add a very limited INCLUDE_ONLY option

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

Dockerfile

@@ -0,0 +1,41 @@
+#FROM debian:bookworm-20231030-slim
+FROM debian:bullseye-20220801
+
+# need to add
+      # removed
+      # libsasl2-modules \
+      # ca-certificates \
+
+# version pinning is being handled in our from line
+# hadolint ignore=DL3008
+RUN true && \
+    apt-get update && \
+    groupadd --gid 1000 user && \
+    useradd -m --home-dir /home/user --shell /bin/sh --uid 1000 --gid 1000 user && \
+    apt-get install -y --no-install-recommends \
+      libsasl2-2 \
+      libsasl2-dev \
+      perl \
+      libdatetime-format-dateparse-perl \
+      autoconf \
+      automake \
+      zlib1g-dev \
+      libdb-dev \
+      libsasl2-dev \
+      libssl-dev \
+      gcc \
+      make \
+      git \
+      && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/* && \
+    true
+
+# Built with
+# apt install build-essential dh-autoreconf git
+# apt install libssl-dev
+# apt install zlib1g-dev
+# apt install libsasl2-dev
+
+WORKDIR /home/user
+USER user

build

@@ -0,0 +1,3 @@
+#!/bin/sh
+# Note we assume this is run with podman. Take -u 0:0 out if using docker
+docker run -u 0:0 -it --rm -v $(pwd):/make -w /make isync-build make 

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(
-[#include <time.h>
+    [AC_RUN_IFELSE([AC_LANG_SOURCE([[
+#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="$LIBS -ldb"
-   AC_TRY_LINK([#include <db.h>],
-               [DB *db;
-	        db_create(&db, 0, 0);
-	        db->truncate(db, 0, 0, 0);
-	        db->open(db, 0, "foo", "foo", DB_HASH, DB_CREATE, 0)],
-	       [ac_cv_berkdb4=yes])
+    AC_LINK_IFELSE([AC_LANG_PROGRAM(
+        [#include <db.h>],
+        [DB *db;
+         db_create(&db, 0, 0);
+         db->truncate(db, 0, 0, 0);
+         db->open(db, 0, "foo", "foo", DB_HASH, DB_CREATE, 0);
+        ])], [ac_cv_berkdb4=yes], [])
     LIBS=$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

@@ -920,6 +920,28 @@ maildir_compare( const void *l, const void *r )
 	return strcmp( lm->base, rm->base );
 }
 
+int is_gmail(const char* name) {
+	// NOTE: This is not an exact science. For instance, there is a good
+	// shot that mail sent from containers will end up matching this pattern
+    char token[16];  // If host name is longer than 12, then we already have our answer
+
+	// we expect files in the form of: "1700172103.R12128272304961211247.hostname,U=27:2,S"
+	// we are looking for "hostname"
+	// All gmail mails have a hostname in the form of "ff6d55f971cc".
+	// All are 12 characters long
+	// All are hexadecimal
+    if (sscanf(name, "%*[^.].%*[^.].%15[^,]", token) == 1) {
+		token[14] = '\0';
+		size_t len = strlen(token);
+		if (len != 12) return 0;
+		if (strspn(token, "0123456789abcdef") == len) return 1;
+    }
+
+	// We are here because a) the input format is not as expected,
+	// or b) the hostname is not gmail
+    return 0;
+}
+
 static int
 maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 {
@@ -991,9 +1013,25 @@ 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");
+			const char *MAGIC_INCLUDE = "^[^\\.]+\\.[^\\.]+\\.[0-9a-f]{12}\\,.*";
+			char *include = getenv("MBSYNC_MAILDIR_INCLUDE_ONLY");
+			if (include && strncmp(MAGIC_INCLUDE, include, strlen(MAGIC_INCLUDE)) != 0) {
+				include = NULL;
+				error("MBSYNC_MAILDIR_INCLUDE_ONLY can only be '%s'\n", MAGIC_INCLUDE);
+			}
+			if (include && filter) {
+				include = NULL;
+				error("MBSYNC_MAILDIR_IGNORE cannot be used with MBSYNC_MAILDIR_INCLUDE_ONLY. INCLUDE_ONLY will be ignored\n");
+			}
+
 			while ((e = readdir( d ))) {
 				if (*e->d_name == '.')
 					continue;
+				if (filter && strstr(e->d_name, filter))
+					continue;
+				if (include && !is_gmail(e->d_name))
+					continue;
 				ctx->total_msgs++;
 				ctx->recent_msgs += i;
 #ifdef USE_DB
@@ -1168,7 +1206,8 @@ 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 +1602,17 @@ 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

@@ -406,11 +406,11 @@ 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;
-	uint idx = 0, sbreak = 0, ebreak = 0, break2 = 0;
+	uint idx = 0, sbreak = 0, ebreak = 0, break2 = UINT_MAX;
 	uint lines = 0, hdr_crs = 0, bdy_crs = 0, app_cr = 0, extra = 0;
 	uint add_subj = 0;
 
@@ -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 && 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++;
@@ -441,7 +442,7 @@ copy_msg_convert( int in_cr, int out_cr, copy_vars_t *vars )
 						sbreak = ebreak = start;
 					if (vars->minimal) {
 						in_len = idx;
-						if (!break2) {
+						if (break2 == UINT_MAX) {
 							break2 = start;
 							add_subj = 1;
 						}
@@ -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:
@@ -493,10 +495,16 @@ 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) {
-		if (break2 && break2 < sbreak) {
+		if (break2 < sbreak) {
 			copy_msg_bytes( &out_buf, in_buf, &idx, break2, in_cr, out_cr );
 			memcpy( out_buf, dummy_pfx, strlen(dummy_pfx) );
 			out_buf += strlen(dummy_pfx);
@@ -512,7 +520,7 @@ copy_msg_convert( int in_cr, int out_cr, copy_vars_t *vars )
 		*out_buf++ = '\n';
 		idx = ebreak;
 
-		if (break2 >= sbreak) {
+		if (break2 != UINT_MAX && break2 >= sbreak) {
 			copy_msg_bytes( &out_buf, in_buf, &idx, break2, in_cr, out_cr );
 			if (!add_subj) {
 				memcpy( out_buf, dummy_pfx, strlen(dummy_pfx) );
@@ -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 )) {
-				warn( "Warning: message %u from %s has incomplete header.\n",
-				      vars->msg->uid, str_fn[1-t] );
+			if (!copy_msg_convert( scr, tcr, vars, 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] );