SocketClient: don't ignore SIGPIPE

1) All current users are better off ignoring SIGPIPE at the beginning
   of their process instead of ignoring it just for SocketClient
2) This isn't thread safe if users did want it, since sigaction()
   ignores SIGPIPE for the entire process
3) This costs 5-10% of logd CPU time when logcat is reading logs

Also clean up the error handling in SocketClient::sendDataLockedv().

Test: kill logcat and see that logd doesn't crash
Test: run simpleperf and see that no cycles are going to sigaction
Change-Id: I6532c8a0d71338e534411707b9a9bd785145c730
diff --git a/libsysutils/src/SocketClient.cpp b/libsysutils/src/SocketClient.cpp
index fe2f3d6..e90afcd 100644
--- a/libsysutils/src/SocketClient.cpp
+++ b/libsysutils/src/SocketClient.cpp
@@ -201,50 +201,31 @@
         return 0;
     }
 
-    int ret = 0;
-    int e = 0; // SLOGW and sigaction are not inert regarding errno
     int current = 0;
 
-    struct sigaction new_action, old_action;
-    memset(&new_action, 0, sizeof(new_action));
-    new_action.sa_handler = SIG_IGN;
-    sigaction(SIGPIPE, &new_action, &old_action);
-
     for (;;) {
-        ssize_t rc = TEMP_FAILURE_RETRY(
-            writev(mSocket, iov + current, iovcnt - current));
-
-        if (rc > 0) {
-            size_t written = rc;
-            while ((current < iovcnt) && (written >= iov[current].iov_len)) {
-                written -= iov[current].iov_len;
-                current++;
-            }
-            if (current == iovcnt) {
-                break;
-            }
-            iov[current].iov_base = (char *)iov[current].iov_base + written;
-            iov[current].iov_len -= written;
-            continue;
-        }
+        ssize_t rc = TEMP_FAILURE_RETRY(writev(mSocket, iov + current, iovcnt - current));
 
         if (rc == 0) {
-            e = EIO;
+            errno = EIO;
             SLOGW("0 length write :(");
-        } else {
-            e = errno;
-            SLOGW("write error (%s)", strerror(e));
+            return -1;
+        } else if (rc < 0) {
+            SLOGW("write error (%s)", strerror(errno));
+            return -1;
         }
-        ret = -1;
-        break;
-    }
 
-    sigaction(SIGPIPE, &old_action, &new_action);
-
-    if (e != 0) {
-        errno = e;
+        size_t written = rc;
+        while (current < iovcnt && written >= iov[current].iov_len) {
+            written -= iov[current].iov_len;
+            current++;
+        }
+        if (current == iovcnt) {
+            return 0;
+        }
+        iov[current].iov_base = (char*)iov[current].iov_base + written;
+        iov[current].iov_len -= written;
     }
-    return ret;
 }
 
 void SocketClient::incRef() {