init: use read_file and write_file to implement do_copy builtin

this will make the implementation more cleaner,
and has error message output when failed on some operations

also add the O_TRUNC flag explicitly for the open function
called in write_file.

And add more test on read_file and write_file functions

Bug: 36726045
Test: manual with hikey
Test: boot and init tests on bullhead
Test: cast with fugu, per b/36726045
Merged-In: If3c30a2fff58cfece2fcd27e69c30382146e6808

Change-Id: If3c30a2fff58cfece2fcd27e69c30382146e6808
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>

1 files changed, 5 insertions, 55 deletions

diff --git a/init/builtins.cpp b/init/builtins.cpp
index 4ad36e078..64c00e954 100644
--- a/init/builtins.cpp
+++ b/init/builtins.cpp
@@ -700,61 +700,11 @@ static int do_write(const std::vector<std::string>& args) {
 }
 
 static int do_copy(const std::vector<std::string>& args) {
-    char *buffer = NULL;
-    int rc = 0;
-    int fd1 = -1, fd2 = -1;
-    struct stat info;
-    int brtw, brtr;
-    char *p;
-
-    if (stat(args[1].c_str(), &info) < 0)
-        return -1;
-
-    if ((fd1 = open(args[1].c_str(), O_RDONLY|O_CLOEXEC)) < 0)
-        goto out_err;
-
-    if ((fd2 = open(args[2].c_str(), O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0660)) < 0)
-        goto out_err;
-
-    if (!(buffer = (char*) malloc(info.st_size)))
-        goto out_err;
-
-    p = buffer;
-    brtr = info.st_size;
-    while(brtr) {
-        rc = read(fd1, p, brtr);
-        if (rc < 0)
-            goto out_err;
-        if (rc == 0)
-            break;
-        p += rc;
-        brtr -= rc;
-    }
-
-    p = buffer;
-    brtw = info.st_size;
-    while(brtw) {
-        rc = write(fd2, p, brtw);
-        if (rc < 0)
-            goto out_err;
-        if (rc == 0)
-            break;
-        p += rc;
-        brtw -= rc;
-    }
-
-    rc = 0;
-    goto out;
-out_err:
-    rc = -1;
-out:
-    if (buffer)
-        free(buffer);
-    if (fd1 >= 0)
-        close(fd1);
-    if (fd2 >= 0)
-        close(fd2);
-    return rc;
+    std::string data;
+    if (read_file(args[1], &data)) {
+        return write_file(args[2], data) ? 0 : 1;
+    }
+    return 1;
 }
 
 static int do_chown(const std::vector<std::string>& args) {