vcs-svn: allow input from file descriptor

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

t/t0081-line-buffer.sh

@@ -131,6 +131,15 @@ test_expect_success PIPE,EXPENSIVE 'longer read (around 65536 bytes)' '
 	long_read_test 65536
 '
 
+test_expect_success 'read from file descriptor' '
+	rm -f input &&
+	echo hello >expect &&
+	echo hello >input &&
+	echo copy 6 |
+	test-line-buffer "&4" 4<input >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'buffer_read_string copes with null byte' '
 	>expect &&
 	q_to_nul <<-\EOF | test-line-buffer >actual &&

test-line-buffer.c

@@ -69,13 +69,18 @@ int main(int argc, char *argv[])
 	else if (argc == 2)
 		filename = argv[1];
 	else
-		usage("test-line-buffer [file] < script");
+		usage("test-line-buffer [file | &fd] < script");
 
 	if (buffer_init(&stdin_buf, NULL))
 		die_errno("open error");
 	if (filename) {
-		if (buffer_init(&file_buf, filename))
-			die_errno("error opening %s", filename);
+		if (*filename == '&') {
+			if (buffer_fdinit(&file_buf, strtouint32(filename + 1)))
+				die_errno("error opening fd %s", filename + 1);
+		} else {
+			if (buffer_init(&file_buf, filename))
+				die_errno("error opening %s", filename);
+		}
 		input = &file_buf;
 	}
 

vcs-svn/line_buffer.c

@@ -17,6 +17,14 @@ int buffer_init(struct line_buffer *buf, const char *filename)
 	return 0;
 }
 
+int buffer_fdinit(struct line_buffer *buf, int fd)
+{
+	buf->infile = fdopen(fd, "r");
+	if (!buf->infile)
+		return -1;
+	return 0;
+}
+
 int buffer_deinit(struct line_buffer *buf)
 {
 	int err;

vcs-svn/line_buffer.h

@@ -13,6 +13,7 @@ struct line_buffer {
 #define LINE_BUFFER_INIT {"", STRBUF_INIT, NULL}
 
 int buffer_init(struct line_buffer *buf, const char *filename);
+int buffer_fdinit(struct line_buffer *buf, int fd);
 int buffer_deinit(struct line_buffer *buf);
 char *buffer_read_line(struct line_buffer *buf);
 char *buffer_read_string(struct line_buffer *buf, uint32_t len);

vcs-svn/line_buffer.txt

@@ -27,10 +27,11 @@ resources.
 Functions
 ---------
 
-`buffer_init`::
-	Open the named file for input.  If filename is NULL,
-	start reading from stdin.  On failure, returns -1 (with
-	errno indicating the nature of the failure).
+`buffer_init`, `buffer_fdinit`::
+	Open the named file or file descriptor for input.
+	buffer_init(buf, NULL) prepares to read from stdin.
+	On failure, returns -1 (with errno indicating the nature
+	of the failure).
 
 `buffer_deinit`::
 	Stop reading from the current file (closing it unless