select: separate parsers to functions

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>

Author: ktock

src/lib/libsyscall.js

@@ -102,6 +102,71 @@ var SyscallsLibrary = {
 #endif
       return ret;
     },
+
+    getTimeoutInMillis(timeout) {
+      // select(2) is declared to accept "struct timeval { time_t tv_sec; suseconds_t tv_usec; }".
+      // However, musl passes the two values to the syscall as an array of long values.
+      // Note that sizeof(time_t) != sizeof(long) in wasm32. The former is 8, while the latter is 4.
+      // This means using "C_STRUCTS.timeval.tv_usec" leads to a wrong offset.
+      // So, instead, we use POINTER_SIZE.
+      var tv_sec = ({{{ makeGetValue('timeout', 0, 'i32') }}}),
+          tv_usec = ({{{ makeGetValue('timeout', POINTER_SIZE, 'i32') }}});
+      return (tv_sec + tv_usec / 1000000) * 1000;
+    },
+
+    parseSelectFDSet(readfds, writefds, exceptfds) {
+      var total = 0;
+
+      var srcReadLow = (readfds ? {{{ makeGetValue('readfds', 0, 'i32') }}} : 0),
+          srcReadHigh = (readfds ? {{{ makeGetValue('readfds', 4, 'i32') }}} : 0);
+      var srcWriteLow = (writefds ? {{{ makeGetValue('writefds', 0, 'i32') }}} : 0),
+          srcWriteHigh = (writefds ? {{{ makeGetValue('writefds', 4, 'i32') }}} : 0);
+      var srcExceptLow = (exceptfds ? {{{ makeGetValue('exceptfds', 0, 'i32') }}} : 0),
+          srcExceptHigh = (exceptfds ? {{{ makeGetValue('exceptfds', 4, 'i32') }}} : 0);
+
+      var dstReadLow = 0,
+          dstReadHigh = 0;
+      var dstWriteLow = 0,
+          dstWriteHigh = 0;
+      var dstExceptLow = 0,
+          dstExceptHigh = 0;
+
+      var check = (fd, low, high, val) => fd < 32 ? (low & val) : (high & val);
+
+      return {
+        getTotal: () => total,
+        setFlags: (fd, flags) => {
+          var mask = 1 << (fd % 32);
+
+          if ((flags & {{{ cDefs.POLLIN }}}) && check(fd, srcReadLow, srcReadHigh, mask)) {
+            fd < 32 ? (dstReadLow = dstReadLow | mask) : (dstReadHigh = dstReadHigh | mask);
+            total++;
+          }
+          if ((flags & {{{ cDefs.POLLOUT }}}) && check(fd, srcWriteLow, srcWriteHigh, mask)) {
+            fd < 32 ? (dstWriteLow = dstWriteLow | mask) : (dstWriteHigh = dstWriteHigh | mask);
+            total++;
+          }
+          if ((flags & {{{ cDefs.POLLPRI }}}) && check(fd, srcExceptLow, srcExceptHigh, mask)) {
+            fd < 32 ? (dstExceptLow = dstExceptLow | mask) : (dstExceptHigh = dstExceptHigh | mask);
+            total++;
+          }
+        },
+        commit: () => {
+          if (readfds) {
+            {{{ makeSetValue('readfds', '0', 'dstReadLow', 'i32') }}};
+            {{{ makeSetValue('readfds', '4', 'dstReadHigh', 'i32') }}};
+          }
+          if (writefds) {
+            {{{ makeSetValue('writefds', '0', 'dstWriteLow', 'i32') }}};
+            {{{ makeSetValue('writefds', '4', 'dstWriteHigh', 'i32') }}};
+          }
+          if (exceptfds) {
+            {{{ makeSetValue('exceptfds', '0', 'dstExceptLow', 'i32') }}};
+            {{{ makeSetValue('exceptfds', '4', 'dstExceptHigh', 'i32') }}};
+          }
+        }
+      };
+    },
   },
 
   $syscallGetVarargI__internal: true,
@@ -552,21 +617,7 @@ var SyscallsLibrary = {
     assert(nfds <= 64, 'nfds must be less than or equal to 64');  // fd sets have 64 bits // TODO: this could be 1024 based on current musl headers
 #endif
 
