Respect HW configs when loading VM from snapshots.

Changing HW configuration properties may cause emulator / guest system crash on
condition that VM has been loaded from a snapshot. This CL addresses this issue
in the following way:

1. Each time a snapshot is saved, a backup copy of HW config is saved with it.
2. Each time a snapshot is loaded, emulator finds an appropriate HW config
   backup, and compares current HW config with the one that was saved in the
   backup, and if configs are different, emulator exits with an appropriate
   error.

Change-Id: I730bec0afbe166e88189fdcc4804b76e109e4422

2 files changed, 63 insertions, 7 deletions

diff --git a/android/utils/ini.c b/android/utils/ini.c
index ff4a8af..43f1321 100644
--- a/android/utils/ini.c
+++ b/android/utils/ini.c
@@ -298,8 +298,18 @@ EXIT:
     return ini;
 }
 
-int
-iniFile_saveToFile( IniFile*  f, const char*  filepath )
+/* Common routine for saving IniFile instance to the given file.
+ * Param:
+ *  f - IniFile instance to save.
+ *  filepath - Path to a file where to save the instance.
+ *  strip - If 1, ignore (don't save) pairs with empty values. If 0, save all
+ *      pairs found in the IniFile instance, including the ones that contain
+ *      empty values.
+ * Returns:
+ *  0 on success, -1 on error (see errno for error code)
+ */
+static int
+iniFile_saveToFileCommon( IniFile*  f, const char*  filepath, int strip )
 {
     FILE*  fp = fopen(filepath, "wt");
     IniPair*  pair    = f->pairs;
@@ -313,11 +323,13 @@ iniFile_saveToFile( IniFile*  f, const char*  filepath )
     }
 
     for ( ; pair < pairEnd; pair++ ) {
-        char  temp[PATH_MAX], *p=temp, *end=p+sizeof(temp);
-        p = bufprint(temp, end, "%s = %s\n", pair->key, pair->value);
-        if (fwrite(temp, p - temp, 1, fp) != 1) {
-            result = -1;
-            break;
+        if ((pair->value && *pair->value) || !strip) {
+            char  temp[PATH_MAX], *p=temp, *end=p+sizeof(temp);
+            p = bufprint(temp, end, "%s = %s\n", pair->key, pair->value);
+            if (fwrite(temp, p - temp, 1, fp) != 1) {
+                result = -1;
+                break;
+            }
         }
     }
 
@@ -325,6 +337,33 @@ iniFile_saveToFile( IniFile*  f, const char*  filepath )
     return result;
 }
 
+int
+iniFile_saveToFile( IniFile*  f, const char*  filepath )
+{
+    return iniFile_saveToFileCommon(f, filepath, 0);
+}
+
+int
+iniFile_saveToFileClean( IniFile*  f, const char*  filepath )
+{
+    return iniFile_saveToFileCommon(f, filepath, 1);
+}
+
+int
+iniFile_getEntry(IniFile* f, int index, char** key, char** value)
+{
+    if (index >= f->numPairs) {
+        D("Index %d exceeds the number of ini file entries %d",
+          index, f->numPairs);
+        return -1;
+    }
+
+    *key = ASTRDUP(f->pairs[index].key);
+    *value = ASTRDUP(f->pairs[index].value);
+
+    return 0;
+}
+
 char*
 iniFile_getString( IniFile*  f, const char*  key, const char* defaultValue )
 {
diff --git a/android/utils/ini.h b/android/utils/ini.h
index 5730ee0..fd56575 100644
--- a/android/utils/ini.h
+++ b/android/utils/ini.h
@@ -37,6 +37,11 @@ IniFile*  iniFile_newFromFile( const char*  filePath);
  */
 int       iniFile_saveToFile( IniFile*  f, const char*  filePath );
 
+/* try to write an IniFile into a given file, ignorig pairs with empty values.
+ * returns 0 on success, -1 on error (see errno for error code)
+ */
+int       iniFile_saveToFileClean( IniFile*  f, const char*  filepath );
+
 /* free an IniFile object */
 void      iniFile_free( IniFile*  f );
 
@@ -48,6 +53,18 @@ int       iniFile_getPairCount( IniFile*  f );
  */
 const char*  iniFile_getValue( IniFile*  f, const char*  key );
 
+/* Copies a 'key, value' pair for an entry in the file.
+ * Param:
+ *  f - Initialized IniFile instance.
+ *  index - Index of the entry to copy. Must be less than value returned from the
+ *      iniFile_getPairCount routine.
+ *  key, value - Receives key, and value strings for the entry. If this routine
+ *      succeeds, the caller must free the buffers allocated for the strings.
+ * Return:
+ *  0 on success, -1 if the index exceeds the capacity of the file
+ */
+int     iniFile_getEntry(IniFile* f, int index, char** key, char** value);
+
 /* returns a copy of the value of a given key, or NULL if defaultValue is NULL.
  * caller must free() it.
  */