Portability improvements to nasm_realpath()

Try harder to nasm_realpath() to be as portable as possible.  Move it
to a separate file since it has gotten complex enough that it is
cleaner that way.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

8 files changed, 201 insertions, 22 deletions

diff --git a/Makefile.in b/Makefile.in
index 56f3589f..568549d6 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -74,6 +74,7 @@ endif
 #-- Begin File Lists --#
 NASM =	nasm.$(O) nasmlib.$(O) ver.$(O) \
 	raa.$(O) saa.$(O) rbtree.$(O) \
+	realpath.$(O) \
 	float.$(O) insnsa.$(O) insnsb.$(O) \
 	directiv.$(O) \
 	assemble.$(O) labels.$(O) hashtbl.$(O) crc64.$(O) parser.$(O) \
@@ -84,15 +85,16 @@ NASM =	nasm.$(O) nasmlib.$(O) ver.$(O) \
 	output/outelfx32.$(O) \
 	output/outobj.$(O) output/outas86.$(O) output/outrdf2.$(O) \
 	output/outdbg.$(O) output/outieee.$(O) output/outmac32.$(O) \
-	output/outmac64.$(O) preproc.$(O) quote.$(O) pptok.$(O) \
+	output/outmac64.$(O) \
+	md5c.$(O) output/codeview.$(O) \
+	preproc.$(O) quote.$(O) pptok.$(O) \
 	macros.$(O) listing.$(O) eval.$(O) exprlib.$(O) stdscan.$(O) \
 	strfunc.$(O) tokhash.$(O) regvals.$(O) regflags.$(O) \
 	ilog2.$(O) \
 	lib/strlcpy.$(O) \
 	preproc-nop.$(O) \
 	disp8.$(O) \
-	iflag.$(O) \
-	md5c.$(O) output/codeview.$(O)
+	iflag.$(O)
 
 NDISASM = ndisasm.$(O) disasm.$(O) sync.$(O) nasmlib.$(O) ver.$(O) \
 	insnsd.$(O) insnsb.$(O) insnsn.$(O) regs.$(O) regdis.$(O) \
@@ -343,6 +345,7 @@ listing.$(O): listing.c compiler.h config.h directiv.h insnsi.h listing.h \
 macros.$(O): macros.c compiler.h config.h directiv.h hashtbl.h insnsi.h \
  nasm.h nasmlib.h opflags.h output/outform.h pptok.h preproc.h regs.h \
  tables.h
+md5c.$(O): md5c.c md5.h
 nasm.$(O): nasm.c assemble.h compiler.h config.h directiv.h eval.h float.h \
  iflag.h iflaggen.h insns.h insnsi.h labels.h listing.h nasm.h nasmlib.h \
  opflags.h output/outform.h parser.h pptok.h preproc.h raa.h regs.h saa.h \
@@ -353,6 +356,9 @@ nasmlib.$(O): nasmlib.c compiler.h config.h directiv.h iflag.h iflaggen.h \
 ndisasm.$(O): ndisasm.c compiler.h config.h directiv.h disasm.h iflag.h \
  iflaggen.h insns.h insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h \
  regs.h sync.h tables.h tokens.h
+output/codeview.$(O): output/codeview.c compiler.h config.h directiv.h \
+ insnsi.h md5.h nasm.h nasmlib.h opflags.h output/outlib.h output/pecoff.h \
+ pptok.h preproc.h regs.h saa.h tables.h version.h
 output/nulldbg.$(O): output/nulldbg.c compiler.h config.h directiv.h \
  insnsi.h nasm.h nasmlib.h opflags.h output/outlib.h pptok.h preproc.h \
  regs.h tables.h
@@ -423,6 +429,9 @@ preproc.$(O): preproc.c compiler.h config.h directiv.h eval.h hashtbl.h \
 quote.$(O): quote.c compiler.h config.h nasmlib.h quote.h
 raa.$(O): raa.c compiler.h config.h nasmlib.h raa.h
 rbtree.$(O): rbtree.c compiler.h config.h rbtree.h
+realpath.$(O): realpath.c compiler.h config.h directiv.h iflag.h iflaggen.h \
+ insns.h insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h regs.h \
+ tables.h tokens.h
 regdis.$(O): regdis.c regdis.h regs.h
 regflags.$(O): regflags.c compiler.h config.h directiv.h insnsi.h nasm.h \
  nasmlib.h opflags.h pptok.h preproc.h regs.h tables.h
diff --git a/Mkfiles/msvc.mak b/Mkfiles/msvc.mak
index a2bae67e..93e910e0 100644
--- a/Mkfiles/msvc.mak
+++ b/Mkfiles/msvc.mak
@@ -25,7 +25,8 @@ CC		= cl
 LD		= link
 CFLAGS		= $(CFLAGS) /W2
 BUILD_CFLAGS	= $(CFLAGS) /I$(srcdir)/inttypes
-INTERNAL_CFLAGS = /I$(srcdir) /I. /DHAVE__SNPRINTF /DHAVE__VSNPRINTF
+INTERNAL_CFLAGS = /I$(srcdir) /I. \
+		  /DHAVE__SNPRINTF /DHAVE__VSNPRINTF /DHAVE__FULLPATH
 ALL_CFLAGS	= $(BUILD_CFLAGS) $(INTERNAL_CFLAGS)
