add an ignore filter based on substring of the file

the result of propagating a deletion is flagging as deleted, so shut up
if the only remote change is exactly that.

configure.ac

@@ -1,4 +1,4 @@
-AC_INIT([isync], [1.4.3])
+AC_INIT([isync], [1.4.4])
 AC_CONFIG_HEADERS([autodefs.h])
 
 AC_CANONICAL_TARGET
@@ -62,8 +62,8 @@ if test "x$ob_cv_perl_ver" = "xno"; then
 fi
 
 AC_CACHE_CHECK([whether strftime supports %z], ob_cv_strftime_z,
-    [AC_TRY_RUN(
+    [AC_RUN_IFELSE([AC_LANG_SOURCE([[
-[#include <time.h>
+#include <time.h>
 #include <string.h>
 
 int main(void)
@@ -73,7 +73,7 @@ int main(void)
     strftime(buf, sizeof(buf), "%z", localtime(&t));
     return !(buf[0] == '+' || buf[0] == '-');
 }
-], [ob_cv_strftime_z=yes], [ob_cv_strftime_z=no], [ob_cv_strftime_z="yes (assumed)"])])
+]])], [ob_cv_strftime_z=yes], [ob_cv_strftime_z=no], [ob_cv_strftime_z="yes (assumed)"])])
 if test "x$ob_cv_strftime_z" = x"no"; then
     AC_MSG_ERROR([libc lacks necessary feature])
 fi
@@ -96,7 +96,7 @@ fi
 
 have_ssl_paths=
 AC_ARG_WITH(ssl,
-  AC_HELP_STRING([--with-ssl[=PATH]], [where to look for SSL [detect]]),
+  AS_HELP_STRING([--with-ssl[=PATH]], [where to look for SSL [detect]]),
   [ob_cv_with_ssl=$withval])
 if test "x$ob_cv_with_ssl" != xno; then
   case $ob_cv_with_ssl in
@@ -193,12 +193,13 @@ AC_CACHE_CHECK([for Berkeley DB >= 4.1], ac_cv_berkdb4,
   [ac_cv_berkdb4=no
     sav_LIBS=$LIBS
     LIBS="$LIBS -ldb"
-   AC_TRY_LINK([#include <db.h>],
+    AC_LINK_IFELSE([AC_LANG_PROGRAM(
-               [DB *db;
+        [#include <db.h>],
-	        db_create(&db, 0, 0);
+        [DB *db;
-	        db->truncate(db, 0, 0, 0);
+         db_create(&db, 0, 0);
-	        db->open(db, 0, "foo", "foo", DB_HASH, DB_CREATE, 0)],
+         db->truncate(db, 0, 0, 0);
-	       [ac_cv_berkdb4=yes])
+         db->open(db, 0, "foo", "foo", DB_HASH, DB_CREATE, 0);
+        ])], [ac_cv_berkdb4=yes], [])
     LIBS=$sav_LIBS
   ])
 if test "x$ac_cv_berkdb4" = xyes; then

src/drv_imap.c

@@ -877,6 +877,11 @@ parse_imap_list( imap_store_t *ctx, char **sp, parse_list_state_t *sts )
 			bytes = (int)(cur->len = strtoul( s + 1, &s, 10 ));
 			if (*s != '}' || *++s)
 				goto bail;
+			if ((uint)bytes >= INT_MAX) {
+				error( "IMAP error: excessively large literal from %s "
+				       "- THIS MIGHT BE AN ATTEMPT TO HACK YOU!\n", ctx->conn.name );
+				goto bail;
+			}
 
 			s = cur->val = nfmalloc( cur->len + 1 );
 			s[cur->len] = 0;
@@ -1434,6 +1439,10 @@ parse_list_rsp_p2( imap_store_t *ctx, list_t *list, char *cmd ATTR_UNUSED )
 	}
 	arg = list->val;
 	argl = (int)list->len;
+	if (argl > 1000) {
+		warn( "IMAP warning: ignoring unreasonably long mailbox name '%.100s[...]'\n", arg );
+		return LIST_OK;
+	}
 	// The server might be weird and have a non-uppercase INBOX. It
 	// may legitimately do so, but we need the canonical spelling.
 	normalize_INBOX( ctx, arg, argl );

