[COMMIT PATCH] More invalid pointer to pointer conversions.

Pedro Alves
2013-03-13T16:48:17Z

As a follow up to:

http://sourceware.org/ml/gdb-patches/2013-03/msg00449.html

In a nutshell, casts between 'char **' <-> 'unsigned char **' and
'char **' <-> 'const char **' are invalid.

I grepped for "\*\*) &" and found these. There's another one in
demangle.c, but I've split fixing that one to a separate patch.

I think the ada_decode_symbol change is perhaps the one that could be
surprising. The function's description has this comment, which makes
things much clearer:

The GSYMBOL parameter is "mutable" in the C++ sense: logically
const, but nevertheless modified to a semantically equivalent form
when a decoded name is cached in it. */

const char *
ada_decode_symbol (const struct general_symbol_info *gsymbol)

With that out of the way, I think the patch ends up being pretty
obvious.

Tested on x86_64 Fedora 17.

gdb/
2013-03-13 Pedro Alves <palves@redhat.com>

* ada-lang.c (ada_decode_symbol): Cast away constness of GSYMBOL
rather than casting 'const char * const *' to 'const char **'.
* ada-lex.l (processInt): Make "trailer" local const. Remove
'const char **' cast.
* arm-linux-tdep.c (arm_stap_parse_special_token): Add 'char *'
locals, and use those as strtol output pointer, instead than doing
invalid casts to from 'const char **' to 'char **'.
(_initialize_demangle): Remove cast.
* i386-tdep.c (i386_stap_parse_special_token): : Add 'char *'
locals, and use those as strtol output pointer, instead than doing
invalid casts to from 'const char **' to 'char **'.
* solib-dsbt.c (dsbt_get_initial_loadmaps): Remove 'gdb_byte**'
casts.
* stap-probe.c (stap_parse_register_operand)
(stap_parse_single_operand): Likewise.
---
gdb/ada-lang.c | 6 ++++--
gdb/ada-lex.l | 5 ++---
gdb/arm-linux-tdep.c | 4 +++-
gdb/i386-tdep.c | 22 +++++++++++++++++-----
gdb/solib-dsbt.c | 4 ++--
gdb/stap-probe.c | 19 +++++++++++++++----
6 files changed, 43 insertions(+), 17 deletions(-)

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 63a85ee..1e5c55e 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -1299,8 +1299,10 @@ static struct htab *decoded_names_store;
const char *
ada_decode_symbol (const struct general_symbol_info *gsymbol)
{
- const char **resultp =
- (const char **) &gsymbol->language_specific.mangled_lang.demangled_name;
+ struct general_symbol_info *gsymbol_rw
+ = (struct general_symbol_info *) gsymbol;
+ const char **resultp
+ = &gsymbol_rw->language_specific.mangled_lang.demangled_name;

if (*resultp == NULL)
{
diff --git a/gdb/ada-lex.l b/gdb/ada-lex.l
index e4d72f2..93df2fb 100644
--- a/gdb/ada-lex.l
+++ b/gdb/ada-lex.l
@@ -329,8 +329,7 @@ processInt (const char *base0, const char *num0, const char *exp0)
ULONGEST result;
long exp;
int base;
-
- char *trailer;
+ const char *trailer;

if (base0 == NULL)
base = 10;
@@ -347,7 +346,7 @@ processInt (const char *base0, const char *num0, const char *exp0)
exp = strtol(exp0, (char **) NULL, 10);

errno = 0;
- result = strtoulst (num0, (const char **) &trailer, base);
+ result = strtoulst (num0, &trailer, base);
if (errno == ERANGE)
error (_("Integer literal out of range"));
if (isxdigit(*trailer))
diff --git a/gdb/arm-linux-tdep.c b/gdb/arm-linux-tdep.c
index 278a665..953e525 100644
--- a/gdb/arm-linux-tdep.c
+++ b/gdb/arm-linux-tdep.c
@@ -1088,6 +1088,7 @@ arm_stap_parse_special_token (struct gdbarch *gdbarch,
{
/* Temporary holder for lookahead. */
const char *tmp = p->arg;
+ char *endp;
/* Used to save the register name. */
const char *start;
char *regname;
@@ -1140,7 +1141,8 @@ arm_stap_parse_special_token (struct gdbarch *gdbarch,
got_minus = 1;
}

- displacement = strtol (tmp, (char **) &tmp, 10);
+ displacement = strtol (tmp, &endp, 10);
+ tmp = endp;

/* Skipping last `]'. */
if (*tmp++ != ']')
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 61ccc3e..e76dcbe 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -3494,6 +3494,7 @@ i386_stap_parse_special_token (struct gdbarch *gdbarch,
char *regname;
int len;
struct stoken str;
+ char *endp;

got_minus[0] = 0;
if (*s == '+')
@@ -3504,7 +3505,8 @@ i386_stap_parse_special_token (struct gdbarch *gdbarch,
got_minus[0] = 1;
}

