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SEGV during AX eval of OP_DOUBLE (unsupported)

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To reproduce the problem, simply try the following with any program:

    (gdb) maintenance agent-eval 1.0
    Critical error handler: process [...] terminated due to access violation

(this is on Windows; on GNU/Linux, the libc copes better)

The problem is quite simple: gen_expr is given an expression that
contains an unrecognized operator (OP_DOUBLE in this case). When that
happens, it tries to report an error with a string image of the operator
in the error message.  Conversion of the opcode into a string is done
using op_string which, despite its name, probably is not what the author
was looking for.  This function returns NULL for a lot of the opcodes,
thus triggering the crash.

There is a function that corresponds to what we are looking for:
expprint.c:op_name. It was static, though, so I made it non-static,
and used it from ax-gdb.c:gen_expr.

gdb/ChangeLog:

        * expression.h (op_name): Add declaration.
        * expprint.c (op_name): Remove declaration.  Make non-static.
        * ax-gdb.c (gen_expr): Use op_name instead of op_string.
This commit is contained in:
Joel Brobecker 2012-03-21 15:16:24 +00:00
parent b781d74fe1
commit bd0b9f9e12
4 changed files with 10 additions and 3 deletions
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6
gdb/ChangeLog
View File

@ -1,3 +1,9 @@
2012-03-21 Joel Brobecker <brobecker@adacore.com>
* expression.h (op_name): Add declaration.
* expprint.c (op_name): Remove declaration. Make non-static.
* ax-gdb.c (gen_expr): Use op_name instead of op_string.
2012-03-21 Thomas Schwinge <thomas@codesourcery.com>
* amd64-linux-nat.c (amd64_linux_siginfo_fixup): Use siginfo_t instead

2
gdb/ax-gdb.c
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@ -2217,7 +2217,7 @@ gen_expr (struct expression *exp, union exp_element **pc,
default:
error (_("Unsupported operator %s (%d) in expression."),
op_string (op), op);
op_name (exp, op), op);
}
}

3
gdb/expprint.c
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@ -647,12 +647,11 @@ op_string (enum exp_opcode op)
/* Support for dumping the raw data from expressions in a human readable
form. */
static char *op_name (struct expression *, enum exp_opcode);
static int dump_subexp_body (struct expression *exp, struct ui_file *, int);
/* Name for OPCODE, when it appears in expression EXP. */
static char *
char *
op_name (struct expression *exp, enum exp_opcode opcode)
{
return exp->language_defn->la_exp_desc->op_name (opcode);

2
gdb/expression.h
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@ -137,6 +137,8 @@ extern struct value *evaluate_subexp_standard
extern void print_expression (struct expression *, struct ui_file *);
extern char *op_name (struct expression *exp, enum exp_opcode opcode);
extern char *op_string (enum exp_opcode);
extern void dump_raw_expression (struct expression *,