vcs-svn: make buffer_skip_bytes return length read

Currently there is no way to detect when input ended if it ended
early during buffer_skip_bytes.  Tell the calling program how many
bytes were actually skipped for easier debugging.

Existing callers will still ignore early EOF.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

vcs-svn/line_buffer.c

@@ -120,15 +120,16 @@ void buffer_copy_bytes(struct line_buffer *buf, off_t len)
 	}
 }
 
-void buffer_skip_bytes(struct line_buffer *buf, off_t len)
+off_t buffer_skip_bytes(struct line_buffer *buf, off_t nbytes)
 {
 	char byte_buffer[COPY_BUFFER_LEN];
-	uint32_t in;
-	while (len > 0 && !feof(buf->infile) && !ferror(buf->infile)) {
-		in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
-		in = fread(byte_buffer, 1, in, buf->infile);
-		len -= in;
+	off_t done = 0;
+	while (done < nbytes && !feof(buf->infile) && !ferror(buf->infile)) {
+		off_t len = nbytes - done;
+		size_t in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
+		done += fread(byte_buffer, 1, in, buf->infile);
 	}
+	return done;
 }
 
 void buffer_reset(struct line_buffer *buf)

vcs-svn/line_buffer.h

@@ -27,6 +27,6 @@ char *buffer_read_string(struct line_buffer *buf, uint32_t len);
 int buffer_read_char(struct line_buffer *buf);
 void buffer_read_binary(struct line_buffer *buf, struct strbuf *sb, uint32_t len);
 void buffer_copy_bytes(struct line_buffer *buf, off_t len);
-void buffer_skip_bytes(struct line_buffer *buf, off_t len);
+off_t buffer_skip_bytes(struct line_buffer *buf, off_t len);
 
 #endif

vcs-svn/line_buffer.txt

@@ -76,7 +76,8 @@ Functions
 
 `buffer_skip_bytes`::
 	Discards `len` bytes from the input stream (stopping early
-	if necessary because of an error or eof).
+	if necessary because of an error or eof).  Return value is
+	the number of bytes successfully read.
 
 `buffer_reset`::
 	Deallocates non-static buffers.