c b/src/machine-id-setup.c
index d584181bed..0f97433804 100644
--- a/src/machine-id-setup.c
+++ b/src/machine-id-setup.c
@@ -35,6 +35,28 @@
 #include "log.h"
 #include "virt.h"
 
+static int shorten_uuid(char destination[36], const char *source) {
+        unsigned i, j;
+
+        for (i = 0, j = 0; i < 36 && j < 32; i++) {
+                int t;
+
+                t = unhexchar(source[i]);
+                if (t < 0)
+                        continue;
+
+                destination[j++] = hexchar(t);
+        }
+
+        if (i == 36 && j == 32) {
+                destination[32] = '\n';
+                destination[33] = 0;
+                return 0;
+        }
+
+        return -EINVAL;
+}
+
 static int generate(char id[34]) {
         int fd, r;
         unsigned char *p;
@@ -75,26 +97,57 @@ static int generate(char id[34]) {
                         close_nointr_nofail(fd);
 
                         if (k >= 36) {
-                                unsigned i, j;
+                                r = shorten_uuid(id, uuid);
+                                if (r >= 0) {
+                                        log_info("Initializing machine ID from KVM UUID");
+                                        return 0;
+                                }
+                        }
+                }
+        }
 
-                                for (i = 0, j = 0; i < 36 && j < 32; i++) {
-                                        int t;
+        /* If that didn't work either, see if we are running in a
+         * container, and a machine ID was passed in via
+         * $container_uuid the way libvirt/LXC does it */
 
-                                        t = unhexchar(uuid[i]);
-                                        if (t < 0)
-                                                continue;
+        r = detect_container(NULL);
+        if (r > 0) {
+                FILE *f;
 
-                                        id[j++] = hexchar(t);
-                                }
+                f = fopen("/proc/1/environ", "re");
+                if (f) {
+                        bool done = false;
 
-                                if (i == 36 && j == 32) {
-                                        id[32] = '\n';
-                                        id[33] = 0;
+                        do {
+                                char line[LINE_MAX];
+                                unsigned i;
 
-                                        log_info("Initializing machine ID from KVM UUID");
-                                        return 0;
+                                for (i = 0; i < sizeof(line)-1; i++) {
+                                        int c;
+
+                                        c = getc(f);
+                                        if (_unlikely_(c == EOF)) {
+                                                done = true;
+                                                break;
+                                        } else if (c == 0)
+                                                break;
+
+                                        line[i] = c;
                                 }
-                        }
+                                line[i] = 0;
+
+                                if (startswith(line, "container_uuid=") &&
+                                    strlen(line + 15) >= 36) {
+                                        r = shorten_uuid(id, line + 15);
+                                        if (r >= 0) {
+                                                log_info("Initializing machine ID from container UUID");
+                                                return 0;
+                                        }
+                                }
+
+                        } while (!done);
+
+                        fclose(f);
                 }
         }