lib/builtins/os_version_check.c

/* ===-- os_version_check.c - OS version checking  -------------------------===
 *
 *                     The LLVM Compiler Infrastructure
 *
 * This file is dual licensed under the MIT and the University of Illinois Open
 * Source Licenses. See LICENSE.TXT for details.
 *
 * ===----------------------------------------------------------------------===
 *
 * This file implements the function __isOSVersionAtLeast, used by
 * Objective-C's @available
 *
 * ===----------------------------------------------------------------------===
 */

#ifdef __APPLE__

#include <CoreFoundation/CoreFoundation.h>
#include <dispatch/dispatch.h>
#include <TargetConditionals.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* These three variables hold the host's OS version. */
static int32_t GlobalMajor, GlobalMinor, GlobalSubminor;
static dispatch_once_t DispatchOnceCounter;

/* Find and parse the SystemVersion.plist file. */
static void parseSystemVersionPList(void *Unused) {
  (void)Unused;

  char *PListPath = "/System/Library/CoreServices/SystemVersion.plist";

#if TARGET_OS_SIMULATOR
  char *PListPathPrefix = getenv("IPHONE_SIMULATOR_ROOT");
  if (!PListPathPrefix)
    return;
  char FullPath[strlen(PListPathPrefix) + strlen(PListPath) + 1];
  strcpy(FullPath, PListPathPrefix);
  strcat(FullPath, PListPath);
  PListPath = FullPath;
#endif
  FILE *PropertyList = fopen(PListPath, "r");
  if (!PropertyList)
    return;

  /* Dynamically allocated stuff. */
  CFDictionaryRef PListRef = NULL;
  CFDataRef FileContentsRef = NULL;
  UInt8 *PListBuf = NULL;

  fseek(PropertyList, 0, SEEK_END);
  long PListFileSize = ftell(PropertyList);
  if (PListFileSize < 0)
    goto Fail;
  rewind(PropertyList);

  PListBuf = malloc((size_t)PListFileSize);
  if (!PListBuf)
    goto Fail;

  size_t NumRead = fread(PListBuf, 1, (size_t)PListFileSize, PropertyList);
  if (NumRead != (size_t)PListFileSize)
    goto Fail;

  /* Get the file buffer into CF's format. We pass in a null allocator here *
   * because we free PListBuf ourselves */
  FileContentsRef = CFDataCreateWithBytesNoCopy(
      NULL, PListBuf, (CFIndex)NumRead, kCFAllocatorNull);
  if (!FileContentsRef)
    goto Fail;

  if (&CFPropertyListCreateWithData)
    PListRef = CFPropertyListCreateWithData(
        NULL, FileContentsRef, kCFPropertyListImmutable, NULL, NULL);
  else {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
    PListRef = CFPropertyListCreateFromXMLData(NULL, FileContentsRef,
                                               kCFPropertyListImmutable, NULL);
#pragma clang diagnostic pop
  }
  if (!PListRef)
    goto Fail;

  CFTypeRef OpaqueValue =
      CFDictionaryGetValue(PListRef, CFSTR("ProductVersion"));
  if (!OpaqueValue || CFGetTypeID(OpaqueValue) != CFStringGetTypeID())
    goto Fail;

  char VersionStr[32];
  if (!CFStringGetCString((CFStringRef)OpaqueValue, VersionStr,
                          sizeof(VersionStr), kCFStringEncodingUTF8))
    goto Fail;
  sscanf(VersionStr, "%d.%d.%d", &GlobalMajor, &GlobalMinor, &GlobalSubminor);

Fail:
  if (PListRef)
    CFRelease(PListRef);
  if (FileContentsRef)
    CFRelease(FileContentsRef);
  free(PListBuf);
  fclose(PropertyList);
}

int32_t __isOSVersionAtLeast(int32_t Major, int32_t Minor, int32_t Subminor) {
  /* Populate the global version variables, if they haven't already. */
  dispatch_once_f(&DispatchOnceCounter, NULL, parseSystemVersionPList);

  if (Major < GlobalMajor) return 1;
  if (Major > GlobalMajor) return 0;
  if (Minor < GlobalMinor) return 1;
  if (Minor > GlobalMinor) return 0;
  return Subminor <= GlobalSubminor;
}

#else

/* Silence an empty translation unit warning. */
typedef int unused;

#endif