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Commit 20514c44 authored by Tom Cherry's avatar Tom Cherry
Browse files

Better logging in libprocessgroup and make resources clean up themselves 

Bug: 36661364
Bug: 36701253
Bug: 37540956

Test: Reboot bullhead
Test: Start and stop services
Change-Id: I97b6e17a7350850db733bee9fc83bdd296d88c61
parent 3d7ee068

libprocessgroup/include/processgroup/processgroup.h

+5 −0
Original line number Diff line number Diff line
@@ -22,8 +22,13 @@ 


__BEGIN_DECLS



// Return 0 and removes the cgroup if there are no longer any processes in it.

// Returns -1 in the case of an error occurring or if there are processes still running

// even after retrying for up to 200ms.

int killProcessGroup(uid_t uid, int initialPid, int signal);



// Returns the same as killProcessGroup(), however it does not retry, which means

// that it only returns 0 in the case that the cgroup exists and it contains no processes.

int killProcessGroupOnce(uid_t uid, int initialPid, int signal);



int createProcessGroup(uid_t uid, int initialPid);

libprocessgroup/processgroup.cpp

+98 −83
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <thread>



#include <android-base/logging.h>

#include <android-base/unique_fd.h>

#include <private/android_filesystem_config.h>



#include <processgroup/processgroup.h>
@@ -64,12 +65,27 @@ using namespace std::chrono_literals; 


std::once_flag init_path_flag;



struct ctx {

    bool initialized;

    int fd;

    char buf[128];

    char *buf_ptr;

    size_t buf_len;

class ProcessGroup {

  public:

    ProcessGroup() : buf_ptr_(buf_), buf_len_(0) {}



    bool Open(uid_t uid, int pid);



    // Return positive number and sets *pid = next pid in process cgroup on success

    // Returns 0 if there are no pids left in the process cgroup

    // Returns -errno if an error was encountered

    int GetOneAppProcess(pid_t* pid);



  private:

    // Returns positive number of bytes filled on success

    // Returns 0 if there was nothing to read

    // Returns -errno if an error was encountered

    int RefillBuffer();



    android::base::unique_fd fd_;

    char buf_[128];

    char* buf_ptr_;

    size_t buf_len_;

};



static const char* getCgroupRootPath() {
@@ -105,87 +121,67 @@ static int convertUidPidToPath(char *path, size_t size, uid_t uid, int pid) 
            pid);

}



static int initCtx(uid_t uid, int pid, struct ctx *ctx)

{

    int ret;

bool ProcessGroup::Open(uid_t uid, int pid) {

    char path[PROCESSGROUP_MAX_PATH_LEN] = {0};

    convertUidPidToPath(path, sizeof(path), uid, pid);

    strlcat(path, PROCESSGROUP_CGROUP_PROCS_FILE, sizeof(path));



    int fd = open(path, O_RDONLY);

    if (fd < 0) {

        ret = -errno;

        PLOG(WARNING) << "failed to open " << path;

        return ret;

    }

    if (fd < 0) return false;



    ctx->fd = fd;

    ctx->buf_ptr = ctx->buf;

    ctx->buf_len = 0;

    ctx->initialized = true;

    fd_.reset(fd);



    LOG(VERBOSE) << "Initialized context for " << path;



    return 0;

    return true;

}



static int refillBuffer(struct ctx *ctx)

{

    memmove(ctx->buf, ctx->buf_ptr, ctx->buf_len);

    ctx->buf_ptr = ctx->buf;

int ProcessGroup::RefillBuffer() {

    memmove(buf_, buf_ptr_, buf_len_);

    buf_ptr_ = buf_;



    ssize_t ret = read(ctx->fd, ctx->buf_ptr + ctx->buf_len,

                sizeof(ctx->buf) - ctx->buf_len - 1);

    ssize_t ret = read(fd_, buf_ptr_ + buf_len_, sizeof(buf_) - buf_len_ - 1);

    if (ret < 0) {

        return -errno;

    } else if (ret == 0) {

        return 0;

    }



    ctx->buf_len += ret;

    ctx->buf[ctx->buf_len] = 0;

    LOG(VERBOSE) << "Read " << ret << " to buffer: " << ctx->buf;

    buf_len_ += ret;

    buf_[buf_len_] = 0;

    LOG(VERBOSE) << "Read " << ret << " to buffer: " << buf_;



    assert(ctx->buf_len <= sizeof(ctx->buf));

    assert(buf_len_ <= sizeof(buf_));



    return ret;

