[RFA/libiberty] Darwin has case-insensitive filesystems

[Joel Brobecker <brobecker at adacore dot com>]

Hello,

HFS+, the FS on Darwin, is case insensitive. So this patch adjusts
filename_cmp.c to ignore the casing when comparing filenames on Darwin.

This is visible in GDB when trying to break on a file whose name
is, say 'Mixed_Case.adb', but was compiled using 'mixed_case.adb'
as the filename.  In that case, GDB says it cannot find 'Mixed_Case.adb'.

There are two parts:
  1. in include/filenames.h: I add a new macro
     HAVE_CASE_INSENSITIVE_FILE_SYSTEM, which is defined on systems
     that have DOS-like file systems, as well as on Darwin.
  2. Adjust filename_cmp and filename_ncmp to take it into account.

I am also wondering whether it makes sense or not to keep the
case-sensitive & no DOS-like features case separate, or whether
we should handle this case using the same code as on Windows/Darwin.
In other words, does it make a difference to be using strcmp/strncmp
when we can, versus always using our loop that compares character by
character?

include/ChangeLog:

        * filenames.h (HAVE_CASE_INSENSITIVE_FILE_SYSTEM): Define
        on Darwin, as well as on the systems that use a DOS-like
        filesystem.

libiberty/ChangeLog:

        * filename_cmp.c (filename_cmp, filename_ncmp): Add handling of
        HAVE_CASE_INSENSITIVE_FILE_SYSTEM.

Tested on x86_64-darwin as well as on x86_64-linux. I haven't tested
on a Windows system yet, but I will get our gdb-testsuite's daily
results before tomorrow.

Does this look OK to commit?

Thanks!
-- 
Joel

---
 include/filenames.h      |    8 ++++++++
 libiberty/filename_cmp.c |   28 ++++++++++++++++++++++------
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/include/filenames.h b/include/filenames.h
index d4955df..75ec330 100644
--- a/include/filenames.h
+++ b/include/filenames.h
@@ -34,10 +34,18 @@ extern "C" {
 #  ifndef HAVE_DOS_BASED_FILE_SYSTEM
 #    define HAVE_DOS_BASED_FILE_SYSTEM 1
 #  endif
+#  ifndef HAVE_CASE_INSENSITIVE_FILE_SYSTEM
+#    define HAVE_CASE_INSENSITIVE_FILE_SYSTEM 1
+#  endif
 #  define HAS_DRIVE_SPEC(f) HAS_DOS_DRIVE_SPEC (f)
 #  define IS_DIR_SEPARATOR(c) IS_DOS_DIR_SEPARATOR (c)
 #  define IS_ABSOLUTE_PATH(f) IS_DOS_ABSOLUTE_PATH (f)
 #else /* not DOSish */
+#  if defined(__APPLE__)
+#    ifndef HAVE_CASE_INSENSITIVE_FILE_SYSTEM
+#      define HAVE_CASE_INSENSITIVE_FILE_SYSTEM 1
+#    endif
+#  endif /* __APPLE__ */
 #  define HAS_DRIVE_SPEC(f) (0)
 #  define IS_DIR_SEPARATOR(c) IS_UNIX_DIR_SEPARATOR (c)
 #  define IS_ABSOLUTE_PATH(f) IS_UNIX_ABSOLUTE_PATH (f)
diff --git a/libiberty/filename_cmp.c b/libiberty/filename_cmp.c
index 0eed120..5179f8d 100644
--- a/libiberty/filename_cmp.c
+++ b/libiberty/filename_cmp.c
@@ -50,19 +50,27 @@ and backward slashes are equal.
 int
 filename_cmp (const char *s1, const char *s2)
 {
-#ifndef HAVE_DOS_BASED_FILE_SYSTEM
+#if !defined(HAVE_DOS_BASED_FILE_SYSTEM) \
+    && !defined(HAVE_CASE_INSENSITIVE_FILE_SYSTEM)
   return strcmp(s1, s2);
 #else
   for (;;)
     {
-      int c1 = TOLOWER (*s1);
-      int c2 = TOLOWER (*s2);
+      int c1 = *s1;
+      int c2 = *s2;
 
+#if defined (HAVE_CASE_INSENSITIVE_FILE_SYSTEM)
+      c1 = TOLOWER (c1);
+      c2 = TOLOWER (c2);
+#endif
+
+#if defined (HAVE_DOS_BASED_FILE_SYSTEM)
       /* On DOS-based file systems, the '/' and the '\' are equivalent.  */
       if (c1 == '/')
         c1 = '\\';
       if (c2 == '/')
         c2 = '\\';
+#endif
 
       if (c1 != c2)
         return (c1 - c2);
@@ -100,21 +108,29 @@ and backward slashes are equal.
 int
 filename_ncmp (const char *s1, const char *s2, size_t n)
 {
-#ifndef HAVE_DOS_BASED_FILE_SYSTEM
+#if !defined(HAVE_DOS_BASED_FILE_SYSTEM) \
+    && !defined(HAVE_CASE_INSENSITIVE_FILE_SYSTEM)
   return strncmp(s1, s2, n);
 #else
   if (!n)
     return 0;
   for (; n > 0; --n)
   {
-      int c1 = TOLOWER (*s1);
-      int c2 = TOLOWER (*s2);
+      int c1 = *s1;
+      int c2 = *s2;
 
+#if defined (HAVE_CASE_INSENSITIVE_FILE_SYSTEM)
+      c1 = TOLOWER (c1);
+      c2 = TOLOWER (c2);
+#endif
+
+#if defined (HAVE_DOS_BASED_FILE_SYSTEM)
       /* On DOS-based file systems, the '/' and the '\' are equivalent.  */
       if (c1 == '/')
         c1 = '\\';
       if (c2 == '/')
         c2 = '\\';
+#endif
 
       if (c1 == '\0' || c1 != c2)
         return (c1 - c2);
-- 
1.7.1