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-rw-r--r--builtin-stripspace.c99
1 files changed, 99 insertions, 0 deletions
diff --git a/builtin-stripspace.c b/builtin-stripspace.c
new file mode 100644
index 0000000000..916355ca5d
--- /dev/null
+++ b/builtin-stripspace.c
@@ -0,0 +1,99 @@
+#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;
+ int strip_comments = 0;
+
+ if (argc > 1 && (!strcmp(argv[1], "-s") ||
+ !strcmp(argv[1], "--strip-comments")))
+ strip_comments = 1;
+
+ size = 1024;
+ buffer = xmalloc(size);
+ if (read_fd(0, &buffer, &size)) {
+ free(buffer);
+ die("could not read the input");
+ }
+
+ size = stripspace(buffer, size, strip_comments);
+ write_or_die(1, buffer, size);
+ if (size)
+ putc('\n', stdout);
+
+ free(buffer);
+ return 0;
+}