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Merge "canned fs_config accepts multiple lines having the same path"

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Treehugger Robot 2021-12-14 19:00:28 +00:00 committed by Gerrit Code Review
parent f1e4354b5d 4bd3687422
commit 1d3b45e4fa
1 changed files with 20 additions and 11 deletions
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31
libcutils/canned_fs_config.cpp
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@ -21,7 +21,6 @@
#include <android-base/strings.h> #include <android-base/strings.h>
#include <errno.h> #include <errno.h>
#include <fnmatch.h>
#include <inttypes.h> #include <inttypes.h>
#include <limits.h> #include <limits.h>
#include <stdio.h> #include <stdio.h>
@ -67,10 +66,10 @@ int load_canned_fs_config(const char* fn) {
} }
// Historical: remove the leading '/' if exists. // Historical: remove the leading '/' if exists.
std::string path = tokens[0].front() == '/' ? std::string(tokens[0], 1) : tokens[0]; std::string path(tokens[0].front() == '/' ? std::string(tokens[0], 1) : tokens[0]);
Entry e{ Entry e{
.path = path, .path = std::move(path),
.uid = static_cast<unsigned int>(atoi(tokens[1].c_str())), .uid = static_cast<unsigned int>(atoi(tokens[1].c_str())),
.gid = static_cast<unsigned int>(atoi(tokens[2].c_str())), .gid = static_cast<unsigned int>(atoi(tokens[2].c_str())),
// mode is in octal // mode is in octal
@ -93,8 +92,15 @@ int load_canned_fs_config(const char* fn) {
canned_data.emplace_back(std::move(e)); canned_data.emplace_back(std::move(e));
} }
std::sort(canned_data.begin(), canned_data.end(), // Note: we used to sort the entries by path names. This was to improve the lookup performance
[](const Entry& a, const Entry& b) -> bool { return a.path < b.path; }); // by doing binary search. However, this is no longer the case. The lookup performance is not
// critical because this tool runs on the host, not on the device. Now, there can be multiple
// entries for the same path. Then the one that comes the last wins. This is to allow overriding
// platform provided fs_config with a user provided fs_config by appending the latter to the
// former.
//
// To implement the strategy, reverse the entries order, and search from the top.
std::reverse(canned_data.begin(), canned_data.end());
std::cout << "loaded " << canned_data.size() << " fs_config entries" << std::endl; std::cout << "loaded " << canned_data.size() << " fs_config entries" << std::endl;
return 0; return 0;
@ -105,12 +111,15 @@ void canned_fs_config(const char* path, [[maybe_unused]] int dir,
unsigned* mode, uint64_t* capabilities) { unsigned* mode, uint64_t* capabilities) {
if (path != nullptr && path[0] == '/') path++; // canned paths lack the leading '/' if (path != nullptr && path[0] == '/') path++; // canned paths lack the leading '/'
const Entry* found = static_cast<Entry*>( const Entry* found = nullptr;
bsearch(path, &canned_data[0], canned_data.size(), sizeof(Entry), // canned_data is already reversed. First match wins.
[](const void* a, const void* b) -> int { for (const auto& entry : canned_data) {
return strcmp(static_cast<const char*>(a), if (path == entry.path) {
static_cast<const Entry*>(b)->path.c_str()); found = &entry;
})); break;
}
continue;
}
if (found == nullptr) { if (found == nullptr) {
std::cerr << "failed to find " << path << " in canned fs_config" << std::endl; std::cerr << "failed to find " << path << " in canned fs_config" << std::endl;