Open_Plugin add checksum on struct offsets

Adding a checksum over the struct offset will allow checking
for compatibility across machines rather than using packed structs
to ensure compability

For any file created by the user from the device  this isn't really a concern

But for files between machines, across installs (sim v device),
possibly even across compilers this at least will alert the user
rather than returning junk data

Change-Id: Id0531bbaa7013dce24dece270849f0a10ac99c20

1 files changed, 32 insertions, 11 deletions

diff --git a/apps/open_plugin.c b/apps/open_plugin.c
index 32b5195334..fe18071454 100644
--- a/apps/open_plugin.c
+++ b/apps/open_plugin.c
@@ -38,6 +38,8 @@
 
 struct open_plugin_entry_t open_plugin_entry = {0};
 
+static const uint32_t open_plugin_csum = OPEN_PLUGIN_CHECKSUM;
+
 static const int op_entry_sz = sizeof(struct open_plugin_entry_t);
 
 static int open_plugin_hash_get_entry(uint32_t hash,
@@ -60,6 +62,13 @@ static inline void op_clear_entry(struct open_plugin_entry_t *entry)
     entry->lang_id = -1;
 }
 
+static int op_entry_checksum(struct open_plugin_entry_t *entry)
+{
+    if (!entry || entry->checksum != open_plugin_csum)
+        return 0;
+    return 1;
+}
+
 static int op_find_entry(int fd, struct open_plugin_entry_t *entry,
                                     uint32_t hash, int32_t lang_id)
 {
@@ -75,6 +84,13 @@ static int op_find_entry(int fd, struct open_plugin_entry_t *entry,
                (entry->hash == hash && hash != 0) ||
                (lang_id == OPEN_PLUGIN_LANG_IGNOREALL))/* return first entry found */
             {
+                /* sanity check */
+                if (op_entry_checksum(entry) <= 0)
+                {
+                    splashf(HZ * 2, "OpenPlugin Invalid entry");
+                    ret = OPEN_PLUGIN_NOT_FOUND;
+                    break;
+                }
                 /* NULL terminate fields NOTE -- all are actually +1 larger */
                 entry->name[OPEN_PLUGIN_NAMESZ] = '\0';
                 /*entry->key[OPEN_PLUGIN_BUFSZ] = '\0';*/
@@ -111,24 +127,27 @@ static int op_update_dat(struct open_plugin_entry_t *entry, bool clear)
     logf("OP update hash: %x lang_id: %d", hash, lang_id);
     logf("OP update name: %s clear: %d", entry->name, (int) clear);
     logf("OP update %s %s %s", entry->name, entry->path, entry->param);
+
 #if (CONFIG_STORAGE & STORAGE_ATA) /* Harddrive -- update existing */
     logf("OP update *Updating entries* %s", OPEN_PLUGIN_DAT);
     fd = open(OPEN_PLUGIN_DAT, O_RDWR | O_CREAT, 0666);
 
     if (fd < 0)
         return OPEN_PLUGIN_NOT_FOUND;
-    /* Only read the hash and lang id */
-    uint32_t hash_langid[2] = {0};
-    while (read(fd, &hash_langid, sizeof(hash_langid)) == sizeof(hash_langid))
+    /* Only read the hash lang id and checksum */
+    uint32_t hash_langid_csum[3] = {0};
+    const off_t hlc_sz = sizeof(hash_langid_csum);
+    while (read(fd, &hash_langid_csum, hlc_sz) == hlc_sz)
     {
-        if (hash_langid[0] == hash || (int32_t)hash_langid[1] == lang_id)
+        if ((hash_langid_csum[0] == hash || (int32_t)hash_langid_csum[1] == lang_id) &&
+             hash_langid_csum[2] == open_plugin_csum)
         {
             logf("OP update *Entry Exists* hash: %x langid: %d",
-                hash_langid[0], (int32_t)hash_langid[1]);
-            lseek(fd, 0-sizeof(hash_langid), SEEK_CUR);/* back to the start of record */
+                hash_langid_csum[0], (int32_t)hash_langid[1]);
+            lseek(fd, 0-hlc_sz, SEEK_CUR);/* back to the start of record */
             break;
         }
-        lseek(fd, op_entry_sz - sizeof(hash_langid), SEEK_CUR); /* finish record */
+        lseek(fd, op_entry_sz - hlc_sz, SEEK_CUR); /* finish record */
     }
     write(fd, entry, op_entry_sz);
     close(fd);
@@ -146,7 +165,8 @@ static int op_update_dat(struct open_plugin_entry_t *entry, bool clear)
         /* copy non-duplicate entries back from original */
         while (read(fd1, entry, op_entry_sz) == op_entry_sz)
         {
-            if (entry->hash != hash && entry->lang_id != lang_id)
+            if (entry->hash != hash && entry->lang_id != lang_id &&
+               op_entry_checksum(entry) > 0)
             {
                 write(fd, entry, op_entry_sz);
             }
@@ -202,8 +222,9 @@ uint32_t open_plugin_add_path(const char *key, const char *plugin, const char *p
 
     if (plugin)
     {
-        open_plugin_entry.hash = hash;
-        open_plugin_entry.lang_id = lang_id;
+        open_plugin_entry.hash     = hash;
+        open_plugin_entry.lang_id  = lang_id;
+        open_plugin_entry.checksum = open_plugin_csum;
         /* name */
         if (path_basename(plugin, (const char **)&pos) == 0)
             pos = "\0";
@@ -242,7 +263,7 @@ retnhash:
 
 void open_plugin_browse(const char *key)
 {
-    logf("OP Browse");
+    logf("OP browse");
     struct browse_context browse;
     char tmp_buf[OPEN_PLUGIN_BUFSZ+1];
     open_plugin_get_entry(key, &open_plugin_entry);