From d527bc9132c2adf94666dc5b9593609d357ea1e4 Mon Sep 17 00:00:00 2001
From: Alexander Momchilov <alexandermomchilov@gmail.com>
Date: Thu, 23 Sep 2021 19:39:13 -0400
Subject: Refactor Platform_CompareKernelVersion API

---
 darwin/DarwinProcessList.c |  2 +-
 darwin/PlatformHelpers.c   | 41 +++++++++++++++++++++--------------------
 darwin/PlatformHelpers.h   | 15 ++++++++++-----
 3 files changed, 32 insertions(+), 26 deletions(-)

diff --git a/darwin/DarwinProcessList.c b/darwin/DarwinProcessList.c
index 1e865f59..bd7821b8 100644
--- a/darwin/DarwinProcessList.c
+++ b/darwin/DarwinProcessList.c
@@ -176,7 +176,7 @@ void ProcessList_goThroughEntries(ProcessList* super, bool pauseProcessUpdate) {
       }
 
       // Disabled for High Sierra due to bug in macOS High Sierra
-      bool isScanThreadSupported  = !(Platform_CompareKernelVersion(17, 0, 0) >= 0 && Platform_CompareKernelVersion(17, 5, 0) < 0);
+      bool isScanThreadSupported  = !Platform_KernelVersionIsBetween((KernelVersion) {17, 0, 0}, (KernelVersion) {17, 5, 0});
 
       if (isScanThreadSupported) {
          DarwinProcess_scanThreads(proc);
diff --git a/darwin/PlatformHelpers.c b/darwin/PlatformHelpers.c
index 9d4fe120..dc9879c5 100644
--- a/darwin/PlatformHelpers.c
+++ b/darwin/PlatformHelpers.c
@@ -20,43 +20,44 @@ in the source distribution for its full text.
 #endif
 
 
-void Platform_GetKernelVersion(struct kern* k) {
-   static short int version_[3] = {0};
-   if (!version_[0]) {
+void Platform_GetKernelVersion(KernelVersion* k) {
+   static KernelVersion cachedKernelVersion;
+
+   if (!cachedKernelVersion.major) {
       // just in case it fails someday
-      version_[0] = version_[1] = version_[2] = -1;
+      cachedKernelVersion = (KernelVersion) { -1, -1, -1 };
       char str[256] = {0};
       size_t size = sizeof(str);
       int ret = sysctlbyname("kern.osrelease", str, &size, NULL, 0);
       if (ret == 0) {
-         sscanf(str, "%hd.%hd.%hd", &version_[0], &version_[1], &version_[2]);
+         sscanf(str, "%hd.%hd.%hd", &cachedKernelVersion.major, &cachedKernelVersion.minor, &cachedKernelVersion.patch);
       }
    }
-   memcpy(k->version, version_, sizeof(version_));
+   memcpy(k, &cachedKernelVersion, sizeof(cachedKernelVersion));
 }
 
-/* compare the given os version with the one installed returns:
-0 if equals the installed version
-positive value if less than the installed version
-negative value if more than the installed version
-*/
-int Platform_CompareKernelVersion(short int major, short int minor, short int component) {
-   struct kern k;
-   Platform_GetKernelVersion(&k);
+int Platform_CompareKernelVersion(KernelVersion v) {
+   struct KernelVersion actualVersion;
+   Platform_GetKernelVersion(&actualVersion);
 
-   if (k.version[0] != major) {
-      return k.version[0] - major;
+   if (actualVersion.major != v.major) {
+      return actualVersion.major - v.major;
    }
-   if (k.version[1] != minor) {
-      return k.version[1] - minor;
+   if (actualVersion.minor != v.minor) {
+      return actualVersion.minor - v.minor;
    }
-   if (k.version[2] != component) {
-      return k.version[2] - component;
+   if (actualVersion.patch != v.patch) {
+      return actualVersion.patch - v.patch;
    }
 
    return 0;
 }
 
+bool Platform_KernelVersionIsBetween(KernelVersion lowerBound, KernelVersion upperBound) {
+   return 0 <= Platform_CompareKernelVersion(lowerBound)
+      && Platform_CompareKernelVersion(upperBound) < 0;
+}
+
 double Platform_calculateNanosecondsPerMachTick() {
    // Check if we can determine the timebase used on this system.
    // If the API is unavailable assume we get our timebase in nanoseconds.
diff --git a/darwin/PlatformHelpers.h b/darwin/PlatformHelpers.h
index 25c5dcc0..f78ca4ea 100644
--- a/darwin/PlatformHelpers.h
+++ b/darwin/PlatformHelpers.h
@@ -11,18 +11,23 @@ in the source distribution for its full text.
 #include <sys/types.h>
 
 
-struct kern {
-   short int version[3];
-};
+typedef struct KernelVersion {
+   short int major;
+   short int minor;
+   short int patch;
+} KernelVersion;
 
-void Platform_GetKernelVersion(struct kern* k);
+void Platform_GetKernelVersion(KernelVersion* k);
 
 /* compare the given os version with the one installed returns:
 0 if equals the installed version
 positive value if less than the installed version
 negative value if more than the installed version
 */
-int Platform_CompareKernelVersion(short int major, short int minor, short int component);
+int Platform_CompareKernelVersion(KernelVersion v);
+
+// lowerBound <= currentVersion < upperBound
+bool Platform_KernelVersionIsBetween(KernelVersion lowerBound, KernelVersion upperBound);
 
 double Platform_calculateNanosecondsPerMachTick(void);
 
-- 
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