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MDEV-11896: thd_security_context - use snprintf to fill buffer with i… #328

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MDEV-11896: thd_security_context - use snprintf to fill buffer with i… #328

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60 changes: 14 additions & 46 deletions sql/sql_class.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -691,9 +691,8 @@ extern "C"
char *thd_security_context(THD *thd, char *buffer, unsigned int length,
unsigned int max_query_len)
{
String str(buffer, length, &my_charset_latin1);
const Security_context *sctx= &thd->main_security_ctx;
char header[256];
char *buffer_start= buffer;
int len;
/*
The pointers thd->query and thd->proc_info might change since they are
Expand All @@ -706,64 +705,33 @@ char *thd_security_context(THD *thd, char *buffer, unsigned int length,
*/
const char *proc_info= thd->proc_info;

len= my_snprintf(header, sizeof(header),
"MySQL thread id %lu, OS thread handle 0x%lx, query id %lu",
thd->thread_id, (ulong) thd->real_id, (ulong) thd->query_id);
str.length(0);
str.append(header, len);
len= my_snprintf(buffer, length,
"MySQL thread id %lu, OS thread handle 0x%lx, query id %lu"
"%s%s%s%s%s%s%s%s",
thd->thread_id, (ulong) thd->real_id, (ulong) thd->query_id,
sctx->host ? " " : "", sctx->host ? sctx->host : "",
sctx->ip ? " " : "", sctx->ip ? sctx->ip : "",
sctx->user ? " " : "", sctx->user ? sctx->user : "",
proc_info ? " " : "", proc_info ? proc_info : "");

if (sctx->host)
{
str.append(' ');
str.append(sctx->host);
}

if (sctx->ip)
{
str.append(' ');
str.append(sctx->ip);
}

if (sctx->user)
{
str.append(' ');
str.append(sctx->user);
}

if (proc_info)
{
str.append(' ');
str.append(proc_info);
}
length-= len;
buffer+= len;

/* Don't wait if LOCK_thd_data is used as this could cause a deadlock */
if (!mysql_mutex_trylock(&thd->LOCK_thd_data))
if (length > 0 && !mysql_mutex_trylock(&thd->LOCK_thd_data))
{
if (thd->query())
{
if (max_query_len < 1)
len= thd->query_length();
else
len= min(thd->query_length(), max_query_len);
str.append('\n');
str.append(thd->query(), len);
len= my_snprintf(buffer, length, "\n%*s", len, thd->query());
}
mysql_mutex_unlock(&thd->LOCK_thd_data);
}

if (str.c_ptr_safe() == buffer)
return buffer;

/*
We have to copy the new string to the destination buffer because the string
was reallocated to a larger buffer to be able to fit.
*/
DBUG_ASSERT(buffer != NULL);
length= min(str.length(), length-1);
memcpy(buffer, str.c_ptr_quick(), length);
/* Make sure that the new string is null terminated */
buffer[length]= '\0';
return buffer;
return buffer_start;
}


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