support "sideload over ADB" mode

Rather than depending on the existence of some place to store a file
that is accessible to users on an an unbootable device (eg, a physical
sdcard, external USB drive, etc.), add support for sideloading
packages sent to the device with adb.

This change adds a "minimal adbd" which supports nothing but receiving
a package over adb (with the "adb sideload" command) and storing it to
a fixed filename in the /tmp ramdisk, from where it can be verified
and sideloaded in the usual way.  This should be leave available even
on locked user-build devices.

The user can select "apply package from ADB" from the recovery menu,
which starts minimal-adb mode (shutting down any real adbd that may be
running).  Once minimal-adb has received a package it exits
(restarting real adbd if appropriate) and then verification and
installation of the received package proceeds.

Change-Id: I6fe13161ca064a98d06fa32104e1f432826582f5
diff --git a/minadbd/services.c b/minadbd/services.c
new file mode 100644
index 0000000..8fc8b3c
--- /dev/null
+++ b/minadbd/services.c
@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2007 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 <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+#include "sysdeps.h"
+#include "fdevent.h"
+
+#define  TRACE_TAG  TRACE_SERVICES
+#include "adb.h"
+
+typedef struct stinfo stinfo;
+
+struct stinfo {
+    void (*func)(int fd, void *cookie);
+    int fd;
+    void *cookie;
+};
+
+
+void *service_bootstrap_func(void *x)
+{
+    stinfo *sti = x;
+    sti->func(sti->fd, sti->cookie);
+    free(sti);
+    return 0;
+}
+
+static void sideload_service(int s, void *cookie)
+{
+    unsigned char buf[4096];
+    unsigned count = (unsigned) cookie;
+    int fd;
+
+    fprintf(stderr, "sideload_service invoked\n");
+
+    fd = adb_creat(ADB_SIDELOAD_FILENAME, 0644);
+    if(fd < 0) {
+        adb_close(s);
+        return;
+    }
+
+    while(count > 0) {
+        unsigned xfer = (count > 4096) ? 4096 : count;
+        if(readx(s, buf, xfer)) break;
+        if(writex(fd, buf, xfer)) break;
+        count -= xfer;
+    }
+
+    if(count == 0) {
+        writex(s, "OKAY", 4);
+    } else {
+        writex(s, "FAIL", 4);
+    }
+    adb_close(fd);
+    adb_close(s);
+
+    if (count == 0) {
+        fprintf(stderr, "adbd exiting after successful sideload\n");
+        sleep(1);
+        exit(0);
+    }
+}
+
+
+#if 0
+static void echo_service(int fd, void *cookie)
+{
+    char buf[4096];
+    int r;
+    char *p;
+    int c;
+
+    for(;;) {
+        r = read(fd, buf, 4096);
+        if(r == 0) goto done;
+        if(r < 0) {
+            if(errno == EINTR) continue;
+            else goto done;
+        }
+
+        c = r;
+        p = buf;
+        while(c > 0) {
+            r = write(fd, p, c);
+            if(r > 0) {
+                c -= r;
+                p += r;
+                continue;
+            }
+            if((r < 0) && (errno == EINTR)) continue;
+            goto done;
+        }
+    }
+done:
+    close(fd);
+}
+#endif
+
+static int create_service_thread(void (*func)(int, void *), void *cookie)
+{
+    stinfo *sti;
+    adb_thread_t t;
+    int s[2];
+
+    if(adb_socketpair(s)) {
+        printf("cannot create service socket pair\n");
+        return -1;
+    }
+
+    sti = malloc(sizeof(stinfo));
+    if(sti == 0) fatal("cannot allocate stinfo");
+    sti->func = func;
+    sti->cookie = cookie;
+    sti->fd = s[1];
+
+    if(adb_thread_create( &t, service_bootstrap_func, sti)){
+        free(sti);
+        adb_close(s[0]);
+        adb_close(s[1]);
+        printf("cannot create service thread\n");
+        return -1;
+    }
+
+    D("service thread started, %d:%d\n",s[0], s[1]);
+    return s[0];
+}
+
+int service_to_fd(const char *name)
+{
+    int ret = -1;
+
+    if (!strncmp(name, "sideload:", 9)) {
+        ret = create_service_thread(sideload_service, (void*) atoi(name + 9));
+#if 0
+    } else if(!strncmp(name, "echo:", 5)){
+        ret = create_service_thread(echo_service, 0);
+#endif
+    }
+    if (ret >= 0) {
+        close_on_exec(ret);
+    }
+    return ret;
+}