fs_mgr: Look for fstab file in /system/etc
Look for the fstab file in /system/etc as an alternative to /, in order
to allow fstab files to be installed using the "prebuilt_etc" Soong
module.
This new path is meant to be used by the vendor ramdisk only. As before,
fstabs should *not* be placed in /system/etc on the system partition.
In more detail: sometimes, multiple nearly-identical fstabs need to be
installed to a device, with the correct one being selected at boot time
(b/191417025 as well as other cases that partners have run into). To
avoid error-prone duplication of configuration files, these fstabs
should be generated from a template by the build system instead of being
duplicated in the source tree. But if this is done, the usual way of
installing fstabs (PRODUCT_COPY_FILES) can't be used; they need to be
made into real build system modules instead.
Currently, the "prebuilt_etc" Soong module can't correctly install the
vendor_ramdisk copy of the fstab(s), since it will install it into the
/system/etc directory whereas Android currently requires that the
vendor_ramdisk copy of the fstab(s) be placed in the root directory.
Earlier I proposed adding a "prebuilt_fstab" module to handle this quirk
(https://r.android.com/1744033). However, it was requested to instead
always look for the fstabs in /etc too, in order to allow "prebuilt_etc"
to be used and because /etc is the appropriate place for this file.
This change implements that suggestion (but actually using /system/etc,
since that is where "prebuilt_etc" actually installs it).
Bug: 191417025
Test: Tested that a device boots both with this, both before and after
http://ag/15075136 which uses the new location.
Change-Id: Id083070e51ae85959167e4615cd96b31a0b1bd6a
diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index d0c89b9..f5ab557 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -413,17 +413,24 @@
return fstab_result;
}
-// Identify path to fstab file. Lookup is based on pattern
-// fstab.<fstab_suffix>, fstab.<hardware>, fstab.<hardware.platform> in
-// folders /odm/etc, vendor/etc, or /.
+// Return the path to the fstab file. There may be multiple fstab files; the
+// one that is returned will be the first that exists of fstab.<fstab_suffix>,
+// fstab.<hardware>, and fstab.<hardware.platform>. The fstab is searched for
+// in /odm/etc/ and /vendor/etc/, as well as in the locations where it may be in
+// the first stage ramdisk during early boot. Previously, the first stage
+// ramdisk's copy of the fstab had to be located in the root directory, but now
+// the system/etc directory is supported too and is the preferred location.
std::string GetFstabPath() {
for (const char* prop : {"fstab_suffix", "hardware", "hardware.platform"}) {
std::string suffix;
if (!fs_mgr_get_boot_config(prop, &suffix)) continue;
- for (const char* prefix :
- {"/odm/etc/fstab.", "/vendor/etc/fstab.", "/fstab.", "/first_stage_ramdisk/fstab."}) {
+ for (const char* prefix : {// late-boot/post-boot locations
+ "/odm/etc/fstab.", "/vendor/etc/fstab.",
+ // early boot locations
+ "/system/etc/fstab.", "/first_stage_ramdisk/system/etc/fstab.",
+ "/fstab.", "/first_stage_ramdisk/fstab."}) {
std::string fstab_path = prefix + suffix;
if (access(fstab_path.c_str(), F_OK) == 0) {
return fstab_path;