X-Git-Url: https://mattmccutchen.net/rsync/rsync.git/blobdiff_plain/654175798bdbdd6403e10c8fa74e8586b3612ea1..deb5bf1dffcfc0507befb1c5fa61d16dea607048:/fileio.c

diff --git a/fileio.c b/fileio.c
index 13bf4079..2b86a5ef 100644
--- a/fileio.c
+++ b/fileio.c
@@ -1,29 +1,31 @@
-/* 
+/*
    Copyright (C) Andrew Tridgell 1998
-   
+   Copyright (C) 2002 by Martin Pool
+
    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 2 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, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
 
 /*
-  File IO utilities used in rsync 
+  File IO utilities used in rsync
   */
 #include "rsync.h"
 
+extern int sparse_files;
+
 static char last_byte;
 static int last_sparse;
-extern int sparse_files;
 
 int sparse_end(int f)
 {
@@ -36,50 +38,97 @@ int sparse_end(int f)
 }
 
 
-static int write_sparse(int f,char *buf,int len)
+static int write_sparse(int f,char *buf,size_t len)
 {
-	int l1=0,l2=0;
+	size_t 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++) ;
+	for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {}
+	for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {}
 
 	last_byte = buf[len-1];
 
 	if (l1 == len || l2 > 0)
 		last_sparse=1;
 
-	if (l1 > 0)
-		do_lseek(f,l1,SEEK_CUR);  
+	if (l1 > 0) {
+		do_lseek(f,l1,SEEK_CUR);
+	}
 
-	if (l1 == len) 
+	if (l1 == len)
 		return len;
 
-	if ((ret=write(f,buf+l1,len-(l1+l2))) != len-(l1+l2)) {
-		if (ret == -1 || ret == 0) return ret;
+	ret = write(f, buf + l1, len - (l1+l2));
+	if (ret == -1 || ret == 0)
+		return ret;
+	else if (ret != (int) (len - (l1+l2)))
 		return (l1+ret);
-	}
 
 	if (l2 > 0)
 		do_lseek(f,l2,SEEK_CUR);
-	
+
 	return len;
 }
 
 
+static char *wf_writeBuf;
+static size_t wf_writeBufSize;
+static size_t wf_writeBufCnt;
 
-int write_file(int f,char *buf,int len)
+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;
+}
 
-	if (!sparse_files) 
-		return write(f,buf,len);
 
-	while (len>0) {
-		int len1 = MIN(len, SPARSE_WRITE_SIZE);
-		int r1 = write_sparse(f, buf, len1);
+/*
+ * write_file does not allow incomplete writes.  It loops internally
+ * until len bytes are written or errno is set.
+ */
+int write_file(int f,char *buf,size_t len)
+{
+	int ret = 0;
+
+	while (len > 0) {
+		int r1;
+		if (sparse_files) {
+			int len1 = MIN(len, SPARSE_WRITE_SIZE);
+			r1 = write_sparse(f, buf, len1);
+		} else {
+			if (!wf_writeBuf) {
+				wf_writeBufSize = WRITE_SIZE * 8;
+				wf_writeBufCnt  = 0;
+				wf_writeBuf = new_array(char, wf_writeBufSize);
+				if (!wf_writeBuf)
+					out_of_memory("write_file");
+			}
+			r1 = MIN(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;
+			if (ret > 0)
+				return ret;
 			return r1;
 		}
 		len -= r1;
@@ -90,129 +139,126 @@ int write_file(int f,char *buf,int len)
 }
 
 
-
-struct map_struct *map_file(int fd,OFF_T len)
+/* 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, OFF_T map_size,
+			    size_t block_size)
 {
-	struct map_struct *ret;
-	ret = (struct map_struct *)malloc(sizeof(*ret));
-	if (!ret) out_of_memory("map_file");
-
-	ret->map = NULL;
-	ret->fd = fd;
-	ret->size = len;
-	ret->p = NULL;
-	ret->p_size = 0;
-	ret->p_offset = 0;
-	ret->p_len = 0;
-
-#ifdef USE_MMAP
-	len = MIN(len, MAX_MAP_SIZE);
-	ret->map = (char *)do_mmap(NULL,len,PROT_READ,MAP_SHARED,fd,0);
-	if (ret->map == (char *)-1) {
-		ret->map = NULL;
-	} else {
-		ret->p_len = len;
-	}
-#endif
-	return ret;
+	struct map_struct *map;
+
+	if (!(map = new(struct map_struct)))
+		out_of_memory("map_file");
+
+	if (block_size && (map_size % block_size))
+		map_size += block_size - (map_size % block_size);
+
+	memset(map, 0, sizeof map[0]);
+	map->fd = fd;
+	map->file_size = len;
+	map->def_window_size = map_size;
+
+	return map;
 }
 