 LDFLAGS		= $(LDFLAGS) /SUBSYSTEM:CONSOLE
 LIBS		=
@@ -44,6 +45,7 @@ X               = .exe
 # Edit in Makefile.in, not here!
 NASM =	nasm.$(O) nasmlib.$(O) ver.$(O) \
 	raa.$(O) saa.$(O) rbtree.$(O) \
+	realpath.$(O) \
 	float.$(O) insnsa.$(O) insnsb.$(O) \
 	directiv.$(O) \
 	assemble.$(O) labels.$(O) hashtbl.$(O) crc64.$(O) parser.$(O) \
@@ -54,15 +56,16 @@ NASM =	nasm.$(O) nasmlib.$(O) ver.$(O) \
 	output/outelfx32.$(O) \
 	output/outobj.$(O) output/outas86.$(O) output/outrdf2.$(O) \
 	output/outdbg.$(O) output/outieee.$(O) output/outmac32.$(O) \
-	output/outmac64.$(O) preproc.$(O) quote.$(O) pptok.$(O) \
+	output/outmac64.$(O) \
+	md5c.$(O) output/codeview.$(O) \
+	preproc.$(O) quote.$(O) pptok.$(O) \
 	macros.$(O) listing.$(O) eval.$(O) exprlib.$(O) stdscan.$(O) \
 	strfunc.$(O) tokhash.$(O) regvals.$(O) regflags.$(O) \
 	ilog2.$(O) \
 	lib/strlcpy.$(O) \
 	preproc-nop.$(O) \
 	disp8.$(O) \
-	iflag.$(O) \
-	md5c.$(O) output/codeview.$(O)
+	iflag.$(O)
 
 NDISASM = ndisasm.$(O) disasm.$(O) sync.$(O) nasmlib.$(O) ver.$(O) \
 	insnsd.$(O) insnsb.$(O) insnsn.$(O) regs.$(O) regdis.$(O) \
@@ -263,6 +266,7 @@ listing.$(O): listing.c compiler.h directiv.h insnsi.h listing.h nasm.h \
  nasmlib.h opflags.h pptok.h preproc.h regs.h tables.h
 macros.$(O): macros.c compiler.h directiv.h hashtbl.h insnsi.h nasm.h \
  nasmlib.h opflags.h output/outform.h pptok.h preproc.h regs.h tables.h
+md5c.$(O): md5c.c md5.h
 nasm.$(O): nasm.c assemble.h compiler.h directiv.h eval.h float.h iflag.h \
  iflaggen.h insns.h insnsi.h labels.h listing.h nasm.h nasmlib.h opflags.h \
  output/outform.h parser.h pptok.h preproc.h raa.h regs.h saa.h stdscan.h \
@@ -273,6 +277,9 @@ nasmlib.$(O): nasmlib.c compiler.h directiv.h iflag.h iflaggen.h insns.h \
 ndisasm.$(O): ndisasm.c compiler.h directiv.h disasm.h iflag.h iflaggen.h \
  insns.h insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h regs.h sync.h \
  tables.h tokens.h
+output/codeview.$(O): output/codeview.c compiler.h directiv.h insnsi.h md5.h \
+ nasm.h nasmlib.h opflags.h output/outlib.h output/pecoff.h pptok.h \
+ preproc.h regs.h saa.h tables.h version.h
 output/nulldbg.$(O): output/nulldbg.c compiler.h directiv.h insnsi.h nasm.h \
  nasmlib.h opflags.h output/outlib.h pptok.h preproc.h regs.h tables.h
 output/nullout.$(O): output/nullout.c compiler.h directiv.h insnsi.h nasm.h \
@@ -337,6 +344,9 @@ preproc.$(O): preproc.c compiler.h directiv.h eval.h hashtbl.h insnsi.h \
