Additional cleanup of start_device_log.

Addresses nnk's post commit review comments on
https://android-review.googlesource.com/#/c/139381/

Remove unneeded code for creating /data/adb.

Add an O_CLOEXEC.

Move the closing of stdin out to main().

Append the pid of the current process to the log file to avoid
clobbering the log if the process crashes and restarts within the same
second.

Change-Id: Ide0be86b4b33256486634c29ba02efaf10cf913d

2 files changed, 19 insertions, 8 deletions

diff --git a/adb/adb.cpp b/adb/adb.cpp
index d37ca36..ad85184 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -79,18 +79,19 @@ void fatal_errno(const char *fmt, ...)
 
 #if !ADB_HOST
 void start_device_log(void) {
-    adb_mkdir("/data/adb", 0775);
-
     struct tm now;
     time_t t;
     tzset();
     time(&t);
     localtime_r(&t, &now);
 
+    char timestamp[PATH_MAX];
+    strftime(timestamp, sizeof(timestamp), "%Y-%m-%d-%H-%M-%S", &now);
+
     char path[PATH_MAX];
-    strftime(path, sizeof(path), "/data/adb/adb-%Y-%m-%d-%H-%M-%S.txt", &now);
+    snprintf(path, sizeof(path), "/data/adb/adb-%s-%d", timestamp, getpid());
 
-    int fd = unix_open(path, O_WRONLY | O_CREAT | O_TRUNC, 0640);
+    int fd = unix_open(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0640);
     if (fd == -1) {
         return;
     }
@@ -100,10 +101,6 @@ void start_device_log(void) {
     dup2(fd, STDERR_FILENO);
     fprintf(stderr, "--- adb starting (pid %d) ---\n", getpid());
     adb_close(fd);
-
-    fd = unix_open("/dev/null", O_RDONLY);
-    dup2(fd, 0);
-    adb_close(fd);
 }
 #endif
 
diff --git a/adb/adb_main.cpp b/adb/adb_main.cpp
index c1e4b13..a03fcf1 100644
--- a/adb/adb_main.cpp
+++ b/adb/adb_main.cpp
@@ -349,9 +349,23 @@ int adb_main(int is_daemon, int server_port)
     return 0;
 }
 
+#if !ADB_HOST
+void close_stdin() {
+    int fd = unix_open("/dev/null", O_RDONLY);
+    if (fd == -1) {
+        perror("failed to open /dev/null, stdin will remain open");
+        return;
+    }
+    dup2(fd, 0);
+    adb_close(fd);
+}
+#endif
+
 int main(int argc, char **argv) {
 #if ADB_HOST
     adb_sysdeps_init();
+#else
+    close_stdin();
 #endif
     adb_trace_init();