1 files changed, 90 insertions, 0 deletions
diff --git a/builtin/stripspace.c b/builtin/stripspace.c
new file mode 100644
index 0000000000..4d3b93fedb
--- /dev/null
+++ b/builtin/stripspace.c
@@ -0,0 +1,90 @@
+#include "builtin.h"
+#include "cache.h"
+
+/*
+ * Returns the length of a line, without trailing spaces.
+ *
+ * If the line ends with newline, it will be removed too.
+ */
+static size_t cleanup(char *line, size_t len)
+{
+	while (len) {
+		unsigned char c = line[len - 1];
+		if (!isspace(c))
+			break;
+		len--;
+	}
+
+	return len;
+}
+
+/*
+ * Remove empty lines from the beginning and end
+ * and also trailing spaces from every line.
+ *
+ * Note that the buffer will not be NUL-terminated.
+ *
+ * Turn multiple consecutive empty lines between paragraphs
+ * into just one empty line.
+ *
+ * If the input has only empty lines and spaces,
+ * no output will be produced.
+ *
+ * If last line does not have a newline at the end, one is added.
+ *
+ * Enable skip_comments to skip every line starting with "#".
+ */
+void stripspace(struct strbuf *sb, int skip_comments)
+{
+	int empties = 0;
+	size_t i, j, len, newlen;
+	char *eol;
+
+	/* We may have to add a newline. */
+	strbuf_grow(sb, 1);
+
+	for (i = j = 0; i < sb->len; i += len, j += newlen) {
+		eol = memchr(sb->buf + i, '\n', sb->len - i);
+		len = eol ? eol - (sb->buf + i) + 1 : sb->len - i;
+
+		if (skip_comments && len && sb->buf[i] == '#') {
+			newlen = 0;
+			continue;
+		}
+		newlen = cleanup(sb->buf + i, len);
+
+		/* Not just an empty line? */
+		if (newlen) {
+			if (empties > 0 && j > 0)
+				sb->buf[j++] = '\n';
+			empties = 0;
+			memmove(sb->buf + j, sb->buf + i, newlen);
+			sb->buf[newlen + j++] = '\n';
+		} else {
+			empties++;
+		}
+	}
+
+	strbuf_setlen(sb, j);
+}
+
+int cmd_stripspace(int argc, const char **argv, const char *prefix)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int strip_comments = 0;
+
+	if (argc == 2 && (!strcmp(argv[1], "-s") ||
+				!strcmp(argv[1], "--strip-comments")))
+		strip_comments = 1;
+	else if (argc > 1)
+		usage("git stripspace [-s | --strip-comments] < <stream>");
+
+	if (strbuf_read(&buf, 0, 1024) < 0)
+		die_errno("could not read the input");
+
+	stripspace(&buf, strip_comments);
+
+	write_or_die(1, buf.buf, buf.len);
+	strbuf_release(&buf);
+	return 0;
+}