 quote.$(O): quote.c compiler.h nasmlib.h quote.h
 raa.$(O): raa.c compiler.h nasmlib.h raa.h
 rbtree.$(O): rbtree.c compiler.h rbtree.h
+realpath.$(O): realpath.c compiler.h directiv.h iflag.h iflaggen.h insns.h \
+ insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h regs.h tables.h \
+ tokens.h
 regdis.$(O): regdis.c regdis.h regs.h
 regflags.$(O): regflags.c compiler.h directiv.h insnsi.h nasm.h nasmlib.h \
  opflags.h pptok.h preproc.h regs.h tables.h
diff --git a/Mkfiles/netware.mak b/Mkfiles/netware.mak
index 0bc23e58..68a2118f 100644
--- a/Mkfiles/netware.mak
+++ b/Mkfiles/netware.mak
@@ -32,6 +32,7 @@ O = o
 # Edit in Makefile.in, not here!
 NASM =	nasm.o nasmlib.o ver.o \
 	raa.o saa.o rbtree.o \
+	realpath.o \
 	float.o insnsa.o insnsb.o \
 	directiv.o \
 	assemble.o labels.o hashtbl.o crc64.o parser.o \
@@ -42,7 +43,9 @@ NASM =	nasm.o nasmlib.o ver.o \
 	outelfx32.o \
 	outobj.o outas86.o outrdf2.o \
 	outdbg.o outieee.o outmac32.o \
-	outmac64.o preproc.o quote.o pptok.o \
+	outmac64.o \
+	md5c.o codeview.o \
+	preproc.o quote.o pptok.o \
 	macros.o listing.o eval.o exprlib.o stdscan.o \
 	strfunc.o tokhash.o regvals.o regflags.o \
 	ilog2.o \
@@ -171,6 +174,7 @@ listing.o: listing.c compiler.h config.h directiv.h insnsi.h listing.h \
  nasm.h nasmlib.h opflags.h pptok.h preproc.h regs.h tables.h
 macros.o: macros.c compiler.h config.h directiv.h hashtbl.h insnsi.h nasm.h \
  nasmlib.h opflags.h outform.h pptok.h preproc.h regs.h tables.h
+md5c.o: md5c.c md5.h
 nasm.o: nasm.c assemble.h compiler.h config.h directiv.h eval.h float.h \
  iflag.h iflaggen.h insns.h insnsi.h labels.h listing.h nasm.h nasmlib.h \
  opflags.h outform.h parser.h pptok.h preproc.h raa.h regs.h saa.h stdscan.h \
@@ -181,6 +185,9 @@ nasmlib.o: nasmlib.c compiler.h config.h directiv.h iflag.h iflaggen.h \
 ndisasm.o: ndisasm.c compiler.h config.h directiv.h disasm.h iflag.h \
  iflaggen.h insns.h insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h \
  regs.h sync.h tables.h tokens.h
+codeview.o: codeview.c compiler.h config.h directiv.h insnsi.h md5.h nasm.h \
+ nasmlib.h opflags.h outlib.h pecoff.h pptok.h preproc.h regs.h saa.h \
+ tables.h version.h
 nulldbg.o: nulldbg.c compiler.h config.h directiv.h insnsi.h nasm.h \
  nasmlib.h opflags.h outlib.h pptok.h preproc.h regs.h tables.h
 nullout.o: nullout.c compiler.h config.h directiv.h insnsi.h nasm.h \
@@ -241,6 +248,9 @@ preproc.o: preproc.c compiler.h config.h directiv.h eval.h hashtbl.h \