-    var total = 0;
-
-    var srcReadLow = (readfds ? {{{ makeGetValue('readfds', 0, 'i32') }}} : 0),
-        srcReadHigh = (readfds ? {{{ makeGetValue('readfds', 4, 'i32') }}} : 0);
-    var srcWriteLow = (writefds ? {{{ makeGetValue('writefds', 0, 'i32') }}} : 0),
-        srcWriteHigh = (writefds ? {{{ makeGetValue('writefds', 4, 'i32') }}} : 0);
-    var srcExceptLow = (exceptfds ? {{{ makeGetValue('exceptfds', 0, 'i32') }}} : 0),
-        srcExceptHigh = (exceptfds ? {{{ makeGetValue('exceptfds', 4, 'i32') }}} : 0);
-
-    var dstReadLow = 0,
-        dstReadHigh = 0;
-    var dstWriteLow = 0,
-        dstWriteHigh = 0;
-    var dstExceptLow = 0,
-        dstExceptHigh = 0;
+    var fdSet = SYSCALLS.parseSelectFDSet(readfds, writefds, exceptfds);
 
     var allLow = (readfds ? {{{ makeGetValue('readfds', 0, 'i32') }}} : 0) |
                  (writefds ? {{{ makeGetValue('writefds', 0, 'i32') }}} : 0) |
@@ -577,6 +628,11 @@ var SyscallsLibrary = {
 
     var check = (fd, low, high, val) => fd < 32 ? (low & val) : (high & val);
 
+    var timeoutInMillis = -1;
+    if (timeout) {
+      timeoutInMillis = SYSCALLS.getTimeoutInMillis(timeout);
+    }
+
     for (var fd = 0; fd < nfds; fd++) {
       var mask = 1 << (fd % 32);
       if (!(check(fd, allLow, allHigh, mask))) {
@@ -588,48 +644,16 @@ var SyscallsLibrary = {
       var flags = SYSCALLS.DEFAULT_POLLMASK;
 
       if (stream.stream_ops.poll) {
-        var timeoutInMillis = -1;
-        if (timeout) {
-          // select(2) is declared to accept "struct timeval { time_t tv_sec; suseconds_t tv_usec; }".
-          // However, musl passes the two values to the syscall as an array of long values.
-          // Note that sizeof(time_t) != sizeof(long) in wasm32. The former is 8, while the latter is 4.
-          // This means using "C_STRUCTS.timeval.tv_usec" leads to a wrong offset.
-          // So, instead, we use POINTER_SIZE.
-          var tv_sec = (readfds ? {{{ makeGetValue('timeout', 0, 'i32') }}} : 0),
-              tv_usec = (readfds ? {{{ makeGetValue('timeout', POINTER_SIZE, 'i32') }}} : 0);
-          timeoutInMillis = (tv_sec + tv_usec / 1000000) * 1000;
-        }
-        flags = stream.stream_ops.poll(stream, timeoutInMillis);
+        flags = stream.stream_ops.poll(stream, ((timeoutInMillis < 0) || readfds) ? timeoutInMillis : 0);
       }
 
-      if ((flags & {{{ cDefs.POLLIN }}}) && check(fd, srcReadLow, srcReadHigh, mask)) {
-        fd < 32 ? (dstReadLow = dstReadLow | mask) : (dstReadHigh = dstReadHigh | mask);
-        total++;
-      }
-      if ((flags & {{{ cDefs.POLLOUT }}}) && check(fd, srcWriteLow, srcWriteHigh, mask)) {
-        fd < 32 ? (dstWriteLow = dstWriteLow | mask) : (dstWriteHigh = dstWriteHigh | mask);
-        total++;
-      }
-      if ((flags & {{{ cDefs.POLLPRI }}}) && check(fd, srcExceptLow, srcExceptHigh, mask)) {
-        fd < 32 ? (dstExceptLow = dstExceptLow | mask) : (dstExceptHigh = dstExceptHigh | mask);
-        total++;
-      }
+      fdSet.setFlags(fd, flags);
     }
 
-    if (readfds) {
-      {{{ makeSetValue('readfds', '0', 'dstReadLow', 'i32') }}};
-      {{{ makeSetValue('readfds', '4', 'dstReadHigh', 'i32') }}};
-    }
-    if (writefds) {
-      {{{ makeSetValue('writefds', '0', 'dstWriteLow', 'i32') }}};
-      {{{ makeSetValue('writefds', '4', 'dstWriteHigh', 'i32') }}};
-    }
-    if (exceptfds) {
-      {{{ makeSetValue('exceptfds', '0', 'dstExceptLow', 'i32') }}};
-      {{{ makeSetValue('exceptfds', '4', 'dstExceptHigh', 'i32') }}};
-    }
 
-    return total;
+    fdSet.commit(fd, flags);
+
+    return fdSet.getTotal();
   },
   _msync_js__i53abi: true,
   _msync_js: (addr, len, prot, flags, fd, offset) => {