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Avoid invalid pointer to pointer conversions. 

Casts between 'char **' <-> 'unsigned char **' and 'char **' <-> const
char **' are actually invalid:

  http://gcc.gnu.org/ml/gcc-help/2013-03/msg00118.html

In a nutshell, char (and variants) can alias anything, but pointers to
chars get no special treatment (cf. C99/N1256, 6.5/7).

Turns out older gcc's actually warn/complain on these constructs,
though newer one's don't:

  http://sourceware.org/ml/gdb-patches/2013-03/msg00429.html
  http://sourceware.org/ml/gdb-patches/2013-03/msg00430.html

This patch fixes the cases I added last week.  It also fixes one other
preexisting case in charset.c, though it seems even older gccs don't
complain of char * <-> const char * aliasing.

Tested on x86_64 Fedora 17.

gdb/
2013-03-11  Pedro Alves  <palves@redhat.com>

	* charset.c (convert_between_encodings): Don't cast between
	different pointer to pointer types.  Instead, make the 'inp' local
	be of the type iconv expects.
	(wchar_iterate): Don't cast between different pointer to pointer
	types.  Instead, use new pointer local of the type iconv expects.
	* target.c (target_read_stralloc, target_fileio_read_stralloc):
	Add new local of type char pointer, and use it to get a
	char/string view of the byte buffer, instead of casting between
	pointer to pointer types.
This commit is contained in:
Pedro Alves 2013-03-11 12:22:20 +00:00
parent 905851752e
commit 39086a0e13
3 changed files with 35 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
gdb/ChangeLog
View File

@ -1,3 +1,15 @@
2013-03-11 Pedro Alves <palves@redhat.com>
* charset.c (convert_between_encodings): Don't cast between
different pointer to pointer types. Instead, make the 'inp' local
be of the type iconv expects.
(wchar_iterate): Don't cast between different pointer to pointer
types. Instead, use new pointer local of the type iconv expects.
* target.c (target_read_stralloc, target_fileio_read_stralloc):
Add new local of type char pointer, and use it to get a
char/string view of the byte buffer, instead of casting between
pointer to pointer types.
2013-03-11 Hafiz Abid Qadeer <abidh@codesourcery.com>
* remote.c (remote_set_trace_buffer_size): Move != operator

13
gdb/charset.c
View File

@ -474,7 +474,7 @@ convert_between_encodings (const char *from, const char *to,
iconv_t desc;
struct cleanup *cleanups;
size_t inleft;
char *inp;
ICONV_CONST char *inp;
unsigned int space_request;
/* Often, the host and target charsets will be the same. */
@ -490,7 +490,7 @@ convert_between_encodings (const char *from, const char *to,
cleanups = make_cleanup (cleanup_iconv, &desc);
inleft = num_bytes;
inp = (char *) bytes;
inp = (ICONV_CONST char *) bytes;
space_request = num_bytes;
@ -506,7 +506,7 @@ convert_between_encodings (const char *from, const char *to,
outp = obstack_base (output) + old_size;
outleft = space_request;
r = iconv (desc, (ICONV_CONST char **) &inp, &inleft, &outp, &outleft);
r = iconv (desc, &inp, &inleft, &outp, &outleft);
/* Now make sure that the object on the obstack only includes
bytes we have converted. */
@ -640,14 +640,15 @@ wchar_iterate (struct wchar_iterator *iter,
out_request = 1;
while (iter->bytes > 0)
{
ICONV_CONST char *inptr = (ICONV_CONST char *) iter->input;
char *outptr = (char *) &iter->out[0];
const gdb_byte *orig_inptr = iter->input;
size_t orig_in = iter->bytes;
size_t out_avail = out_request * sizeof (gdb_wchar_t);
size_t num;
size_t r = iconv (iter->desc,
(ICONV_CONST char **) &iter->input,
&iter->bytes, &outptr, &out_avail);
size_t r = iconv (iter->desc, &inptr, &iter->bytes, &outptr, &out_avail);
iter->input = (gdb_byte *) inptr;
if (r == (size_t) -1)
{

30
gdb/target.c
View File

@ -2378,11 +2378,12 @@ char *
target_read_stralloc (struct target_ops *ops, enum target_object object,
const char *annex)
{
char *buffer;
gdb_byte *buffer;
char *bufstr;
LONGEST i, transferred;
transferred = target_read_alloc_1 (ops, object, annex,
(gdb_byte **) &buffer, 1);
transferred = target_read_alloc_1 (ops, object, annex, &buffer, 1);
bufstr = (char *) buffer;
if (transferred < 0)
return NULL;
@ -2390,11 +2391,11 @@ target_read_stralloc (struct target_ops *ops, enum target_object object,
if (transferred == 0)
return xstrdup ("");
buffer[transferred] = 0;
bufstr[transferred] = 0;
/* Check for embedded NUL bytes; but allow trailing NULs. */
for (i = strlen (buffer); i < transferred; i++)
if (buffer[i] != 0)
for (i = strlen (bufstr); i < transferred; i++)
if (bufstr[i] != 0)
{
warning (_("target object %d, annex %s, "
"contained unexpected null characters"),
@ -2402,7 +2403,7 @@ target_read_stralloc (struct target_ops *ops, enum target_object object,
break;
}
return buffer;
return bufstr;
}
/* Memory transfer methods. */
@ -3542,11 +3543,12 @@ target_fileio_read_alloc (const char *filename, gdb_byte **buf_p)
char *
target_fileio_read_stralloc (const char *filename)
{
char *buffer;
gdb_byte *buffer;
char *bufstr;
LONGEST i, transferred;
transferred = target_fileio_read_alloc_1 (filename,
(gdb_byte **) &buffer, 1);
transferred = target_fileio_read_alloc_1 (filename, &buffer, 1);
bufstr = (char *) buffer;
if (transferred < 0)
return NULL;
@ -3554,11 +3556,11 @@ target_fileio_read_stralloc (const char *filename)
if (transferred == 0)
return xstrdup ("");
buffer[transferred] = 0;
bufstr[transferred] = 0;
/* Check for embedded NUL bytes; but allow trailing NULs. */
for (i = strlen (buffer); i < transferred; i++)
if (buffer[i] != 0)
for (i = strlen (bufstr); i < transferred; i++)
if (bufstr[i] != 0)
{
warning (_("target file %s "
"contained unexpected null characters"),
@ -3566,7 +3568,7 @@ target_fileio_read_stralloc (const char *filename)
break;
}
return buffer;
return bufstr;
}