[PATCH 3/4] vcs-svn: make buffer_copy_bytes return length read

[Jonathan Nieder <jrnieder@gmail.com>]

Currently buffer_copy_bytes does not report to its caller whether
it encountered an early end of file.

Add a return value representing the number of bytes read (but not
the number of bytes copied).  This way all three unusual conditions
can be distinguished: input error with buffer_ferror, output error
with ferror(outfile), input error or early end of input by checking
the return value.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
Intuitive?

 vcs-svn/line_buffer.c |   18 +++++++++---------
 vcs-svn/line_buffer.h |    3 ++-
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/vcs-svn/line_buffer.c b/vcs-svn/line_buffer.c
index 58e076f..36f177c 100644
--- a/vcs-svn/line_buffer.c
+++ b/vcs-svn/line_buffer.c
@@ -71,19 +71,19 @@ char *buffer_read_string(uint32_t len)
 	return ferror(infile) ? NULL : s;
 }
 
-void buffer_copy_bytes(uint32_t len)
+uint32_t buffer_copy_bytes(uint32_t nbytes)
 {
-	uint32_t in;
-	while (len > 0 && !feof(infile) && !ferror(infile)) {
-		in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
+	uint32_t done = 0;
+	while (done < nbytes && !feof(infile) && !ferror(infile)) {
+		uint32_t len = nbytes - done;
+		uint32_t in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
 		in = fread(byte_buffer, 1, in, infile);
-		len -= in;
+		done += in;
 		fwrite(byte_buffer, 1, in, stdout);
-		if (ferror(stdout)) {
-			buffer_skip_bytes(len);
-			return;
-		}
+		if (ferror(stdout))
+			return done + buffer_skip_bytes(nbytes - done);
 	}
+	return done;
 }
 
 uint32_t buffer_skip_bytes(uint32_t nbytes)
diff --git a/vcs-svn/line_buffer.h b/vcs-svn/line_buffer.h
index b9dd929..7766636 100644
--- a/vcs-svn/line_buffer.h
+++ b/vcs-svn/line_buffer.h
@@ -6,7 +6,8 @@ int buffer_deinit(void);
 int buffer_ferror(void);
 char *buffer_read_line(void);
 char *buffer_read_string(uint32_t len);
-void buffer_copy_bytes(uint32_t len);
+/* Returns number of bytes read (not necessarily written). */
+uint32_t buffer_copy_bytes(uint32_t len);
 uint32_t buffer_skip_bytes(uint32_t len);
 void buffer_reset(void);
 
-- 
1.7.2.3.554.gc9b5c.dirty