lib: path-util: Improved conditional expressions in path_normalize() to match the...

Added some more assertions in the process to make sure subtractions are always valid.

diff --git a/src/lib/path-util.c b/src/lib/path-util.c
index e3e74d77cefbcc4b3d765fbf90ccb638dfc4ec69..e7d8a230e51a025a6be166357a5f5568ff0c77f4 100644 (file)
--- a/src/lib/path-util.c
+++ b/src/lib/path-util.c
@@ -81,14 +81,16 @@ static int path_normalize(const char *path, bool resolve_links,
                } else if (seglen == 2 && p[0] == '.' && p[1] == '.') {
                        /* a reference to parent segment; back up to previous
                         * slash */
-                       if (npath_pos > npath + 1) {
+                       i_assert(npath_pos >= npath);
+                       if ((npath_pos - npath) > 1) {
                                if (*(npath_pos-1) == '/')
                                        npath_pos--;
                                for (; *(npath_pos-1) != '/'; npath_pos--);
                        }
                } else {
                        /* allocate space if necessary */
-                       if ((npath_pos + seglen + 1) >= (npath + asize)) {
+                       i_assert(npath_pos >= npath);
+                       if ((size_t)((npath_pos - npath) + seglen + 1) >= asize) {
                                ptrdiff_t npath_offset = npath_pos - npath;
                                asize = nearest_power(npath_offset + seglen + 2);
                                npath = t_buffer_reget(npath, asize);
@@ -96,8 +98,8 @@ static int path_normalize(const char *path, bool resolve_links,
                        }
 
                        /* make sure npath now ends in slash */
+                       i_assert(npath_pos > npath);
                        if (*(npath_pos-1) != '/') {
-                               i_assert(npath_pos >= npath);
                                i_assert((size_t)((npath_pos - npath) + 1) < asize);
                                *(npath_pos++) = '/';
                        }
@@ -138,7 +140,8 @@ static int path_normalize(const char *path, bool resolve_links,
                                   [npath][0][preserved tail][link buffer][room for tail][0]
                                 */
                                espace = ltlen + tlen + 2;
-                               if ((npath_pos + espace + lsize) >= (npath + asize)) {
+                               i_assert(npath_pos >= npath);
+                               if ((size_t)((npath_pos - npath) + espace + lsize) >= asize) {
                                        ptrdiff_t npath_offset = npath_pos - npath;
                                        asize = nearest_power((npath_offset + espace + lsize) + 1);
                                        lsize = asize - (npath_offset + espace);
@@ -184,8 +187,9 @@ static int path_normalize(const char *path, bool resolve_links,
                                           we need to allocate more space as well if lsize == ret,
                                           because the returned link may have gotten truncated */
                                        espace = ltlen + tlen + 2;
-                                       if ((npath_pos + espace + lsize) >= (npath + asize) ||
-                                            lsize == (size_t)ret) {
+                                       i_assert(npath_pos >= npath);
+                                       if ((size_t)((npath_pos - npath) + espace + lsize) >= asize ||
+                                           lsize == (size_t)ret) {
                                                ptrdiff_t npath_offset = npath_pos - npath;
                                                asize = nearest_power((npath_offset + espace + lsize) + 1);
                                                lsize = asize - (npath_offset + espace);
@@ -215,7 +219,8 @@ static int path_normalize(const char *path, bool resolve_links,
                                        npath_pos = npath + 1;
                                } else {
                                        /* relative symlink; back up to previous segment */
-                                       if (npath_pos > npath + 1) {
+                                       i_assert(npath_pos >= npath);
+                                       if ((npath_pos - npath) > 1) {
                                                if (*(npath_pos-1) == '/')
                                                        npath_pos--;
                                                for (; *(npath_pos-1) != '/'; npath_pos--);
@@ -237,7 +242,7 @@ static int path_normalize(const char *path, bool resolve_links,
        i_assert((size_t)(npath_pos - npath) < asize);
 
        /* remove any trailing slash */
-       if (npath_pos > npath + 1 && *(npath_pos-1) == '/')
+       if ((npath_pos - npath) > 1 && *(npath_pos-1) == '/')
                npath_pos--;
        *npath_pos = '\0';