- Normally, if expected is 0, it means that it is not known how
- much data is expected. However, if use_expected is specified,
- then expected being zero means exactly that. */
- while (!use_expected || (*len < expected))
+ The idea is to be able to read a line of input, or otherwise a hunk
+ of text, such as the head of an HTTP request, without crossing the
+ boundary, so that the next call to fd_read etc. reads the data
+ after the hunk. To achieve that, this function does the following:
+
+ 1. Peek at available data.
+
+ 2. Determine whether the peeked data, along with the previously
+ read data, includes the terminator.
+
+ 2a. If yes, read the data until the end of the terminator, and
+ exit.
+
+ 2b. If no, read the peeked data and goto 1.
+
+ The function is careful to assume as little as possible about the
+ implementation of peeking. For example, every peek is followed by
+ a read. If the read returns a different amount of data, the
+ process is retried until all data arrives safely.
+
+ SIZEHINT is the buffer size sufficient to hold all the data in the
+ typical case (it is used as the initial buffer size). MAXSIZE is
+ the maximum amount of memory this function is allowed to allocate,
+ or 0 if no upper limit is to be enforced.
+
+ This function should be used as a building block for other
+ functions -- see fd_read_line as a simple example. */
+
+char *
+fd_read_hunk (int fd, hunk_terminator_t terminator, long sizehint, long maxsize)
+{
+ long bufsize = sizehint;
+ char *hunk = xmalloc (bufsize);
+ int tail = 0; /* tail position in HUNK */
+
+ assert (maxsize >= bufsize);
+
+ while (1)