Use real path of all files internally, requires _XOPEN_SOURCE>=500, fixes issue #137

Makefile

@@ -1,12 +1,13 @@
-VERSION = git-20140218
+VERSION = git-20140317
 
 PREFIX    = /usr/local
 MANPREFIX = $(PREFIX)/share/man
 
-CC      = gcc
-CFLAGS  = -std=c99 -Wall -pedantic -O2 -I$(PREFIX)/include -DHAVE_GIFLIB
-LDFLAGS = -L$(PREFIX)/lib
-LIBS    = -lX11 -lImlib2 -lgif
+CC       = gcc
+CFLAGS   = -std=c99 -Wall -pedantic -O2
+CPPFLAGS = -I$(PREFIX)/include -D_XOPEN_SOURCE=500 -DHAVE_GIFLIB
+LDFLAGS  = -L$(PREFIX)/lib
+LIBS     = -lX11 -lImlib2 -lgif
 
 SRC = commands.c exif.c image.c main.c options.c thumbs.c util.c window.c
 OBJ = $(SRC:.c=.o)
@@ -16,7 +17,7 @@ all: sxiv
 $(OBJ): Makefile config.h
 
 .c.o:
-	$(CC) $(CFLAGS) -DVERSION=\"$(VERSION)\" -c -o $@ $<
+	$(CC) $(CFLAGS) $(CPPFLAGS) -DVERSION=\"$(VERSION)\" -c -o $@ $<
 
 config.h:
 	cp config.def.h $@

main.c

@@ -127,16 +127,28 @@ void check_add_file(char *filename)
 		filecnt *= 2;
 		files = (fileinfo_t*) s_realloc(files, filecnt * sizeof(fileinfo_t));
 	}
+
+#if defined _BSD_SOURCE || defined _XOPEN_SOURCE && \
+    ((_XOPEN_SOURCE - 0) >= 500 || defined _XOPEN_SOURCE_EXTENDED)
+
+	if ((files[fileidx].path = realpath(filename, NULL)) == NULL) {
+		warn("could not get real path of file: %s\n", filename);
+		return;
+	}
+#else
 	if (*filename != '/') {
-		files[fileidx].path = absolute_path(filename);
-		if (files[fileidx].path == NULL) {
+		if ((files[fileidx].path = absolute_path(filename)) == NULL) {
 			warn("could not get absolute path of file: %s\n", filename);
 			return;
 		}
+	} else {
+		files[fileidx].path = NULL;
 	}
+#endif
+
 	files[fileidx].loaded = false;
 	files[fileidx].name = s_strdup(filename);
-	if (*filename == '/')
+	if (files[fileidx].path == NULL)
 		files[fileidx].path = files[fileidx].name;
 	if ((bn = strrchr(files[fileidx].name , '/')) != NULL && bn[1] != '\0')
 		files[fileidx].base = ++bn;