Implemented a more reasonable solution for drive truncation with regular files

libisoburn/burn_wrap.c

@@ -273,6 +273,8 @@ ex:
 /**
     @param flag bit0= load
                 bit1= regard overwriteable media as blank
+                bit2= if the drive is a regular disk file: truncate it to
+                      the write start address
 */
 int isoburn_drive_aquire(struct burn_drive_info *drive_infos[],
                          char *adr, int flag)
@@ -298,6 +300,12 @@ int isoburn_drive_aquire(struct burn_drive_info *drive_infos[],
  if(ret<=0)
    goto ex;
 
+ if(flag&4) {
+   ret= isoburn_find_emulator(&o, (*drive_infos)[0].drive, 0);
+   if(ret>0 && o!=NULL)
+     o->truncate= 1;
+ }
+
  ret= 1;
 ex:
  if(ret<=0) {
@@ -496,10 +504,13 @@ int isoburn_disc_track_lba_nwa(struct burn_drive *d,
 void isoburn_disc_write(struct burn_write_opts *opts, struct burn_disc *disc)
 {
  int ret;
+ off_t nwa= 0;
  struct isoburn *o;
  struct burn_drive *drive;
  char reasons[BURN_REASONS_LEN],msg[160+BURN_REASONS_LEN];
+ char adr[BURN_DRIVE_ADR_LEN];
  enum burn_write_types write_type;
+ struct stat stbuf;
 
  drive= burn_write_opts_get_drive(opts);
  ret= isoburn_find_emulator(&o, drive, 0);
@@ -509,8 +520,10 @@ void isoburn_disc_write(struct burn_write_opts *opts, struct burn_disc *disc)
    o->wrote_well= -1;
    if(o->emulation_mode!=0) {
      burn_write_opts_set_multi(opts, 0);
-     if(o->emulation_mode>0 && o->nwa >= 0)
+     if(o->emulation_mode>0 && o->nwa >= 0) {
        burn_write_opts_set_start_byte(opts, ((off_t) o->nwa) * (off_t) 2048);
+       nwa= o->nwa;
+     }
    }
  }
 
@@ -539,6 +552,19 @@ void isoburn_disc_write(struct burn_write_opts *opts, struct burn_disc *disc)
 				 ((off_t) Hardcoded_cd_rw_nwA) * (off_t) 2048);
 #endif
 
+ if(o->truncate) {
+   ret= burn_drive_get_drive_role(drive);
+   if(ret==2) {
+     ret= burn_drive_d_get_adr(drive, adr);
+     if(ret>0) {
+       ret= lstat(adr, &stbuf);
+       if(ret!=-1)
+         if(S_ISREG(stbuf.st_mode))
+           truncate(adr, nwa * (off_t) 2048);
+     }
+   }
+ }
+
  burn_disc_write(opts, disc);
 }
 

libisoburn/isoburn.c

@@ -69,6 +69,7 @@ int isoburn_new(struct isoburn **objpt, int flag)
  o->emulation_mode= 0;
  o->min_start_byte= 0;
  o->nwa= 0;
+ o->truncate= 0;
 
 #ifdef Libisoburn_no_fifO
  o->iso_source= NULL;

libisoburn/isoburn.h

@@ -42,8 +42,12 @@ struct isoburn {
  /* Aligned start address to be used for processing (counted in blocks) */
  int nwa;
 
+ /* Truncate to .nwa an eventual regular file serving as output drive */
+ int truncate;
+
  /* Eventual freely fabricated isoburn_disc_get_status().
-    BURN_DISC_UNREADY means that normally emulated status is in effect.
+    BURN_DISC_UNREADY means that this variable is disabled
+    and normally emulated status is in effect.
  */
  enum burn_disc_status fabricated_disc_status;
 

libisoburn/libisoburn.h

@@ -328,7 +328,8 @@ int isoburn_drive_scan_and_grab(struct burn_drive_info *drive_infos[],
     @param flag   bit0= attempt to load the disc tray.
                         Else: failure if not loaded.
                   bit1= regard overwriteable media as blank
-                  
+                  bit2= if the drive is a regular disk file: truncate it to
+                        the write start address
     @return       1 = success , 0 = drive not found , <0 = other error
 */
 int isoburn_drive_aquire(struct burn_drive_info *drive_infos[],

