Peter Castro: Cygwin improvements for dynamic libraries, text/binary, paths

1 files changed, 56 insertions, 0 deletions

diff --git a/Src/main.c b/Src/main.c
index c9c5fa867..30eef5a25 100644
--- a/Src/main.c
+++ b/Src/main.c
@@ -30,6 +30,62 @@
 #include "zsh.mdh"
 #include "main.pro"
 
+/*
+ * Support for Cygwin binary/text mode filesystems.
+ * Peter A. Castro <doctor@fruitbat.org>
+ *
+ * This deserves some explaination, because it uses Cygwin specific
+ * runtime functions.
+ *
+ * Cygwin supports the notion of binary or text mode access to files
+ * based on the mount attributes of the filesystem.  If a file is on
+ * a binary mounted filesystem, you get exactly what's in the file, CRLF's
+ * and all.  If it's on a text mounted filesystem, Cygwin will strip out
+ * the CRs.  This presents a problem because zsh code doesn't allow for
+ * CRLF's as line terminators.  So, we must force all open files to be
+ * in text mode reguardless of the underlying filesystem attributes.
+ * However, we only want to do this for reading, not writing as we still
+ * want to write files in the mode of the filesystem.  To do this,
+ * we have two options: augment all {f}open() calls to have O_TEXT added to
+ * the list of file mode options, or have the Cygwin runtime do it for us.
+ * I choose the latter. :)
+ *
+ * Cygwin's runtime provides pre-execution hooks which allow you to set
+ * various attributes for the process which effect how the process functions.
+ * One of these attributes controls how files are opened.  I've set
+ * it up so that all files opened RDONLY will have the O_TEXT option set,
+ * thus forcing line termination manipulation.  This seems to solve the
+ * problem (at least the Test suite runs clean :).
+ *
+ * Note: this may not work in later implementations.  This will override
+ * all mode options passed into open().  Cygwin (really Windows) doesn't
+ * support all that much in options, so for now this is OK, but later on
+ * it may not, in which case O_TEXT will have to be added to all opens calls
+ * appropriately.
+ *
+ * This function is actually a hook in the Cygwin runtime which
+ * is called before the main of a program.  Because it's part of the program
+ * pre-startup, it must be located in the program main and not in a DLL.
+ * It must also be made an export so the linker resolves this function to
+ * our code instead of the default Cygwin stub routine.
+ */
+
+/**/
+#ifdef __CYGWIN__
+/**/
+mod_export void
+cygwin_premain0 (int argc, char **argv, void *myself)
+{
+    static struct __cygwin_perfile pf[] =
+    {
+        {"", O_RDONLY | O_TEXT},
+        {NULL, 0}
+    };
+    cygwin_internal (CW_PERFILE, pf);
+}
+/**/
+#endif /* __CYGWIN__ */
+
 /**/
 int
 main(int argc, char **argv)