New API call iso_write_opts_set_tail_blocks() for tail padding inside ISO image

libisofs/ecma119.c

@@ -922,7 +922,7 @@ int ecma119_writer_create(Ecma119Image *target)
 
 /** compute how many padding bytes are needed */
 static
-int pad_writer_compute_data_blocks(IsoImageWriter *writer)
+int mspad_writer_compute_data_blocks(IsoImageWriter *writer)
 {
     Ecma119Image *target;
     uint32_t min_size;
@@ -933,24 +933,25 @@ int pad_writer_compute_data_blocks(IsoImageWriter *writer)
     target = writer->target;
     min_size = 32 + target->partition_offset;
     if (target->curblock < min_size) {
-        target->pad_blocks = min_size - target->curblock;
+        target->mspad_blocks = min_size - target->curblock;
         target->curblock = min_size;
     }
     return ISO_SUCCESS;
 }
 
 static
-int pad_writer_write_vol_desc(IsoImageWriter *writer)
+int mspad_writer_write_vol_desc(IsoImageWriter *writer)
 {
     /* nothing to do */
     return ISO_SUCCESS;
 }
+
 static
-int pad_writer_write_data(IsoImageWriter *writer)
+int mspad_writer_write_data(IsoImageWriter *writer)
 {
     int ret;
     Ecma119Image *t;
-    uint32_t pad[BLOCK_SIZE];
+    uint8_t pad[BLOCK_SIZE];
     size_t i;
 
     if (writer == NULL) {
@@ -958,12 +959,12 @@ int pad_writer_write_data(IsoImageWriter *writer)
     }
     t = writer->target;
 
-    if (t->pad_blocks == 0) {
+    if (t->mspad_blocks == 0) {
         return ISO_SUCCESS;
     }
 
     memset(pad, 0, BLOCK_SIZE);
-    for (i = 0; i < t->pad_blocks; ++i) {
+    for (i = 0; i < t->mspad_blocks; ++i) {
         ret = iso_write(t, pad, BLOCK_SIZE);
         if (ret < 0) {
             return ret;
@@ -974,14 +975,14 @@ int pad_writer_write_data(IsoImageWriter *writer)
 }
 
 static
-int pad_writer_free_data(IsoImageWriter *writer)
+int mspad_writer_free_data(IsoImageWriter *writer)
 {
     /* nothing to do */
     return ISO_SUCCESS;
 }
 
 static
-int pad_writer_create(Ecma119Image *target)
+int mspad_writer_create(Ecma119Image *target)
 {
     IsoImageWriter *writer;
 
@@ -990,10 +991,10 @@ int pad_writer_create(Ecma119Image *target)
         return ISO_OUT_OF_MEM;
     }
 
-    writer->compute_data_blocks = pad_writer_compute_data_blocks;
+    writer->compute_data_blocks = mspad_writer_compute_data_blocks;
-    writer->write_vol_desc = pad_writer_write_vol_desc;
+    writer->write_vol_desc = mspad_writer_write_vol_desc;
-    writer->write_data = pad_writer_write_data;
+    writer->write_data = mspad_writer_write_data;
-    writer->free_data = pad_writer_free_data;
+    writer->free_data = mspad_writer_free_data;
     writer->data = NULL;
     writer->target = target;
 
@@ -1002,6 +1003,100 @@ int pad_writer_create(Ecma119Image *target)
     return ISO_SUCCESS;
 }
 
