Libc-1439.40.11.tar.gz

[apple/libc.git] / darwin / subsystem.c

diff --git a/darwin/subsystem.c b/darwin/subsystem.c
new file mode 100644 (file)
index 0000000..e591a3d
--- /dev/null
+++ b/darwin/subsystem.c
@@ -0,0 +1,124 @@
+/*
+* Copyright (c) 2019 Apple Inc. All rights reserved.
+*
+* @APPLE_LICENSE_HEADER_START@
+*
+* This file contains Original Code and/or Modifications of Original Code
+* as defined in and that are subject to the Apple Public Source License
+* Version 2.0 (the 'License'). You may not use this file except in
+* compliance with the License. Please obtain a copy of the License at
+* http://www.opensource.apple.com/apsl/ and read it before using this
+* file.
+*
+* The Original Code and all software distributed under the License are
+* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+* Please see the License for the specific language governing rights and
+* limitations under the License.
+*
+* @APPLE_LICENSE_HEADER_END@
+*/
+
+#include <fcntl.h>
+#include <stdbool.h>
+#include <string.h>
+#include <subsystem.h>
+#include <sys/errno.h>
+#include <sys/syslimits.h>
+#include <_simple.h>
+
+#define SUBSYSTEM_ROOT_PATH_KEY "subsystem_root_path"
+
+void _subsystem_init(const char *apple[]);
+
+static char * subsystem_root_path = NULL;
+static size_t subsystem_root_path_len = 0;
+
+/*
+ * Takes the apple array, and initializes subsystem
+ * support in Libc.
+ */
+void
+_subsystem_init(const char **apple)
+{
+       char * subsystem_root_path_string = _simple_getenv(apple, SUBSYSTEM_ROOT_PATH_KEY);
+       if (subsystem_root_path_string) {
+               subsystem_root_path = subsystem_root_path_string;
+               subsystem_root_path_len = strnlen(subsystem_root_path, PATH_MAX);
+       }
+}
+
+/*
+ * Takes a buffer, a subsystem path, and a file path, and constructs the
+ * subsystem path for the given file path.  Assumes that the subsystem root
+ * path will be "/" terminated.
+ */
+static bool
+construct_subsystem_path(char * buf, size_t buf_size, const char * subsystem_root_path, const char * file_path)
+{
+       size_t return_a = strlcpy(buf, subsystem_root_path, buf_size);
+       size_t return_b = strlcat(buf, file_path, buf_size);
+
+       if ((return_a >= buf_size) || (return_b >= buf_size)) {
+               return false;
+       }
+
+       return true;
+}
+
+int
+open_with_subsystem(const char * path, int oflag)
+{
+       /* Don't support file creation. */
+       if (oflag & O_CREAT){
+               errno = EINVAL;
+               return -1;
+       }
+
+       int result;
+
+       result = open(path, oflag);
+
+       if ((result < 0) && (errno == ENOENT) && (subsystem_root_path)) {
+               /*
+                * If the file doesn't exist relative to root, search
+                * for it relative to the subsystem root.
+                */
+               char subsystem_path[PATH_MAX];
+
+               if (construct_subsystem_path(subsystem_path, sizeof(subsystem_path), subsystem_root_path, path)) {
+                       result = open(subsystem_path, oflag);
+               } else {
+                       errno = ENAMETOOLONG;
+               }
+       }
+
+       return result;
+}
+
+int
+stat_with_subsystem(const char *restrict path, struct stat *restrict buf)
+{
+       int result;
+
+       result = stat(path, buf);
+
+       if ((result < 0) && (errno == ENOENT) && (subsystem_root_path)) {
+               /*
+                * If the file doesn't exist relative to root, search
+                * for it relative to the subsystem root.
+                */
+               char subsystem_path[PATH_MAX];
+
+               if (construct_subsystem_path(subsystem_path, sizeof(subsystem_path), subsystem_root_path, path)) {
+                       result = stat(subsystem_path, buf);
+               } else {
+                       errno = ENAMETOOLONG;
+               }
+       }
+
+       return result;
+}
+