fix problems with text-mode ports on Windows

Closes PR 14198

Merge to v6.0
(cherry picked from commit 335177f1bc)

pkgs/racket-pkgs/racket-test/tests/racket/port.rktl

@@ -841,6 +841,48 @@
   (test #f file-position* p2)
   (err/rt-test (file-position p2) exn:fail:filesystem?))
 
+;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Text mode, file positions, and buffers
+
+(let ()
+  (define path (build-path (find-system-path 'temp-dir) "test.txt"))
+
+  (define ofile (open-output-file path #:mode 'text #:exists 'replace))
+  (fprintf ofile "abc\ndef\nghi\n")
+  (close-output-port ofile)
+
+  (let ()
+    (define ifile (open-input-file path #:mode 'text))
+    (test "abc" read-line ifile)
+    (define pos (file-position ifile))
+    (test "def" read-line ifile)
+    (file-position ifile pos)
+    (test "def" read-line ifile))
+
+  (let ()
+    (define ifile (open-input-file path #:mode 'text))
+    (file-stream-buffer-mode ifile 'none)
+    (test "abc" read-line ifile)
+    (define pos (file-position ifile))
+    (test "def" read-line ifile)
+    (file-position ifile pos)
+    (test "def" read-line ifile))
+
+  (let* ([bs (call-with-input-file path
+	       #:mode 'text 
+	       (lambda (p) (read-bytes (file-size path) p)))])
+    ;; Check text-mode conversion at every boundary:
+    (for ([i (in-range (add1 (bytes-length bs)))])
+	 (define p (open-input-file path #:mode 'text))
+	 (file-stream-buffer-mode p 'none)
+	 (define a (read-bytes i p))
+	 (define b (read-bytes (- (bytes-length bs) i) p))
+	 (test #t eof-object? (read-byte p))
+	 (close-input-port p)
+	 (test bs bytes-append a b)))
+
+  (delete-file path))
+
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (report-errs)

racket/src/racket/include/scheme.h

@@ -1484,6 +1484,9 @@ struct Scheme_Input_Port
   Scheme_Object *special, *ungotten_special;
   Scheme_Object *unless, *unless_cache;
   struct Scheme_Output_Port *output_half;
+#ifdef WINDOWS_FILE_HANDLES
+  char *bufwidths; /* to track CRLF => LF conversions in the buffer */
+#endif
 };
 
 struct Scheme_Output_Port

racket/src/racket/src/mzmarksrc.c

@@ -646,6 +646,9 @@ input_port {
   gcMARK2(ip->input_extras_ready, gc);
   gcMARK2(ip->unless, gc);
   gcMARK2(ip->unless_cache, gc);
+#ifdef WINDOWS_FILE_HANDLES
+  gcMARK2(ip->bufwidths, gc);
+#endif
 
  size:
   gcBYTES_TO_WORDS(sizeof(Scheme_Input_Port));

racket/src/racket/src/port.c

@@ -313,7 +313,7 @@ int scheme_get_serialized_fd_flags(Scheme_Object* p, Scheme_Serialized_File_FD *
     so->name = ((Scheme_Output_Port *)p)->name;
   }
   so->regfile = fds->regfile;
-  so->textmode = fds->textmode;
+  so->textmode = (fds->textmode ? 1 : 0);
   so->flush_mode = fds->flush;
   return 1;
 }
@@ -5463,6 +5463,22 @@ do_file_position(const char *who, int argc, Scheme_Object *argv[], int can_false
           Scheme_Input_Port *ip;
           ip = scheme_input_port_record(argv[0]);
 	  pll -= ((Scheme_FD *)ip->port_data)->bufcount;
+# ifdef WINDOWS_FILE_HANDLES
+          if (((Scheme_FD *)ip->port_data)->textmode) {
+            int bp, bd;
+            bd = ((Scheme_FD *)ip->port_data)->buffpos;
+            for (bp = ((Scheme_FD *)ip->port_data)->bufcount; bp--; ) {
+              if (ip->bufwidths[bp + bd]) {
+                /* this is a LF converted from CRLF */
+                pll--;
+              }
+            }
+            if (((Scheme_FD *)ip->port_data)->textmode > 1) {
+              /* one more for leftover CR */
+              pll--;
+            }
+          }
+# endif
 	} else {
           Scheme_Output_Port *op;
           op = scheme_output_port_record(argv[0]);
@@ -6699,7 +6715,7 @@ static intptr_t fd_get_string_slow(Scheme_Input_Port *port,
       rgot = target_size;
 
       /* Pending CR in text mode? */
-      if (fip->textmode == 2) {
+      if (fip->textmode > 1) {
         delta = 1;
         if (rgot > 1)
           rgot--;
@@ -6723,27 +6739,33 @@ static intptr_t fd_get_string_slow(Scheme_Input_Port *port,
         int i, j;
         unsigned char *buf;
 
-        if (fip->textmode == 2) {
+        if (fip->textmode > 1) {
           /* we had added a CR */
           bc++;
           fip->textmode = 1;
         }
 
-        /* If bc is only 1, then we've reached the end, and
+        /* If bc is only 1 in buffer mode, then we've reached the end, and
            any leftover CR there should stay. */
-        if (bc > 1) {
+        if ((bc > 1) || (bc && (target_size == 1))) {
           /* Collapse CR-LF: */
+          char *bufwidths = port->bufwidths; /* for file-position */
           buf = fip->buffer;
           for (i = 0, j = 0; i < bc - 1; i++) {
             if ((buf[i] == '\r')
                 && (buf[i+1] == '\n')) {
+              bufwidths[j] = 1;
               buf[j++] = '\n';
               i++;
-            } else
+            } else {
+              bufwidths[j] = 0;
               buf[j++] = buf[i];
+            }
           }
-          if (i < bc) /* common case: didn't end with CRLF */
+          if (i < bc) { /* common case: didn't end with CRLF */
+            bufwidths[j] = 0;
             buf[j++] = buf[i];
+          }
           bc = j;
           /* Check for CR at end; if there, save it to maybe get a
              LF on the next read: */
@@ -6817,8 +6839,14 @@ static intptr_t fd_get_string_slow(Scheme_Input_Port *port,
       }
 
       if (!fip->bufcount) {
-        fip->buffpos = 0;
-        return EOF;
+        if (fip->textmode > 1) {
+          /* have a CR pending, so maybe keep trying */
+          if (nonblock > 0)
+            return 0;
+        } else {
+          fip->buffpos = 0;
+          return EOF;
+        }
       } else {
         bc = ((size <= fip->bufcount)
               ? size
@@ -7023,7 +7051,7 @@ make_fd_input_port(intptr_t fd, Scheme_Object *name, int regfile, int win_textmo
   if (regfile || isatty(fd))
     fip->textmode = 1;
 #else
-  fip->textmode = win_textmode;  
+  fip->textmode = (win_textmode ? 1 : 0);
 #endif
 
   if (refcount) {
@@ -7053,6 +7081,14 @@ make_fd_input_port(intptr_t fd, Scheme_Object *name, int regfile, int win_textmo
 
   ip->pending_eof = 1; /* means that pending EOFs should be tracked */
 
+#ifdef WINDOWS_FILE_HANDLES
+  if (fip->textmode) {
+    char *bw;
+    bw = (char *)scheme_malloc_atomic(MZPORT_FD_BUFFSIZE);
+    ip->bufwidths = bw;
+  }
+#endif
+
 #ifdef WINDOWS_FILE_HANDLES
   if (!regfile && !start_closed) {
     /* To get non-blocking I/O for anything that can block, we create