+
+/** ----- Zero padding writer ----- */
+
+struct iso_zero_writer_data_struct {
+    uint32_t num_blocks;
+};
+
+static
+int zero_writer_compute_data_blocks(IsoImageWriter *writer)
+{
+    Ecma119Image *target;
+    struct iso_zero_writer_data_struct *data;
+
+    if (writer == NULL)
+        return ISO_ASSERT_FAILURE;
+    target = writer->target;
+    data = (struct iso_zero_writer_data_struct *) writer->data;
+    target->curblock += data->num_blocks;
+    return ISO_SUCCESS;
+}
+
+static
+int zero_writer_write_vol_desc(IsoImageWriter *writer)
+{
+    /* nothing to do */
+    return ISO_SUCCESS;
+}
+
+static
+int zero_writer_write_data(IsoImageWriter *writer)
+{
+    int ret;
+    Ecma119Image *t;
+    struct iso_zero_writer_data_struct *data;
+    uint8_t pad[BLOCK_SIZE];
+    size_t i;
+
+    if (writer == NULL)
+        return ISO_ASSERT_FAILURE;
+    t = writer->target;
+    data = (struct iso_zero_writer_data_struct *) writer->data;
+
+    if (data->num_blocks == 0) 
+        return ISO_SUCCESS;
+    memset(pad, 0, BLOCK_SIZE);
+    for (i = 0; i < data->num_blocks; ++i) {
+        ret = iso_write(t, pad, BLOCK_SIZE);
+        if (ret < 0) 
+            return ret;
+    }
+    return ISO_SUCCESS;
+}
+
+static
+int zero_writer_free_data(IsoImageWriter *writer)
+{
+    if (writer == NULL)
+        return ISO_SUCCESS;
+    if (writer->data == NULL)
+        return ISO_SUCCESS;
+    free(writer->data);
+    writer->data = NULL;
+    return ISO_SUCCESS;
+}
+
+static
+int zero_writer_create(Ecma119Image *target, uint32_t num_blocks)
+{
+    IsoImageWriter *writer;
+    struct iso_zero_writer_data_struct *data;
+
+    writer = malloc(sizeof(IsoImageWriter));
+    if (writer == NULL) {
+        return ISO_OUT_OF_MEM;
+    }
+    data = calloc(1, sizeof(struct iso_zero_writer_data_struct));
+    if (data == NULL) {
+        free(writer);
+        return ISO_OUT_OF_MEM;
+    }
+    data->num_blocks = num_blocks;
+
+    writer->compute_data_blocks = zero_writer_compute_data_blocks;
+    writer->write_vol_desc = zero_writer_write_vol_desc;
+    writer->write_data = zero_writer_write_data;
+    writer->free_data = zero_writer_free_data;
+    writer->data = data;
+    writer->target = target;
+
+    /* add this writer to image */
+    target->writers[target->nwriters++] = writer;
+    return ISO_SUCCESS;
+}
+
 static
 int transplant_checksum_buffer(Ecma119Image *target, int flag)
 {
@@ -1095,7 +1190,7 @@ int write_head_part2(Ecma119Image *target, int *write_count, int flag)
     if (target->partition_offset <= 0)
         return ISO_SUCCESS;
 
-    /* Write padding up to target->partition_offset + 16 */
+    /* Write multi-session padding up to target->partition_offset + 16 */
     memset(buf, 0, 2048);
     for(; *write_count < target->partition_offset + 16; (*write_count)++) {
         res = iso_write(target, buf, BLOCK_SIZE);
@@ -1513,6 +1608,8 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
     
 #endif /* Libisofs_with_libjtE */
 
+    target->tail_blocks = opts->tail_blocks;
+
     /*
      * 2. Based on those options, create needed writers: iso, joliet...
      * Each writer inits its structures and stores needed info into
@@ -1531,7 +1628,7 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
     }
 
     /* the number of writers is dependent of the extensions */
-    nwriters = 1 + 1 + 1; /* ECMA-119 + padding + files */
+    nwriters = 1 + 1 + 1; /* ECMA-119 + multi-session padding + files */
 
     if (target->eltorito) {
         nwriters++;
@@ -1542,7 +1639,8 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
     if (target->iso1999) {
         nwriters++;
     }
-
+    if (target->tail_blocks > 0) 
+        nwriters++;
     if ((target->md5_file_checksums & 1) || target->md5_session_checksum) {
         nwriters++;
         image_checksums_mad = 1; /* from here on the loaded checksums are
@@ -1605,7 +1703,7 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
      * Create the writer for possible padding to ensure that in case of image
      * growing we can safely overwrite the first 64 KiB of image.
      */
-    ret = pad_writer_create(target);
+    ret = mspad_writer_create(target);
     if (ret < 0) {
         goto target_cleanup;
     }
@@ -1616,6 +1714,15 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
         goto target_cleanup;
     }
     file_src_writer_index = target->nwriters - 1;
+
+
+    /* IMPORTANT: This must be the last writer before the checksum writer */
+    if (target->tail_blocks > 0) {
+        ret = zero_writer_create(target, target->tail_blocks);
+        if (ret < 0)
+            goto target_cleanup;
+    }
+
     if ((target->md5_file_checksums & 1) || target->md5_session_checksum) {
         ret = checksum_writer_create(target);
         if (ret < 0)
@@ -2063,6 +2170,8 @@ int iso_write_opts_new(IsoWriteOpts **opts, int profile)
     wopts->libjte_handle = NULL;
 #endif /* Libisofs_with_libjtE */
 
