From: Ralph Ronnquist <ralph.ronnquist@gmail.com>
Date: Fri, 15 Jul 2022 01:28:04 +0000 (+1000)
Subject: allow overwriting without changing size
X-Git-Tag: 0.4~11^2~3
X-Git-Url: https://git.rrq.au/?a=commitdiff_plain;h=a83a2cd9258ecb0420a019bb5d4cd32db8a444ac;hp=332f7fd744dea0cfea9e29efea6d8ff576ba39ac;p=rrq%2Ffusefile.git

allow overwriting without changing size
---

diff --git a/fusefile.c b/fusefile.c
index 00f7f7f..476ca9d 100644
--- a/fusefile.c
+++ b/fusefile.c
@@ -23,9 +23,9 @@
     2001-2007 Miklos Szeredi <miklos@szeredi.hu>.
 */
 
-#define FUSE_USE_VERSION 31
+#define FUSE_USE_VERSION 33
 
-#include <fuse/fuse.h>
+#include <fuse.h>
 #include <fuse/fuse_lowlevel.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -48,6 +48,12 @@ static struct {
     ssize_t size;
 } sources;
 
+static struct {
+    time_t atime;
+    time_t mtime;
+    time_t ctime;
+} times;
+    
 #if DEBUG
 static void print_source(struct Source *p) {
     fprintf( stderr, "%p { %s, %ld, %ld, %ld, %d }\n",
@@ -76,7 +82,9 @@ static size_t scan_source(char *in,struct Source *p) {
 	    m = i;
 	}
     }
+#if DEBUG
     fprintf( stderr, "m=%d s=%d\n", m, s );
+#endif
     // Copy the filename, and set from and to
     p->filename = strndup( in, ( s < 0 )? e : s );
     struct stat buf;
@@ -88,7 +96,9 @@ static size_t scan_source(char *in,struct Source *p) {
     if ( p->from < 0 ) {
 	p->from = 0;
     }
+#if DEBUG
     fprintf( stderr, "p->from=%ld\n", p->from );
+#endif
     p->to = ( m < 0 )? buf.st_size : atol( in+m+1 );
     if ( p->from > p->to || p->to > buf.st_size ) {
 	return 1;
@@ -112,7 +122,11 @@ static int setup_sources(char **argv,int i,int n) {
 	}
 	p->start = sources.size;
 	sources.size += p->to - p->from;
-	p->fd = open( p->filename, O_RDONLY );
+	p->fd = open( p->filename, O_RDWR );
+	if ( p->fd < 0 ) {
+	    fprintf( stderr, "** %s opened read-only\n", p->filename );
+	    p->fd = open( p->filename, O_RDONLY );
+	}
 	if ( p->fd < 0 ) {
 	    perror( p->filename );
 	    return 1;
@@ -124,8 +138,10 @@ static int setup_sources(char **argv,int i,int n) {
     return 0;
 }
 
-static int fusefile_getattr(const char *path, struct stat *stbuf )
-{
+static int fusefile_getattr(const char *path,struct stat *stbuf) {
+#if DEBUG
+    fprintf( stderr, "fusefile_getattr( %s )\n", path );
+#endif
     if ( strcmp( path, "/" ) != 0 ) {
 	return -ENOENT;
     }
@@ -133,40 +149,49 @@ static int fusefile_getattr(const char *path, struct stat *stbuf )
     fprintf( stderr, "getattr %ld\n", sources.size );
 #endif
     memset( stbuf, 0, sizeof( struct stat ) );
-    stbuf->st_mode = S_IFREG | 0444; // Hmmm
+    stbuf->st_mode = S_IFREG | 0644; // Hmmm
     stbuf->st_nlink = 1;
     stbuf->st_size = sources.size;
-    time_t now = time( 0 );
-    stbuf->st_atime = now;
-    stbuf->st_mtime = now;
-    stbuf->st_ctime = now;
+    stbuf->st_atime = times.atime;
+    stbuf->st_mtime = times.mtime;
+    stbuf->st_ctime = times.ctime;
     stbuf->st_uid = getuid();
     stbuf->st_gid = getgid();
     return 0;
 }
 
