Internal error trying to print uninitialized string.
authorJoel Brobecker <brobecker@adacore.com>
Mon, 8 Dec 2014 15:37:00 +0000 (10:37 -0500)
committerJoel Brobecker <brobecker@adacore.com>
Sat, 13 Dec 2014 16:00:24 +0000 (11:00 -0500)
commitc1b5a1a6e732a65350af930c499b23018f8663cc
tree3f1780b967531dc51b7067e7ed53cc0d1252de7e
parent3c46a02f5083c4a9c07b563d44b8b6ded6d85bb1
Internal error trying to print uninitialized string.

Trying to print the value of a string whose size is not known at
compile-time before it gets assigned a value can lead to the following
internal error:

    (gdb) p my_str
    $1 =
    /[...]/utils.c:1089: internal-error: virtual memory exhausted.

What happens is that my_str is described as a reference to an array
type whose bounds are dynamic. During the read of that variable's
value (in default_read_var_value), we end up resolving dynamic types
which, for reference types, makes us also resolve the target of that
reference type. This means we resolve our variable to a reference
to an array whose bounds are undefined, and unfortunately very far
appart.

So, when we pass that value to ada-valprint, and in particular to
da_val_print_ref, we eventually try to allocate too large of a buffer
corresponding to the (bogus) size of our array, hence the internal
error.

This patch fixes the problem by adding a size_check before trying
to print the dereferenced value. To perform this check, a function
that was previously specific to ada-lang.c (check_size) gets
exported, and renamed to something less prone to name collisions
(ada_ensure_varsize_limit).

gdb/ChangeLog:

        * ada-lang.h (ada_ensure_varsize_limit): Declare.
        * ada-lang.c (check_size): Remove advance declaration.
        (ada_ensure_varsize_limit): Renames check_size.
        Replace calls to check_size by calls to ada_ensure_varsize_limit
        throughout.
        * ada-valprint.c (ada_val_print_ref): Add call to
        ada_ensure_varsize_limit.  Add comment explaining why.

gdb/testsuite/ChangeLog:

        * gdb.ada/str_uninit: New testcase.
gdb/ChangeLog
gdb/ada-lang.c
gdb/ada-lang.h
gdb/ada-valprint.c
gdb/testsuite/ChangeLog
gdb/testsuite/gdb.ada/str_uninit.exp [new file with mode: 0644]
gdb/testsuite/gdb.ada/str_uninit/parse.adb [new file with mode: 0644]
gdb/testsuite/gdb.ada/str_uninit/pck.adb [new file with mode: 0644]
gdb/testsuite/gdb.ada/str_uninit/pck.ads [new file with mode: 0644]