src/drv_maildir.c

@@ -991,9 +991,12 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 #endif /* USE_DB */
 				return DRV_BOX_BAD;
 			}
+			const char *filter = getenv("MBSYNC_MAILDIR_IGNORE");
 			while ((e = readdir( d ))) {
 				if (*e->d_name == '.')
 					continue;
+				if (filter && strstr(e->d_name, filter))
+					continue;
 				ctx->total_msgs++;
 				ctx->recent_msgs += i;
 #ifdef USE_DB
@@ -1168,7 +1171,8 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 					}
 					goto retry;
 				}
-				entry->size = (uint)st.st_size;
+				// The clipped value is good enough for MaxSize comparisons.
+				entry->size = st.st_size > UINT_MAX ? UINT_MAX : (uint)st.st_size;
 			}
 			if (want_tuid || want_msgid) {
 				if (!(f = fopen( buf, "r" ))) {
@@ -1563,12 +1567,17 @@ maildir_fetch_msg( store_t *gctx, message_t *gmsg, msg_data_t *data, int minimal
 		}
 	}
 	fstat( fd, &st );
+	if (st.st_size > INT_MAX) {
+		error( "Maildir error: %s is too big", buf );
+		goto mbad;
+	}
 	data->len = st.st_size;
 	if (data->date == -1)
 		data->date = st.st_mtime;
 	data->data = nfmalloc( data->len );
 	if (read( fd, data->data, data->len ) != data->len) {
 		sys_error( "Maildir error: cannot read %s", buf );
+	  mbad:
 		close( fd );
 		cb( DRV_MSG_BAD, aux );
 		return;

src/sync.c

@@ -406,7 +406,7 @@ copy_msg_bytes( char **out_ptr, const char *in_buf, uint *in_idx, uint in_len, i
 }
 
 static int
-copy_msg_convert( int in_cr, int out_cr, copy_vars_t *vars )
+copy_msg_convert( int in_cr, int out_cr, copy_vars_t *vars, int t )
 {
 	char *in_buf = vars->data.data;
 	uint in_len = vars->data.len;
@@ -428,9 +428,10 @@ copy_msg_convert( int in_cr, int out_cr, copy_vars_t *vars )
 					if (!vars->minimal)
 						goto oke;
 				} else {
-					if (break2 == UINT_MAX && vars->minimal && !strncasecmp( in_buf + start, "Subject:", 8 )) {
+					if (break2 == UINT_MAX && vars->minimal &&
+					    starts_with_upper( in_buf + start, (int)(in_len - start), "SUBJECT:", 8 )) {
 						break2 = start + 8;
-						if (in_buf[break2] == ' ')
+						if (break2 < in_len && in_buf[break2] == ' ')
 							break2++;
 					}
 					lines++;
@@ -451,7 +452,8 @@ copy_msg_convert( int in_cr, int out_cr, copy_vars_t *vars )
 				goto nloop;
 			}
 		}
-		/* invalid message */
+		warn( "Warning: message %u from %s has incomplete header; skipping.\n",
+		      vars->msg->uid, str_fn[1-t] );
 		free( in_buf );
 		return 0;
 	  oke:
@@ -493,6 +495,12 @@ copy_msg_convert( int in_cr, int out_cr, copy_vars_t *vars )
 	}
 
 	vars->data.len = in_len + extra;
+	if (vars->data.len > INT_MAX) {
+		warn( "Warning: message %u from %s is too big after conversion; skipping.\n",
+		      vars->msg->uid, str_fn[1-t] );
+		free( in_buf );
+		return 0;
+	}
 	char *out_buf = vars->data.data = nfmalloc( vars->data.len );
 	idx = 0;
 	if (vars->srec) {
@@ -556,9 +564,7 @@ msg_fetched( int sts, void *aux )
 		scr = (svars->drv[1-t]->get_caps( svars->ctx[1-t] ) / DRV_CRLF) & 1;
 		tcr = (svars->drv[t]->get_caps( svars->ctx[t] ) / DRV_CRLF) & 1;
 		if (vars->srec || scr != tcr) {
-			if (!copy_msg_convert( scr, tcr, vars )) {
+			if (!copy_msg_convert( scr, tcr, vars, t )) {
-				warn( "Warning: message %u from %s has incomplete header.\n",
-				      vars->msg->uid, str_fn[1-t] );
 				vars->cb( SYNC_NOGOOD, 0, vars );
 				return;
 			}
@@ -1690,7 +1696,11 @@ box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux
 						JLOG( "> %u %u 0", (srec->uid[F], srec->uid[N]), "near side expired, orphaning far side" );
 						srec->uid[N] = 0;
 					} else {
-						if (srec->msg[t] && (srec->msg[t]->status & M_FLAGS) && srec->msg[t]->flags != srec->flags)
+						if (srec->msg[t] && (srec->msg[t]->status & M_FLAGS) &&
+						    // Ignore deleted flag, as that's what we'll change ourselves ...
+						    (((srec->msg[t]->flags & ~F_DELETED) != (srec->flags & ~F_DELETED)) ||
+						     // ... except for undeletion, as that's the opposite.
+						     (!(srec->msg[t]->flags & F_DELETED) && (srec->flags & F_DELETED))))
 							notice( "Notice: conflicting changes in (%u,%u)\n", srec->uid[F], srec->uid[N] );
 						if (svars->chan->ops[t] & OP_DELETE) {
 							debug( "  %sing delete\n", str_hl[t] );