logwrapper.c revision d18304287dbabc7835be771400b85d4ae8b63de6 
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 <sys/types.h>
19#include <sys/wait.h>
20#include <stdio.h>
21#include <stdlib.h>
22#include <unistd.h>
23#include <errno.h>
24#include <fcntl.h>
25
26#include "private/android_filesystem_config.h"
27#include "cutils/log.h"
28
29int parent(const char *tag, int parent_read) {
30    int status;
31    char buffer[4096];
32
33    int a = 0;  // start index of unprocessed data
34    int b = 0;  // end index of unprocessed data
35    int sz;
36    while ((sz = read(parent_read, &buffer[b], sizeof(buffer) - 1 - b)) > 0) {
37
38        sz += b;
39        // Log one line at a time
40        for (b = 0; b < sz; b++) {
41            if (buffer[b] == '\r') {
42                buffer[b] = '\0';
43            } else if (buffer[b] == '\n') {
44                buffer[b] = '\0';
45
46                LOG(LOG_INFO, tag, "%s", &buffer[a]);
47                a = b + 1;
48            }
49        }
50
51        if (a == 0 && b == sizeof(buffer) - 1) {
52            // buffer is full, flush
53            buffer[b] = '\0';
54            LOG(LOG_INFO, tag, &buffer[a]);
55            b = 0;
56        } else if (a != b) {
57            // Keep left-overs
58            b -= a;
59            memmove(buffer, &buffer[a], b);
60            a = 0;
61        } else {
62            a = 0;
63            b = 0;
64        }
65
66    }
67    // Flush remaining data
68    if (a != b) {
69        buffer[b] = '\0';
70        LOG(LOG_INFO, tag, &buffer[a]);
71    }
72    status = 0xAAAA;
73    if (wait(&status) != -1) {  // Wait for child
74        if (WIFEXITED(status)) {
75            LOG(LOG_INFO, "logwrapper", "%s terminated by exit(%d)", tag,
76                    WEXITSTATUS(status));
77            return WEXITSTATUS(status);
78        } else if (WIFSIGNALED(status))
79            LOG(LOG_INFO, "logwrapper", "%s terminated by signal %d", tag,
80                    WTERMSIG(status));
81        else if (WIFSTOPPED(status))
82            LOG(LOG_INFO, "logwrapper", "%s stopped by signal %d", tag,
83                    WSTOPSIG(status));
84    } else
85        LOG(LOG_INFO, "logwrapper", "%s wait() failed: %s (%d)", tag,
86                strerror(errno), errno);
87    return -EAGAIN;
88}
89
90void child(int argc, const char**argv) {
91    // create null terminated argv_child array
92    char* argv_child[argc + 1];
93    memcpy(argv_child, argv, argc * sizeof(char *));
94    argv_child[argc] = NULL;
95
96    // XXX: PROTECT FROM VIKING KILLER
97    if (execv(argv_child[0], argv_child)) {
98        LOG(LOG_ERROR, "logwrapper",
99            "executing %s failed: %s", argv_child[0], strerror(errno));
100        exit(-1);
101    }
102}
103
104int logwrap(int argc, const char* argv[], int background)
105{
106    pid_t pid;
107
108    int parent_ptty;
109    int child_ptty;
110    char *child_devname = NULL;
111
112    /* Use ptty instead of socketpair so that STDOUT is not buffered */
113    parent_ptty = open("/dev/ptmx", O_RDWR);
114    if (parent_ptty < 0) {
115	LOG(LOG_ERROR, "logwrapper", "Cannot create parent ptty");
116	return -errno;
117    }
118
119    if (grantpt(parent_ptty) || unlockpt(parent_ptty) ||
120            ((child_devname = (char*)ptsname(parent_ptty)) == 0)) {
121	LOG(LOG_ERROR, "logwrapper", "Problem with /dev/ptmx");
122	return -1;
123    }
124
125    pid = fork();
126    if (pid < 0) {
127	LOG(LOG_ERROR, "logwrapper", "Failed to fork");
128        return -errno;
129    } else if (pid == 0) {
130        child_ptty = open(child_devname, O_RDWR);
131        if (child_ptty < 0) {
132	    LOG(LOG_ERROR, "logwrapper", "Problem with child ptty");
133            return -errno;
134        }
135
136        // redirect stdout and stderr
137        close(parent_ptty);
138        dup2(child_ptty, 1);
139        dup2(child_ptty, 2);
140        close(child_ptty);
141
142        if (background) {
143            int fd = open("/dev/cpuctl/bg_non_interactive/tasks", O_WRONLY);
144
145            if (fd >=0 ) {
146                char text[64];
147
148                sprintf(text, "%d", getpid());
149                if (write(fd, text, strlen(text)) < 0) {
150                    LOG(LOG_WARN, "logwrapper",
151                        "Unable to background process (%s)", strerror(errno));
152                    close(fd);
153                }
154                close(fd);
155            } else {
156                LOG(LOG_WARN, "logwrapper",
157                    "Unable to background process (%s)", strerror(errno));
158            }
159        }
160
161        child(argc, argv);
162    } else {
163        return parent(argv[0], parent_ptty);
164    }
165
166    return 0;
167}
168