process_name.c revision 14d0c6c7c0e9abd39e4b4d0a384d12de5ecbdbfc
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stdlib.h>
18#include <string.h>
19#include <cutils/process_name.h>
20#include <cutils/properties.h>
21#include <unistd.h>
22#include <sys/types.h>
23#include <sys/stat.h>
24#include <fcntl.h>
25
26#if defined(HAVE_PRCTL)
27#include <sys/prctl.h>
28#endif
29
30#define PROCESS_NAME_DEVICE "/sys/qemu_trace/process_name"
31
32static const char* process_name = "unknown";
33static int running_in_emulator = -1;
34
35void set_process_name(const char* new_name) {
36    char  propBuf[PROPERTY_VALUE_MAX];
37
38    if (new_name == NULL) {
39        return;
40    }
41
42    // We never free the old name. Someone else could be using it.
43    int len = strlen(new_name);
44    char* copy = (char*) malloc(len + 1);
45    strcpy(copy, new_name);
46    process_name = (const char*) copy;
47
48#if defined(HAVE_PRCTL)
49    if (len < 16) {
50        prctl(PR_SET_NAME, (unsigned long) new_name, 0, 0, 0);
51    } else {
52        prctl(PR_SET_NAME, (unsigned long) new_name + len - 15, 0, 0, 0);
53    }
54#endif
55
56    // If we know we are not running in the emulator, then return.
57    if (running_in_emulator == 0) {
58        return;
59    }
60
61    // If the "running_in_emulator" variable has not been initialized,
62    // then do it now.
63    if (running_in_emulator == -1) {
64        property_get("ro.kernel.qemu", propBuf, "");
65        if (propBuf[0] == '1') {
66            running_in_emulator = 1;
67        } else {
68            running_in_emulator = 0;
69            return;
70        }
71    }
72
73    // If the emulator was started with the "-trace file" command line option
74    // then we want to record the process name in the trace even if we are
75    // not currently tracing instructions (so that we will know the process
76    // name when we do start tracing instructions).  We do not need to execute
77    // this code if we are just running in the emulator without the "-trace"
78    // command line option, but we don't know that here and this function
79    // isn't called frequently enough to bother optimizing that case.
80    int fd = open(PROCESS_NAME_DEVICE, O_RDWR);
81    if (fd < 0)
82        return;
83    write(fd, process_name, strlen(process_name) + 1);
84    close(fd);
85}
86
87const char* get_process_name(void) {
88    return process_name;
89}
90