Add ParseFstabFromString(), remove ReadFstabFromFp()
ReadFstabFromFp() have two callers right now, ReadFstabFromFile() and
ReadFstabFromDt(). ReadFstabFromFile() opens a FILE* and pass it to
ReadFstabFromFp(), and ReadFstabFromDt() wraps a std::string::c_str()
buffer in a FILE* adaptor with fmemopen().
There's no need for such adaptor, just change ReadFstabFromFp() to
accept std::string and we're good.
Bug: 204056804
Test: atest CtsFsMgrTestCases
Test: m libfstab_fuzzer
Change-Id: I71190c7356a354aa06d1be3fdc4ca76611b3896d
diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index 0b083e5..d53dc54 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -525,34 +525,23 @@
} // namespace
-bool ReadFstabFromFp(FILE* fstab_file, bool proc_mounts, Fstab* fstab_out) {
+bool ParseFstabFromString(const std::string& fstab_str, bool proc_mounts, Fstab* fstab_out) {
const int expected_fields = proc_mounts ? 4 : 5;
- ssize_t len;
- size_t alloc_len = 0;
- char *line = NULL;
- char* p;
+
Fstab fstab;
- while ((len = getline(&line, &alloc_len, fstab_file)) != -1) {
- /* if the last character is a newline, shorten the string by 1 byte */
- if (line[len - 1] == '\n') {
- line[len - 1] = '\0';
- }
-
- /* Skip any leading whitespace */
- p = line;
- while (isspace(*p)) {
- p++;
- }
- /* ignore comments or empty lines */
- if (*p == '#' || *p == '\0')
- continue;
-
+ for (const auto& line : android::base::Split(fstab_str, "\n")) {
auto fields = android::base::Tokenize(line, " \t");
+
+ // Ignore empty lines and comments.
+ if (fields.empty() || android::base::StartsWith(fields.front(), '#')) {
+ continue;
+ }
+
if (fields.size() < expected_fields) {
LERROR << "Error parsing fstab: expected " << expected_fields << " fields, got "
<< fields.size();
- goto err;
+ return false;
}
FstabEntry entry;
@@ -566,7 +555,7 @@
// For /proc/mounts, ignore everything after mnt_freq and mnt_passno
if (!proc_mounts && !ParseFsMgrFlags(std::move(*it++), &entry)) {
LERROR << "Error parsing fs_mgr_flags";
- goto err;
+ return false;
}
if (entry.fs_mgr_flags.logical) {
@@ -578,21 +567,17 @@
if (fstab.empty()) {
LERROR << "No entries found in fstab";
- goto err;
+ return false;
}
/* If an A/B partition, modify block device to be the real block device */
if (!fs_mgr_update_for_slotselect(&fstab)) {
LERROR << "Error updating for slotselect";
- goto err;
+ return false;
}
- free(line);
+
*fstab_out = std::move(fstab);
return true;
-
-err:
- free(line);
- return false;
}
void TransformFstabForDsu(Fstab* fstab, const std::string& dsu_slot,
@@ -691,16 +676,18 @@
}
bool ReadFstabFromFile(const std::string& path, Fstab* fstab_out) {
- auto fstab_file = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
- if (!fstab_file) {
- PERROR << __FUNCTION__ << "(): cannot open file: '" << path << "'";
+ const bool is_proc_mounts = (path == "/proc/mounts");
+ // /proc/mounts could be a symlink to /proc/self/mounts.
+ const bool follow_symlinks = is_proc_mounts;
+
+ std::string fstab_str;
+ if (!android::base::ReadFileToString(path, &fstab_str, follow_symlinks)) {
+ PERROR << __FUNCTION__ << "(): failed to read file: '" << path << "'";
return false;
}
- bool is_proc_mounts = path == "/proc/mounts";
-
Fstab fstab;
- if (!ReadFstabFromFp(fstab_file.get(), is_proc_mounts, &fstab)) {
+ if (!ParseFstabFromString(fstab_str, is_proc_mounts, &fstab)) {
LERROR << __FUNCTION__ << "(): failed to load fstab from : '" << path << "'";
return false;
}
@@ -747,15 +734,7 @@
return false;
}
- std::unique_ptr<FILE, decltype(&fclose)> fstab_file(
- fmemopen(static_cast<void*>(const_cast<char*>(fstab_buf.c_str())),
- fstab_buf.length(), "r"), fclose);
- if (!fstab_file) {
- if (verbose) PERROR << __FUNCTION__ << "(): failed to create a file stream for fstab dt";
- return false;
- }
-
- if (!ReadFstabFromFp(fstab_file.get(), false, fstab)) {
+ if (!ParseFstabFromString(fstab_buf, /* proc_mounts = */ false, fstab)) {
if (verbose) {
LERROR << __FUNCTION__ << "(): failed to load fstab from kernel:" << std::endl
<< fstab_buf;
diff --git a/fs_mgr/fuzz/fs_mgr_fstab_fuzzer.cpp b/fs_mgr/fuzz/fs_mgr_fstab_fuzzer.cpp
index 1fddbf8..6a8a191 100644
--- a/fs_mgr/fuzz/fs_mgr_fstab_fuzzer.cpp
+++ b/fs_mgr/fuzz/fs_mgr_fstab_fuzzer.cpp
@@ -19,12 +19,8 @@
#include <fstab/fstab.h>
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
- std::unique_ptr<FILE, decltype(&fclose)> fstab_file(
- fmemopen(static_cast<void*>(const_cast<uint8_t*>(data)), size, "r"), fclose);
- if (fstab_file == nullptr) {
- return 0;
- }
+ std::string make_fstab_str(reinterpret_cast<const char*>(data), size);
android::fs_mgr::Fstab fstab;
- android::fs_mgr::ReadFstabFromFp(fstab_file.get(), /* proc_mounts= */ false, &fstab);
+ android::fs_mgr::ParseFstabFromString(make_fstab_str, /* proc_mounts = */ false, &fstab);
return 0;
}
diff --git a/fs_mgr/include_fstab/fstab/fstab.h b/fs_mgr/include_fstab/fstab/fstab.h
index d9c326d..054300e 100644
--- a/fs_mgr/include_fstab/fstab/fstab.h
+++ b/fs_mgr/include_fstab/fstab/fstab.h
@@ -94,8 +94,8 @@
// Unless explicitly requested, a lookup on mount point should always return the 1st one.
using Fstab = std::vector<FstabEntry>;
-// Exported for testability. Regular users should use ReadFstabFromfile().
-bool ReadFstabFromFp(FILE* fstab_file, bool proc_mounts, Fstab* fstab_out);
+// Exported for testability. Regular users should use ReadFstabFromFile().
+bool ParseFstabFromString(const std::string& fstab_str, bool proc_mounts, Fstab* fstab_out);
bool ReadFstabFromFile(const std::string& path, Fstab* fstab);
bool ReadFstabFromDt(Fstab* fstab, bool verbose = true);