Merge lp:~seb128/whoopsie-preferences/touch-writable-image into lp:whoopsie-preferences

[Sebastien Bacher]

Hack to support system-image read-only /etc, and modify files in
/etc/writable/ instead (similar to what is used in systemd in Ubuntu)
(lp: #1437633)

Hack to support system-image read-only /etc, and modify files in
/etc/writable/ instead (similar to what is used in systemd in Ubuntu)
(lp: #1437633)

[lp:~seb128/whoopsie-preferences/touch-writable-image]

57. By Sebastien Bacher on 2015-05-19

Hack to support system-image read-only /etc, and modify files in
/etc/writable/ instead (similar to what is used in systemd in Ubuntu)
(lp: #1437633)

[Iain Lane (laney)]

I think this is fine. I was confused about why you use a static string for the return variable, but I suppose it's so you don't have to free it?

I have one small comment but I'll fix it when merging. Will test and upload.

review: Approve

[Sebastien Bacher (seb128)]

thanks for the review

> I was confused about why you use a static string for the return variable, but I suppose it's so you don't have to free it?

right, that's what is done in the systemd patch and I though it was a good idea and that we could do the same here

[Iain Lane (laney)]

btw I had to add code to resolve the symlink to an absolute path (systemd has a helper to do this), because we create relative symlinks in livecd-rootfs but the code expects an absolute path

=== modified file 'src/whoopsie-preferences.c'
--- src/whoopsie-preferences.c	2015-04-02 20:07:45 +0000
+++ src/whoopsie-preferences.c	2015-05-19 18:26:50 +0000
@@ -23,6 +23,11 @@
 #include <gio/gio.h>
 #include <stdlib.h>
 #include <polkit/polkit.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdio.h>
+#include <unistd.h>
+
 #include <libwhoopsie/identifier.h>
 
 #include "libwhoopsie-preferences.h"
@@ -34,6 +39,45 @@
 static GKeyFile* key_file = NULL;
 static PolkitAuthority* authority = NULL;
 
+/* Hack for Ubuntu phone: check if path is an existing symlink to
+ * /etc/writable; if it is, update that instead */
+static const char* writable_filename(const char *config) {
+        const char *result = config;
+        struct stat sb;
+        char *linkname = NULL;
+        ssize_t r;
+        static char realfile_buf[PATH_MAX];
+
+        if (lstat(config, &sb) == -1) {
+            return config;
+        }
+        
+        linkname = g_malloc(sb.st_size + 1);
+        if (linkname == NULL) {
+            return result;
+        }
+        
+        r = readlink(config, linkname, sb.st_size + 1);
+        
+        if (r < 0) {
+            g_free (linkname);
+            return result;
+        }
+        if (r > sb.st_size) {
+            g_free (linkname);
+            return result;
+        }
+        linkname[sb.st_size] = '\0';
+
+        if (g_str_has_prefix (linkname, "/etc/writable")) {
+            g_snprintf(realfile_buf, sizeof(realfile_buf), "%s", linkname);
+            result = realfile_buf;
+        }
+
+        g_free (linkname);
+        return result;
+}
+
 gboolean
 whoopsie_preferences_load_configuration (void)
 {
@@ -54,7 +98,7 @@
         ret = FALSE;
         goto out;
     }
-    if (!g_file_set_contents (CONFIG_PATH, data, data_size, &error)) {
+    if (!g_file_set_contents (writable_filename(CONFIG_PATH), data, data_size, &error)) {
         g_print ("Could not write configuration: %s\n", error->message);
         ret = FALSE;
         goto out;
@@ -281,7 +325,7 @@
                 g_print ("Could not process configuration: %s\n", error->message);
                 return FALSE;
             }
-            if (!g_file_set_contents (CONFIG_PATH, data, data_size, &error)) {
+            if (!g_file_set_contents (writable_filename(CONFIG_PATH), data, data_size, &error)) {
                 g_print ("Could not write configuration: %s\n", error->message);
                 return FALSE;
             }