+    wopts->tail_blocks = 0;
+
     *opts = wopts;
     return ISO_SUCCESS;
 }
@@ -2532,4 +2641,9 @@ int iso_write_opts_detach_jte(IsoWriteOpts *opts, void **libjte_handle)
 #endif /* Libisofs_with_libjtE */
 }
  
- 
+int iso_write_opts_set_tail_blocks(IsoWriteOpts *opts, uint32_t num_blocks)
+{
+     opts->tail_blocks = num_blocks;
+     return ISO_SUCCESS;
+}
+

libisofs/ecma119.h

@@ -330,6 +330,10 @@ struct iso_write_opts {
     struct libjte_env *libjte_handle;
 #endif /* Libisofs_with_libjtE */
 
+    /* A trailing padding of zero bytes which belongs to the image
+    */
+    uint32_t tail_blocks;
+
 };
 
 typedef struct ecma119_image Ecma119Image;
@@ -499,7 +503,7 @@ struct ecma119_image
      * file data is written in the first 64 KiB, that are the bytes we usually
      * overwrite.
      */
-    uint32_t pad_blocks;
+    uint32_t mspad_blocks;
 
     size_t nwriters;
     IsoImageWriter **writers;
@@ -577,6 +581,7 @@ struct ecma119_image
     struct libjte_env *libjte_handle;
 #endif /* Libisofs_with_libjtE */
 
+    uint32_t tail_blocks;
 };
 
 #define BP(a,b) [(b) - (a) + 1]

libisofs/libisofs.h

@@ -1887,6 +1887,29 @@ int iso_write_opts_attach_jte(IsoWriteOpts *opts, void *libjte_handle);
 int iso_write_opts_detach_jte(IsoWriteOpts *opts, void **libjte_handle);
 
 
+/**
+ * Cause a number of blocks with zero bytes to be written after the payload
+ * data, but before the eventual checksum data. Unlike libburn tail padding,
+ * these blocks are counted as part of the image and covered by eventual
+ * image checksums.
+ * A reason for such padding can be the wish to prevent the Linux read-ahead
+ * bug by sacrificial data which still belong to image and Jigdo template.
+ * Normally such padding would be the job of the burn program which should know
+ * that it is needed with CD write type TAO if Linux read(2) shall be able
+ * to read all payload blocks.
+ * 150 blocks = 300 kB is the traditional sacrifice to the Linux kernel.
+ * @param opts
+ *        The option set to be manipulated.
+ * @param num_blocks
+ *        Number of extra 2 kB blocks to be written.
+ * @return
+ *        ISO_SUCCESS or error
+ *
+ * @since 0.6.38
+ */
+int iso_write_opts_set_tail_blocks(IsoWriteOpts *opts, uint32_t num_blocks);
+
+
 /**
  * Inquire the start address of the file data blocks after having used
  * IsoWriteOpts with iso_image_create_burn_source().

libisofs/libisofs.ver

@@ -286,6 +286,7 @@ iso_write_opts_set_rrip_version_1_10;
 iso_write_opts_set_scdbackup_tag;
 iso_write_opts_set_sort_files;
 iso_write_opts_set_system_area;
+iso_write_opts_set_tail_blocks;
 iso_zisofs_get_params;
 iso_zisofs_get_refcounts;
 iso_zisofs_set_params;

libisofs/messages.c

@@ -299,7 +299,7 @@ const char *iso_error_to_msg(int errcode)
     case ISO_LIBJTE_END_FAILED:
         return "Failed to finish Jigdo Template Extraction";
     case ISO_LIBJTE_FILE_FAILED:
-        return "Failed process file for Jigdo Template Extraction";
+        return "Failed to process file for Jigdo Template Extraction";
     default:
         return "Unknown error";
     }