-static int fusefile_open(const char *path, struct fuse_file_info *fi)
-{
+static int fusefile_chmod(const char *path,mode_t m) {
+#if DEBUG
+    fprintf( stderr, "fusefile_chmod( %s, %d )\n", path, m );
+#endif
+    return -1;
+}
+
+static int fusefile_open(const char *path,struct fuse_file_info *fi) {
+#if DEBUG
+    fprintf( stderr, "fusefile_open( %s, %d )\n", path, fi->flags );
+    fprintf( stderr, "fixing( %d )\n", fi->flags | O_CLOEXEC );
+#endif
     if ( strcmp( path, "/" ) != 0 ) {
 	return -ENOENT;
     }
+    // set O-CLOEXEC  for this opening?
+    times.atime = time( 0 );
     return 0;
 }
 
 static int find_source(off_t offset) {
     int lo = 0;
     int hi = sources.count;
-    if ( offset > sources.size ) {
+    if ( offset >= sources.size ) {
 	return -1;
     }
-    while ( lo < hi ) {
+    while ( lo + 1 < hi ) {
 	int m = ( lo + hi ) / 2;
-	if ( sources.array[m].start > offset ) {
+	if ( offset < sources.array[ m ].start ) {
 	    hi = m;
-	} else if ( m+1 < hi && sources.array[m+1].start < offset ) {
-	    lo = m+1;
 	} else {
-	    return m;
+	    lo = m;
 	}
     }
     return lo;
@@ -174,22 +199,25 @@ static int find_source(off_t offset) {
 
 // Read <size> bytes from <offset> in file
 static int fusefile_read(const char *path, char *buf, size_t size,
-                     off_t offset, struct fuse_file_info *fi)
+			 off_t off, struct fuse_file_info *fi)
 {
+#if DEBUG
+    fprintf( stderr, "fusefile_read( %s )\n", path );
+#endif
     if( strcmp( path, "/" ) != 0 ) {
 	return -ENOENT;
     }
 #if DEBUG
-    fprintf( stderr, "read %ld %ld\n", offset, size );
+    fprintf( stderr, "read %ld %ld\n", off, size );
 #endif
     size_t rr = 0;
     while ( size > 0 ) {
 #if DEBUG
-	fprintf( stderr, "find_source %ld %ld\n", offset, size );
+	fprintf( stderr, "find_source %ld %ld\n", off, size );
 #endif
-	int i = find_source( offset );
+	int i = find_source( off );
 	if ( i < 0 ) {
-	    return -ENOENT;
+	    return ( off == sources.size )? 0 : -ENOENT;
 	}
 	if ( sources.array[i].fd < 0 ) {
 	    return -ENOENT;
@@ -197,7 +225,7 @@ static int fusefile_read(const char *path, char *buf, size_t size,
 #if DEBUG
 	print_source( &sources.array[i] );
 #endif
-	size_t b = offset - sources.array[i].start + sources.array[i].from;
+	size_t b = off - sources.array[i].start + sources.array[i].from;
 	size_t n = sources.array[i].to - b;
 	if ( n > size ) {
 	    n = size;
@@ -221,24 +249,164 @@ static int fusefile_read(const char *path, char *buf, size_t size,
 	    break;
 	}
 	rr += r;
-	offset += r;
+	off += r;
 	size -= r;
     }
+    times.atime = time( 0 );
     return rr;
 }
 
