1 files changed, 171 insertions, 0 deletions
diff --git a/csum-file.c b/csum-file.c
new file mode 100644
index 0000000000..fc97d6e045
--- /dev/null
+++ b/csum-file.c
@@ -0,0 +1,171 @@
+/*
+ * 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 "progress.h"
+#include "csum-file.h"
+
+static void flush(struct sha1file *f, void *buf, unsigned int count)
+{
+	if (0 <= f->check_fd && count)  {
+		unsigned char check_buffer[8192];
+		ssize_t ret = read_in_full(f->check_fd, check_buffer, count);
+
+		if (ret < 0)
+			die_errno("%s: sha1 file read error", f->name);
+		if (ret < count)
+			die("%s: sha1 file truncated", f->name);
+		if (memcmp(buf, check_buffer, count))
+			die("sha1 file '%s' validation error", f->name);
+	}
+
+	for (;;) {
+		int ret = xwrite(f->fd, buf, count);
+		if (ret > 0) {
+			f->total += ret;
+			display_throughput(f->tp, f->total);
+			buf = (char *) buf + ret;
+			count -= ret;
+			if (count)
+				continue;
+			return;
+		}
+		if (!ret)
+			die("sha1 file '%s' write error. Out of diskspace", f->name);
+		die_errno("sha1 file '%s' write error", f->name);
+	}
+}
+
+void sha1flush(struct sha1file *f)
+{
+	unsigned offset = f->offset;
+
+	if (offset) {
+		git_SHA1_Update(&f->ctx, f->buffer, offset);
+		flush(f, f->buffer, offset);
+		f->offset = 0;
+	}
+}
+
+int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
+{
+	int fd;
+
+	sha1flush(f);
+	git_SHA1_Final(f->buffer, &f->ctx);
+	if (result)
+		hashcpy(result, f->buffer);
+	if (flags & (CSUM_CLOSE | CSUM_FSYNC)) {
+		/* write checksum and close fd */
+		flush(f, f->buffer, 20);
+		if (flags & CSUM_FSYNC)
+			fsync_or_die(f->fd, f->name);
+		if (close(f->fd))
+			die_errno("%s: sha1 file error on close", f->name);
+		fd = 0;
+	} else
+		fd = f->fd;
+	if (0 <= f->check_fd) {
+		char discard;
+		int cnt = read_in_full(f->check_fd, &discard, 1);
+		if (cnt < 0)
+			die_errno("%s: error when reading the tail of sha1 file",
+				  f->name);
+		if (cnt)
+			die("%s: sha1 file has trailing garbage", f->name);
+		if (close(f->check_fd))
+			die_errno("%s: sha1 file error on close", f->name);
+	}
+	free(f);
+	return fd;
+}
+
+int sha1write(struct sha1file *f, void *buf, unsigned int count)
+{
+	while (count) {
+		unsigned offset = f->offset;
+		unsigned left = sizeof(f->buffer) - offset;
+		unsigned nr = count > left ? left : count;
+		void *data;
+
+		if (f->do_crc)
+			f->crc32 = crc32(f->crc32, buf, nr);
+
+		if (nr == sizeof(f->buffer)) {
+			/* process full buffer directly without copy */
+			data = buf;
+		} else {
+			memcpy(f->buffer + offset, buf, nr);
+			data = f->buffer;
+		}
+
+		count -= nr;
+		offset += nr;
+		buf = (char *) buf + nr;
+		left -= nr;
+		if (!left) {
+			git_SHA1_Update(&f->ctx, data, offset);
+			flush(f, data, offset);
+			offset = 0;
+		}
+		f->offset = offset;
+	}
+	return 0;
+}
+
+struct sha1file *sha1fd(int fd, const char *name)
+{
+	return sha1fd_throughput(fd, name, NULL);
+}
+
+struct sha1file *sha1fd_check(const char *name)
+{
+	int sink, check;
+	struct sha1file *f;
+
+	sink = open("/dev/null", O_WRONLY);
+	if (sink < 0)
+		return NULL;
+	check = open(name, O_RDONLY);
+	if (check < 0) {
+		int saved_errno = errno;
+		close(sink);
+		errno = saved_errno;
+		return NULL;
+	}
+	f = sha1fd(sink, name);
+	f->check_fd = check;
+	return f;
+}
+
+struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
+{
+	struct sha1file *f = xmalloc(sizeof(*f));
+	f->fd = fd;
+	f->check_fd = -1;
+	f->offset = 0;
+	f->total = 0;
+	f->tp = tp;
+	f->name = name;
+	f->do_crc = 0;
+	git_SHA1_Init(&f->ctx);
+	return f;
+}
+
+void crc32_begin(struct sha1file *f)
+{
+	f->crc32 = crc32(0, NULL, 0);
+	f->do_crc = 1;
+}
+
+uint32_t crc32_end(struct sha1file *f)
+{
+	f->do_crc = 0;
+	return f->crc32;
+}