/* find-suffix.c: return the stuff after a dot. Copyright 1992, 1993, 1995, 2008, 2011, 2016 Karl Berry. This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, see . */ #include #include /* Return pointer to first character after `.' in last directory element of NAME. If the name is `foo' or `/foo.bar/baz', we have no extension. */ /* The the result of strrchr(NAME, '.'), when not NULL, is a non-const pointer into the string NAME. However, this is cheating (motivated by limitations of the C language) when the argument NAME is a const string, because in that case the (technically non-const) result from strrchr() is certainly not modifiable. We do not want to repeat this kind of cheating for find_suffix() and therefore declare find_suffix(NAME) as const. When find_suffix(NAME) is non-NULL and the argument NAME is modifiable (i.e., non-const) then NAME+(find_suffix(NAME)-NAME) is an equivalent modifiable string and the pointer arithmetic is optimized away by modern compilers. */ const_string find_suffix (const_string name) { const_string dot_pos = strrchr (name, '.'); const_string p; if (dot_pos == NULL) return NULL; for (p = dot_pos + 1; *p; p++) { if (IS_DIR_SEP (*p)) return NULL; } return dot_pos + 1; }