1 files changed, 61 insertions, 0 deletions
diff --git a/builtin-stripspace.c b/builtin-stripspace.c
new file mode 100644
index 0000000000..2ce1264f7b
--- /dev/null
+++ b/builtin-stripspace.c
@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include "builtin.h"
+
+/*
+ * Remove empty lines from the beginning and end.
+ *
+ * Turn multiple consecutive empty lines into just one
+ * empty line.  Return true if it is an incomplete line.
+ */
+static int cleanup(char *line)
+{
+	int len = strlen(line);
+
+	if (len && line[len-1] == '\n') {
+		if (len == 1)
+			return 0;
+		do {
+			unsigned char c = line[len-2];
+			if (!isspace(c))
+				break;
+			line[len-2] = '\n';
+			len--;
+			line[len] = 0;
+		} while (len > 1);
+		return 0;
+	}
+	return 1;
+}
+
+void stripspace(FILE *in, FILE *out)
+{
+	int empties = -1;
+	int incomplete = 0;
+	char line[1024];
+
+	while (fgets(line, sizeof(line), in)) {
+		incomplete = cleanup(line);
+
+		/* Not just an empty line? */
+		if (line[0] != '\n') {
+			if (empties > 0)
+				fputc('\n', out);
+			empties = 0;
+			fputs(line, out);
+			continue;
+		}
+		if (empties < 0)
+			continue;
+		empties++;
+	}
+	if (incomplete)
+		fputc('\n', out);
+}
+
+int cmd_stripspace(int argc, const char **argv, char **envp)
+{
+	stripspace(stdin, stdout);
+	return 0;
+}