Implement sparse system images (fix #299) (#303)

* Packaged libsparse

libsparse from the Android project provides multiple tools like img2simg
and simg2img.
These are used to split a large image for the system partition into
separate smaller chunks with sparse headers

This is required for several devices (at least bullhead, fp2 and titan)
because it fixes the "Invalid sparse file format at header magi" error

https://github.com/postmarketOS/pmbootstrap/issues/299

* Added new variable deviceinfo_flash_sparse (fixes #299)

Right after the system image is generated, pmbootstrap checks this
variable. In case it is true, run img2simg on it

* motorola-titan: enable deviceinfo_flash_sparse

* libsparse: use source from github: anestisb/android-simg2img

It is not that easy to use the upstream archive because everytime
you download it, the files have the current date as creation date
and that makes the file have a different checksum every download
https://github.com/postmarketOS/pmbootstrap/pull/303#issuecomment-319017197

aports/device/device-motorola-titan/APKBUILD

 pkgname=device-motorola-titan
 pkgver=1
-pkgrel=9
+pkgrel=10
 pkgdesc="Motorola Moto G 2014"
 url="https://github.com/postmarketOS"
 arch="noarch"
@@ -27,7 +27,7 @@ package() {
 		"$pkgdir"/etc/profile.d/00-$pkgname.sh
 }
 
-sha512sums="e090f4cb7ef2641c6c89ba4ed4f9d4be95eee716c7a3e8690f069bdbe2a88155fd19b63e849cebc501846ef6f58d7cfa63d331c43b4aded964f1261f6083cd95  deviceinfo
+sha512sums="09abd5f4681d9479650cfa64fcbc58528827017757539c3faf142ca92e8537691f9fb88f5d84ece086af7f23be2ac03e196f49ae708a832f1331f40cc96bab29  deviceinfo
 f37e6324abf0b0fc8a3d360d6d11bb0648090a438a55ca7f04a9d494719e687ce445ae107ace642edf293afb6ca82615bcb5d0ddb6c46c1a7f8ee3c213b7c5c4  90-android-touch-dev.rules
 8590967fa10388a890fdfafdb1070b9ab22dc89e06a3a8834806c772191e3b67de7b914b0d68e5ddf581cee715cb90f3f24abcb8762c415ff328c6da23e55d52  initfs-hook.sh
 2f7cdf558a6bff56fd343d29a1ca6c27e75715bedfad661700dfcfb01acd1bdfcfecdfccf619f1e56c1e6331be146f8882a14d3a2cd33830e9d00bb6118971a3  profile.sh"

aports/device/device-motorola-titan/deviceinfo

@@ -26,6 +26,7 @@ deviceinfo_flash_offset_tags="0x00000100"
 deviceinfo_flash_pagesize="2048"
 deviceinfo_kernel_cmdline="androidboot.bootdevice=msm_sdcc.1 androidboot.hardware=qcom vmalloc=400M utags.blkdev=/dev/block/platform/msm_sdcc.1/by-name/utags buildvariant=userdebug"
 deviceinfo_generate_bootimg="true"
+deviceinfo_flash_sparse="true"
 
 # Weston red screen workaround (see issue #54)
 deviceinfo_weston_pixman_type="2"

aports/main/libsparse/APKBUILD

+pkgname=libsparse
+pkgver="1.0.0"
+pkgrel=1
+pkgdesc="Android Sparse library"
+url="https://android.googlesource.com"
+arch="all"
+license="APACHE2"
+depends="python3"
+makedepends="zlib-dev"
+subpackages=""
+source="$pkgname-$pkgver.tar.gz::https://github.com/anestisb/android-simg2img/archive/${pkgver}.tar.gz"
+options="!check"
+
+build() {
+    cd "$srcdir"/android-simg2img-"$pkgver"
+    sed -i -e 's./usr/bin/env python./usr/bin/env python3.' simg_dump.py
+    make sparse
+    make
+}
+
+package() {
+    cd "$srcdir"/android-simg2img-"$pkgver"
+
+    for i in append2simg img2simg simg2img simg2simg simg_dump.py; do
+        install -D -m755 "$i" "$pkgdir"/usr/bin/"$i" || return 1
+    done
+}
+
+sha512sums="e43ad20760243ee88441d3016dea776224373377a5f0d367fca2da8b44f4dcc17c779ad2aed79b2f04861f4e56ec3472c0f2dc5c8fc12dc87f57d608cfc8faf6  libsparse-1.0.0.tar.gz"

pmb/config/__init__.py

@@ -184,6 +184,7 @@ deviceinfo_attributes = [
     "flash_offset_second",
     "flash_offset_tags",
     "flash_pagesize",
+    "flash_sparse",
     "kernel_cmdline",
 
     # weston

pmb/install/install.py

@@ -127,6 +127,17 @@ def install(args):
     fix_mount_folders(args)
     pmb.chroot.shutdown(args, True)
 
+    # Convert system image to sparse using img2simg
+    if args.deviceinfo["flash_sparse"] == "true":
+        logging.info("(native) make sparse system image")
+        pmb.chroot.apk.install(args, ["libsparse"])
+        sys_image = args.device + ".img"
+        sys_image_sparse = args.device + "-sparse.img"
+        pmb.chroot.user(args, ["img2simg", sys_image, sys_image_sparse],
+                        working_dir="/home/user/rootfs/")
+        pmb.chroot.user(args, ["mv", "-f", sys_image_sparse, sys_image],
+                        working_dir="/home/user/rootfs/")
+
     # Kernel flash information
     logging.info("*** (5/5) FLASHING TO DEVICE ***")
     logging.info("Run the following to flash your installation to the"