code-golfing: cleanup osc color related code

* adds missing function prototype
* move xgetcolor() prototype to win.h (that's where all the other x.c
  func prototype seems to be declared at)
* check for snprintf error/truncation
* reduces code duplication for osc 10/11/12
* unify osc_color_response() and osc4_color_response() into a single function

the latter two was suggested by Quentin Rameau in his patch review on
the hackers list.

3 files changed, 33 insertions, 60 deletions

diff --git a/st.c b/st.c
index f43cfd3..6ba467d 100644
--- a/st.c
+++ b/st.c
@@ -161,6 +161,7 @@ static void csidump(void);
 static void csihandle(void);
 static void csiparse(void);
 static void csireset(void);
+static void osc_color_response(int, int, int);
 static int eschandle(uchar);
 static void strdump(void);
 static void strhandle(void);
@@ -1835,39 +1836,28 @@ csireset(void)
 }
 
 void
-osc4_color_response(int num)
+osc_color_response(int num, int index, int is_osc4)
 {
         int n;
         char buf[32];
         unsigned char r, g, b;
 
-        if (xgetcolor(num, &r, &g, &b)) {
-                fprintf(stderr, "erresc: failed to fetch osc4 color %d\n", num);
+        if (xgetcolor(is_osc4 ? num : index, &r, &g, &b)) {
+                fprintf(stderr, "erresc: failed to fetch %s color %d\n",
+                        is_osc4 ? "osc4" : "osc",
+                        is_osc4 ? num : index);
                 return;
         }
 
-        n = snprintf(buf, sizeof buf, "\033]4;%d;rgb:%02x%02x/%02x%02x/%02x%02x\007",
-                     num, r, r, g, g, b, b);
-
-        ttywrite(buf, n, 1);
-}
-
-void
-osc_color_response(int index, int num)
-{
-        int n;
-        char buf[32];
-        unsigned char r, g, b;
-
-        if (xgetcolor(index, &r, &g, &b)) {
-                fprintf(stderr, "erresc: failed to fetch osc color %d\n", index);
-                return;
+        n = snprintf(buf, sizeof buf, "\033]%s%d;rgb:%02x%02x/%02x%02x/%02x%02x\007",
+                     is_osc4 ? "4;" : "", num, r, r, g, g, b, b);
+        if (n < 0 || n >= sizeof(buf)) {
+                fprintf(stderr, "error: %s while printing %s response\n",
+                        n < 0 ? "snprintf failed" : "truncation occurred",
+                        is_osc4 ? "osc4" : "osc");
+        } else {
+                ttywrite(buf, n, 1);
         }
-
-        n = snprintf(buf, sizeof buf, "\033]%d;rgb:%02x%02x/%02x%02x/%02x%02x\007",
-                     num, r, r, g, g, b, b);
-
-        ttywrite(buf, n, 1);
 }
 
 void
@@ -1875,6 +1865,11 @@ strhandle(void)
 {
         char *p = NULL, *dec;
         int j, narg, par;
+        const struct { int idx; char *str; } osc_table[] = {
+                { defaultfg, "foreground" },
+                { defaultbg, "background" },
+                { defaultcs, "cursor" }
+        };
 
         term.esc &= ~(ESC_STR_END|ESC_STR);
         strparse();
@@ -1909,43 +1904,22 @@ strhandle(void)
                         }
                         return;
                 case 10:
-                        if (narg < 2)
-                                break;
-
-                        p = strescseq.args[1];
-
-                        if (!strcmp(p, "?"))
-                                osc_color_response(defaultfg, 10);
-                        else if (xsetcolorname(defaultfg, p))
-                                fprintf(stderr, "erresc: invalid foreground color: %s\n", p);
-                        else
-                                tfulldirt();
-                        return;
                 case 11:
-                        if (narg < 2)
-                                break;
-
-                        p = strescseq.args[1];
-
-                        if (!strcmp(p, "?"))
-                                osc_color_response(defaultbg, 11);
-                        else if (xsetcolorname(defaultbg, p))
-                                fprintf(stderr, "erresc: invalid background color: %s\n", p);
-                        else
-                                tfulldirt();
-                        return;
                 case 12:
                         if (narg < 2)
                                 break;
-
                         p = strescseq.args[1];
-
-                        if (!strcmp(p, "?"))
-                                osc_color_response(defaultcs, 12);
-                        else if (xsetcolorname(defaultcs, p))
-                                fprintf(stderr, "erresc: invalid cursor color: %s\n", p);
-                        else
+                        if ((j = par - 10) < 0 || j >= LEN(osc_table))
+                                break; /* shouldn't be possible */
+
+                        if (!strcmp(p, "?")) {
+                                osc_color_response(par, osc_table[j].idx, 0);
+                        } else if (xsetcolorname(osc_table[j].idx, p)) {
+                                fprintf(stderr, "erresc: invalid %s color: %s\n",
+                                        osc_table[j].str, p);
+                        } else {
                                 tfulldirt();
+                        }
                         return;
                 case 4: /* color set */
                         if (narg < 3)
@@ -1955,9 +1929,9 @@ strhandle(void)
                 case 104: /* color reset */
                         j = (narg > 1) ? atoi(strescseq.args[1]) : -1;
 
-                        if (p && !strcmp(p, "?"))
-                                osc4_color_response(j);
-                        else if (xsetcolorname(j, p)) {
+                        if (p && !strcmp(p, "?")) {
+                                osc_color_response(j, 0, 1);
+                        } else if (xsetcolorname(j, p)) {
                                 if (par == 104 && narg <= 1)
                                         return; /* color reset without parameter */
                                 fprintf(stderr, "erresc: invalid color j=%d, p=%s\n",
diff --git a/st.h b/st.h
index 519b9bd..fd3b0d8 100644
--- a/st.h
+++ b/st.h
@@ -111,8 +111,6 @@ void *xmalloc(size_t);
 void *xrealloc(void *, size_t);
 char *xstrdup(const char *);
 
-int xgetcolor(int x, unsigned char *r, unsigned char *g, unsigned char *b);
-
 /* config.h globals */
 extern char *utmp;
 extern char *scroll;
diff --git a/win.h b/win.h
index e6e4369..6de960d 100644
--- a/win.h
+++ b/win.h
@@ -30,6 +30,7 @@ void xdrawline(Line, int, int, int);
 void xfinishdraw(void);
 void xloadcols(void);
 int xsetcolorname(int, const char *);
+int xgetcolor(int, unsigned char *, unsigned char *, unsigned char *);
 void xseticontitle(char *);
 void xsettitle(char *);
 int xsetcursor(int);