 quote.o: quote.c compiler.h config.h nasmlib.h quote.h
 raa.o: raa.c compiler.h config.h nasmlib.h raa.h
 rbtree.o: rbtree.c compiler.h config.h rbtree.h
+realpath.o: realpath.c compiler.h config.h directiv.h iflag.h iflaggen.h \
+ insns.h insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h regs.h \
+ tables.h tokens.h
 regdis.o: regdis.c regdis.h regs.h
 regflags.o: regflags.c compiler.h config.h directiv.h insnsi.h nasm.h \
  nasmlib.h opflags.h pptok.h preproc.h regs.h tables.h
diff --git a/Mkfiles/openwcom.mak b/Mkfiles/openwcom.mak
index 2d85eba8..7f69f7d8 100644
--- a/Mkfiles/openwcom.mak
+++ b/Mkfiles/openwcom.mak
@@ -48,6 +48,7 @@ X               = .exe
 # Edit in Makefile.in, not here!
 NASM =	nasm.$(O) nasmlib.$(O) ver.$(O) &
 	raa.$(O) saa.$(O) rbtree.$(O) &
+	realpath.$(O) &
 	float.$(O) insnsa.$(O) insnsb.$(O) &
 	directiv.$(O) &
 	assemble.$(O) labels.$(O) hashtbl.$(O) crc64.$(O) parser.$(O) &
@@ -58,7 +59,9 @@ NASM =	nasm.$(O) nasmlib.$(O) ver.$(O) &
 	output/outelfx32.$(O) &
 	output/outobj.$(O) output/outas86.$(O) output/outrdf2.$(O) &
 	output/outdbg.$(O) output/outieee.$(O) output/outmac32.$(O) &
-	output/outmac64.$(O) preproc.$(O) quote.$(O) pptok.$(O) &
+	output/outmac64.$(O) &
+	md5c.$(O) output/codeview.$(O) &
+	preproc.$(O) quote.$(O) pptok.$(O) &
 	macros.$(O) listing.$(O) eval.$(O) exprlib.$(O) stdscan.$(O) &
 	strfunc.$(O) tokhash.$(O) regvals.$(O) regflags.$(O) &
 	ilog2.$(O) &
@@ -309,6 +312,7 @@ listing.$(O): listing.c compiler.h config.h directiv.h insnsi.h listing.h &
 macros.$(O): macros.c compiler.h config.h directiv.h hashtbl.h insnsi.h &
  nasm.h nasmlib.h opflags.h output/outform.h pptok.h preproc.h regs.h &
  tables.h
+md5c.$(O): md5c.c md5.h
 nasm.$(O): nasm.c assemble.h compiler.h config.h directiv.h eval.h float.h &
  iflag.h iflaggen.h insns.h insnsi.h labels.h listing.h nasm.h nasmlib.h &
  opflags.h output/outform.h parser.h pptok.h preproc.h raa.h regs.h saa.h &
@@ -319,6 +323,9 @@ nasmlib.$(O): nasmlib.c compiler.h config.h directiv.h iflag.h iflaggen.h &
 ndisasm.$(O): ndisasm.c compiler.h config.h directiv.h disasm.h iflag.h &
  iflaggen.h insns.h insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h &
  regs.h sync.h tables.h tokens.h
+output/codeview.$(O): output/codeview.c compiler.h config.h directiv.h &
+ insnsi.h md5.h nasm.h nasmlib.h opflags.h output/outlib.h output/pecoff.h &
+ pptok.h preproc.h regs.h saa.h tables.h version.h
 output/nulldbg.$(O): output/nulldbg.c compiler.h config.h directiv.h &
  insnsi.h nasm.h nasmlib.h opflags.h output/outlib.h pptok.h preproc.h &
  regs.h tables.h
@@ -389,6 +396,9 @@ preproc.$(O): preproc.c compiler.h config.h directiv.h eval.h hashtbl.h &
