Changeset 3117 in kBuild for trunk/src

Timestamp:

Oct 30, 2017 5:49:42 PM (8 years ago)

Author:

bird

Message:

mscfakes.c,cat.c: msc_write: Do the console optimizations. Make the ENOSPC workaround more reliable (looks like _write may actually return a count that is higher than the input, or something else to that effect is going tits up). Fixed a bug if we ever should write more than 1GB in one go, it would've spun forever.

Location:

trunk/src/kmk/kmkbuiltin

Files:

• cat.c (modified) (1 diff)
• mscfakes.c (modified) (6 diffs)

trunk/src/kmk/kmkbuiltin/cat.c

@@ -81 +81 @@
 
 
-#ifdef KBUILD_OS_WINDOWS
-/* This is a trick to seriuosly speed up console output windows. */
-# undef write
-# define write maybe_con_write
-extern ssize_t maybe_con_write(int, void const *, size_t);
-#endif
-
-
 int bflag, eflag, nflag, sflag, tflag, vflag;
 /*int rval;*/

trunk/src/kmk/kmkbuiltin/mscfakes.c

@@ -48 +48 @@
 #include <Windows.h>
 #undef timeval
+
+extern ssize_t maybe_con_write(int, void const *, size_t);
 
 
@@ -474 +476 @@
 ssize_t msc_write(int fd, const void *pvSrc, size_t cbSrc)
 {
+#define MSC_WRITE_MAX_CHUNK (UINT_MAX / 32)
     ssize_t cbRet;
-    if (cbSrc < UINT_MAX / 4)
-    {
+    if (cbSrc <= MSC_WRITE_MAX_CHUNK)
+    {
+        /* Console output optimization: */
+        if (cbSrc > 0 && isatty(fd))
+            return maybe_con_write(fd, pvSrc, cbSrc);
+
 #ifndef MSC_WRITE_TEST
         cbRet = _write(fd, pvSrc, (unsigned int)cbSrc);
@@ -485 +492 @@
         {
             /* ENOSPC on pipe kludge. */
-            int cbLimit;
+            unsigned int cbLimit;
             int cSinceLastSuccess;
 
@@ -502 +509 @@
             /* Likely a full pipe buffer, try write smaller amounts and do some
                sleeping inbetween each unsuccessful one. */
-            cbLimit = cbSrc / 4;
+            cbLimit = (unsigned)(cbSrc / 4);
             if (cbLimit < 4)
                 cbLimit = 4;
@@ -513 +520 @@
 #endif
 
-            while (cbSrc > 0)
+            while ((ssize_t)cbSrc > 0)
             {
-                unsigned int cbAttempt = cbSrc > cbLimit ? (int)cbLimit : (int)cbSrc;
+                unsigned int cbAttempt = cbSrc > cbLimit ? cbLimit : (unsigned int)cbSrc;
                 ssize_t cbActual = _write(fd, pvSrc, cbAttempt);
                 if (cbActual > 0)
                 {
-                    assert(cbActual <= (ssize_t)cbAttempt);
+                    /* For some reason, it seems like we cannot trust _write to return
+                       a number that's less or equal to the number of bytes we passed
+                       in to the call.  (Also reason for signed check in loop.) */
+                    if (cbActual > cbAttempt)
+                        cbActual = cbAttempt;
+
                     pvSrc  = (char *)pvSrc + cbActual;
                     cbSrc -= cbActual;
@@ -559 +571 @@
         while (cbSrc > 0)
         {
-            size_t  cbToWrite = cbSrc > UINT_MAX / 4 ? UINT_MAX / 4 : cbSrc;
+            size_t  cbToWrite = cbSrc > MSC_WRITE_MAX_CHUNK ? MSC_WRITE_MAX_CHUNK : cbSrc;
             ssize_t cbWritten = msc_write(fd, pvSrc, cbToWrite);
             if (cbWritten > 0)