Remove MAX_PATH restrictions from RTS, I/O manager and various utilities

Summary:
This shims out fopen and sopen so that they use modern APIs under the hood
along with namespaced paths.

This lifts the MAX_PATH restrictions from Haskell programs and makes the new
limit ~32k.

There are only some slight caveats that have been documented.

Some utilities have not been upgraded such as lndir, since all these things are
different cabal packages I have been forced to copy the source in different places
which is less than ideal. But it's the only way to keep sdist working.

Test Plan: ./validate

Reviewers: hvr, bgamari, erikd, simonmar

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #10822

Differential Revision: https://phabricator.haskell.org/D4416

3 files changed, 13 insertions, 11 deletions

diff --git a/utils/unlit/ghc.mk b/utils/unlit/ghc.mk
index 8911f4e856..0560aa57b8 100644
--- a/utils/unlit/ghc.mk
+++ b/utils/unlit/ghc.mk
@@ -11,7 +11,7 @@
 # -----------------------------------------------------------------------------
 
 # built by ghc-stage0
-utils/unlit_dist_C_SRCS  = unlit.c
+utils/unlit_dist_C_SRCS  = unlit.c fs.c
 utils/unlit_dist_PROGNAME = unlit
 utils/unlit_dist_TOPDIR  = YES
 utils/unlit_dist_INSTALL_INPLACE = YES
diff --git a/utils/unlit/unlit.c b/utils/unlit/unlit.c
index 4eb91d71be..97f853b268 100644
--- a/utils/unlit/unlit.c
+++ b/utils/unlit/unlit.c
@@ -7,7 +7,7 @@
  * column on each line.  It is hoped that this style of programming will
  * encourage the writing of accurate and clearly documented programs
  * in which the writer may include motivating arguments, examples
- * and explanations.  
+ * and explanations.
  *
  * Unlit is a filter that can be used to strip all of the comment lines
  * out of a literate script file.  The command format for unlit is:
@@ -40,6 +40,7 @@
  * And \begin{pseudocode} ... \end{pseudocode}.  -- LA
  */
 
+#include "fs.h"
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -115,7 +116,7 @@ static void myputc(char c, FILE *ostream)
 {
     if (putc(c,ostream) == EOF) {
 	writeerror();
-    }	
+    }
 }
 
 #define TABPOS 8
@@ -179,7 +180,7 @@ static line readline(FILE *istream, FILE *ostream) {
 
     if (c==EOF)
         return ENDFILE;
-  
+
     if ( c == '#' ) {
       if ( ignore_shebang ) {
          c1 = egetc(istream);
@@ -335,10 +336,10 @@ int main(int argc,char **argv)
         else if (strcmp(*argv,"-h")==0) {
 	  if (argc > 1) {
 	    argc--; argv++;
-	    if (prefix_str) 
+	    if (prefix_str)
 	      free(prefix_str);
 	    prefix_str = (char*)malloc(sizeof(char)*(1+strlen(*argv)));
-	    if (prefix_str) 
+	    if (prefix_str)
 	      strcpy(prefix_str, *argv);
 	  }
         } else if (strcmp(*argv,"-#")==0)
@@ -362,16 +363,16 @@ int main(int argc,char **argv)
         file    = "stdin";
     }
     else
-        if ((istream=fopen(argv[0], "r")) == NULL) {
+        if ((istream=__hs_fopen(argv[0], "r")) == NULL) {
             fprintf(stderr, CANNOTOPEN, argv[0]);
             exit(1);
         }
 
     ofilename=argv[1];
-    if (strcmp(argv[1], "-")==0) 
-        ostream = stdout; 
+    if (strcmp(argv[1], "-")==0)
+        ostream = stdout;
     else
-        if ((ostream=fopen(argv[1], "w")) == NULL)  {
+        if ((ostream=__hs_fopen(argv[1], "w")) == NULL)  {
             fprintf(stderr, CANNOTOPEN, argv[1]);
             exit(1);
         }
diff --git a/utils/unlit/unlit.cabal b/utils/unlit/unlit.cabal
index a621f04bc7..622a55934d 100644
--- a/utils/unlit/unlit.cabal
+++ b/utils/unlit/unlit.cabal
@@ -13,4 +13,5 @@ build-type: Simple
 Executable unlit
     Default-Language: Haskell2010
     Main-Is: unlit.c
-    C-Sources: unlit.c
+    C-Sources: unlit.c, fs.c
+    Includes: fs.h