Add s/foo/bar/: prefix for formats to substitute bar for foo.

format.c

@@ -99,6 +99,7 @@ format_job_cmp(struct format_job *fj1, struct format_job *fj2)
 #define FORMAT_TIMESTRING 0x1
 #define FORMAT_BASENAME 0x2
 #define FORMAT_DIRNAME 0x4
+#define FORMAT_SUBSTITUTE 0x8
 
 /* Entry in format tree. */
 struct format_entry {
@@ -682,8 +683,9 @@ int
 format_replace(struct format_tree *ft, const char *key, size_t keylen,
     char **buf, size_t *len, size_t *off)
 {
-	char		*copy, *copy0, *endptr, *ptr, *saved, *trimmed, *value;
-	size_t		 valuelen;
+	char		*copy, *copy0, *endptr, *ptr, *found, *new, *value;
+	char		*from = NULL, *to = NULL;
+	size_t		 valuelen, newlen, fromlen, tolen, used;
 	u_long		 limit = 0;
 	int		 modifiers = 0, brackets;
 
@@ -721,6 +723,29 @@ format_replace(struct format_tree *ft, const char *key, size_t keylen,
 		modifiers |= FORMAT_TIMESTRING;
 		copy += 2;
 		break;
+	case 's':
+		if (copy[1] != '/')
+			break;
+		from = copy + 2;
+		for (copy = from; *copy != '\0' && *copy != '/'; copy++)
+			/* nothing */;
+		if (copy[0] != '/' || copy == from) {
+			copy = copy0;
+			break;
+		}
+		copy[0] = '\0';
+		to = copy + 1;
+		for (copy = to; *copy != '\0' && *copy != '/'; copy++)
+			/* nothing */;
+		if (copy[0] != '/' || copy[1] != ':') {
+			copy = copy0;
+			break;
+		}
+		copy[0] = '\0';
+
+		modifiers |= FORMAT_SUBSTITUTE;
+		copy += 2;
+		break;
 	}
 
 	/*
@@ -734,7 +759,7 @@ format_replace(struct format_tree *ft, const char *key, size_t keylen,
 		*ptr = '\0';
 
 		value = ptr + 1;
-		saved = format_find(ft, copy + 1, modifiers);
+		found = format_find(ft, copy + 1, modifiers);
 
 		brackets = 0;
 		for (ptr = ptr + 1; *ptr != '\0'; ptr++) {
@@ -748,29 +773,56 @@ format_replace(struct format_tree *ft, const char *key, size_t keylen,
 		if (*ptr == '\0')
 			goto fail;
 
-		if (saved != NULL && *saved != '\0' &&
-		    (saved[0] != '0' || saved[1] != '\0')) {
+		if (found != NULL && *found != '\0' &&
+		    (found[0] != '0' || found[1] != '\0')) {
 			*ptr = '\0';
 		} else
 			value = ptr + 1;
 		value = format_expand(ft, value);
-		free(saved);
-		saved = value;
+		free(found);
 	} else {
-		saved = value = format_find(ft, copy, modifiers);
+		value = format_find(ft, copy, modifiers);
 		if (value == NULL)
-			saved = value = xstrdup("");
+			value = xstrdup("");
+	}
+
+	/* Perform substitution if any. */
+	if (modifiers & FORMAT_SUBSTITUTE) {
+		fromlen = strlen(from);
+		tolen = strlen(to);
+
+		newlen = strlen(value) + 1;
+		copy = new = xmalloc(newlen);
+		for (ptr = value; *ptr != '\0'; /* nothing */) {
+			if (strncmp(ptr, from, fromlen) != 0) {
+				*new++ = *ptr++;
+				continue;
+			}
+			used = new - copy;
+
+			newlen += tolen;
+			copy = xrealloc(copy, newlen);
+
+			new = copy + used;
+			memcpy(new, to, tolen);
+
+			new += tolen;
+			ptr += fromlen;
+		}
+		*new = '\0';
+		free(value);
+		value = copy;
 	}
 
 	/* Truncate the value if needed. */
 	if (limit != 0) {
-		value = trimmed = utf8_trimcstr(value, limit);
-		free(saved);
-		saved = trimmed;
+		new = utf8_trimcstr(value, limit);
+		free(value);
+		value = new;
 	}
-	valuelen = strlen(value);
 
 	/* Expand the buffer and copy in the value. */
+	valuelen = strlen(value);
 	while (*len - *off < valuelen + 1) {
 		*buf = xreallocarray(*buf, 2, *len);
 		*len *= 2;
@@ -778,7 +830,7 @@ format_replace(struct format_tree *ft, const char *key, size_t keylen,
 	memcpy(*buf + *off, value, valuelen);
 	*off += valuelen;
 
-	free(saved);
+	free(value);
 	free(copy0);
 	return (0);
 

tmux.1

@@ -3311,6 +3311,13 @@ prefixes are
 and
 .Xr dirname 3
 of the variable respectively.
+A prefix of the form
+.Ql s/foo/bar/:
+will substitute
+.Ql foo
+with
+.Ql bar
+throughout.
 .Pp
 In addition, the first line of a shell command's output may be inserted using
 .Ql #() .