- displacements[0] = strtol (s, (char **) &s, 10);
+ displacements[0] = strtol (s, &endp, 10);
+ s = endp;

if (*s != '+' && *s != '-')
{
@@ -3521,7 +3523,8 @@ i386_stap_parse_special_token (struct gdbarch *gdbarch,
got_minus[1] = 1;
}

- displacements[1] = strtol (s, (char **) &s, 10);
+ displacements[1] = strtol (s, &endp, 10);
+ s = endp;

if (*s != '+' && *s != '-')
{
@@ -3538,7 +3541,8 @@ i386_stap_parse_special_token (struct gdbarch *gdbarch,
got_minus[2] = 1;
}

- displacements[2] = strtol (s, (char **) &s, 10);
+ displacements[2] = strtol (s, &endp, 10);
+ s = endp;

if (*s != '(' || s[1] != '%')
break;
@@ -3628,7 +3632,12 @@ i386_stap_parse_special_token (struct gdbarch *gdbarch,
break;

if (isdigit (*s))
- offset = strtol (s, (char **) &s, 10);
+ {
+ char *endp;
+
+ offset = strtol (s, &endp, 10);
+ s = endp;
+ }

if (*s != '(' || s[1] != '%')
break;
@@ -3675,6 +3684,8 @@ i386_stap_parse_special_token (struct gdbarch *gdbarch,

if (*s == ',')
{
+ char *endp;
+
++s;
if (*s == '+')
++s;
@@ -3684,7 +3695,8 @@ i386_stap_parse_special_token (struct gdbarch *gdbarch,
size_minus = 1;
}

- size = strtol (s, (char **) &s, 10);
+ size = strtol (s, &endp, 10);
+ s = endp;

if (*s != ')')
break;
diff --git a/gdb/solib-dsbt.c b/gdb/solib-dsbt.c
index c41326b..ea2acd1 100644
--- a/gdb/solib-dsbt.c
+++ b/gdb/solib-dsbt.c
@@ -298,7 +298,7 @@ dsbt_get_initial_loadmaps (void)
struct dsbt_info *info = get_dsbt_info ();

if (0 >= target_read_alloc (&current_target, TARGET_OBJECT_FDPIC,
- "exec", (gdb_byte**) &buf))
+ "exec", &buf))
{
info->exec_loadmap = NULL;
error (_("Error reading DSBT exec loadmap"));
@@ -308,7 +308,7 @@ dsbt_get_initial_loadmaps (void)
dsbt_print_loadmap (info->exec_loadmap);

if (0 >= target_read_alloc (&current_target, TARGET_OBJECT_FDPIC,
- "interp", (gdb_byte**)&buf))
+ "interp", &buf))
{
info->interp_loadmap = NULL;
error (_("Error reading DSBT interp loadmap"));
diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c
index 9b67304..1079e3b 100644
--- a/gdb/stap-probe.c
+++ b/gdb/stap-probe.c
@@ -422,9 +422,11 @@ stap_parse_register_operand (struct stap_parse_info *p)
{
/* The value of the displacement. */
long displacement;
+ char *endp;

disp_p = 1;
- displacement = strtol (p->arg, (char **) &p->arg, 10);
+ displacement = strtol (p->arg, &endp, 10);
+ p->arg = endp;

/* Generating the expression for the displacement. */
write_exp_elt_opcode (OP_LONG);
@@ -598,7 +600,12 @@ stap_parse_single_operand (struct stap_parse_info *p)
tmp = skip_spaces_const (tmp);

if (isdigit (*tmp))
- number = strtol (tmp, (char **) &tmp, 10);
+ {
+ char *endp;
+
+ number = strtol (tmp, &endp, 10);
+ tmp = endp;
+ }

if (!reg_ind_prefix
|| strncmp (tmp, reg_ind_prefix, reg_ind_prefix_len) != 0)
@@ -627,11 +634,13 @@ stap_parse_single_operand (struct stap_parse_info *p)
{
/* A temporary variable, needed for lookahead. */
const char *tmp = p->arg;
+ char *endp;
long number;

/* We can be dealing with a numeric constant (if `const_prefix' is
NULL), or with a register displacement. */
- number = strtol (tmp, (char **) &tmp, 10);
+ number = strtol (tmp, &endp, 10);
+ tmp = endp;

if (p->inside_paren_p)
tmp = skip_spaces_const (tmp);
@@ -667,9 +676,11 @@ stap_parse_single_operand (struct stap_parse_info *p)
{
/* We are dealing with a numeric constant. */
long number;
+ char *endp;

p->arg += const_prefix_len;
- number = strtol (p->arg, (char **) &p->arg, 10);
+ number = strtol (p->arg, &endp, 10);
+ p->arg = endp;

write_exp_elt_opcode (OP_LONG);
write_exp_elt_type (builtin_type (gdbarch)->builtin_long);