memory: memchrsub and strchrsub

src/nvim/memory.c

@@ -1,5 +1,6 @@
  // Various routines dealing with allocation and deallocation of memory.
 
+#include <assert.h>
 #include <errno.h>
 #include <inttypes.h>
 #include <string.h>
@@ -251,6 +252,37 @@ void *xmemscan(const void *addr, char c, size_t size)
   return p ? p : (char *)addr + size;
 }
 
+/// Replaces every instance of `c` with `x`.
+///
+/// @warning Will read past `str + strlen(str)` if `c == NUL`.
+///
+/// @param str A NUL-terminated string.
+/// @param c   The unwanted byte.
+/// @param x   The replacement.
+void strchrsub(char *str, char c, char x)
+  FUNC_ATTR_NONNULL_ALL
+{
+  assert(c != '\0');
+  while ((str = strchr(str, c))) {
+    *str++ = x;
+  }
+}
+
+/// Replaces every instance of `c` with `x`.
+///
+/// @param data An object in memory. May contain NULs.
+/// @param c    The unwanted byte.
+/// @param x    The replacement.
+/// @param len  The length of data.
+void memchrsub(void *data, char c, char x, size_t len)
+  FUNC_ATTR_NONNULL_ALL
+{
+  char *p = data, *end = (char *)data + len;
+  while ((p = memchr(p, c, (size_t)(end - p)))) {
+    *p++ = x;
+  }
+}
+
 /// The xstpcpy() function shall copy the string pointed to by src (including
 /// the terminating NUL character) into the array pointed to by dst.
 ///