pwd: implement -LP if DESKTOP

function                                             old     new   delta
pwd_main                                              41     244    +203

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

coreutils/pwd.c

@@ -20,13 +20,63 @@
 
 /* This is a NOFORK applet. Be very careful! */
 
+static int logical_getcwd(void)
+{
+	struct stat st1;
+	struct stat st2;
+	char *wd;
+	char *p;
+
+	wd = getenv("PWD");
+	if (!wd || wd[0] != '/')
+		return 0;
+
+	p = wd;
+	while (*p) {
+		/* doing strstr(p, "/.") by hand is smaller and faster... */
+		if (*p++ != '/')
+			continue;
+		if (*p != '.')
+			continue;
+		/* we found "/.", skip to next char */
+		p++;
+		if (*p == '.')
+			p++; /* we found "/.." */
+		if (*p == '\0' || *p == '/')
+    			return 0; /* "/./" or "/../" component: bad */
+	}
+
+	if (stat(wd, &st1) != 0)
+		return 0;
+	if (stat(".", &st2) != 0)
+		return 0;
+	if (st1.st_ino != st2.st_ino)
+		return 0;
+	if (st1.st_dev != st2.st_dev)
+		return 0;
+
+	puts(wd);
+	return 1;
+}
+
 int pwd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int pwd_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 {
 	char *buf;
 
+	if (ENABLE_DESKTOP) {
+		/* TODO: assume -L if $POSIXLY_CORRECT? (coreutils does that)
+		 * Rationale:
+		 * POSIX requires a default of -L, but most scripts expect -P
+		 */
+		unsigned opt = getopt32(argv, "LP");
+		if ((opt & 1) && logical_getcwd())
+			return fflush_all();
+	}
+
 	buf = xrealloc_getcwd_or_warn(NULL);
-	if (buf != NULL) {
+
+	if (buf) {
 		puts(buf);
 		free(buf);
 		return fflush_all();