process_name.c revision f6eba8fac812c70087af225f207f2d924f6e1ffa 
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 <string.h>
18#include <cutils/process_name.h>
19#include <cutils/properties.h>
20#include <unistd.h>
21#include <sys/types.h>
22#include <sys/stat.h>
23#include <fcntl.h>
24
25#if defined(HAVE_PRCTL)
26#include <sys/prctl.h>
27#endif
28
29#define PROCESS_NAME_DEVICE "/sys/qemu_trace/process_name"
30
31static const char* process_name = "unknown";
32static int running_in_emulator = -1;
33
34void set_process_name(const char* new_name) {
35    char  propBuf[PROPERTY_VALUE_MAX];
36
37    if (new_name == NULL) {
38        return;
39    }
40
41    // We never free the old name. Someone else could be using it.
42    int len = strlen(new_name);
43    char* copy = (char*) malloc(len + 1);
44    strcpy(copy, new_name);
45    process_name = (const char*) copy;
46
47#if defined(HAVE_PRCTL)
48    if (len < 16) {
49        prctl(PR_SET_NAME, (unsigned long) new_name, 0, 0, 0);
50    } else {
51        prctl(PR_SET_NAME, (unsigned long) new_name + len - 15, 0, 0, 0);
52    }
53#endif
54
55    // If we know we are not running in the emulator, then return.
56    if (running_in_emulator == 0) {
57        return;
58    }
59
60    // If the "running_in_emulator" variable has not been initialized,
61    // then do it now.
62    if (running_in_emulator == -1) {
63        property_get("ro.kernel.qemu", propBuf, "");
64        if (propBuf[0] == '1') {
65            running_in_emulator = 1;
66        } else {
67            running_in_emulator = 0;
68            return;
69        }
70    }
71
72    // If the emulator was started with the "-trace file" command line option
73    // then we want to record the process name in the trace even if we are
74    // not currently tracing instructions (so that we will know the process
75    // name when we do start tracing instructions).  We do not need to execute
76    // this code if we are just running in the emulator without the "-trace"
77    // command line option, but we don't know that here and this function
78    // isn't called frequently enough to bother optimizing that case.
79    int fd = open(PROCESS_NAME_DEVICE, O_RDWR);
80    if (fd < 0)
81        return;
82    write(fd, process_name, strlen(process_name) + 1);
83    close(fd);
84}
85
86const char* get_process_name(void) {
87    return process_name;
88}
89