 quote.$(O): quote.c compiler.h config.h nasmlib.h quote.h
 raa.$(O): raa.c compiler.h config.h nasmlib.h raa.h
 rbtree.$(O): rbtree.c compiler.h config.h rbtree.h
+realpath.$(O): realpath.c compiler.h config.h directiv.h iflag.h iflaggen.h &
+ insns.h insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h regs.h &
+ tables.h tokens.h
 regdis.$(O): regdis.c regdis.h regs.h
 regflags.$(O): regflags.c compiler.h config.h directiv.h insnsi.h nasm.h &
  nasmlib.h opflags.h pptok.h preproc.h regs.h tables.h
diff --git a/Mkfiles/owlinux.mak b/Mkfiles/owlinux.mak
index 85ad1b8e..90c7b357 100644
--- a/Mkfiles/owlinux.mak
+++ b/Mkfiles/owlinux.mak
@@ -59,6 +59,7 @@ X               = .exe
 # Edit in Makefile.in, not here!
 NASM =	nasm.$(O) nasmlib.$(O) ver.$(O) \
 	raa.$(O) saa.$(O) rbtree.$(O) \
+	realpath.$(O) \
 	float.$(O) insnsa.$(O) insnsb.$(O) \
 	directiv.$(O) \
 	assemble.$(O) labels.$(O) hashtbl.$(O) crc64.$(O) parser.$(O) \
@@ -69,7 +70,9 @@ NASM =	nasm.$(O) nasmlib.$(O) ver.$(O) \
 	output/outelfx32.$(O) \
 	output/outobj.$(O) output/outas86.$(O) output/outrdf2.$(O) \
 	output/outdbg.$(O) output/outieee.$(O) output/outmac32.$(O) \
-	output/outmac64.$(O) preproc.$(O) quote.$(O) pptok.$(O) \
+	output/outmac64.$(O) \
+	md5c.$(O) output/codeview.$(O) \
+	preproc.$(O) quote.$(O) pptok.$(O) \
 	macros.$(O) listing.$(O) eval.$(O) exprlib.$(O) stdscan.$(O) \
 	strfunc.$(O) tokhash.$(O) regvals.$(O) regflags.$(O) \
 	ilog2.$(O) \
@@ -277,6 +280,7 @@ listing.$(O): listing.c compiler.h directiv.h insnsi.h listing.h nasm.h \
  nasmlib.h opflags.h pptok.h preproc.h regs.h tables.h
 macros.$(O): macros.c compiler.h directiv.h hashtbl.h insnsi.h nasm.h \
  nasmlib.h opflags.h output/outform.h pptok.h preproc.h regs.h tables.h
+md5c.$(O): md5c.c md5.h
 nasm.$(O): nasm.c assemble.h compiler.h directiv.h eval.h float.h iflag.h \
  iflaggen.h insns.h insnsi.h labels.h listing.h nasm.h nasmlib.h opflags.h \
  output/outform.h parser.h pptok.h preproc.h raa.h regs.h saa.h stdscan.h \
@@ -287,6 +291,9 @@ nasmlib.$(O): nasmlib.c compiler.h directiv.h iflag.h iflaggen.h insns.h \
 ndisasm.$(O): ndisasm.c compiler.h directiv.h disasm.h iflag.h iflaggen.h \
  insns.h insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h regs.h sync.h \
  tables.h tokens.h
+output/codeview.$(O): output/codeview.c compiler.h directiv.h insnsi.h md5.h \
+ nasm.h nasmlib.h opflags.h output/outlib.h output/pecoff.h pptok.h \
+ preproc.h regs.h saa.h tables.h version.h
 output/nulldbg.$(O): output/nulldbg.c compiler.h directiv.h insnsi.h nasm.h \
  nasmlib.h opflags.h output/outlib.h pptok.h preproc.h regs.h tables.h
 output/nullout.$(O): output/nullout.c compiler.h directiv.h insnsi.h nasm.h \
@@ -351,6 +358,9 @@ preproc.$(O): preproc.c compiler.h directiv.h eval.h hashtbl.h insnsi.h \
 quote.$(O): quote.c compiler.h nasmlib.h quote.h
 raa.$(O): raa.c compiler.h nasmlib.h raa.h
 rbtree.$(O): rbtree.c compiler.h rbtree.h
+realpath.$(O): realpath.c compiler.h directiv.h iflag.h iflaggen.h insns.h \
+ insnsi.h nasm.h nasmlib.h opflags.h pptok.h preproc.h regs.h tables.h \
+ tokens.h
 regdis.$(O): regdis.c regdis.h regs.h
 regflags.$(O): regflags.c compiler.h directiv.h insnsi.h nasm.h nasmlib.h \
  opflags.h pptok.h preproc.h regs.h tables.h
diff --git a/configure.in b/configure.in
index fba5d323..f3274263 100644
--- a/configure.in
+++ b/configure.in
@@ -126,6 +126,12 @@ AC_CHECK_HEADERS(strings.h)
 dnl Look for <stdbool.h>
 AC_CHECK_HEADERS(stdbool.h)
 
+dnl Look for <unistd.h>
+AC_CHECK_HEADERS(unistd.h)
+
+dnl Look for <sys/param.h>
+AC_CHECK_HEADERS(sys/param.h)
+
 dnl Checks for library functions.