+/**
+ * Write a full block of data over the sources at the offset
+ */
+static int write_block(off_t off,const char *buf,size_t size) {
+#if DEBUG
+    fprintf( stderr, "write_block( %ld, ?, %ld )\n", off, size );
+#endif
+    while ( size > 0 ) {
+	int index = find_source( off ); // index of source file
+	if ( index < 0 ) {
+	    return -EIO; // past EOF
+	}
+	struct Source *source = &sources.array[ index ];
+	off_t from = off - source->start;
+	off_t max = source->to - source->from - from;
+	if ( lseek( source->fd, from, SEEK_SET ) < 0 ) {
+	    return -EIO;
+	}
+	ssize_t todo = ( size < max )? size : max;
+	while ( todo > 0 ) {
+	    times.mtime = time( 0 );
+	    ssize_t n = write( source->fd, buf, todo );
+	    if ( n <= 0 ) {
+		return -EIO; // Something wrong
+	    }
+	    buf += n;
+	    todo -= n;
+	    size -= n;
+	    off += n;
+	}
+    }
+    return 0;
+}
+
+static int fusefile_write_buf(const char *path, struct fuse_bufvec *buf,
+			      off_t off, struct fuse_file_info *fi) {
+#if DEBUG
+    fprintf( stderr, "fusefile_write_buf( %s )\n", path );
+#endif
+    if ( strcmp( path, "/" ) != 0 ) {
+	return -ENOENT;
+    }
+
+    size_t size = 0;
+    int i;
+    for ( i = 0; i < buf->count; i++ ) {
+	struct fuse_buf *p = &buf->buf[i];
+	if ( p->flags & FUSE_BUF_IS_FD ) {
+#if DEBUG
+	    fprintf( stderr, "Content held in a file ... HELP!!\n" );
+#endif
+	    return -EIO;
+	}
+	if ( write_block( off, (char*) p->mem, p->size ) < 0 ) {
+	    return -EIO;
+	}
+	size += p->size;
+    }
+#if DEBUG
+    fprintf( stderr, "fusefile_write_buf written %ld\n", size );
+#endif
+    return size;
+}
+
+/**
+ * Write a fragment at <off>. This overwrites files.
+ */
+static int fusefile_write(const char *path, const char *buf, size_t size,
+			  off_t off, struct fuse_file_info *fi)
+{
+#if DEBUG
+    fprintf( stderr, "fusefile_write( %s %ld )\n", path, size );
+#endif
+    if ( strcmp( path, "/" ) != 0 ) {
+	return -ENOENT;
+    }
+
+    if ( write_block( off, buf, size ) < 0 ) {
+	return -EIO;
+    }
+    return size;
+}
+
 static void fusefile_destroy(void *data) {
-    char *mnt = (char*) data;
+    char *mnt = (char*) data; // As passed to fuse_main
+#if DEBUG
+    fprintf( stderr, "fusefile_destroy( %s )\n", mnt? mnt : "" );
+#endif
     if ( mnt ) {
 	unlink( mnt );
     }
 }
 
+static int fusefile_flush(const char *path, struct fuse_file_info *info) {
+#if DEBUG
+    fprintf( stderr, "fusefile_flush( %s )\n", path );
+#endif
+    if ( strcmp( path, "/" ) != 0 ) {
+	return -ENOENT;
+    }
+    return 0;
+}
+
+static int fusefile_release(const char *path, struct fuse_file_info *fi) {
+#if DEBUG
+    fprintf( stderr, "fusefile_release( %s, %d )\n", path, fi->flags );
+#endif
+    if ( strcmp( path, "/" ) != 0 ) {
+	return -ENOENT;
+    }
+    return 0;
+}
+
+static int fusefile_fsync(const char *path, int x, struct fuse_file_info *fi) {
+#if DEBUG
+    fprintf( stderr, "fusefile_fsync( %s, %d )\n", path, x );
+#endif
+    if ( strcmp( path, "/" ) != 0 ) {
+	return -ENOENT;
+    }
+    return 0;
+}
+
+/**
+ * 
+ */
+static int fusefile_truncate(const char *path, off_t len) {
+#if DEBUG
+    fprintf( stderr, "fusefile_truncate( %s, %ld )\n", path, len );
+#endif
+    if ( strcmp( path, "/" ) != 0 ) {
+	return -ENOENT;
+    }
+    return -EIO;
+}
+
 static struct fuse_operations fusefile_oper = {
     .getattr = fusefile_getattr,
+    .chmod = fusefile_chmod,
     .open = fusefile_open,
     .read = fusefile_read,
+    .write = fusefile_write,
+    .write_buf = fusefile_write_buf,
     .destroy = fusefile_destroy,
+    .flush = fusefile_flush,
+    .release = fusefile_release,
+    .fsync = fusefile_fsync,
+    .truncate = fusefile_truncate,
+    //.truncate = fusefile_truncate,
+    //.release = fusefile_release,
+    //void *(*init) (struct fuse_conn_info *conn);
 };
 
