1 files changed, 328 insertions, 0 deletions
diff --git a/fileio.c b/fileio.c
new file mode 100644
index 0000000..f80af19
--- /dev/null
+++ b/fileio.c
@@ -0,0 +1,328 @@
+/*
+ * File IO utilities used in rsync.
+ *
+ * Copyright (C) 1998 Andrew Tridgell
+ * Copyright (C) 2002 Martin Pool
+ * Copyright (C) 2004-2020 Wayne Davison
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, visit the http://fsf.org website.
+ */
+
+#include "rsync.h"
+#include "inums.h"
+
+#ifndef ENODATA
+#define ENODATA EAGAIN
+#endif
+
+/* We want all reads to be aligned on 1K boundaries. */
+#define ALIGN_BOUNDARY 1024
+/* How far past the boundary is an offset? */
+#define ALIGNED_OVERSHOOT(oft) ((oft) & (ALIGN_BOUNDARY-1))
+/* Round up a length to the next boundary */
+#define ALIGNED_LENGTH(len) ((((len) - 1) | (ALIGN_BOUNDARY-1)) + 1)
+
+extern int sparse_files;
+
+OFF_T preallocated_len = 0;
+
+static OFF_T sparse_seek = 0;
+static OFF_T sparse_past_write = 0;
+
+int sparse_end(int f, OFF_T size)
+{
+	int ret;
+
+	sparse_past_write = 0;
+
+	if (!sparse_seek)
+		return 0;
+
+#ifdef HAVE_FTRUNCATE
+	ret = do_ftruncate(f, size);
+#else
+	if (do_lseek(f, sparse_seek-1, SEEK_CUR) != size-1)
+		ret = -1;
+	else {
+		do {
+			ret = write(f, "", 1);
+		} while (ret < 0 && errno == EINTR);
+
+		ret = ret <= 0 ? -1 : 0;
+	}
+#endif
+
+	sparse_seek = 0;
+
+	return ret;
+}
+
+/* Note that the offset is just the caller letting us know where
+ * the current file position is in the file. The use_seek arg tells
+ * us that we should seek over matching data instead of writing it. */
+static int write_sparse(int f, int use_seek, OFF_T offset, const char *buf, int len)
+{
+	int l1 = 0, l2 = 0;
+	int ret;
+
+	for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {}
+	for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {}
+
+	sparse_seek += l1;
+
+	if (l1 == len)
+		return len;
+
+	if (sparse_seek) {
+		if (sparse_past_write >= preallocated_len) {
+			if (do_lseek(f, sparse_seek, SEEK_CUR) < 0)
+				return -1;
+		} else if (do_punch_hole(f, sparse_past_write, sparse_seek) < 0) {
+			sparse_seek = 0;
+			return -1;
+		}
+	}
+	sparse_seek = l2;
+	sparse_past_write = offset + len - l2;
+
+	if (use_seek) {
+		/* The in-place data already matches. */
+		if (do_lseek(f, len - (l1+l2), SEEK_CUR) < 0)
+			return -1;
+		return len;
+	}
+
+	while ((ret = write(f, buf + l1, len - (l1+l2))) <= 0) {
+		if (ret < 0 && errno == EINTR)
+			continue;
+		sparse_seek = 0;
+		return ret;
+	}
+
+	if (ret != (int)(len - (l1+l2))) {
+		sparse_seek = 0;
+		return l1+ret;
+	}
+
+	return len;
+}
+
+static char *wf_writeBuf;
+static size_t wf_writeBufSize;
+static size_t wf_writeBufCnt;
+
+int flush_write_file(int f)
+{
+	int ret = 0;
+	char *bp = wf_writeBuf;
+
+	while (wf_writeBufCnt > 0) {
+		if ((ret = write(f, bp, wf_writeBufCnt)) < 0) {
+			if (errno == EINTR)
+				continue;
+			return ret;
+		}
+		wf_writeBufCnt -= ret;
+		bp += ret;
+	}
+	return ret;
+}
+
+/* write_file does not allow incomplete writes.  It loops internally
+ * until len bytes are written or errno is set.  Note that use_seek and
+ * offset are only used in sparse processing (see write_sparse()). */
+int write_file(int f, int use_seek, OFF_T offset, const char *buf, int len)
+{
+	int ret = 0;
+
+	while (len > 0) {
+		int r1;
+		if (sparse_files > 0) {
+			int len1 = MIN(len, SPARSE_WRITE_SIZE);
+			r1 = write_sparse(f, use_seek, offset, buf, len1);
+			offset += r1;
+		} else {
+			if (!wf_writeBuf) {
+				wf_writeBufSize = WRITE_SIZE * 8;
+				wf_writeBufCnt  = 0;
+				wf_writeBuf = new_array(char, wf_writeBufSize);
+			}
+			r1 = (int)MIN((size_t)len, wf_writeBufSize - wf_writeBufCnt);
+			if (r1) {
+				memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1);
+				wf_writeBufCnt += r1;
+			}
+			if (wf_writeBufCnt == wf_writeBufSize) {
+				if (flush_write_file(f) < 0)
+					return -1;
+				if (!r1 && len)
+					continue;
+			}
+		}
+		if (r1 <= 0) {
+			if (ret > 0)
+				return ret;
+			return r1;
+		}
+		len -= r1;
+		buf += r1;
+		ret += r1;
+	}
+	return ret;
+}
+
+/* An in-place update found identical data at an identical location. We either
+ * just seek past it, or (for an in-place sparse update), we give the data to
+ * the sparse processor with the use_seek flag set. */
+int skip_matched(int fd, OFF_T offset, const char *buf, int len)
+{
+	OFF_T pos;
+
+	if (sparse_files > 0) {
+		if (write_file(fd, 1, offset, buf, len) != len)
+			return -1;
+		return 0;
+	}
+
+	if (flush_write_file(fd) < 0)
+		return -1;
+
+	if ((pos = do_lseek(fd, len, SEEK_CUR)) != offset + len) {
+		rsyserr(FERROR_XFER, errno, "lseek returned %s, not %s",
+			big_num(pos), big_num(offset));
+		return -1;
+	}
+
+	return 0;
+}
+
+/* This provides functionality somewhat similar to mmap() but using read().