 AC_SUBST(XOBJS)
 
@@ -155,6 +161,11 @@ AC_CHECK_FUNCS(strlcpy)
 AC_CHECK_FUNCS(getuid)
 AC_CHECK_FUNCS(getgid)
 
+AC_CHECK_FUNCS(realpath)
+AC_CHECK_FUNCS(canonicalize_file_name)
+AC_CHECK_FUNCS(_fullpath)
+AC_CHECK_FUNCS(pathconf)
+
 dnl Check for functions that might not be declared in the headers for
 dnl various idiotic reasons (mostly because of library authors
 dnl abusing the meaning of __STRICT_ANSI__)
diff --git a/nasmlib.c b/nasmlib.c
index 9d57adbc..ecd6d8df 100644
--- a/nasmlib.c
+++ b/nasmlib.c
@@ -696,18 +696,6 @@ char *nasm_opt_val(char *p, char **val, char **next)
     return p;
 }
 
-#ifdef _WIN32
-char *nasm_realpath(const char *rel_path)
-{
-    return _fullpath(NULL, rel_path, 0);
-}
-#else
-char *nasm_realpath(const char *rel_path)
-{
-    return realpath(rel_path, NULL);
-}
-#endif
-
 /*
  * initialized data bytes length from opcode
  */
diff --git a/realpath.c b/realpath.c
new file mode 100644
index 00000000..a1c21010
--- /dev/null
+++ b/realpath.c
@@ -0,0 +1,131 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2016 The NASM Authors - All Rights Reserved
+ *   See the file AUTHORS included with the NASM distribution for
+ *   the specific copyright holders.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following
+ *   conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ *     copyright notice, this list of conditions and the following
+ *     disclaimer in the documentation and/or other materials provided
+ *     with the distribution.
+ *
+ *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * realpath.c	As system-independent as possible implementation of realpath()
+ */
+
+#include "compiler.h"
+
+#include <stdlib.h>
+#include <errno.h>
+#include <limits.h>
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifdef HAVE_SYS_PARAM_H
+# include <sys/param.h>
+#endif
+
+#include "nasmlib.h"
+
+#if 0 /* def HAVE_CANONICALIZE_FILE_NAME */
+
+/*
+ * GNU-specific, but avoids the realpath(..., NULL)
+ * portability problem if it exists.
+ */
+char *nasm_realpath(const char *rel_path)
+{
+    return canonicalize_file_name(rel_path);
+}
+
+#elif defined(HAVE_REALPATH)
+
+/*
+ * POSIX.1-2008 defines realpath(..., NULL); POSIX.1-2001 doesn't guarantee
+ * that a NULL second argument is supported.
+ */
+
+char *nasm_realpath(const char *rel_path)
+{
+    char *buf;
+
+    buf = realpath(rel_path, NULL);
+    if (buf)
+        return buf;
+
+    /* Not all implemetations of realpath() support a NULL second argument */
+    if (errno == EINVAL) {
+        int path_max = -1;
+        char *buf;
+
+# ifdef PATH_MAX
+        path_max = PATH_MAX;    /* SUSv2 */
+# elif defined(MAXPATHLEN)
+        path_max = MAXPATHLEN;  /* Solaris */
+# elif defined(HAVE_PATHCONF) && defined(_PC_PATH_MAX)
+        path_max = pathconf(path, _PC_PATH_MAX); /* POSIX */
+# endif
+        if (path_max < 0)
+            path_max = 65536;    /* Crazily high, we hope */
+
+        buf = nasm_malloc(path_max);
+
+        if (!realpath(rel_path, buf)) {
+            nasm_free(buf);
+            buf = NULL;
+        } else {
+            /* On some systems, pathconf() can return a very large value */
+
+            buf[path_max - 1] = '\0'; /* Just in case overrun is possible */
+            buf = nasm_realloc(buf, strlen(buf) + 1);
+        }
+    }
+
+    return buf;
+}
+
+#elif defined(HAVE__FULLPATH)
+
+/*
+ * win32/win64 API
+ */
+
+char *nasm_realpath(const char *rel_path)
+{
+    return _fullpath(NULL, rel_path, 0);
+}
+
+#else
+
+/*
+ * There is nothing we know how to do here, so hope it just works anyway.
+ */
+
+char *nasm_realpath(const char *rel_path)
+{
+    return nasm_strdup(rel_path);
+}
+
+#endif