+ size_t alloc = BUFSIZ;
+
+ /* For a regular file, allocate a buffer that has exactly the right
+ size. This avoids the need to do dynamic reallocations later. */
+ {
+ struct stat st;
+
+ if (fstat (fileno (stream), &st) >= 0 && S_ISREG (st.st_mode))
+ {
+ off_t pos = ftello (stream);
+
+ if (pos >= 0 && pos < st.st_size)
+ {
+ off_t alloc_off = st.st_size - pos;
+
+ /* '1' below, accounts for the trailing NUL. */
+ if (SIZE_MAX - 1 < alloc_off)
+ {
+ errno = ENOMEM;
+ return NULL;
+ }
+
+ alloc = alloc_off + 1;
+ }
+ }
+ }
+
+ if (!(buf = malloc (alloc)))
+ return NULL; /* errno is ENOMEM. */
+
+ {
+ size_t size = 0; /* number of bytes read so far */
+ int save_errno;
+
+ for (;;)
+ {
+ /* This reads 1 more than the size of a regular file
+ so that we get eof immediately. */
+ size_t requested = alloc - size;
+ size_t count = fread (buf + size, 1, requested, stream);
+ size += count;
+
+ if (count != requested)
+ {
+ save_errno = errno;
+ if (ferror (stream))
+ break;