fs_mgr: refactor: consolidate device tree file reading in one place
If Device tree values are read for comparison, they produce false
negatives with std::strings due to trailing '\0'. This change
consolidates the triming of trailing null into a single helper function
to be used everywhere fs_mgr reads DT values for comparison or other
reasons where it wishes to have the trailing null trimmed.
b/27805372
Test: Boot sailfish w/ early mount /vendor
Change-Id: If71efc830dc440323df764c7461867e71ed6515b
Signed-off-by: Sandeep Patil <sspatil@google.com>
diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index e35eaa4..5b0243d 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -135,6 +135,24 @@
return size;
}
+/* fills 'dt_value' with the underlying device tree value string without
+ * the trailing '\0'. Returns true if 'dt_value' has a valid string, 'false'
+ * otherwise.
+ */
+static bool read_dt_file(const std::string& file_name, std::string* dt_value)
+{
+ if (android::base::ReadFileToString(file_name, dt_value)) {
+ if (!dt_value->empty()) {
+ // trim the trailing '\0' out, otherwise the comparison
+ // will produce false-negatives.
+ dt_value->resize(dt_value->size() - 1);
+ return true;
+ }
+ }
+
+ return false;
+}
+
static int parse_flags(char *flags, struct flag_list *fl,
struct fs_mgr_flag_values *flag_vals,
char *fs_options, int fs_options_len)
@@ -298,11 +316,7 @@
static bool is_dt_fstab_compatible() {
std::string dt_value;
std::string file_name = kAndroidDtDir + "/fstab/compatible";
-
- if (android::base::ReadFileToString(file_name, &dt_value)) {
- // trim the trailing '\0' out, otherwise the comparison
- // will produce false-negatives.
- dt_value.resize(dt_value.size() - 1);
+ if (read_dt_file(file_name, &dt_value)) {
if (dt_value == "android,fstab") {
return true;
}
@@ -339,41 +353,36 @@
std::string file_name;
std::string value;
file_name = android::base::StringPrintf("%s/%s/dev", fstabdir_name.c_str(), dp->d_name);
- if (!android::base::ReadFileToString(file_name, &value)) {
+ if (!read_dt_file(file_name, &value)) {
LERROR << "dt_fstab: Failed to find device for partition " << dp->d_name;
fstab.clear();
break;
}
- // trim the terminating '\0' out
- value.resize(value.size() - 1);
fstab_entry.push_back(value);
fstab_entry.push_back(android::base::StringPrintf("/%s", dp->d_name));
file_name = android::base::StringPrintf("%s/%s/type", fstabdir_name.c_str(), dp->d_name);
- if (!android::base::ReadFileToString(file_name, &value)) {
+ if (!read_dt_file(file_name, &value)) {
LERROR << "dt_fstab: Failed to find type for partition " << dp->d_name;
fstab.clear();
break;
}
- value.resize(value.size() - 1);
fstab_entry.push_back(value);
file_name = android::base::StringPrintf("%s/%s/mnt_flags", fstabdir_name.c_str(), dp->d_name);
- if (!android::base::ReadFileToString(file_name, &value)) {
+ if (!read_dt_file(file_name, &value)) {
LERROR << "dt_fstab: Failed to find type for partition " << dp->d_name;
fstab.clear();
break;
}
- value.resize(value.size() - 1);
fstab_entry.push_back(value);
file_name = android::base::StringPrintf("%s/%s/fsmgr_flags", fstabdir_name.c_str(), dp->d_name);
- if (!android::base::ReadFileToString(file_name, &value)) {
+ if (!read_dt_file(file_name, &value)) {
LERROR << "dt_fstab: Failed to find type for partition " << dp->d_name;
fstab.clear();
break;
}
- value.resize(value.size() - 1);
fstab_entry.push_back(value);
fstab += android::base::Join(fstab_entry, " ");
@@ -386,14 +395,9 @@
bool is_dt_compatible() {
std::string file_name = kAndroidDtDir + "/compatible";
std::string dt_value;
- if (android::base::ReadFileToString(file_name, &dt_value)) {
- if (!dt_value.empty()) {
- // trim the trailing '\0' out, otherwise the comparison
- // will produce false-negatives.
- dt_value.resize(dt_value.size() - 1);
- if (dt_value == "android,firmware") {
- return true;
- }
+ if (read_dt_file(file_name, &dt_value)) {
+ if (dt_value == "android,firmware") {
+ return true;
}
}