From: Andre Noll <maan@systemlinux.org>
Date: Sat, 5 Apr 2008 21:52:03 +0000 (+0200)
Subject: para_afh: Accept negative values for begin_chunk and end_chunk.
X-Git-Tag: v0.3.2~10
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=dc6a1021f7f36f5c4379f75492cab82f74e1609d;ds=sidebyside

para_afh: Accept negative values for begin_chunk and end_chunk.

Negative values are interpreted as offsets counted from the
end of the audio file.
---

diff --git a/afh.c b/afh.c
index 86f34ace..dd69d9e4 100644
--- a/afh.c
+++ b/afh.c
@@ -64,18 +64,26 @@ static int cat_file(void *audio_file_data, struct afh_info *afhi)
 	size_t size;
 
 
-	if (conf.begin_chunk_arg < 0)
-		return -ERRNO_TO_PARA_ERROR(EINVAL);
-	first_chunk = conf.begin_chunk_arg;
-
-	if (conf.end_chunk_given) {
-		if (conf.end_chunk_arg < 0)
-			return -ERRNO_TO_PARA_ERROR(EINVAL);
-		if (conf.end_chunk_arg >= afhi->chunks_total)
+	if (conf.begin_chunk_arg < 0) {
+		if (-conf.begin_chunk_arg > afhi->chunks_total)
 			return -ERRNO_TO_PARA_ERROR(EINVAL);
-		last_chunk = conf.end_chunk_arg;
+		first_chunk = afhi->chunks_total + conf.begin_chunk_arg;
+	} else
+		first_chunk = conf.begin_chunk_arg;
+	if (conf.end_chunk_given) {
+		if (conf.end_chunk_arg < 0) {
+			if (-conf.end_chunk_arg > afhi->chunks_total)
+				return -ERRNO_TO_PARA_ERROR(EINVAL);
+			last_chunk = afhi->chunks_total + conf.end_chunk_arg;
+		} else {
+			if (conf.end_chunk_arg >= afhi->chunks_total)
+				return -ERRNO_TO_PARA_ERROR(EINVAL);
+			last_chunk = conf.end_chunk_arg;
+		}
 	} else
 		last_chunk = afhi->chunks_total - 1;
+	if (first_chunk >= last_chunk)
+		return -ERRNO_TO_PARA_ERROR(EINVAL);
 	if (!afhi->chunks_total)
 		return 1;
 	afh_get_header(afhi, audio_file_data, &buf, &size);
diff --git a/afh.ggo b/afh.ggo
index 7fb9d5ac..c7552ef9 100644
--- a/afh.ggo
+++ b/afh.ggo
@@ -75,8 +75,14 @@ default="0"
 dependon="stream"
 optional
 details="
-	The chunk_num argument must be non-negative as chunks start
-	at zero.
+	The chunk_num argument must be between -num_chunks and
+	num_chunks - 1 inclusively where num_chunks is the total number
+	of chunks which is printed when using the --info option. If
+	chunk_num is negative, the given number of chunks are counted
+	backwards from the end of the file. For example --begin_chunk
+	-100 instructs para_afh to start output at chunk num_chunks
+	- 100. This is mainly useful for cutting off the end of an
+	audio file.
 "
 
 option "end_chunk" e
@@ -86,8 +92,8 @@ int typestr="chunk_num"
 dependon="stream"
 optional
 details="
-	The chunk_num argument must be less than the total number of
-	chunks. The default is to write up to the last chunk.
+	For the chunk_num argument the same rules as for --begin_chunk
+	apply.	The default is to write up to the last chunk.
 "
 
 option "just_in_time" j