msvcrt: Change how fread splits reading into chunks.

dlls/msvcrt/file.c

@@ -4300,7 +4300,7 @@ MSVCRT_size_t CDECL MSVCRT__fread_nolock(void *ptr, MSVCRT_size_t size, MSVCRT_s
   while(rcnt>0)
   {
     int i;
-    if (!file->_cnt && rcnt<MSVCRT_BUFSIZ && (file->_flag & (MSVCRT__IOMYBUF | MSVCRT__USERBUF))) {
+    if (!file->_cnt && rcnt<file->_bufsiz && (file->_flag & (MSVCRT__IOMYBUF | MSVCRT__USERBUF))) {
       i = MSVCRT__read(file->_file, file->_base, file->_bufsiz);
       file->_ptr = file->_base;
       if (i != -1) {
@@ -4319,10 +4319,10 @@ MSVCRT_size_t CDECL MSVCRT__fread_nolock(void *ptr, MSVCRT_size_t size, MSVCRT_s
       }
     } else if (rcnt > INT_MAX) {
       i = MSVCRT__read(file->_file, ptr, INT_MAX);
-    } else if (rcnt < MSVCRT_BUFSIZ) {
+    } else if (rcnt < (file->_bufsiz ? file->_bufsiz : MSVCRT_INTERNAL_BUFSIZ)) {
       i = MSVCRT__read(file->_file, ptr, rcnt);
     } else {
-      i = MSVCRT__read(file->_file, ptr, rcnt - MSVCRT_BUFSIZ/2);
+      i = MSVCRT__read(file->_file, ptr, rcnt - rcnt % (file->_bufsiz ? file->_bufsiz : MSVCRT_INTERNAL_BUFSIZ));
     }
     pread += i;
     rcnt -= i;

dlls/msvcrt/tests/file.c

@@ -222,7 +222,7 @@ static void test_readmode( BOOL ascii_mode )
     static const char outbuffer[] = "0,1,2,3,4,5,6,7,8,9\r\n\r\nA,B,C,D,E\r\nX,Y,Z";
     static const char padbuffer[] = "ghjghjghjghj";
     static const char nlbuffer[] = "\r\n";
-    char buffer[2*BUFSIZ+256];
+    static char buffer[8192];
     const char *optr;
     int fd;
     FILE *file;
@@ -327,7 +327,7 @@ static void test_readmode( BOOL ascii_mode )
     ok(feof(file)==0,"feof failure in %s\n", IOMODE);
     ok(fread(buffer,2,1,file)==0,"fread failure in %s\n",IOMODE);
     ok(feof(file)!=0,"feof failure in %s\n", IOMODE);
-    
+
     /* test some additional functions */
     rewind(file);
     ok(ftell(file) == 0,"Did not start at beginning of file in %s\n", IOMODE);
@@ -350,6 +350,30 @@ static void test_readmode( BOOL ascii_mode )
 
     fclose (file);
     unlink ("fdopen.tst");
+
+    /* test INTERNAL_BUFSIZ read containing 0x1a character (^Z) */
+    fd = open("fdopen.tst", O_WRONLY | O_CREAT | O_BINARY, _S_IREAD |_S_IWRITE);
+    ok(fd != -1, "open failed\n");
+    memset(buffer, 'a', sizeof(buffer));
+    buffer[1] = 0x1a;
+    ok(write(fd, buffer, sizeof(buffer)) == sizeof(buffer), "write failed\n");
+    ok(close(fd) != -1, "close failed\n");
+
+    fd = open("fdopen.tst", O_RDONLY);
+    ok(fd != -1, "open failed\n");
+    file = fdopen(fd, ascii_mode ? "r" : "rb");
+    ok(file != NULL, "fdopen failed\n");
+
+    memset(buffer, 0, sizeof(buffer));
+    i = fread(buffer, 4096, 1, file);
+    ok(!i, "fread succeeded\n");
+    ok(file->_bufsiz == 4096, "file->_bufsiz = %d\n", file->_bufsiz);
+    for(i=0; i<4096; i++)
+        if(buffer[i] != (i==1 ? 0x1a : 'a')) break;
+    ok(i==4096, "buffer[%d] = %d\n", i, buffer[i]);
+
+    fclose(file);
+    unlink("fdopen.tst");
 }
 
 static void test_asciimode(void)