+ * It gives sliding window access to a file.  mmap() is not used because of
+ * the possibility of another program (such as a mailer) truncating the
+ * file thus giving us a SIGBUS. */
+struct map_struct *map_file(int fd, OFF_T len, int32 read_size, int32 blk_size)
+{
+	struct map_struct *map;
+
+	map = new0(struct map_struct);
+
+	if (blk_size && (read_size % blk_size))
+		read_size += blk_size - (read_size % blk_size);
+
+	map->fd = fd;
+	map->file_size = len;
+	map->def_window_size = ALIGNED_LENGTH(read_size);
+
+	return map;
+}
+
+
+/* slide the read window in the file */
+char *map_ptr(struct map_struct *map, OFF_T offset, int32 len)
+{
+	OFF_T window_start, read_start;
+	int32 window_size, read_size, read_offset, align_fudge;
+
+	if (len == 0)
+		return NULL;
+	if (len < 0) {
+		rprintf(FERROR, "invalid len passed to map_ptr: %ld\n",
+			(long)len);
+		exit_cleanup(RERR_FILEIO);
+	}
+
+	/* in most cases the region will already be available */
+	if (offset >= map->p_offset && offset+len <= map->p_offset+map->p_len)
+		return map->p + (offset - map->p_offset);
+
+	/* nope, we are going to have to do a read. Work out our desired window */
+	align_fudge = (int32)ALIGNED_OVERSHOOT(offset);
+	window_start = offset - align_fudge;
+	window_size = map->def_window_size;
+	if (window_start + window_size > map->file_size)
+		window_size = (int32)(map->file_size - window_start);
+	if (window_size < len + align_fudge)
+		window_size = ALIGNED_LENGTH(len + align_fudge);
+
+	/* make sure we have allocated enough memory for the window */
+	if (window_size > map->p_size) {
+		map->p = realloc_array(map->p, char, window_size);
+		map->p_size = window_size;
+	}
+
+	/* Now try to avoid re-reading any bytes by reusing any bytes from the previous buffer. */
+	if (window_start >= map->p_offset && window_start < map->p_offset + map->p_len
+	 && window_start + window_size >= map->p_offset + map->p_len) {
+		read_start = map->p_offset + map->p_len;
+		read_offset = (int32)(read_start - window_start);
+		read_size = window_size - read_offset;
+		memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
+	} else {
+		read_start = window_start;
+		read_size = window_size;
+		read_offset = 0;
+	}
+
+	if (read_size <= 0) {
+		rprintf(FERROR, "invalid read_size of %ld in map_ptr\n",
+			(long)read_size);
+		exit_cleanup(RERR_FILEIO);
+	}
+
+	if (map->p_fd_offset != read_start) {
+		OFF_T ret = do_lseek(map->fd, read_start, SEEK_SET);
+		if (ret != read_start) {
+			rsyserr(FERROR, errno, "lseek returned %s, not %s",
+				big_num(ret), big_num(read_start));
+			exit_cleanup(RERR_FILEIO);
+		}
+		map->p_fd_offset = read_start;
+	}
+	map->p_offset = window_start;
+	map->p_len = window_size;
+
+	while (read_size > 0) {
+		int32 nread = read(map->fd, map->p + read_offset, read_size);
+		if (nread <= 0) {
+			if (!map->status)
+				map->status = nread ? errno : ENODATA;
+			/* The best we can do is zero the buffer -- the file
+			 * has changed mid transfer! */
+			memset(map->p + read_offset, 0, read_size);
+			break;
+		}
+		map->p_fd_offset += nread;
+		read_offset += nread;
+		read_size -= nread;
+	}
+
+	return map->p + align_fudge;
+}
+
+int unmap_file(struct map_struct *map)
+{
+	int	ret;
+
+	if (map->p) {
+		free(map->p);
+		map->p = NULL;
+	}
+	ret = map->status;
+#if 0 /* I don't think we really need this. */
+	force_memzero(map, sizeof map[0]);
+#endif
+	free(map);
+
+	return ret;
+}