 static void usage() {
@@ -250,6 +418,32 @@ static void usage() {
     exit( 1 );
 }
 
+/**
+ * Set up the arguments for the fuse_main call, adding our own.
+ */
+static int setup_argv(int argc,char ***argv) {
+    char *OURS[] = {
+	"-odefault_permissions",
+	(*argv)[ --argc ]  // note: (*argv)[ argc-1 ] = the mount point
+    };
+#define OURSN ( sizeof( OURS ) / sizeof( char* ) )
+    int N = argc + OURSN; // new argv-tobe size, excluding null
+    char **out = malloc( ( N + 1 ) * sizeof( char* ) );
+    int i;
+    for ( i = 0; i < argc; i++ ) {
+	out[ i ] = (*argv)[i];
+	fprintf( stderr, " %s", out[ i ] );
+    }
+    for ( i = 0; i < OURSN; i++ ) {
+	out[ argc + i ] = OURS[i];
+	fprintf( stderr, " %s", out[ i ] );
+    }
+    out[ N ] = 0;
+    fprintf( stderr, "\n" );
+    (*argv) = out;
+    return N;
+}
+
 /**
  * Mount a concatenation of files,
  * [ <fuse options> ] <mount> <file/from-to> ...
@@ -260,6 +454,7 @@ int main(int argc, char *argv[])
     int mt;
     int fg;
     int i;
+    int fuseargc;
     struct stat stbuf;
     int temporary = 0;
     // Scan past options
@@ -268,27 +463,37 @@ int main(int argc, char *argv[])
 	    break;
 	}
     }
-    if ( i > argc - 2 ) { // At least one source
+    if ( i > argc - 2 ) { // At least mount point plus one source
 	usage();
     }
-    i++;
+    mnt = argv[ i++ ]; // First non-option argument is the mount pount
+    fuseargc = i;
     if ( setup_sources( argv, i, argc-i ) ) {
 	return 1;
     }
-    mnt = argv[i-1];
     if ( stat( mnt, &stbuf ) == -1 ) {
 	int fd = open( mnt, O_CREAT | O_RDWR, S_IRUSR | S_IWUSR );
 	if ( fd < 0 ) {
 	    perror( mnt );
 	    return 1;
 	}
+	time_t now = time( 0 );
+	times.atime = now;
+	times.mtime = now;
+	times.ctime = now;
 	temporary = 1;
 	close( fd );
     } else if ( ! S_ISREG( stbuf.st_mode ) ) {
 	fprintf( stderr, "mountpoint is not a regular file\n" );
 	return 1;
+    } else {
+	times.atime = stbuf.st_atime;
+	times.mtime = stbuf.st_mtime;
+	times.ctime = stbuf.st_ctime;
     }
-    struct fuse_args args = FUSE_ARGS_INIT( i, argv );
+
+    fuseargc = setup_argv( fuseargc, &argv );
+    struct fuse_args args = FUSE_ARGS_INIT( fuseargc, argv );
     if ( fuse_parse_cmdline( &args, &mnt, &mt, &fg ) ) {
 	return 1;
     }
@@ -297,5 +502,5 @@ int main(int argc, char *argv[])
 	fprintf( stderr, "missing mountpoint parameter\n" );
 	return 1;
     }
-    return fuse_main( i, argv, &fusefile_oper, temporary? mnt : NULL );
+    return fuse_main( fuseargc, argv, &fusefile_oper, temporary? mnt : NULL );
 }