From 5d9e5efbcdab4a5442e332944765f67eb7005be5 Mon Sep 17 00:00:00 2001
From: Mark Salyzyn <salyzyn@google.com>
Date: Wed, 1 Apr 2015 11:02:00 -0700
Subject: [PATCH] libcutils: add fs_config_generate

Bug: 19908228
Change-Id: Icb0e189a86758bb779b9bdf7c0d92216d297869f
---
 include/private/android_filesystem_config.h |  2 ++
 libcutils/fs_config.c                       | 21 +++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/private/android_filesystem_config.h b/include/private/android_filesystem_config.h
index fed81f84b..02fe2b5fb 100644
--- a/include/private/android_filesystem_config.h
+++ b/include/private/android_filesystem_config.h
@@ -215,6 +215,8 @@ __BEGIN_DECLS
 void fs_config(const char *path, int dir,
                unsigned *uid, unsigned *gid, unsigned *mode, uint64_t *capabilities);
 
+ssize_t fs_config_generate(char *buffer, size_t length, const struct fs_path_config *pc);
+
 __END_DECLS
 
 #endif
diff --git a/libcutils/fs_config.c b/libcutils/fs_config.c
index bdb24dc3e..7fd66cdfd 100644
--- a/libcutils/fs_config.c
+++ b/libcutils/fs_config.c
@@ -63,6 +63,8 @@ static inline uint64_t get8LE(const uint8_t* src)
     return ((uint64_t) high << 32) | (uint64_t) low;
 }
 
+#define ALIGN(x, alignment) ( ((x) + ((alignment) - 1)) & ~((alignment) - 1) )
+
 /* Rules for directories.
 ** These rules are applied based on "first match", so they
 ** should start with the most specific path and work their
@@ -261,3 +263,22 @@ void fs_config(const char *path, int dir,
     *mode = (*mode & (~07777)) | pc->mode;
     *capabilities = pc->capabilities;
 }
+
+ssize_t fs_config_generate(char *buffer, size_t length, const struct fs_path_config *pc)
+{
+    struct fs_path_config_from_file *p = (struct fs_path_config_from_file *)buffer;
+    size_t len = ALIGN(sizeof(*p) + strlen(pc->prefix) + 1, sizeof(uint64_t));
+
+    if ((length < len) || (len > UINT16_MAX)) {
+        return -ENOSPC;
+    }
+    memset(p, 0, len);
+    uint16_t host_len = len;
+    p->len = get2LE((const uint8_t *)&host_len);
+    p->mode = get2LE((const uint8_t *)&(pc->mode));
+    p->uid = get2LE((const uint8_t *)&(pc->uid));
+    p->gid = get2LE((const uint8_t *)&(pc->gid));
+    p->capabilities = get8LE((const uint8_t *)&(pc->capabilities));
+    strcpy(p->prefix, pc->prefix);
+    return len;
+}