}



static pid_t getOneAppProcess(uid_t uid, int appProcessPid, struct ctx *ctx)

{

    if (!ctx->initialized) {

        int ret = initCtx(uid, appProcessPid, ctx);

        if (ret < 0) {

            return ret;

        }

    }

int ProcessGroup::GetOneAppProcess(pid_t* out_pid) {

    *out_pid = 0;



    char* eptr;

    while ((eptr = (char *)memchr(ctx->buf_ptr, '\n', ctx->buf_len)) == NULL) {

        int ret = refillBuffer(ctx);

        if (ret == 0) {

            return -ERANGE;

        }

        if (ret < 0) {

            return ret;

        }

    while ((eptr = static_cast<char*>(memchr(buf_ptr_, '\n', buf_len_))) == nullptr) {

        int ret = RefillBuffer();

        if (ret <= 0) return ret;

    }



    *eptr = '\0';

    char *pid_eptr = NULL;

    char* pid_eptr = nullptr;

    errno = 0;

    long pid = strtol(ctx->buf_ptr, &pid_eptr, 10);

    long pid = strtol(buf_ptr_, &pid_eptr, 10);

    if (errno != 0) {

        return -errno;

    }

    if (pid_eptr != eptr) {

        return -EINVAL;

        errno = EINVAL;

        return -errno;

    }



    ctx->buf_len -= (eptr - ctx->buf_ptr) + 1;

    ctx->buf_ptr = eptr + 1;

    buf_len_ -= (eptr - buf_ptr_) + 1;

    buf_ptr_ = eptr + 1;



    return (pid_t)pid;

    *out_pid = static_cast<pid_t>(pid);

    return 1;

}



static int removeProcessGroup(uid_t uid, int pid)
@@ -219,8 +215,8 @@ static void removeUidProcessGroups(const char *uid_path) 
            }



            snprintf(path, sizeof(path), "%s/%s", uid_path, dir->d_name);

            LOG(VERBOSE) << "removing " << path;

            if (rmdir(path) == -1) PLOG(WARNING) << "failed to remove " << path;

            LOG(VERBOSE) << "Removing " << path;

            if (rmdir(path) == -1) PLOG(WARNING) << "Failed to remove " << path;

        }

    }

}
@@ -231,7 +227,7 @@ void removeAllProcessGroups() 
    const char* cgroup_root_path = getCgroupRootPath();

    std::unique_ptr<DIR, decltype(&closedir)> root(opendir(cgroup_root_path), closedir);

    if (root == NULL) {

        PLOG(ERROR) << "failed to open " << cgroup_root_path;

        PLOG(ERROR) << "Failed to open " << cgroup_root_path;

    } else {

        dirent* dir;

        while ((dir = readdir(root.get())) != nullptr) {
@@ -246,20 +242,26 @@ void removeAllProcessGroups() 


            snprintf(path, sizeof(path), "%s/%s", cgroup_root_path, dir->d_name);

            removeUidProcessGroups(path);

            LOG(VERBOSE) << "removing " << path;

            if (rmdir(path) == -1) PLOG(WARNING) << "failed to remove " << path;

            LOG(VERBOSE) << "Removing " << path;

            if (rmdir(path) == -1) PLOG(WARNING) << "Failed to remove " << path;

        }

    }

}



// Returns number of processes killed on success

// Returns 0 if there are no processes in the process cgroup left to kill

// Returns -errno on error

static int doKillProcessGroupOnce(uid_t uid, int initialPid, int signal) {

    int processes = 0;

    struct ctx ctx;

    pid_t pid;



    ctx.initialized = false;

    ProcessGroup process_group;

    if (!process_group.Open(uid, initialPid)) {

        PLOG(WARNING) << "Failed to open process cgroup uid " << uid << " pid " << initialPid;

        return -errno;

    }



    while ((pid = getOneAppProcess(uid, initialPid, &ctx)) >= 0) {

    int ret;

    pid_t pid;

    int processes = 0;

    while ((ret = process_group.GetOneAppProcess(&pid)) > 0 && pid >= 0) {

        processes++;

        if (pid == 0) {

            // Should never happen...  but if it does, trying to kill this
@@ -267,55 +269,68 @@ static int doKillProcessGroupOnce(uid_t uid, int initialPid, int signal) { 
            LOG(WARNING) << "Yikes, we've been told to kill pid 0!  How about we don't do that?";

            continue;

        }

        LOG(VERBOSE) << "Killing pid " << pid << " in uid " << uid

                     << " as part of process group " << initialPid;

