platform_system_core/libprocinfo/process.cpp
Josh Gao 911d729c8a libprocinfo: introduce.
Add a new library for parsing /proc files. Start with helpers for
parsing /proc/<pid>/status and /proc/<pid>/task.

Bug: http://b/30705528
Test: libprocinfo_test32/64 on host/bullhead
Change-Id: I5757514c0aede8a9d75834b55aae42a5cf762b95
2016-11-14 13:42:18 -08:00

109 lines
3 KiB
C++

/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <procinfo/process.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <string>
#include <android-base/unique_fd.h>
using android::base::unique_fd;
namespace android {
namespace procinfo {
bool GetProcessInfo(pid_t tid, ProcessInfo* process_info) {
char path[PATH_MAX];
snprintf(path, sizeof(path), "/proc/%d", tid);
unique_fd dirfd(open(path, O_DIRECTORY | O_RDONLY));
if (dirfd == -1) {
PLOG(ERROR) << "failed to open " << path;
return false;
}
return GetProcessInfoFromProcPidFd(dirfd.get(), process_info);
}
bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info) {
int status_fd = openat(fd, "status", O_RDONLY | O_CLOEXEC);
if (status_fd == -1) {
PLOG(ERROR) << "failed to open status fd in GetProcessInfoFromProcPidFd";
return false;
}
std::unique_ptr<FILE, decltype(&fclose)> fp(fdopen(status_fd, "r"), fclose);
if (!fp) {
PLOG(ERROR) << "failed to open status file in GetProcessInfoFromProcPidFd";
close(status_fd);
return false;
}
int field_bitmap = 0;
static constexpr int finished_bitmap = 127;
char* line = nullptr;
size_t len = 0;
while (getline(&line, &len, fp.get()) != -1 && field_bitmap != finished_bitmap) {
char* tab = strchr(line, '\t');
if (tab == nullptr) {
continue;
}
size_t header_len = tab - line;
std::string header = std::string(line, header_len);
if (header == "Name:") {
std::string name = line + header_len + 1;
// line includes the trailing newline.
name.pop_back();
process_info->name = std::move(name);
field_bitmap |= 1;
} else if (header == "Pid:") {
process_info->tid = atoi(tab + 1);
field_bitmap |= 2;
} else if (header == "Tgid:") {
process_info->pid = atoi(tab + 1);
field_bitmap |= 4;
} else if (header == "PPid:") {
process_info->ppid = atoi(tab + 1);
field_bitmap |= 8;
} else if (header == "TracerPid:") {
process_info->tracer = atoi(tab + 1);
field_bitmap |= 16;
} else if (header == "Uid:") {
process_info->uid = atoi(tab + 1);
field_bitmap |= 32;
} else if (header == "Gid:") {
process_info->gid = atoi(tab + 1);
field_bitmap |= 64;
}
}
free(line);
return field_bitmap == finished_bitmap;
}
} /* namespace procinfo */
} /* namespace android */