[Bug gdb/17891] New: SIGFPE results in infinite loop?

["dje at google dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=17891

            Bug ID: 17891
           Summary: SIGFPE results in infinite loop?
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: dje at google dot com

I was testing current gdb on a program compiled with Two Level Linetables
http://wiki.dwarfstd.org/index.php?title=TwoLevelLineTables
and found gdb went into an infinite loop of SIGFPE->handle_sigfpe->SIGFPE
->handle_sigfpe->...

The bug for bad line table header version handling is bug 17890.

This bug is for the bad SIGFPE handling.

How is this supposed to work?

Repro:
Add a divide-by-zero to gdb after the event loop has been set up, put a
breakpoint on handle_sigfpe, run, continue, continue, continue, ...

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 715b090..a4bc9ff 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -17140,6 +17140,9 @@ dwarf_decode_line_header (unsigned int offset, struct
dwarf2_cu *cu)
   struct dwarf2_section_info *section;
   bfd *abfd;

+  i = 0;
+  i = 3/i;
+
   section = get_debug_line_section (cu);
   dwarf2_read_section (dwarf2_per_objfile->objfile, section);
   if (section->buffer == NULL)


Program received signal SIGFPE, Arithmetic exception.
0x00000000007c688c in dwarf_decode_line_header (offset=0, cu=0x12b5610)
    at ../../binutils-gdb/gdb/dwarf2read.c:17144
17144     i = 3/i;
(top-gdb) c
Continuing.

Breakpoint 3, handle_sigfpe (sig=8) at ../../binutils-gdb/gdb/event-top.c:1006
1006      mark_async_signal_handler (sigfpe_token);
(top-gdb) 
Continuing.

Program received signal SIGFPE, Arithmetic exception.
0x00000000007c688c in dwarf_decode_line_header (offset=0, cu=0x12b5610)
    at ../../binutils-gdb/gdb/dwarf2read.c:17144
17144     i = 3/i;
(top-gdb) 
Continuing.

Breakpoint 3, handle_sigfpe (sig=8) at ../../binutils-gdb/gdb/event-top.c:1006
1006      mark_async_signal_handler (sigfpe_token);
(top-gdb) 
...

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