0001-vold-switchable-pair.patch

From 8a4f1fb196fa5160485eb246035f1dd5691bd620 Mon Sep 17 00:00:00 2001
From: Ricardo Cerqueira <cyanogenmod@cerqueira.org>
Date: Fri, 19 Aug 2011 18:42:27 +0100
Subject: [PATCH] vold: Allow pre-configured device pairs to switch mountpoints

The use-case for this are devices with internal extended storage
(pseudo-SDCard emmc) and an actual microSD card reader.
In CM, we choose to use the microSD as primary storage, and leave
the internal partition mostly unused; some users usually come up with
imaginative and data-destroying ways of working around that.

This allows us to specify a pair of mountpoints which can be
switched from a user preference. For this vold.fstab:

-----
dev_mount sdcard /mnt/sdcard ...<path-to-microSD-sysfs>
dev_mount emmc /mnt/emmc ...<path-to-emmc-partition>
-----

We can add to build.prop:
"ro.vold.switchablepair=/mnt/sdcard,/mnt/emmc"

A persistent toggle (persist.sys.vold.switchexternal), controllable
through CMParts, can be presented to the user to allow choosing
something other than our default as primary storage.

Updated to 4.4 by @Dazzozo.

Change-Id: I9559fa442c833e3168287d820b7b8347736abb15
---
 DirectVolume.cpp | 38 ++++++++++++++++++++++++++++++++++++++
 DirectVolume.h   |  4 ++--
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/DirectVolume.cpp b/DirectVolume.cpp
index 57dc555..b176d15 100644
--- a/DirectVolume.cpp
+++ b/DirectVolume.cpp
@@ -24,6 +24,7 @@
 #define LOG_TAG "DirectVolume"
 
 #include <cutils/log.h>
+#include <cutils/properties.h>
 #include <sysutils/NetlinkEvent.h>
 
 #include "DirectVolume.h"
@@ -35,6 +36,7 @@
 
 DirectVolume::DirectVolume(VolumeManager *vm, const fstab_rec* rec, int flags) :
         Volume(vm, rec, flags) {
+    char switchable[PROPERTY_VALUE_MAX];
     mPaths = new PathCollection();
     for (int i = 0; i < MAX_PARTITIONS; i++)
         mPartMinors[i] = -1;
@@ -62,6 +64,42 @@ DirectVolume::DirectVolume(VolumeManager *vm, const fstab_rec* rec, int flags) :
     mMountpoint = strdup(mount);
     snprintf(mount, PATH_MAX, "%s/%s", Volume::FUSE_DIR, rec->label);
     mFuseMountpoint = strdup(mount);
+
+    property_get("persist.sys.vold.switchexternal", switchable, "0");
+    if (!strcmp(switchable,"1")) {
+        char *first, *second = NULL;
+        char label[PATH_MAX];
+        const char *delim = ",";
+        int lblidx = strlen(Volume::FUSE_DIR) + 1;
+        bool swap = true;
+
+        property_get("ro.vold.switchablepair", switchable, "");
+
+        if (!(first = strtok(switchable, delim))) {
+            SLOGE("Mount switch requested, but no switchable mountpoints found");
+            swap = false;
+        } else if (!(second = strtok(NULL, delim))) {
+            SLOGE("Mount switch requested, but bad switchable mountpoints found");
+            swap = false;
+        }
+
+        if (swap) {
+            free(mMountpoint);
+            free(mFuseMountpoint);
+
+            if (!strcmp(mount,first)) {
+                mFuseMountpoint = strdup(second);
+                strcpy(label, second+lblidx);
+                snprintf(second, PATH_MAX, "%s/%s", Volume::MEDIA_DIR, label);
+                mMountpoint = strdup(second);
+            } else if (!strcmp(mount,second)) {
+                mFuseMountpoint = strdup(first);
+                strcpy(label, first+lblidx);
+                snprintf(first, PATH_MAX, "%s/%s", Volume::MEDIA_DIR, label);
+                mMountpoint = strdup(first);
+            }
+        }
+    }
 #endif
 
     setState(Volume::State_NoMedia);
diff --git a/DirectVolume.h b/DirectVolume.h
index 396ac91..8b6e9a8 100644
--- a/DirectVolume.h
+++ b/DirectVolume.h
@@ -31,8 +31,8 @@ class DirectVolume : public Volume {
 public:
     static const int MAX_PARTITIONS = VOLD_MAX_PARTITIONS;
 protected:
-    const char* mMountpoint;
-    const char* mFuseMountpoint;
+    char* mMountpoint;
+    char* mFuseMountpoint;
 
     PathCollection *mPaths;
     int            mDiskMajor;
-- 
1.8.1.2