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/*
* Copyright (C) 2008 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 <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include "private/android_filesystem_config.h"
#include "cutils/log.h"
void fatal(const char *msg) {
fprintf(stderr, "%s", msg);
ALOG(LOG_ERROR, "logwrapper", "%s", msg);
exit(-1);
}
void usage() {
fatal(
"Usage: logwrapper [-d] BINARY [ARGS ...]\n"
"\n"
"Forks and executes BINARY ARGS, redirecting stdout and stderr to\n"
"the Android logging system. Tag is set to BINARY, priority is\n"
"always LOG_INFO.\n"
"\n"
"-d: Causes logwrapper to SIGSEGV when BINARY terminates\n"
" fault address is set to the status of wait()\n");
}
void parent(const char *tag, int seg_fault_on_exit, int parent_read) {
int status;
char buffer[4096];
int a = 0; // start index of unprocessed data
int b = 0; // end index of unprocessed data
int sz;
char *btag = basename(tag);
if (!btag) btag = (char*) tag;
while ((sz = read(parent_read, &buffer[b], sizeof(buffer) - 1 - b)) > 0) {
sz += b;
// Log one line at a time
for (b = 0; b < sz; b++) {
if (buffer[b] == '\r') {
buffer[b] = '\0';
} else if (buffer[b] == '\n') {
buffer[b] = '\0';
ALOG(LOG_INFO, btag, "%s", &buffer[a]);
a = b + 1;
}
}
if (a == 0 && b == sizeof(buffer) - 1) {
// buffer is full, flush
buffer[b] = '\0';
ALOG(LOG_INFO, btag, "%s", &buffer[a]);
b = 0;
} else if (a != b) {
// Keep left-overs
b -= a;
memmove(buffer, &buffer[a], b);
a = 0;
} else {
a = 0;
b = 0;
}
}
// Flush remaining data
if (a != b) {
buffer[b] = '\0';
ALOG(LOG_INFO, btag, "%s", &buffer[a]);
}
status = 0xAAAA;
if (wait(&status) != -1) { // Wait for child
if (WIFEXITED(status) && WEXITSTATUS(status))
ALOG(LOG_INFO, "logwrapper", "%s terminated by exit(%d)", tag,
WEXITSTATUS(status));
else if (WIFSIGNALED(status))
ALOG(LOG_INFO, "logwrapper", "%s terminated by signal %d", tag,
WTERMSIG(status));
else if (WIFSTOPPED(status))
ALOG(LOG_INFO, "logwrapper", "%s stopped by signal %d", tag,
WSTOPSIG(status));
} else
ALOG(LOG_INFO, "logwrapper", "%s wait() failed: %s (%d)", tag,
strerror(errno), errno);
if (seg_fault_on_exit)
*(int *)status = 0; // causes SIGSEGV with fault_address = status
}
void child(int argc, char* argv[]) {
// create null terminated argv_child array
char* argv_child[argc + 1];
memcpy(argv_child, argv, argc * sizeof(char *));
argv_child[argc] = NULL;
if (execvp(argv_child[0], argv_child)) {
ALOG(LOG_ERROR, "logwrapper",
"executing %s failed: %s\n", argv_child[0], strerror(errno));
exit(-1);
}
}
int main(int argc, char* argv[]) {
pid_t pid;
int seg_fault_on_exit = 0;
int parent_ptty;
int child_ptty;
char *child_devname = NULL;
if (argc < 2) {
usage();
}
if (strncmp(argv[1], "-d", 2) == 0) {
seg_fault_on_exit = 1;
argc--;
argv++;
}
if (argc < 2) {
usage();
}
/* Use ptty instead of socketpair so that STDOUT is not buffered */
parent_ptty = open("/dev/ptmx", O_RDWR);
if (parent_ptty < 0) {
fatal("Cannot create parent ptty\n");
}
if (grantpt(parent_ptty) || unlockpt(parent_ptty) ||
((child_devname = (char*)ptsname(parent_ptty)) == 0)) {
fatal("Problem with /dev/ptmx\n");
}
pid = fork();
if (pid < 0) {
fatal("Failed to fork\n");
} else if (pid == 0) {
child_ptty = open(child_devname, O_RDWR);
if (child_ptty < 0) {
fatal("Problem with child ptty\n");
}
// redirect stdout and stderr
close(parent_ptty);
dup2(child_ptty, 1);
dup2(child_ptty, 2);
close(child_ptty);
child(argc - 1, &argv[1]);
} else {
// switch user and group to "log"
// this may fail if we are not root,
// but in that case switching user/group is unnecessary
setgid(AID_LOG);
setuid(AID_LOG);
parent(argv[1], seg_fault_on_exit, parent_ptty);
}
return 0;
}
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