Libguestfs - Jan 2014 - Re: [PATCH 2/2] lib: utf16: Fix const-correctness issues in _hivex_recode function.

---
 lib/write.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/write.c b/lib/write.c
index 8c4dd8e..384c6b2 100644
--- a/lib/write.c
+++ b/lib/write.c
@@ -954,7 +954,6 @@ hivex_node_set_values (hive_h *h, hive_node_h node,
   for (i = 0; i < nr_values; ++i) {
     /* Allocate vk record to store this (key, value) pair. */
     static const char vk_id[2] = { 'v', 'k' };
-    size_t name_len = strlen (values[i].key);
     size_t recoded_name_len;
     int use_utf16;
     char* recoded_name = _hivex_encode_string (values[i].key,
&recoded_name_len,
-- 
1.8.4.2

This patch assumes that iconv doesn't actually modify the
input buffer, even though it is declared as char *.
---
 lib/hivex-internal.h | 6 +++---
 lib/utf16.c          | 9 +++++----
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/lib/hivex-internal.h b/lib/hivex-internal.h
index 7a548c0..6bc8638 100644
--- a/lib/hivex-internal.h
+++ b/lib/hivex-internal.h
@@ -268,9 +268,9 @@ extern size_t * _hivex_return_offset_list (offset_list
*list);
 extern void _hivex_print_offset_list (offset_list *list, FILE *fp);
 
 /* utf16.c */
-extern char* _hivex_recode (char *input_encoding,
-                            const char *input, size_t input_len,
-                            char *output_encoding, size_t *output_len);
+extern char * _hivex_recode (const char *input_encoding,
+                             const char *input, size_t input_len,
+                             const char *output_encoding, size_t *output_len);
 #define _hivex_windows_utf16_to_utf8(_input, _len) \
   _hivex_recode ("UTF-16LE", _input, _len, "UTF-8", NULL)
 #define _hivex_windows_latin1_to_utf8(_input, _len) \
diff --git a/lib/utf16.c b/lib/utf16.c
index 437613b..3641580 100644
--- a/lib/utf16.c
+++ b/lib/utf16.c
@@ -30,8 +30,8 @@
 #include "hivex-internal.h"
 
 char *
-_hivex_recode (char *input_encoding, const char *input, size_t input_len,
-               char *output_encoding, size_t *output_len)
+_hivex_recode (const char *input_encoding, const char *input, size_t input_len,
+               const char *output_encoding, size_t *output_len)
 {
   iconv_t ic = iconv_open (output_encoding, input_encoding);
   if (ic == (iconv_t) -1)
@@ -51,10 +51,11 @@ _hivex_recode (char *input_encoding, const char *input,
size_t input_len,
     errno = err;
     return NULL;
   }
-  char *inp = input;
+  const char *inp = input;
   char *outp = out;
 
-  size_t r = iconv (ic, &inp, &inlen, &outp, &outlen);
+  /* Surely iconv doesn't really modify the input buffer? XXX */
+  size_t r = iconv (ic, (char **) &inp, &inlen, &outp,
&outlen);
   if (r == (size_t) -1) {
     if (errno == E2BIG) {
       int err = errno;
-- 
1.8.4.2

On Tuesday 31 December 2013 14:27:11 Richard W.M. Jones
wrote:
> This patch assumes that iconv doesn't actually modify the
> input buffer, even though it is declared as char *.
> ---
> [...]
> @@ -51,10 +51,11 @@ _hivex_recode (char *input_encoding, const char
> *input, size_t input_len, errno = err;
>      return NULL;
>    }
> -  char *inp = input;
> +  const char *inp = input;
>    char *outp = out;
> 
> -  size_t r = iconv (ic, &inp, &inlen, &outp, &outlen);
> +  /* Surely iconv doesn't really modify the input buffer? XXX */
> +  size_t r = iconv (ic, (char **) &inp, &inlen, &outp,
&outlen);
>    if (r == (size_t) -1) {
This (the constness of the input argument) is the difference between the 
iconv implementation provided in GNU libc and the other ones, even 
though it reflects POSIX [1].

The iconv.m4 module in gnulib checks for this too, and AC_DEFINE's 
ICONV_CONST as "const" (or empty) depending on the actual prototype of
iconv(3).

[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/iconv.html

-- 
Pino Toscano