Apologies, you are correct. I'll book an appointment with the optician!
-Chris.
On 08/02/2013 00:15, David Holmes wrote:
On 7/02/2013 10:54 PM, Chris Hegarty wrote:
On 02/07/2013 11:54 AM, David Holmes wrote:
....
AFAICS setting len=0 means len==0 will be true and so we will
free(result).
And if len != 0 then we will have already freed result, so avoiding a
double-free.
Here's the code as it stands today.
Yes .... I don't see the problem
113 result = (WCHAR*)malloc(MAX_PATH * sizeof(WCHAR));
114 if (result != NULL) {
we've entered this block so we must free result evetually.
115 DWORD len = (*GetFinalPathNameByHandle_func)(h, result, MAX_PATH, 0);
116 if (len >= MAX_PATH) {
117 /* retry with a buffer of the right size */
118 result = (WCHAR*)realloc(result, (len+1) * sizeof(WCHAR));
119 if (result != NULL) {
120 len = (*GetFinalPathNameByHandle_func)(h, result, len, 0);
121 } else {
122 len = 0;
123 }
124 }
125 if (len > 0) {
len was good so we've gone this path
126 /**
127 * Strip prefix (should be \\?\ or \\?\UNC)
128 */
129 if (result[0] == L'\\' && result[1] == L'\\' &&
130 result[2] == L'?' && result[3] == L'\\')
131 {
132 int isUnc = (result[4] == L'U' &&
133 result[5] == L'N' &&
134 result[6] == L'C');
135 int prefixLen = (isUnc) ? 7 : 4;
136 /* actual result length (includes terminator) */
137 int resultLen = len - prefixLen + (isUnc ? 1 : 0) + 1;
138
139 /* copy result without prefix into new buffer */
140 WCHAR *tmp = (WCHAR*)malloc(resultLen * sizeof(WCHAR));
141 if (tmp == NULL) {
142 len = 0; <<<<<<<<<<<<<<<<<<< HERE
malloc failed so we need to bail out. We will now skip to line 161
143 } else {
144 WCHAR *p = result;
145 p += prefixLen;
146 if (isUnc) {
147 WCHAR *p2 = tmp;
148 p2[0] = L'\\';
149 p2++;
150 wcscpy(p2, p);
151 } else {
152 wcscpy(tmp, p);
153 }
154 free(result);
155 result = tmp;
156 }
157 }
158 }
159
160 /* unable to get final path */
161 if (len == 0 && result != NULL) {
We reach here because len==0 and result != NULL
162 free(result);
163 result = NULL;
164 }
165 }
Looks fine to me.
David
-Chris.
