Fix filename extension detection on relative paths

Added "sir" (reverse string index search) function to eval.c which enables the emacs.rc script to fetch the filename extension correctly even when loading the file using a relative path. Signed-off-by: Luiz A. Bühnemann <[email protected]>
torvalds · May 11, 2022 · 4a7c6ca · 4a7c6ca
1 parent 1cdcf9d
commit 4a7c6ca
Show file tree

Hide file tree

Showing 4 changed files with 48 additions and 1 deletion.
diff --git a/efunc.h b/efunc.h
@@ -346,6 +346,7 @@ extern char *mklower(char *str);
 extern int abs(int x);
 extern int ernd(void);
 extern int sindex(char *source, char *pattern);
+extern int rsindex(char *source, char *pattern);
 extern char *xlat(char *source, char *lookup, char *trans);
 
 /* crypt.c */

diff --git a/emacs.rc b/emacs.rc
@@ -198,7 +198,7 @@ bind-to-key execute-macro-40 M-?
 		add-mode "wrap"
 		!return
 	!endif
-	set %rctmp &sin $cfname "."
+	set %rctmp &sir $cfname "."
 	!if &equ %rctmp 0
 		!return
 	!endif

diff --git a/eval.c b/eval.c
@@ -166,6 +166,8 @@ char *gtfun(char *fname)
 		return itoa(~atoi(arg1));
 	case UFXLATE:
 		return xlat(arg1, arg2, arg3);
+	case UFRSINDEX:
+		return itoa(rsindex(arg1, arg2));
 	}
 
 	exit(-11);		/* never should get here */
@@ -972,6 +974,48 @@ int sindex(char *source, char *pattern)
 	return 0;
 }
 
+/*
+ * reverse find pattern within source
+ *
+ * char *source;	source string to search
+ * char *pattern;	string to look for
+ */
+int rsindex(char *source, char *pattern)
+{
+	char *sp;		/* ptr to current position to scan */
+	char *csp;		/* ptr to source string during comparison */
+	char *cp;		/* ptr to place to check for equality */
+	int lp;
+	int ls;
+
+	ls = strlen(source);
+	lp = strlen(pattern);
+	if (ls == 0 || lp == 0 || ls < lp)
+		return 0;
+
+	/* scanning through the source string */
+	sp = source + ls - lp;
+	while (sp >= source) {
+		/* scan through the pattern */
+		cp = pattern;
+		csp = sp;
+		while (*cp) {
+			if (!eq(*cp, *csp))
+				break;
+			++cp;
+			++csp;
+		}
+
+		/* was it a match? */
+		if (*cp == 0)
+			return (int) (sp - source) + 1;
+		--sp;
+	}
+
+	/* no match at all.. */
+	return 0;
+}
+
 /*
  * Filter a string through a translation table
  *

diff --git a/evar.h b/evar.h
@@ -162,6 +162,7 @@ static struct user_function funcs[] = {
 	{ "bxo", DYNAMIC },	/* bitwise xor   9-10-87  jwm */
 	{ "bno", MONAMIC },	/* bitwise not */
 	{ "xla", TRINAMIC },	/* XLATE character string translation */
+	{ "sir", DYNAMIC }	/* reverse find the index of one string in another */
 };
 
 /* And its preprocesor definitions. */
@@ -205,5 +206,6 @@ static struct user_function funcs[] = {
 #define UFBXOR		36
 #define	UFBNOT		37
 #define	UFXLATE		38
+#define UFRSINDEX	39
 
 #endif  /* EVAR_H_ */