[geary: 1/2] Geary.Imap.FolderSession: Don't crash on empty preview

[Michael Gratton <mjog src gnome org>]

commit b57567ff9eb746e71975cf1e2bbd8dcd9d62f0f1
Author: Guido Günther <agx sigxcpu org>
Date:   Tue Feb 23 19:33:35 2021 +0100

    Geary.Imap.FolderSession: Don't crash on empty preview
    
    If we didn't set a preview we crash like
    
        *[wrn] 12:54:59.0908 geary:application-certificate-manager.vala:74: No GCR slot URIs found, GCR 
certificate pinning unavailable
        *[wrn] 12:55:10.0501 Geary: [goa_account_1614080076_2] [imap] [GearyImapClientSession(selected:INBOX 
selected RW, GearyImapClientConnection(0001/imap.example.com:993/up)), Imap.Folder(>INBOX), ro: false, 
permanent_flags: \Answered \Flagged \* \Seen \Deleted \Draft, accepts_user_flags: true] 
GearyImapFolderSession: No preview specifiers "body.peek[1]<0.256>" and "body.peek[1.mime]" found
        *[wrn] 12:55:10.0502 Geary: [goa_account_1614080076_2] [imap] [GearyImapClientSession(selected:INBOX 
selected RW, GearyImapClientConnection(0001/imap.example.com:993/up)), Imap.Folder(>INBOX), ro: false, 
permanent_flags: \Answered \Flagged \* \Seen \Deleted \Draft, accepts_user_flags: true] 
GearyImapFolderSession:  - has body[1.mime]
        *[wrn] 12:55:10.0502 Geary: [goa_account_1614080076_2] [imap] [GearyImapClientSession(selected:INBOX 
selected RW, GearyImapClientConnection(0001/imap.example.com:993/up)), Imap.Folder(>INBOX), ro: false, 
permanent_flags: \Answered \Flagged \* \Seen \Deleted \Draft, accepts_user_flags: true] 
GearyImapFolderSession:  - has body[header.fields (references)]
        *[wrn] 12:55:10.0502 Geary: [goa_account_1614080076_2] [imap] [GearyImapClientSession(selected:INBOX 
selected RW, GearyImapClientConnection(0001/imap.example.com:993/up)), Imap.Folder(>INBOX), ro: false, 
permanent_flags: \Answered \Flagged \* \Seen \Deleted \Draft, accepts_user_flags: true] 
GearyImapFolderSession:  - has body[1]<0>
        ![crt] 12:55:10.0502 GLib:Did not see expected message GLib-GObject-WARNING **: g_object_weak_unref: 
couldn't find weak ref *
        ![crt] 12:55:10.0502 geary:geary_email_set_message_preview: assertion 'GEARY_RF_C822_IS_PREVIEW_TEXT 
(preview)' failed
    
        (gdb) bt
        #0  __GI_raise (sig=sig@entry=5) at ../sysdeps/unix/sysv/linux/raise.c:50
        #1  0x0000ffff919a71d8 in _g_log_abort (breakpoint=1) at ../../../glib/gmessages.c:554
        #2  g_logvPython Exception <class 'gdb.MemoryError'> Cannot access memory at address 0x8:
         (log_domain=0xffff91f1d908 "geary", log_level=10, format=<optimized out>, args=#3  
0x0000ffff919a7440 in g_log (log_domain=<optimized out>, log_level=<optimized out>, format=<optimized out>)
            at ../../../glib/gmessages.c:1415
        #4  0x0000ffff91eabaf8 in geary_imap_folder_session_fetched_data_to_email
            (error=0xffff11aeb2f0, preview_charset_specifier=0xaaaafe108120 
[GearyImapFetchBodyDataSpecifier], preview_specifier=0xaaaafe0ec070 [GearyImapFetchBodyDataSpecifier], 
body_specifier=0x0, header_specifiers_length1=<optimized out>, header_specifiers=0x0, required_fields=927, 
fetched_data=<optimized out>, uid=0xaaaafe48de90 [GearyImapUID], self=0xaaaafe1059b0 [GearyImapFolderSession])
            at src/engine/libgeary-engine.a.p/imap/api/imap-folder-session.c:6795
        #5  __lambda103_ (error=0xffff11aeb360, _data28_=0xaaaafdf2d760) at 
src/engine/libgeary-engine.a.p/imap/api/imap-folder-session.c:4541
        #6  ___lambda103__geary_nonblocking_concurrent_concurrent_callback (cancellable=<optimized out>, 
self=0xaaaafdf2d760, error=0xffff11aeb360) at 
src/engine/libgeary-engine.a.p/imap/api/imap-folder-session.c:4640
        #7  0x0000ffff91e412d0 in geary_nonblocking_concurrent_concurrent_operation_execute 
(self=0xaaaafe48f6d0 [GearyNonblockingConcurrentConcurrentOperation])
            at src/engine/libgeary-engine.a.p/nonblocking/nonblocking-concurrent.c:672
        #8  geary_nonblocking_concurrent_on_work_ready (op=0xaaaafe48f6d0 
[GearyNonblockingConcurrentConcurrentOperation], self=<optimized out>)
            at src/engine/libgeary-engine.a.p/nonblocking/nonblocking-concurrent.c:501
        #9  _geary_nonblocking_concurrent_on_work_ready_gfunc (data=0xaaaafe48f6d0, self=<optimized out>) at 
src/engine/libgeary-engine.a.p/nonblocking/nonblocking-concurrent.c:296
        #10 0x0000ffff919ca3c8 in g_thread_pool_thread_proxy (data=<optimized out>) at 
../../../glib/gthreadpool.c:354
        #11 0x0000ffff919c98f4 in g_thread_proxy (data=0xaaaafde2e120) at ../../../glib/gthread.c:820
        #12 0x0000ffff8b437628 in start_thread (arg=0xffff11aeb520) at pthread_create.c:477
        #13 0x0000ffff916a801c in thread_start () at ../sysdeps/unix/sysv/linux/aarch64/clone.S:78
    
    Create an empty preview to avoid that.

 src/engine/imap/api/imap-folder-session.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/engine/imap/api/imap-folder-session.vala b/src/engine/imap/api/imap-folder-session.vala
index 3b777ee6a..bf4cd2bcf 100644
--- a/src/engine/imap/api/imap-folder-session.vala
+++ b/src/engine/imap/api/imap-folder-session.vala
@@ -1037,7 +1037,7 @@ private class Geary.Imap.FolderSession : Geary.Imap.SessionObject {
                 preview_specifier
             );
 
-            RFC822.PreviewText? preview = null;
+            RFC822.PreviewText preview = new RFC822.PreviewText(new Memory.StringBuffer(""));
             if (preview_headers != null && preview_headers.size > 0 &&
                 preview_body != null && preview_body.size > 0) {
                 preview = new RFC822.PreviewText.with_header(