1 files changed, 94 insertions, 0 deletions
diff --git a/builtin-stripspace.c b/builtin-stripspace.c
new file mode 100644
index 0000000000..55716873dc
--- /dev/null
+++ b/builtin-stripspace.c
@@ -0,0 +1,94 @@
+#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)
+{
+	if (len) {
+		if (line[len - 1] == '\n')
+			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 has a newline at the end, it will be removed.
+ *
+ * Enable skip_comments to skip every line starting with "#".
+ */
+size_t stripspace(char *buffer, size_t length, int skip_comments)
+{
+	int empties = -1;
+	size_t i, j, len, newlen;
+	char *eol;
+
+	for (i = j = 0; i < length; i += len, j += newlen) {
+		eol = memchr(buffer + i, '\n', length - i);
+		len = eol ? eol - (buffer + i) + 1 : length - i;
+
+		if (skip_comments && len && buffer[i] == '#') {
+			newlen = 0;
+			continue;
+		}
+		newlen = cleanup(buffer + i, len);
+
+		/* Not just an empty line? */
+		if (newlen) {
+			if (empties != -1)
+				buffer[j++] = '\n';
+			if (empties > 0)
+				buffer[j++] = '\n';
+			empties = 0;
+			memmove(buffer + j, buffer + i, newlen);
+			continue;
+		}
+		if (empties < 0)
+			continue;
+		empties++;
+	}
+
+	return j;
+}
+
+int cmd_stripspace(int argc, const char **argv, const char *prefix)
+{
+	char *buffer;
+	unsigned long size;
+
+	size = 1024;
+	buffer = xmalloc(size);
+	if (read_fd(0, &buffer, &size)) {
+		free(buffer);
+		die("could not read the input");
+	}
+
+	size = stripspace(buffer, size, 0);
+	write_or_die(1, buffer, size);
+	if (size)
+		putc('\n', stdout);
+
+	free(buffer);
+	return 0;
+}