New junkcode.

junkcode/fork0@users.sf.net-pathexpand/pathexpand.c

+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/*
+ * Returns the analog of "cd path" from a directory "cwd".
+ * The root is defined as empty path (instead of "/")
+ * An attempt to go past the root (with "..") leaves the path at root.
+ * The cwd is not expanded.
+ */
+char *pathexpand(const char *cwd, const char *path)
+{
+	static const char SEP[] = "/";
+	if (!*path) /* empty path -> "." (don't move) */
+		path = ".";
+	if (!*cwd || *SEP == *path) /* no cwd, or path begins with "/" */
+		cwd = "";
+
+	while (*cwd && *SEP == *cwd)
+		++cwd;
+
+	size_t len = strlen(cwd);
+	char *out = malloc(len + 1 + strlen(path) + 1);
+	char *p = strcpy(out, cwd) + len;
+
+	for (; *path; ++path)
+	{
+		char *pl;
+		if (p > out && p[-1] != *SEP)
+			*p++ = *SEP;
+		pl = p;
+		while (*path && *SEP != *path)
+			*p++ = *path++;
+		*p = '\0';
+		/* ..."//"... */
+		if (p == pl)
+			; /* just ignore */
+		/* ..."/./"...  */
+		else if ( p - pl == 1 && '.' == *pl )
+			--p; /* just ignore */
+		/* ..."/../"...  */
+		else if ( p - pl == 2 && '.' == pl[0] && '.' == pl[1] )
+		{
+			/* drop the last element of the resulting path */
+			if (pl > out && --pl > out)
+				for (--pl; pl > out && *SEP != *pl; --pl)
+					;
+			p = pl > out ? ++pl: out;
+		}
+		/* ..."/path/"...  */
+		else if (*path)
+			*p++ = *path; /* just add the separator */
+
+		if (!*path)
+			break;
+	}
+	if (p > out+1 && *SEP == p[-1])
+		--p;
+	*p = '\0';
+	return out;
+}
+
+#ifdef CHECK_PATHEXPAND
+static void check(const char *cwd, const char *path, const char *good)
+{
+	static int n = 0;
+	printf("%-2d: %10s$ cd %s", ++n, cwd, path);
+	char *t = pathexpand(cwd, path);
+	if ( strcmp(t, good) )
+		printf(" ____________________failed(%s)\n", t);
+	else
+		printf(" \033[32m%s\033[0m\n", t);
+	free(t);
+}
+
+int main(int argc, char **argv)
+{
+	/* 1 */ check("/onelevel", "aa", "onelevel/aa");
+	/* 2 */ check("/", "..", "");
+	/* 3 */ check("/", "../..", "");
+	/* 4 */ check("/one", "aa/../bb", "one/bb");
+	/* 5 */ check("/one/two", "aa//bb", "one/two/aa/bb");
+	/* 6 */ check("", "/aa//bb", "aa/bb");
+	/* 7 */ check("/one/two", "", "one/two");
+	/* 8 */ check("/one/two", "aa/..bb/x/../cc/", "one/two/aa/..bb/cc");
+	/* 9 */ check("/one/two", "aa/x/././cc////", "one/two/aa/x/cc");
+	/* 10 */ check("/one/two", "../../../../aa", "aa");
+	/* 11 */ check("one/", "../one/two", "one/two");
+	/* 12 */ check("", "../../two", "two");
+	/* 13 */ check("a/b/c", "../../two", "a/two");
+	/* 14 */ check("a/b/", "../two", "a/two");
+	/* 15 */ check("///", "../two", "two");
+	return 0;
+}
+#endif
+