1 files changed, 107 insertions, 0 deletions
diff --git a/csum-file.c b/csum-file.c
new file mode 100644
index 0000000..9ab9971
--- /dev/null
+++ b/csum-file.c
@@ -0,0 +1,107 @@
+/*
+ * csum-file.c
+ *
+ * Copyright (C) 2005 Linus Torvalds
+ *
+ * Simple file write infrastructure for writing SHA1-summed
+ * files. Useful when you write a file that you want to be
+ * able to verify hasn't been messed with afterwards.
+ */
+#include "cache.h"
+#include "csum-file.h"
+
+static void sha1flush(struct sha1file *f, unsigned int count)
+{
+	void *buf = f->buffer;
+
+	for (;;) {
+		int ret = xwrite(f->fd, buf, count);
+		if (ret > 0) {
+			buf = (char *) buf + ret;
+			count -= ret;
+			if (count)
+				continue;
+			return;
+		}
+		if (!ret)
+			die("sha1 file '%s' write error. Out of diskspace", f->name);
+		die("sha1 file '%s' write error (%s)", f->name, strerror(errno));
+	}
+}
+
+int sha1close(struct sha1file *f, unsigned char *result, int final)
+{
+	unsigned offset = f->offset;
+	if (offset) {
+		SHA1_Update(&f->ctx, f->buffer, offset);
+		sha1flush(f, offset);
+		f->offset = 0;
+	}
+	if (!final)
+		return 0;	/* only want to flush (no checksum write, no close) */
+	SHA1_Final(f->buffer, &f->ctx);
+	if (result)
+		hashcpy(result, f->buffer);
+	sha1flush(f, 20);
+	if (close(f->fd))
+		die("%s: sha1 file error on close (%s)", f->name, strerror(errno));
+	free(f);
+	return 0;
+}
+
+int sha1write(struct sha1file *f, void *buf, unsigned int count)
+{
+	if (f->do_crc)
+		f->crc32 = crc32(f->crc32, buf, count);
+	while (count) {
+		unsigned offset = f->offset;
+		unsigned left = sizeof(f->buffer) - offset;
+		unsigned nr = count > left ? left : count;
+
+		memcpy(f->buffer + offset, buf, nr);
+		count -= nr;
+		offset += nr;
+		buf = (char *) buf + nr;
+		left -= nr;
+		if (!left) {
+			SHA1_Update(&f->ctx, f->buffer, offset);
+			sha1flush(f, offset);
+			offset = 0;
+		}
+		f->offset = offset;
+	}
+	return 0;
+}
+
+struct sha1file *sha1fd(int fd, const char *name)
+{
+	struct sha1file *f;
+	unsigned len;
+
+	f = xmalloc(sizeof(*f));
+
+	len = strlen(name);
+	if (len >= PATH_MAX)
+		die("you wascally wabbit, you");
+	f->namelen = len;
+	memcpy(f->name, name, len+1);
+
+	f->fd = fd;
+	f->error = 0;
+	f->offset = 0;
+	f->do_crc = 0;
+	SHA1_Init(&f->ctx);
+	return f;
+}
+
+void crc32_begin(struct sha1file *f)
+{
+	f->crc32 = crc32(0, Z_NULL, 0);
+	f->do_crc = 1;
+}
+
+uint32_t crc32_end(struct sha1file *f)
+{
+	f->do_crc = 0;
+	return f->crc32;
+}