xorriso/xorriso.1

@@ -2,7 +2,7 @@
 .\" First parameter, NAME, should be all caps
 .\" Second parameter, SECTION, should be 1-8, maybe w/ subsection
 .\" other parameters are allowed: see man(7), man(1)
-.TH XORRISO 1 "February 20, 2008"
+.TH XORRISO 1 "February 21, 2008"
 .\" Please adjust this date whenever revising the manpage.
 .\"
 .\" Some roff macros, for reference:
@@ -1289,8 +1289,9 @@ persists until things happen like -commit, -rollback, -dev, or end of xorriso.
 If no output file was chosen before or during a "mkisofs" option list, then
 standard output (-outdev "-") will get into effect before pathspecs get
 added. If -o points to a regular file, then it will be truncated to 0 bytes
-before "mkisofs" options are processed. Directories and symbolic links
+when finally writing begins. This truncation does not happen if the drive
-are no valid -o targets.
+is chosen by xorriso options before or after -as mkisofs.
+Directories and symbolic links are no valid -o targets.
 .br
 Writing to stdout is possible only if -as "mkisofs" was among the start
 arguments or if other start arguments pointed the output drive to

xorriso/xorriso.c

@@ -6524,11 +6524,13 @@ int Xorriso_genisofs(struct XorrisO *xorriso, char *whom,
  if(adr[0]) {
    if(strncmp(adr, "stdio:", 6)==0 && strncmp(adr, "stdio:/dev/fd/", 14)!=0) {
      ret= Sfile_type(adr+6, 1);
-     if(ret==-1)
+     if(ret==-1) {
        /* ok */;
-     else if(ret==1) {
 
-       /* >>> would prefer to do this later ... or leave it to libburn */;
+#ifdef NIX
+     } else if(ret==1) {
+
+       /* <<< is now done in libisoburn by bit4 of Xorriso_option_dev() */
 
        ret= truncate(adr+6, (off_t) 0);
        if(ret==-1) {
@@ -6540,6 +6542,8 @@ int Xorriso_genisofs(struct XorrisO *xorriso, char *whom,
        sprintf(xorriso->info_text, "-as %s: Truncated existing -o %s",
                whom, Text_shellsafe(adr+6, sfe, 0));
        Xorriso_msgs_submit(xorriso, 0, xorriso->info_text, 0, "NOTE", 0);
+#endif /* NIX */
+
      } else if(ret==2 || ret==3) {
        sprintf(xorriso->info_text,
                "-as %s: Cannot accept %s as target: -o %s",
@@ -6548,7 +6552,8 @@ int Xorriso_genisofs(struct XorrisO *xorriso, char *whom,
        Xorriso_msgs_submit(xorriso, 0, xorriso->info_text, 0, "FAILURE", 0);
      }
    }
-   ret= Xorriso_option_dev(xorriso, adr, 2|8); /* overwriteable as blank */
+   /* Regard overwriteable as blank, truncate regular files on write start */
+   ret= Xorriso_option_dev(xorriso, adr, 2|8|16);
    if(ret<=0)
      goto ex;
  }
@@ -7505,6 +7510,8 @@ int Xorriso_option_cut_out(struct XorrisO *xorriso, char *disk_path,
                 bit1= use as outdev
                 bit2= do not -reassure
                 bit3= regard overwriteable media as blank
+                bit4= if the drive is a regular disk file: truncate it to
+                      the write start address
     @return <=0 error , 1 success, 2 revoked by -reassure
 */
 int Xorriso_option_dev(struct XorrisO *xorriso, char *in_adr, int flag)
@@ -7564,7 +7571,7 @@ int Xorriso_option_dev(struct XorrisO *xorriso, char *in_adr, int flag)
    }
    ret= Xorriso_give_up_drive(xorriso, flag&3);
  } else
-   ret= Xorriso_aquire_drive(xorriso, adr, (flag&3)|((flag&8)>>1)); 
+   ret= Xorriso_aquire_drive(xorriso, adr, (flag&3)|((flag&(8|16))>>1)); 
  if(ret<=0)
    return(ret);
  return(1);

xorriso/xorriso_timestamp.h

@@ -1 +1 @@
-#define Xorriso_timestamP "2008.02.21.130047"
+#define Xorriso_timestamP "2008.02.21.185203"

xorriso/xorrisoburn.c

@@ -420,6 +420,8 @@ int Xorriso_create_empty_iso(struct XorrisO *xorriso, int flag)
 /* @param flag bit0= aquire as isoburn input drive
                bit1= aquire as libburn output drive (as isoburn drive if bit0)
                bit2= regard overwriteable media as blank
+               bit3= if the drive is a regular disk file: truncate it to
+                     the write start address
    @return <=0 failure , 1= ok
            2=success, but not writeable with bit1
            3=success, but not blank and not ISO with bit0
@@ -477,7 +479,7 @@ int Xorriso_aquire_drive(struct XorrisO *xorriso, char *adr, int flag)
  }
 
  if(dinfo==NULL) {
-   ret= isoburn_drive_aquire(&dinfo, libburn_adr, 1|((flag&4)>>1));
+   ret= isoburn_drive_aquire(&dinfo, libburn_adr, 1|((flag&(8|4))>>1));
    Xorriso_process_msg_queues(xorriso,0);
    if(ret<=0) {
      sprintf(xorriso->info_text,"Cannot aquire drive '%s'", adr);