logwrapper.c revision e7732280e7af281d35f90d7794a31a7f6e10f185 
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, "%s", &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, "%s", &buffer[a]);
71    }
72    status = 0xAAAA;
73    if (wait(&status) != -1) {  // Wait for child
74        if (WIFEXITED(status)) {
75            if (WEXITSTATUS(status) != 0) {
76                LOG(LOG_INFO, "logwrapper", "%s terminated by exit(%d)", tag,
77                        WEXITSTATUS(status));
78            }
79            return WEXITSTATUS(status);
80        } else if (WIFSIGNALED(status))
81            LOG(LOG_INFO, "logwrapper", "%s terminated by signal %d", tag,
82                    WTERMSIG(status));
83        else if (WIFSTOPPED(status))
84            LOG(LOG_INFO, "logwrapper", "%s stopped by signal %d", tag,
85                    WSTOPSIG(status));
86    } else
87        LOG(LOG_INFO, "logwrapper", "%s wait() failed: %s (%d)", tag,
88                strerror(errno), errno);
89    return -EAGAIN;
90}
91
92void child(int argc, const char**argv) {
93    // create null terminated argv_child array
94    char* argv_child[argc + 1];
95    memcpy(argv_child, argv, argc * sizeof(char *));
96    argv_child[argc] = NULL;
97
98    // XXX: PROTECT FROM VIKING KILLER
99    if (execv(argv_child[0], argv_child)) {
100        LOG(LOG_ERROR, "logwrapper",
101            "executing %s failed: %s", argv_child[0], strerror(errno));
102    }
103    _exit(1);
104}
105
106int logwrap(int argc, const char* argv[], int background)
107{
108    pid_t pid;
109
110    int parent_ptty;
111    int child_ptty;
112    char child_devname[64];  // same size as libc/unistd/ptsname_r.c
113
114    /* Use ptty instead of socketpair so that STDOUT is not buffered */
115    parent_ptty = open("/dev/ptmx", O_RDWR);
116    if (parent_ptty < 0) {
117	LOG(LOG_ERROR, "logwrapper", "Cannot create parent ptty");
118	return -errno;
119    }
120
121    if (grantpt(parent_ptty) || unlockpt(parent_ptty) ||
122            ptsname_r(parent_ptty, child_devname, sizeof(child_devname))) {
123        close(parent_ptty);
124	LOG(LOG_ERROR, "logwrapper", "Problem with /dev/ptmx");
125	return -1;
126    }
127
128    pid = fork();
129    if (pid < 0) {
130        close(parent_ptty);
131	LOG(LOG_ERROR, "logwrapper", "Failed to fork");
132        return -errno;
133    } else if (pid == 0) {
134        /*
135         * Child
136         */
137        child_ptty = open(child_devname, O_RDWR);
138        if (child_ptty < 0) {
139            close(parent_ptty);
140	    LOG(LOG_ERROR, "logwrapper", "Problem with child ptty");
141            _exit(errno < 128 ? errno : 1);  // XXX lame
142        }
143
144        // redirect stdout and stderr
145        close(parent_ptty);
146        dup2(child_ptty, 1);
147        dup2(child_ptty, 2);
148        close(child_ptty);
149
150        if (background) {
151            int fd = open("/dev/cpuctl/bg_non_interactive/tasks", O_WRONLY);
152            if (fd >= 0) {
153                char text[64];
154                sprintf(text, "%d", getpid());
155                if (write(fd, text, strlen(text)) < 0) {
156                    LOG(LOG_WARN, "logwrapper",
157                        "Unable to background process (%s)", strerror(errno));
158                }
159                close(fd);
160            } else {
161                LOG(LOG_WARN, "logwrapper",
162                    "Unable to background process (%s)", strerror(errno));
163            }
164        }
165
166        child(argc, argv);
167    } else {
168        /*
169         * Parent
170         */
171        int rc = parent(argv[0], parent_ptty);
172        close(parent_ptty);
173        return rc;
174    }
175
176    return 0;
177}
178