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Commit d8602917 authored by Jiyong Park's avatar Jiyong Park
Browse files

canned_fs_config.cpp is written in C++ 

This re-writes the file using C++, in preparation for a follow-up
change.

Also, removes debugging code that is no longer used.

Bug: 209971551
Test: m
Change-Id: I82a793cfdd7abd10024e304df7bd4ae323ffeabf
parent 46de7add

libcutils/Android.bp

+2 −1
Original line number Diff line number Diff line
@@ -156,7 +156,6 @@ cc_library { 
    },

    srcs: [

        "config_utils.cpp",

        "canned_fs_config.cpp",

        "iosched_policy.cpp",

        "load_file.cpp",

        "native_handle.cpp",
@@ -173,6 +172,7 @@ cc_library { 
        not_windows: {

            srcs: libcutils_nonwindows_sources + [

                "ashmem-host.cpp",

                "canned_fs_config.cpp",

                "fs_config.cpp",

                "trace-host.cpp",

            ],
@@ -193,6 +193,7 @@ cc_library { 
            srcs: libcutils_nonwindows_sources + [

                "android_reboot.cpp",

                "ashmem-dev.cpp",

                "canned_fs_config.cpp",

                "fs_config.cpp",

                "klog.cpp",

                "partition_utils.cpp",

libcutils/canned_fs_config.cpp

+74 −78
Original line number Diff line number Diff line
@@ -18,111 +18,107 @@ 
#include <private/canned_fs_config.h>

#include <private/fs_config.h>



#include <android-base/strings.h>



#include <errno.h>

#include <fnmatch.h>

#include <inttypes.h>

#include <limits.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>



typedef struct {

    const char* path;

#include <algorithm>

#include <fstream>

#include <iostream>

#include <string>

#include <vector>



using android::base::ConsumePrefix;

using android::base::StartsWith;

using android::base::Tokenize;



struct Entry {

    std::string path;

    unsigned uid;

    unsigned gid;

    unsigned mode;

    uint64_t capabilities;

} Path;

};



static Path* canned_data = NULL;

static int canned_alloc = 0;

static int canned_used = 0;



static int path_compare(const void* a, const void* b) {

    return strcmp(((Path*)a)->path, ((Path*)b)->path);

}

static std::vector<Entry> canned_data;



int load_canned_fs_config(const char* fn) {

    char buf[PATH_MAX + 200];

    FILE* f;

    std::ifstream input(fn);

    for (std::string line; std::getline(input, line);) {

        // Historical: the root dir can be represented as a space character.

        // e.g. " 1000 1000 0755" is parsed as

        // path = " ", uid = 1000, gid = 1000, mode = 0755.

        // But at the same time, we also have accepted

        // "/ 1000 1000 0755".

        if (StartsWith(line, " ")) {

            line.insert(line.begin(), '/');

        }



    f = fopen(fn, "r");

    if (f == NULL) {

        fprintf(stderr, "failed to open %s: %s\n", fn, strerror(errno));

        std::vector<std::string> tokens = Tokenize(line, " ");

        if (tokens.size() < 4) {

            std::cerr << "Ill-formed line: " << line << " in " << fn << std::endl;

            return -1;

        }



    while (fgets(buf, sizeof(buf), f)) {

        Path* p;

        char* token;

        char* line = buf;

        bool rootdir;



        while (canned_used >= canned_alloc) {

            canned_alloc = (canned_alloc+1) * 2;

            canned_data = (Path*) realloc(canned_data, canned_alloc * sizeof(Path));

        }

        p = canned_data + canned_used;

        if (line[0] == '/') line++;

        rootdir = line[0] == ' ';

        p->path = strdup(rootdir ? "" : strtok(line, " "));

        p->uid = atoi(strtok(rootdir ? line : NULL, " "));

        p->gid = atoi(strtok(NULL, " "));

        p->mode = strtol(strtok(NULL, " "), NULL, 8);   // mode is in octal

        p->capabilities = 0;



        do {

            token = strtok(NULL, " ");

            if (token && strncmp(token, "capabilities=", 13) == 0) {

                p->capabilities = strtoll(token+13, NULL, 0);

