>From 341ac1c69df18eac9a5ebf0cfc5553fa62bff3bd Mon Sep 17 00:00:00 2001
From: Christian Kellermann <address@hidden>
Date: Wed, 28 Sep 2011 17:23:57 +0200
Subject: [PATCH] Replace ##sys#file-info with ##sys#file-exists

This also introduces a simpler runtime function that calls access to
test for file accessability.

This fixes bug #706 reported by Sven Hartrumpf.

The old version  returned false whenever fstat failed.  In Sven's case
the size parameter overflowed, and file-exists? returns #f.

Thanks to Thomas Chust for the suggestion.
---
 chicken.h   |    3 ++-
 library.scm |    3 ++-
 runtime.c   |   31 +++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/chicken.h b/chicken.h
index 8c6eff3..47b12f7 100644
--- a/chicken.h
+++ b/chicken.h
@@ -572,7 +572,7 @@ static inline int isinf_ld (long double x)
 #define C_CIRCULAR_DATA_ERROR                         36
 #define C_BAD_ARGUMENT_TYPE_NO_BOOLEAN_ERROR          37
 #define C_BAD_ARGUMENT_TYPE_NO_LOCATIVE_ERROR         38
-
+#define C_SYSCALL_ERROR                               39
 
 /* Platform information */
 #if defined(C_BIG_ENDIAN)
@@ -1674,6 +1674,7 @@ C_fctexport void C_ccall C_make_tagged_pointer(C_word c, C_word closure, C_word
 C_fctexport void C_ccall C_ensure_heap_reserve(C_word c, C_word closure, C_word k, C_word n) C_noret;
 C_fctexport void C_ccall C_return_to_host(C_word c, C_word closure, C_word k) C_noret;
 C_fctexport void C_ccall C_file_info(C_word c, C_word closure, C_word k, C_word port) C_noret;
+C_fctexport void C_ccall C_file_exists(C_word c, C_word closure, C_word k, C_word port) C_noret;
 C_fctexport void C_ccall C_get_environment_variable(C_word c, C_word closure, C_word k, C_word name) C_noret;
 C_fctexport void C_ccall C_get_symbol_table_info(C_word c, C_word closure, C_word k) C_noret;
 C_fctexport void C_ccall C_get_memory_info(C_word c, C_word closure, C_word k) C_noret;
diff --git a/library.scm b/library.scm
index e07e9c4..5fef68e 100644
--- a/library.scm
+++ b/library.scm
@@ -191,6 +191,7 @@ EOF
 (define ##sys#call-host (##core#primitive "C_return_to_host"))
 (define return-to-host ##sys#call-host)
 (define ##sys#file-info (##core#primitive "C_file_info"))
+(define ##sys#file-exists (##core#primitive "C_file_exists"))
 (define ##sys#symbol-table-info (##core#primitive "C_get_symbol_table_info"))
 (define ##sys#memory-info (##core#primitive "C_get_memory_info"))
 (define (current-milliseconds) (##core#inline_allocate ("C_a_i_current_milliseconds" 4) #f))
@@ -1979,7 +1980,7 @@ EOF
   (##sys#pathname-resolution
     name
     (lambda (name)
-      (and (##sys#file-info (##sys#platform-fixup-pathname name)) name) )
+      (and (##sys#file-exists (##sys#platform-fixup-pathname name)) name) )
     #:exists?) )
 
 (define (directory-exists? name)
diff --git a/runtime.c b/runtime.c
index c0c91bc..32804cf 100644
--- a/runtime.c
+++ b/runtime.c
@@ -737,6 +737,7 @@ static C_PTABLE_ENTRY *create_initial_ptable()
   C_pte(C_ensure_heap_reserve);
   C_pte(C_return_to_host);
   C_pte(C_file_info);
+  C_pte(C_file_exists);
   C_pte(C_get_symbol_table_info);
   C_pte(C_get_memory_info);
   C_pte(C_decode_seconds);
@@ -1616,6 +1617,11 @@ void barf(int code, char *loc, ...)
     c = 0;
     break;
 
+  case C_SYSCALL_ERROR:
+    msg = C_text("Underlying syscall error");
+    c = 1;
+    break;
+
   default: panic(C_text("illegal internal error code"));
   }
   
@@ -7776,6 +7782,31 @@ void C_ccall C_file_info(C_word c, C_word closure, C_word k, C_word name)
   file_info_2(NULL);
 }
 
+void C_ccall C_file_exists(C_word c, C_word closure, C_word k, C_word name)
+{
+  C_word v = C_SCHEME_FALSE;
+  int call_res = 0;
+
+  int len = C_header_size(name);
+  char *buffer2;
+  int res = 0;
+
+  buffer2 = buffer;
+  if(len >= sizeof(buffer)) {
+    if((buffer2 = (char *)C_malloc(len + 1)) == NULL)
+      barf(C_OUT_OF_MEMORY_ERROR, "stat");
+  }
+  C_strncpy(buffer2, C_c_string(name), len);
+  buffer2[ len ] = '\0';
+  call_res=access(buffer2, F_OK);
+  if (call_res == 0) {
+    v = C_SCHEME_TRUE;
+  } else if (errno != ENOENT) {
+    barf(C_SYSCALL_ERROR, "access");
+  }
+
+  C_kontinue(k, v);
+}
 
 void file_info_2(void *dummy)
 {
-- 
1.7.4.1