no longer use mmap() in rsync because of the risk of a SIGBUS when

another program (such as a mailer) truncates a file.

To offset the speed loss I have rewritten the map_ptr() code to make
much better use of read().

diff --git a/configure.in b/configure.in
index 147755f..79aab77 100644 (file)
--- a/configure.in
+++ b/configure.in
@@ -49,7 +49,7 @@ fi
 
 AC_FUNC_MEMCMP
 AC_FUNC_UTIME_NULL
-AC_CHECK_FUNCS(mmap munmap waitpid getcwd strdup strerror chown chmod mknod)
+AC_CHECK_FUNCS(waitpid getcwd strdup strerror chown chmod mknod)
 AC_CHECK_FUNCS(fchmod fstat strchr readlink link utime utimes strftime)
 AC_CHECK_FUNCS(memmove getopt_long lchown vsnprintf snprintf setsid glob strpbrk)
 AC_CHECK_FUNCS(strlcat strlcpy)

diff --git a/fileio.c b/fileio.c
index 13bf407..c39d6b0 100644 (file)
--- a/fileio.c
+++ b/fileio.c
@@ -49,8 +49,9 @@ static int write_sparse(int f,char *buf,int len)
        if (l1 == len || l2 > 0)
                last_sparse=1;
 
-       if (l1 > 0)
+       if (l1 > 0) {
                do_lseek(f,l1,SEEK_CUR);  
+       }
 
        if (l1 == len) 
                return len;
@@ -72,8 +73,9 @@ int write_file(int f,char *buf,int len)
 {
        int ret = 0;
 
-       if (!sparse_files) 
+       if (!sparse_files) {
                return write(f,buf,len);
+       }
 
        while (len>0) {
                int len1 = MIN(len, SPARSE_WRITE_SIZE);
@@ -91,123 +93,116 @@ int write_file(int f,char *buf,int 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)
 {
-       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;
+       map = (struct map_struct *)malloc(sizeof(*map));
+       if (!map) out_of_memory("map_file");
+
+       map->fd = fd;
+       map->file_size = len;
+       map->p = NULL;
+       map->p_size = 0;
+       map->p_offset = 0;
+       map->p_fd_offset = 0;
+       map->p_len = 0;
+
+       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
 
+       /* 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 */
+       if (offset > 2*CHUNK_SIZE) {
+               window_start = offset - 2*CHUNK_SIZE;
+               window_start &= ~((OFF_T)(CHUNK_SIZE-1)); /* assumes power of 2 */
+       } else {
+               window_start = 0;
+       }
+       window_size = MAX_MAP_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 = (char *)Realloc(map->p, 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;
+                       /* 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;
        }
+
+       map->p_offset = window_start;
+       map->p_len = window_size;
   
-       return map->p; 
+       return map->p + (offset - map->p_offset); 
 }
 
 
 void unmap_file(struct map_struct *map)
 {
-#ifdef USE_MMAP
-       if (map->map) {
-               munmap(map->map,map->p_len);
-               map->map = NULL;
-       }
-#endif
        if (map->p) {
                free(map->p);
                map->p = NULL;

diff --git a/match.c b/match.c
index dc4dbd1..29b5251 100644 (file)
--- a/match.c
+++ b/match.c
@@ -120,7 +120,7 @@ static void matched(int f,struct sum_struct *s,struct map_struct *buf,
                last_match = offset;
 
        if (buf)
-               show_progress(last_match, buf->size);
+               show_progress(last_match, buf->file_size);
 
        if (i == -1) end_progress();
 }

diff --git a/rsync.h b/rsync.h
index 5ea5301..af76aac 100644 (file)
--- a/rsync.h
+++ b/rsync.h
@@ -52,7 +52,7 @@
 #define SPARSE_WRITE_SIZE (1024)
 #define WRITE_SIZE (32*1024)
 #define CHUNK_SIZE (32*1024)
-#define MAX_MAP_SIZE (1*1024*1024)
+#define MAX_MAP_SIZE (256*1024)
 #define IO_BUFFER_SIZE (4092)
 #define MAX_READ_BUFFER (1024*1024)
 
@@ -148,11 +148,6 @@
 #endif
 #include <errno.h>
 
-#if defined(HAVE_MMAP) && defined(HAVE_MUNMAP)
-#include <sys/mman.h>
-#define USE_MMAP 1
-#endif
-
 #ifdef HAVE_UTIME_H
 #include <utime.h>
 #endif
@@ -303,6 +298,7 @@ struct file_struct {
        char *sum;
 };
 
+
 struct file_list {
        int count;
        int malloced;
@@ -326,9 +322,9 @@ struct sum_struct {
 };
 
 struct map_struct {
-       char *map,*p;
+       char *p;
        int fd,p_size,p_len;
-       OFF_T size, p_offset;
+       OFF_T file_size, p_offset, p_fd_offset;
 };
 
 struct exclude_struct {