added stacked overlays

diff --git a/fusefile.c b/fusefile.c
index 9e5cb45d835b771e73548b8b443461474fcaa487..e05b90ebdf4c8a3de0c45d56a562dc71f4031fc4 100644 (file)
--- a/fusefile.c
+++ b/fusefile.c
@@ -41,6 +41,8 @@ struct Region {
     off_t end;
 };
 
+#define REGIONKEEP(r) ((r,beg == r.end)?: 0 : 1)
+
 struct Source {
     char *filename;
     ssize_t from;
@@ -50,6 +52,8 @@ struct Source {
     int dirty;
 };
 
+#define ENDSOURCE( S ) ( S.start + ( S.to - S.from ) )
+
 static struct {
     struct Source *array;
     int count;
@@ -65,12 +69,12 @@ static struct {
 /**
  * Overlay
  */
-static struct {
+static struct Overlay {
     struct Source source;
     struct Region *table;
     size_t count;
     size_t limit;
-} overlay;
+} overlay; // The current overlay.
 
 static void usage();
 
@@ -270,13 +274,24 @@ static void overlay_mark(off_t beg,off_t end) {
 #endif
 }
 
-static void setup_overlay(char *filename) {
-    overlay.source.filename = filename;
-    overlay.source.fd = open( filename, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR );
-    if ( overlay.source.fd < 0 ) {
-       perror( filename );
+/**
+ * Capture overlay filenames for processing after source fragments.
+ */
+static void overlay_setup(char *filenames) {
+    overlay.source.filename = filenames;
+}
+
+// Duplicate the source record data at the given index.
+static void dup_source_item(int index) {
+    sources.count++;
+    sources.array = realloc(
+       sources.array, sources.count * sizeof( struct Source ) );
+    if ( sources.array == 0 ) {
+       fprintf( stderr, "** OOM when expanding frament table\n" );
        usage();
     }
+    memcpy( &sources.array[ index+1 ], &sources.array[ index ],
+           sizeof( struct Source ) );
 }
 
 #if DEBUG
@@ -626,6 +641,111 @@ static void overlay_load() {
     }
 }
 
+/**
+ * Inject an overlay fragment into the source table, end return the
+ * end of the injected fragment.
+ */
+static off_t overlay_inject_from_region(off_t beg,off_t end) {
+    int index = find_source( beg );
+    if ( index < 0 ) {
+       fprintf( stderr, "** Injecting %s at %ld failed\n",
+                overlay.source.filename, beg );
+       usage();
+    }
+    if ( end > ENDSOURCE( sources.array[ index ] ) ) {
+       end = ENDSOURCE( sources.array[ index ] );
+    }
+    struct Region frags[3] = {
+       { sources.array[ index ].start, beg },
+       { beg, ENDSOURCE( sources.array[ index ] ) },
+       { ENDSOURCE( sources.array[ index ] ), end } };
+    ssize_t size = frags[0].end - frags[0].beg;
+    if ( size ) {
+       // "Duplicate" the indexed source data, copying the filename
+       dup_source_item( index );
+       sources.array[ index ].to = sources.array[ index ].from + size;
+       index++;
+       sources.array[ index ].start = beg;
+       sources.array[ index ].from = sources.array[ index-1 ].to;
+    }
+    size = frags[2].end        - frags[2].beg;
+    if ( size ) {
+       dup_source_item( index );
+       sources.array[ index+1 ].start = frags[2].beg;
+       sources.array[ index+1 ].from = sources.array[ index+1 ].to -size;
+    }
+    // Replace the [index] fragment
+    sources.array[ index ].filename = overlay.source.filename;
+    sources.array[ index ].start = beg;
+    sources.array[ index ].from = beg;
+    sources.array[ index ].to = end;
+    sources.array[ index ].fd = overlay.source.fd; //?
+    return end;
+}
+
+/**
+ * Inject the current (unopened) overlay into the source list.
+ */
+static void overlay_inject() {
+    overlay.source.fd = open( overlay.source.filename, O_RDONLY );
+    if ( overlay.source.fd < 0 ) {
+       perror( overlay.source.filename );
+       usage();
+    }
+    
+    if ( lseek( overlay.source.fd, overlay.source.to, SEEK_SET ) < 0 ) {
+       perror( overlay.source.filename );
+       usage();
+    }
+    size_t count = 0;
+    size_t size = sizeof( overlay.count );
+    if ( read( overlay.source.fd, &count, size ) != size ) {
+       fprintf( stderr, "** error injecting %s\n", overlay.source.filename );
+       usage();
+    }
+    if ( count == 0 ) {
+       close( overlay.source.fd );
+       return;
+    }
+    size = count * sizeof( struct Region );
+    overlay.table = calloc( sizeof( struct Region ), count );
+    if ( read( overlay.source.fd, overlay.table, size ) != size ) {
+       fprintf( stderr, "** error injecting %s\n", overlay.source.filename );
+       usage();
+    }
+    size_t i;
+    for ( i = 0; i < count; i++ ) {
+       off_t beg = overlay.table[i].beg;
+       while ( beg < overlay.table[i].end ) {
+           beg = overlay_inject_from_region( beg, overlay.table[i].end );
+       }
+    }
+    free( overlay.table );
+    overlay.table = 0;
+    close( overlay.source.fd );
+}
+
+/**
+ * Each stacked overlay file is nested into to source list
+ */
+static void overlay_post_setup() {
+    char *end;
+    while ( ( end = strchr( overlay.source.filename, ':' ) ) ) {
+       *end = 0; //  
+       overlay_inject();
+       overlay.source.filename = end + 1;
+    }
+    if ( *overlay.source.filename ) {
+       overlay.source.fd = open( overlay.source.filename,
+                                 O_RDWR | O_CREAT, S_IRUSR | S_IWUSR );
+       if ( overlay.source.fd < 0 ) {
+           perror( overlay.source.filename );
+           usage();
+       }
+       overlay_load();
+    }
+}
+
 /**
  * Write a full block of data over the sources at the offset
  */
@@ -799,8 +919,6 @@ void *fusefile_init(struct fuse_conn_info *fci) {
     return 0;
 }
 
-#define ENDSOURCE( S ) ( S.start + ( S.to - S.from ) )
-
 /**
  * Dump the current fragmentation to stdout.
  */
@@ -926,11 +1044,10 @@ int main(int argc, char *argv[])
     }
     fuseargc = i;
     mnt = argv[ i++ ]; // First non-option argument is the mount pount
-    char *overlaytag = "-overlay:";
-    int overlaytagsize = strlen( overlaytag );
-    if ( strncmp( argv[i], overlaytag, overlaytagsize ) == 0 ) {
-       // consume "-overlay:filename"
-       setup_overlay( argv[i++] + overlaytagsize ); // Need a writable file
+    if ( strcmp( argv[i], "-overlay:" ) == 0 ) {
+       // consume "-overlay:filename[,filename]*"
+       // Verify file access; to overlay must be writable.
+       overlay_setup( argv[i++] + strlen( "-overlay:" ) );
        if ( i >= argc ) {
            usage();
        }
@@ -940,7 +1057,7 @@ int main(int argc, char *argv[])
     }
     if ( overlay.source.filename ) {
        overlay.source.to = sources.size; // Register total size.
-       overlay_load();
+       overlay_post_setup();
     }
     if ( stat( mnt, &stbuf ) == -1 ) {
        int fd = open( mnt, O_CREAT | O_RDWR, S_IRUSR | S_IWUSR );