        // Historical: remove the leading '/' if exists.

        std::string path = tokens[0].front() == '/' ? std::string(tokens[0], 1) : tokens[0];



        Entry e{

                .path = path,

                .uid = static_cast<unsigned int>(atoi(tokens[1].c_str())),

                .gid = static_cast<unsigned int>(atoi(tokens[2].c_str())),

                // mode is in octal

                .mode = static_cast<unsigned int>(strtol(tokens[3].c_str(), nullptr, 8)),

                .capabilities = 0,

        };



        for (size_t i = 4; i < tokens.size(); i++) {

            std::string_view sv = tokens[i];

            if (ConsumePrefix(&sv, "capabilities=")) {

                e.capabilities = strtoll(std::string(sv).c_str(), nullptr, 0);

                break;

            }

        } while (token);



        canned_used++;

            // Historical: there can be tokens like "selabel=..." here. They have been ignored.

            // It's not an error because selabels are applied separately in e2fsdroid using the

            // file_contexts files set via -S option.

            std::cerr << "info: ignored token \"" << sv << "\" in " << fn << std::endl;

        }



    fclose(f);

        canned_data.emplace_back(std::move(e));

    }



    qsort(canned_data, canned_used, sizeof(Path), path_compare);

    printf("loaded %d fs_config entries\n", canned_used);

    std::sort(canned_data.begin(), canned_data.end(),

              [](const Entry& a, const Entry& b) -> bool { return a.path < b.path; });



    std::cout << "loaded " << canned_data.size() << " fs_config entries" << std::endl;

    return 0;

}



static const int kDebugCannedFsConfig = 0;

void canned_fs_config(const char* path, [[maybe_unused]] int dir,

                      [[maybe_unused]] const char* target_out_path, unsigned* uid, unsigned* gid,

                      unsigned* mode, uint64_t* capabilities) {

    if (path != nullptr && path[0] == '/') path++;  // canned paths lack the leading '/'



void canned_fs_config(const char* path, int dir, const char* target_out_path,

                      unsigned* uid, unsigned* gid, unsigned* mode, uint64_t* capabilities) {

    Path key, *p;

    const Entry* found = static_cast<Entry*>(

            bsearch(path, &canned_data[0], canned_data.size(), sizeof(Entry),

                    [](const void* a, const void* b) -> int {

                        return strcmp(static_cast<const char*>(a),

                                      static_cast<const Entry*>(b)->path.c_str());

                    }));



    key.path = path;

    if (path[0] == '/') key.path++; // canned paths lack the leading '/'

    p = (Path*) bsearch(&key, canned_data, canned_used, sizeof(Path), path_compare);

    if (p == NULL) {

        fprintf(stderr, "failed to find [%s] in canned fs_config\n", path);

    if (found == nullptr) {

        std::cerr << "failed to find " << path << " in canned fs_config" << std::endl;

        exit(1);

    }

    *uid = p->uid;

    *gid = p->gid;

    *mode = p->mode;

    *capabilities = p->capabilities;



    if (kDebugCannedFsConfig) {

        // for debugging, run the built-in fs_config and compare the results.



        unsigned c_uid, c_gid, c_mode;

        uint64_t c_capabilities;



        fs_config(path, dir, target_out_path, &c_uid, &c_gid, &c_mode, &c_capabilities);



        if (c_uid != *uid) printf("%s uid %d %d\n", path, *uid, c_uid);

        if (c_gid != *gid) printf("%s gid %d %d\n", path, *gid, c_gid);

        if (c_mode != *mode) printf("%s mode 0%o 0%o\n", path, *mode, c_mode);

        if (c_capabilities != *capabilities) {

            printf("%s capabilities %" PRIx64 " %" PRIx64 "\n",

                path,

                *capabilities,

                c_capabilities);

        }

    }



    *uid = found->uid;

    *gid = found->gid;

    *mode = found->mode;

    *capabilities = found->capabilities;

}