This patch fixes a problem with utf-8 strings and the sidebar, it rewrites
entirely make_sidebar_entry so it also fixes some segfaults due to
misallocations and overflows.

See:
http://bugs.debian.org/584581
http://bugs.debian.org/603287

Author: Antonio Radici <antonio@dyne.org>

Index: mutt/sidebar.c
===================================================================
--- mutt.orig/sidebar.c	2011-05-02 13:36:10.000000000 +0000
+++ mutt/sidebar.c	2011-05-02 13:36:30.000000000 +0000
@@ -30,6 +30,7 @@
 #include <libgen.h>
 #include "keymap.h"
 #include <stdbool.h>
+#include <wchar.h>
 
 /*BUFFY *CurBuffy = 0;*/
 static BUFFY *TopBuffy = 0;
@@ -111,36 +112,72 @@
 
 char *make_sidebar_entry(char *box, int size, int new, int flagged)
 {
-	static char *entry = 0;
-	char *c;
-	int i = 0;
-	int delim_len = strlen(SidebarDelim);
-
-	c = realloc(entry, SidebarWidth - delim_len + 2);
-	if ( c ) entry = c;
-	entry[SidebarWidth - delim_len + 1] = 0;
-	for (; i < SidebarWidth - delim_len + 1; entry[i++] = ' ' );
-	i = strlen(box);
-	strncpy( entry, box, i < (SidebarWidth - delim_len + 1) ? i : (SidebarWidth - delim_len + 1) );
-
-        if (size == -1)
-                sprintf(entry + SidebarWidth - delim_len - 3, "?");
-        else if ( new ) {
-          if (flagged > 0) {
-              sprintf(
-		        entry + SidebarWidth - delim_len - 5 - quick_log10(size) - quick_log10(new) - quick_log10(flagged),
-		        "% d(%d)[%d]", size, new, flagged);
-          } else {
-              sprintf(
-                      entry + SidebarWidth - delim_len - 3 - quick_log10(size) - quick_log10(new),
-                      "% d(%d)", size, new);
-          }
-        } else if (flagged > 0) {
-              sprintf( entry + SidebarWidth - delim_len - 3 - quick_log10(size) - quick_log10(flagged), "% d[%d]", size, flagged);
-        } else {
-              sprintf( entry + SidebarWidth - delim_len - 1 - quick_log10(size), "% d", size);
-        }
-	return entry;
+    char int_store[20]; // up to 64 bits integers
+    int right_width, left_width;
+    int box_len, box_bytes;
+    int int_len;
+    int right_offset = 0;
+    int delim_len = strlen(SidebarDelim);
+    static char *entry;
+
+    right_width = left_width = 0;
+    box_len = box_bytes = 0;
+
+    // allocate an entry big enough to contain SidebarWidth wide chars
+    entry = malloc((SidebarWidth*4)+1); // TODO: error check
+
+    // determine the right space (i.e.: how big are the numbers that we want to print)
+    if ( size > 0 ) {
+        int_len = snprintf(int_store, sizeof(int_store), "%d", size);
+        right_width += int_len;
+    } else {
+        right_width = 1; // to represent 0
+    }
+    if ( new > 0 ) {
+        int_len = snprintf(int_store, sizeof(int_store), "%d", new);
+        right_width += int_len + 2; // 2 is for ()
+    }
+    if ( flagged > 0 ) {
+        int_len = snprintf(int_store, sizeof(int_store), "%d", flagged);
+        right_width += int_len + 2; // 2 is for []
+    }
+
+    // determine how much space we have for *box and its padding (if any)
+    left_width = SidebarWidth - right_width - 1 - delim_len; // 1 is for the space
+    //fprintf(stdout, "left_width: %d right_width: %d\n", left_width, right_width);
+    // right side overflow case
+    if ( left_width <= 0 ) {
+        snprintf(entry, SidebarWidth*4, "%-*.*s ...", SidebarWidth-4-delim_len, SidebarWidth-4-delim_len, box);
+        return entry;
+    }
+    right_width -= delim_len;
+
+    // to support utf-8 chars we need to add enough space padding in case there
+    // are less chars than bytes in *box
+    box_len = mbstowcs(NULL, box, 0);
+    box_bytes = strlen(box);
+    // debug
+    //fprintf(stdout, "box_len: %d box_bytes: %d (diff: %d)\n", box_len, box_bytes, (box_bytes-box_len));
+    // if there is less string than the space we allow, then we will add the
+    // spaces
+    if ( box_len != -1 && box_len < left_width ) {
+        left_width += (box_bytes - box_len);
+    }
+    // otherwise sprintf will truncate the string for us (therefore, no else case)
+
+    // print the sidebar entry (without new and flagged messages, at the moment)
+    //fprintf(stdout, "left_width: %d right_width: %d\n", left_width, right_width);
+    right_offset = snprintf(entry, SidebarWidth*4, "%-*.*s %d", left_width, left_width, box, size);
+
+    // then pad new and flagged messages if any
+    if ( new > 0 ) {
+        right_offset += snprintf(entry+right_offset, SidebarWidth*4-right_offset, "(%d)", new);
+    }
+    if ( flagged > 0 ) {
+        right_offset += snprintf(entry+right_offset, SidebarWidth*4-right_offset, "[%d]", flagged);
+    }
+
+    return entry;
 }
 
 void set_curbuffy(char buf[LONG_STRING])