win32: update sysinfo(2) implementation

Add a call to GetPerformanceInfo.  Treat the SystemCache member of
the PERFORMANCE_INFORMATION structure as buffer RAM.  Deduct it
from available RAM.

The numbers reported by 'free' move about in vaguely sensible
ways when I start and stop programs, though I still don't know
if they're in any way accurate.

2 files changed, 23 insertions, 15 deletions

diff --git a/include/mingw.h b/include/mingw.h
index c2a8b61bf..5cb5cb88c 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -364,8 +364,6 @@ struct sysinfo {
         unsigned long totalhigh; /* Total high memory size */
         unsigned long freehigh;  /* Available high memory size */
         unsigned int mem_unit;   /* Memory unit size in bytes */
-        char _f[20-2*sizeof(long)-sizeof(int)];
-        /* Padding to 64 bytes */
 };
 
 int sysinfo(struct sysinfo *info);
diff --git a/win32/mingw.c b/win32/mingw.c
index ddc64b43a..73179dac9 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -5,6 +5,7 @@
 #include <aclapi.h>
 #endif
 #include <ntdef.h>
+#include <psapi.h>
 
 #if defined(__MINGW64_VERSION_MAJOR)
 #if ENABLE_GLOBBING
@@ -1371,25 +1372,34 @@ int mingw_unlink(const char *pathname)
 int sysinfo(struct sysinfo *info)
 {
         DECLARE_PROC_ADDR(BOOL, GlobalMemoryStatusEx, LPMEMORYSTATUSEX);
+        DECLARE_PROC_ADDR(BOOL, GetPerformanceInfo, PPERFORMANCE_INFORMATION, DWORD);
         MEMORYSTATUSEX mem;
+        PERFORMANCE_INFORMATION perf;
 
         memset((void *)info, 0, sizeof(struct sysinfo));
-
-        if (!INIT_PROC_ADDR(kernel32.dll, GlobalMemoryStatusEx)) {
-                return -1;
+        memset((void *)&perf, 0, sizeof(PERFORMANCE_INFORMATION));
+        info->mem_unit = 4096;
+
+        if (INIT_PROC_ADDR(psapi.dll, GetPerformanceInfo)) {
+                perf.cb = sizeof(PERFORMANCE_INFORMATION);
+                GetPerformanceInfo(&perf, perf.cb);
+        }
+
+        if (INIT_PROC_ADDR(kernel32.dll, GlobalMemoryStatusEx)) {
+                mem.dwLength = sizeof(MEMORYSTATUSEX);
+                if (GlobalMemoryStatusEx(&mem)) {
+                        info->totalram = mem.ullTotalPhys >> 12;
+                        info->bufferram = (perf.SystemCache * perf.PageSize) >> 12;
+                        if ((mem.ullAvailPhys >> 12) > info->bufferram)
+                                info->freeram = (mem.ullAvailPhys >> 12) - info->bufferram;
+                        info->totalswap = (mem.ullTotalPageFile - mem.ullTotalPhys) >> 12;
+                        if (mem.ullAvailPageFile > mem.ullAvailPhys)
+                                info->freeswap = (mem.ullAvailPageFile-mem.ullAvailPhys) >> 12;
+                }
         }
 
-        mem.dwLength = sizeof(MEMORYSTATUSEX);
-        if (!GlobalMemoryStatusEx(&mem))
-                return -1;
-
-        info->mem_unit = 1;
-        info->totalram = mem.ullTotalPhys;
-        info->freeram = mem.ullAvailPhys;
-        info->totalswap = mem.ullTotalPageFile - mem.ullTotalPhys;
-        info->freeswap = mem.ullAvailPageFile - mem.ullAvailPhys;
-
         info->uptime = GetTickCount64() / 1000;
+        info->procs = perf.ProcessCount;
 
         return 0;
 }