        LOG(VERBOSE) << "Killing pid " << pid << " in uid " << uid << " as part of process cgroup "

                     << initialPid;

        if (kill(pid, signal) == -1) {

            PLOG(WARNING) << "kill(" << pid << ", " << signal << ") failed";

        }

    }



    if (ctx.initialized) {

        close(ctx.fd);

    return ret >= 0 ? processes : ret;

}



    return processes;

}



static int killProcessGroup(uid_t uid, int initialPid, int signal, int retry) {

static int killProcessGroup(uid_t uid, int initialPid, int signal, int retries) {

    std::chrono::steady_clock::time_point start = std::chrono::steady_clock::now();



    int retry = retries;

    int processes;

    while ((processes = doKillProcessGroupOnce(uid, initialPid, signal)) > 0) {

        LOG(VERBOSE) << "killed " << processes << " processes for processgroup " << initialPid;

        LOG(VERBOSE) << "Killed " << processes << " processes for processgroup " << initialPid;

        if (retry > 0) {

            std::this_thread::sleep_for(5ms);

            --retry;

        } else {

            LOG(ERROR) << "failed to kill " << processes << " processes for processgroup "

                       << initialPid;

            break;

        }

    }



    std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();

    if (processes < 0) {

        PLOG(ERROR) << "Error encountered killing process cgroup uid " << uid << " pid "

                    << initialPid;

        return -1;

    }



    std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();

    auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();

    LOG(VERBOSE) << "Killed process group uid " << uid << " pid " << initialPid << " in "

                 << static_cast<int>(ms) << "ms, " << processes << " procs remain";



    // We only calculate the number of 'processes' when killing the processes.

    // In the retries == 0 case, we only kill the processes once and therefore

    // will not have waited then recalculated how many processes are remaining

    // after the first signals have been sent.

    // Logging anything regarding the number of 'processes' here does not make sense.



    if (processes == 0) {

        if (retries > 0) {

            LOG(INFO) << "Successfully killed process cgroup uid " << uid << " pid " << initialPid

                      << " in " << static_cast<int>(ms) << "ms";

        }

        return removeProcessGroup(uid, initialPid);

    } else {

        if (retries > 0) {

            LOG(ERROR) << "Failed to kill process cgroup uid " << uid << " pid " << initialPid

                       << " in " << static_cast<int>(ms) << "ms, " << processes

                       << " processes remain";

        }

        return -1;

    }

}



int killProcessGroup(uid_t uid, int initialPid, int signal) {

    return killProcessGroup(uid, initialPid, signal, 40 /*maxRetry*/);

    return killProcessGroup(uid, initialPid, signal, 40 /*retries*/);

}



int killProcessGroupOnce(uid_t uid, int initialPid, int signal) {

    return killProcessGroup(uid, initialPid, signal, 0 /*maxRetry*/);

    return killProcessGroup(uid, initialPid, signal, 0 /*retries*/);

}



static bool mkdirAndChown(const char *path, mode_t mode, uid_t uid, gid_t gid)
@@ -341,14 +356,14 @@ int createProcessGroup(uid_t uid, int initialPid) 
    convertUidToPath(path, sizeof(path), uid);



    if (!mkdirAndChown(path, 0750, AID_SYSTEM, AID_SYSTEM)) {

        PLOG(ERROR) << "failed to make and chown " << path;

        PLOG(ERROR) << "Failed to make and chown " << path;

        return -errno;

    }



    convertUidPidToPath(path, sizeof(path), uid, initialPid);



    if (!mkdirAndChown(path, 0750, AID_SYSTEM, AID_SYSTEM)) {

        PLOG(ERROR) << "failed to make and chown " << path;

        PLOG(ERROR) << "Failed to make and chown " << path;

        return -errno;

    }
@@ -357,7 +372,7 @@ int createProcessGroup(uid_t uid, int initialPid) 
    int fd = open(path, O_WRONLY);

    if (fd == -1) {

        int ret = -errno;

        PLOG(ERROR) << "failed to open " << path;

        PLOG(ERROR) << "Failed to open " << path;

        return ret;

    }
@@ -367,7 +382,7 @@ int createProcessGroup(uid_t uid, int initialPid) 
    int ret = 0;

    if (write(fd, pid, len) < 0) {

        ret = -errno;

        PLOG(ERROR) << "failed to write '" << pid << "' to " << path;

        PLOG(ERROR) << "Failed to write '" << pid << "' to " << path;

    }



    close(fd);