Code drop from //branches/cupcake/...@124589
diff --git a/logwrapper/logwrapper.c b/logwrapper/logwrapper.c
index c7a2534..f00bfbf 100644
--- a/logwrapper/logwrapper.c
+++ b/logwrapper/logwrapper.c
@@ -21,7 +21,9 @@
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
+#include <fcntl.h>
+#include "private/android_filesystem_config.h"
#include "cutils/log.h"
void fatal(const char *msg) {
@@ -32,48 +34,74 @@
void usage() {
fatal(
- "Usage: logwrapper BINARY [ARGS ...]\n"
+ "Usage: logwrapper [-x] 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");
+ "always LOG_INFO.\n"
+ "\n"
+ "-x: Causes logwrapper to SIGSEGV when BINARY terminates\n"
+ " fault address is set to the status of wait()\n");
}
-void parent(const char *tag, int parent_read) {
+void parent(const char *tag, int seg_fault_on_exit, int parent_read) {
int status;
- char buffer[1024];
+ char buffer[4096];
int a = 0; // start index of unprocessed data
int b = 0; // end index of unprocessed data
int sz;
- while ((sz = read(parent_read, &buffer[b], 1023 - b)) > 0) {
+ while ((sz = read(parent_read, &buffer[b], sizeof(buffer) - 1 - b)) > 0) {
+
+ sz += b;
// Log one line at a time
- for (b = a; b < sz; b++) {
- if (buffer[b] == '\n') {
+ for (b = 0; b < sz; b++) {
+ if (buffer[b] == '\r') {
+ buffer[b] = '\0';
+ } else if (buffer[b] == '\n') {
buffer[b] = '\0';
LOG(LOG_INFO, tag, &buffer[a]);
a = b + 1;
}
}
- if (a == 0 && b == 1023) {
+ if (a == 0 && b == sizeof(buffer) - 1) {
// buffer is full, flush
buffer[b] = '\0';
LOG(LOG_INFO, tag, &buffer[a]);
b = 0;
- } else {
+ } else if (a != b) {
// Keep left-overs
- b = sz - a;
+ b -= a;
memmove(buffer, &buffer[a], b);
a = 0;
+ } else {
+ a = 0;
+ b = 0;
}
+
}
// Flush remaining data
if (a != b) {
buffer[b] = '\0';
LOG(LOG_INFO, tag, &buffer[a]);
}
- wait(&status); // Wait for child
+ status = 0xAAAA;
+ if (wait(&status) != -1) { // Wait for child
+ if (WIFEXITED(status))
+ LOG(LOG_INFO, "logwrapper", "%s terminated by exit(%d)", tag,
+ WEXITSTATUS(status));
+ else if (WIFSIGNALED(status))
+ LOG(LOG_INFO, "logwrapper", "%s terminated by signal %d", tag,
+ WTERMSIG(status));
+ else if (WIFSTOPPED(status))
+ LOG(LOG_INFO, "logwrapper", "%s stopped by signal %d", tag,
+ WSTOPSIG(status));
+ } else
+ LOG(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[]) {
@@ -91,35 +119,62 @@
int main(int argc, char* argv[]) {
pid_t pid;
+ int seg_fault_on_exit = 0;
- int pipe_fds[2];
- int *parent_read = &pipe_fds[0];
- int *child_write = &pipe_fds[1];
+ int parent_ptty;
+ int child_ptty;
+ char *child_devname = NULL;
if (argc < 2) {
usage();
}
- if (pipe(pipe_fds) < 0) {
- fatal("Cannot create pipe\n");
+ 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_read);
- dup2(*child_write, 1);
- dup2(*child_write, 2);
- close(*child_write);
+ close(parent_ptty);
+ dup2(child_ptty, 1);
+ dup2(child_ptty, 2);
+ close(child_ptty);
child(argc - 1, &argv[1]);
} else {
- close(*child_write);
+ // 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], *parent_read);
+ parent(argv[1], seg_fault_on_exit, parent_ptty);
}
return 0;