syms_from_objfile() warnings and win32-nat.c IO redirection (Was: suppress annoying warnings about cygwin1.dbg)

[Brian Dessent <brian at dessent dot net>]

Daniel Jacobowitz wrote:

> The redirection to /dev/null is silly and should go away, by the way,
> so relying on it isn't the right fix.  I don't remember if my recently
> posted WIP patch removed it.  I think it did for most but not all
> cases.

So I tried simply removing the two problematic warnings in
syms_from_objfile(), and then getting rid of the hacky
safe_symbol_file_add() wrapper in win32-nat.c.  This obviously has the
desired effect of not seeing the popups in insight, but now gdb has
become much more chatty.  This is what happens when you run a Hello
World program:

$ /build/combined/gdb/gdb --quiet hello
Reading symbols from /tmp/hello.exe...done.
(gdb) start
Reading in symbols for /home/brian/hello.c...done.
Breakpoint 1 at 0x401065: file /home/brian/hello.c, line 4.
Reading symbols from /winxp/system32/ntdll.dll...Minimal symbols from
ntdll.dll...done.
Reading symbols from /winxp/system32/kernel32.dll...Minimal symbols from
KERNEL32.dll...done.
Reading symbols from /usr/bin/cygwin1.dll...Reading symbols from
/usr/bin/cygwin1.dbg...done.
done.
Reading symbols from /winxp/system32/advapi32.dll...Minimal symbols from
ADVAPI32.dll...done.
Reading symbols from /winxp/system32/rpcrt4.dll...Minimal symbols from
RPCRT4.dll...done.
Reading symbols from /winxp/system32/shimeng.dll...
Minimal symbols from ShimEng.dll...done.
Reading symbols from /winxp/system32/secur32.dll...Minimal symbols from
Secur32.dll...done.
[New thread 1988.0xa1c]
Reading symbols from /winxp/system32/user32.dll...Minimal symbols from
USER32.dll...done.
Reading symbols from /winxp/system32/gdi32.dll...Minimal symbols from
GDI32.dll...done.
main (argc=1, 
    argv=0x662740) at /home/brian/hello.c:4
4       {
(gdb) c
Hello world!
Reading symbols from /winxp/system32/psapi.dll...Minimal symbols from
PSAPI.DLL...done.

Program exited normally.
(gdb) 

In insight, it's somewhat better because the "Reading symbols from %s"
messages are suppressed due to the hooks, but not the "Minimal symbols
from %s", with the result in the console of:

(gdb) start
Reading in symbols for /home/brian/hello.c...done.
Breakpoint 1 at 0x401065: file /home/brian/hello.c, line 4.
Minimal symbols from ntdll.dll...Minimal symbols from
KERNEL32.dll...Minimal symbols from ADVAPI32.dll...Minimal symbols from
RPCRT4.dll...Minimal symbols from ShimEng.dll...Minimal symbols from
Secur32.dll...[New thread 3520.0xa5c]
Minimal symbols from USER32.dll...Minimal symbols from GDI32.dll...main
(argc=2, argv=0x662980) at /home/brian/hello.c:4

(gdb) c
[Deleting thread 3520.0xa5c]
Minimal symbols from PSAPI.DLL...
Program exited normally.

(gdb)

For comparison, the output of current unmodified stock CVS gdb is:

$ /build/combined/gdb/gdb --quiet hello
Reading symbols from /tmp/hello.exe...done.
(gdb) start
Reading in symbols for /home/brian/hello.c...done.
Breakpoint 1 at 0x401065: file /home/brian/hello.c, line 4.
[New thread 3256.0xdc]
main (argc=1, 
    argv=0x662740) at /home/brian/hello.c:4
4       {
(gdb) c
Hello world!

Program exited normally.
(gdb)

Obviously (?) this is way too much spew, so if we want to eliminate the
hacky IO redirection, what's the way forward?  It seems to me that the
"Minimal symbols from %s.." (coff-pe-read.c:read_pe_exported_syms()) is
pure noise, so it could just be eliminated.  However, how do we gate the
output of "Reading in symbols for %s" so that it shows for the user's
objects but not for the dozens of system DLLs?  Is there an existing API
for this?  I gather the answer is no, otherwise the hacky IO redirection
stuff would have never been done.  Or do we just say that we shouldn't
try to filter these messages and let the user see them all?  The result
of *that* looks like this:

$ /build/combined/gdb/gdb --quiet hello
Reading symbols from /tmp/hello.exe...done.
(gdb) start
Reading in symbols for /home/brian/hello.c...done.
Breakpoint 1 at 0x401065: file /home/brian/hello.c, line 4.
Reading symbols from /winxp/system32/ntdll.dll...done.
Reading symbols from /winxp/system32/kernel32.dll...done.
Reading symbols from /usr/bin/cygwin1.dll...Reading symbols from
/usr/bin/cygwin1.dbg...done.
done.
Reading symbols from /winxp/system32/advapi32.dll...done.
Reading symbols from /winxp/system32/rpcrt4.dll...done.
Reading symbols from /winxp/system32/shimeng.dll...done.
Reading symbols from /winxp/system32/secur32.dll...done.
[New thread 3084.0x968]
Reading symbols from /winxp/system32/user32.dll...done.
Reading symbols from /winxp/system32/gdi32.dll...done.
main (argc=1, argv=0x662740) at /home/brian/hello.c:4
4       {
(gdb) c
Hello world!
Reading symbols from /winxp/system32/psapi.dll...done.
[Deleting thread 3084.0x968]

Program exited normally.
(gdb) quit

Again, this is for a trivial program that contains one call to puts()
and nothing else.  For a less trivial example, you can get dozens of
these as there are potentially many DLLs get loaded during the lifetime
of the app, and so it can be somewhat spammy.

Ideas?

Brian