acme: accept expanded URLs in look

Just as look expands a click in /etc/passwd to the full name
(provided that file exists), it now expands a click in https://9fans.net/
to the full URL (provided the prefix is http:// or https://).
Probably more adjustment is needed.

src/cmd/acme/look.c

@@ -30,7 +30,7 @@ plumbthread(void *v)
 
 	USED(v);
 	threadsetname("plumbproc");
-	
+
 	/*
 	 * Loop so that if plumber is restarted, acme need not be.
 	 */
@@ -46,7 +46,7 @@ plumbthread(void *v)
 		}
 		plumbeditfid = fid;
 		plumbsendfid = plumbopenfid("send", OWRITE|OCEXEC);
-	
+
 		/*
 		 * Relay messages.
 		 */
@@ -432,9 +432,9 @@ includename(Text *t, Rune *r, int n)
 	char buf[128];
 	Rune Lsysinclude[] = { '/', 's', 'y', 's', '/', 'i', 'n', 'c', 'l', 'u', 'd', 'e', 0 };
 	Rune Lusrinclude[] = { '/', 'u', 's', 'r', '/', 'i', 'n', 'c', 'l', 'u', 'd', 'e', 0 };
-	Rune Lusrlocalinclude[] = { '/', 'u', 's', 'r', '/', 'l', 'o', 'c', 'a', 'l', 
+	Rune Lusrlocalinclude[] = { '/', 'u', 's', 'r', '/', 'l', 'o', 'c', 'a', 'l',
 			'/', 'i', 'n', 'c', 'l', 'u', 'd', 'e', 0 };
-	Rune Lusrlocalplan9include[] = { '/', 'u', 's', 'r', '/', 'l', 'o', 'c', 'a', 'l', 
+	Rune Lusrlocalplan9include[] = { '/', 'u', 's', 'r', '/', 'l', 'o', 'c', 'a', 'l',
 			'/', 'p', 'l', 'a', 'n', '9', '/', 'i', 'n', 'c', 'l', 'u', 'd', 'e', 0 };
 	Runestr file;
 	int i;
@@ -443,7 +443,7 @@ includename(Text *t, Rune *r, int n)
 		sprint(buf, "/%s/include", objtype);
 		objdir = bytetorune(buf, &i);
 		objdir = runerealloc(objdir, i+1);
-		objdir[i] = '\0';	
+		objdir[i] = '\0';
 	}
 
 	w = t->w;
@@ -514,6 +514,19 @@ dirname(Text *t, Rune *r, int n)
 	return tmp;
 }
 
+static int
+texthas(Text *t, uint q0, Rune *r)
+{
+	int i;
+
+	if((int)q0 < 0)
+		return FALSE;
+	for(i=0; r[i]; i++)
+		if(q0+i >= t->file->b.nc || textreadc(t, q0+i) != r[i])
+			return FALSE;
+	return TRUE;
+}
+
 int
 expandfile(Text *t, uint q0, uint q1, Expand *e)
 {
@@ -522,12 +535,14 @@ expandfile(Text *t, uint q0, uint q1, Expand *e)
 	Rune *r, c;
 	Window *w;
 	Runestr rs;
+	Rune Lhttpcss[] = {'h', 't', 't', 'p', ':', '/', '/', 0};
+	Rune Lhttpscss[] = {'h', 't', 't', 'p', 's', ':', '/', '/', 0};
 
 	amax = q1;
 	if(q1 == q0){
 		colon = -1;
 		while(q1<t->file->b.nc && isfilec(c=textreadc(t, q1))){
-			if(c == ':'){
+			if(c == ':' && !texthas(t, q1-4, Lhttpcss) && !texthas(t, q1-5, Lhttpscss)){
 				colon = q1;
 				break;
 			}
@@ -535,7 +550,7 @@ expandfile(Text *t, uint q0, uint q1, Expand *e)
 		}
 		while(q0>0 && (isfilec(c=textreadc(t, q0-1)) || isaddrc(c) || isregexc(c))){
 			q0--;
-			if(colon<0 && c==':')
+			if(colon<0 && c==':' && !texthas(t, q0-4, Lhttpcss) && !texthas(t, q0-5, Lhttpscss))
 				colon = q0;
 		}
 		/*
@@ -565,8 +580,23 @@ expandfile(Text *t, uint q0, uint q1, Expand *e)
 	if(n == 0)
 		return FALSE;
 	/* see if it's a file name */
-	r = runemalloc(n);
+	r = runemalloc(n+1);
 	bufread(&t->file->b, q0, r, n);
+	r[n] = 0;
+	/* is it a URL? look for http:// and https:// prefix */
+	if(runestrncmp(r, Lhttpcss, 7) == 0 || runestrncmp(r, Lhttpscss, 8) == 0){
+		// Avoid capturing end-of-sentence punctuation.
+		if(r[n-1] == '.') {
+			e->q1--;
+			n--;
+		}
+		e->name = r;
+		e->nname = n;
+		e->u.at = t;
+		e->a0 = e->q1;
+		e->a1 = e->q1;
+		return TRUE;
+	}
 	/* first, does it have bad chars? */
 	nname = -1;
 	for(i=0; i<n; i++){
@@ -728,7 +758,7 @@ openfile(Text *t, Expand *e)
 			/*
 			 * Unrooted path in new window.
 			 * This can happen if we type a pwd-relative path
-			 * in the topmost tag or the column tags.  
+			 * in the topmost tag or the column tags.
 			 * Most of the time plumber takes care of these,
 			 * but plumber might not be running or might not
 			 * be configured to accept plumbed directories.