 
+/* slide the read window in the file */
 char *map_ptr(struct map_struct *map,OFF_T offset,int len)
 {
 	int nread;
+	OFF_T window_start, read_start;
+	int window_size, read_size, read_offset;
 
-	if (len == 0) 
+	if (len == 0)
 		return NULL;
 
-	if (len > (map->size-offset))
-		len = map->size-offset;
-
-#ifdef USE_MMAP
-	if (map->map) {
-		if (offset >= map->p_offset && 
-		    offset+len <= map->p_offset+map->p_len) {
-			return (map->map + (offset - map->p_offset));
-		}
-		if (munmap(map->map, map->p_len) != 0) {
-			rprintf(FERROR,"munmap failed : %s\n", strerror(errno));
-			exit_cleanup(RERR_MALLOC);
-		}
-
-		/* align the mmap region on a nice boundary back a bit from
-		   where it is asked for to allow for some seeking */
-		if (offset > 2*CHUNK_SIZE) {
-			map->p_offset = offset - 2*CHUNK_SIZE;
-			map->p_offset &= ~((OFF_T)(CHUNK_SIZE-1));
-		} else {
-			map->p_offset = 0;
-		}
-		
-		/* map up to MAX_MAP_SIZE */
-		map->p_len = MAX(len, MAX_MAP_SIZE);
-		map->p_len = MIN(map->p_len, map->size - map->p_offset);
-
-		map->map = (char *)do_mmap(NULL,map->p_len,PROT_READ,
-					   MAP_SHARED,map->fd,map->p_offset);
-
-		if (map->map == (char *)-1) {
-			map->map = NULL;
-			map->p_len = 0;
-			map->p_offset = 0;
-		} else {
-			return (map->map + (offset - map->p_offset));
-		}
+	/* can't go beyond the end of file */
+	if (len > (map->file_size - offset)) {
+		len = map->file_size - offset;
 	}
-#endif
 
-	if (offset >= map->p_offset && 
+	/* 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));
 	}
 
-	len = MAX(len,CHUNK_SIZE);
-	if (len > (map->size-offset))
-		len = map->size-offset;
-
-	if (len > map->p_size) {
-		if (map->p) free(map->p);
-		map->p = (char *)malloc(len);
-		if (!map->p) out_of_memory("map_ptr");
-		map->p_size = len;
+	/* nope, we are going to have to do a read. Work out our desired window */
+	window_start = offset;
+	window_size = map->def_window_size;
+	if (window_start + window_size > map->file_size) {
+		window_size = map->file_size - window_start;
+	}
+	if (offset + len > window_start + window_size) {
+		window_size = (offset+len) - window_start;
 	}
 
-	map->p_offset = offset;
-	map->p_len = len;
+	/* 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);
+		if (!map->p)
+			out_of_memory("map_ptr");
+		map->p_size = window_size;
+	}
 
-	if (do_lseek(map->fd,offset,SEEK_SET) != offset) {
-		rprintf(FERROR,"lseek failed in map_ptr\n");
-		exit_cleanup(RERR_FILEIO);
+	/* 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 = 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 ((nread=read(map->fd,map->p,len)) != len) {		
-		if (nread < 0) nread = 0;
-		/* the best we can do is zero the buffer - the file
-                   has changed mid transfer! */
-		memset(map->p+nread, 0, len - nread);
+	if (read_size <= 0) {
+		rprintf(FINFO,"Warning: unexpected read size of %d in map_ptr\n", read_size);
+	} else {
+		if (map->p_fd_offset != read_start) {
+			if (do_lseek(map->fd,read_start,SEEK_SET) != read_start) {
+				rprintf(FERROR,"lseek failed in map_ptr\n");
+				exit_cleanup(RERR_FILEIO);
+			}
+			map->p_fd_offset = read_start;
+		}
+
+		if ((nread=read(map->fd,map->p + read_offset,read_size)) != read_size) {
+			if (nread < 0) {
+				nread = 0;
+				if (!map->status)
+					map->status = errno;
+			}
+			/* the best we can do is zero the buffer - the file
+			   has changed mid transfer! */
+			memset(map->p+read_offset+nread, 0, read_size - nread);
+		}
+		map->p_fd_offset += nread;
 	}
-  
-	return map->p; 
+
+	map->p_offset = window_start;
+	map->p_len = window_size;
+
+	return map->p + (offset - map->p_offset);
 }
 
 
-void unmap_file(struct map_struct *map)
+int unmap_file(struct map_struct *map)
 {
-#ifdef USE_MMAP
-	if (map->map) {
-		munmap(map->map,map->p_len);
-		map->map = NULL;
-	}
-#endif
+	int	ret;
+
 	if (map->p) {
 		free(map->p);
 		map->p = NULL;
 	}
-	memset(map, 0, sizeof(*map));
+	ret = map->status;
+	memset(map, 0, sizeof map[0]);
 	free(map);
-}
 
+	return ret;
+}