[Libcdio-devel] modifications of ISO9660 and UDF headers for MSVC

[Pete Batard]

Two additional patches that modify the ISO9660 and UDF headers for MSVC 
usage.

The most controversial has to be the ISO9660 as MSVC simply cannot use a 
zero sized array, even at the end of a struct, if that struct is going 
to be included in the middle of another.

Therefore, instead of defining:

     iso711_t filename_len;
     char     filename[];

We leverage the fact that iso711_t and char are the same size and the 
following union:

union {
     iso711_t        len;
     char            str[1];
} filename;

This avoids the use of an empty array, while most of the existing code 
unchanged. The only gotcha however is that the actual string payload of 
filename.str[] starts at 1, not 0.

I'm hoping this is acceptable as a workaround, as dealing with zero 
sized arrays is the one item we cannot avoid for MSVC support.

I guess these can be construed as API change, so probably warrant an API 
bump.

Regards,

/Pete

>From c40dd3269e049611cc1f53e01b1d0bec0fb50957 Mon Sep 17 00:00:00 2001
From: Pete Batard <address@hidden>
Date: Sun, 29 Jan 2012 17:15:50 +0000
Subject: [PATCH 1/3] ISO9660: fix iso9660.h header for MSVC compatibility

* MSVC compilers cannot handle a zero sized array in the middle
  of a struct, and iso9660_dir_s is reused within iso9660_pvd_s.
* Leverage the fact that iso711_t and char are the same size and
  use an union.
* The only gotcha is that the actual string payload now starts at 1
* also fix the use of pre_user_data as MSVC cannot use a const to
  initialize the size of an array
---
 include/cdio/iso9660.h   |   14 ++++++++++++--
 lib/iso9660/iso9660.c    |    4 ++--
 lib/iso9660/iso9660_fs.c |   26 ++++++++++++--------------
 lib/iso9660/rock.c       |    8 ++++----
 4 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/include/cdio/iso9660.h b/include/cdio/iso9660.h
index 4f5786f..c6ddf64 100644
--- a/include/cdio/iso9660.h
+++ b/include/cdio/iso9660.h
@@ -273,8 +273,18 @@ struct iso9660_dir_s {
                                           the Extent described by this
                                           Directory Record is
                                           recorded. (9.1.9) */
-  iso711_t         filename_len;      /*! number of bytes in filename field */
-  char             filename[EMPTY_ARRAY_SIZE];
+/*! MSVC compilers cannot handle a zero sized array in the middle
+    of a struct, and iso9660_dir_s is reused within iso9660_pvd_s.
+    Therefore, instead of defining:
+       iso711_t filename_len;
+       char     filename[];
+    we leverage the fact that iso711_t and char are the same size
+    and use an union. The only gotcha is that the actual string
+    payload of filename.str[] starts at 1, not 0. */
+  union { 
+    iso711_t        len;
+    char            str[1];
+  } filename;
 } GNUC_PACKED;
 
 /*! 
diff --git a/lib/iso9660/iso9660.c b/lib/iso9660/iso9660.c
index e06ebad..6edd7bd 100644
--- a/lib/iso9660/iso9660.c
+++ b/lib/iso9660/iso9660.c
@@ -771,10 +771,10 @@ iso9660_dir_add_entry_su(void *dir,
 
   idr->volume_sequence_number = to_723(1);
 
-  idr->filename_len = to_711(strlen(filename) 
+  idr->filename.len = to_711(strlen(filename) 
                              ? strlen(filename) : 1); /* working hack! */
 
-  memcpy(idr->filename, filename, from_711(idr->filename_len));
+  memcpy(&idr->filename.str[1], filename, from_711(idr->filename.len));
   memcpy(&dir8[offset] + su_offset, su_data, su_size);
 }
 
diff --git a/lib/iso9660/iso9660_fs.c b/lib/iso9660/iso9660_fs.c
index ff62077..61f8560 100644
--- a/lib/iso9660/iso9660_fs.c
+++ b/lib/iso9660/iso9660_fs.c
@@ -107,12 +107,10 @@ adjust_fuzzy_pvd( iso9660_t *p_iso )
      frame and a header. 
    */
   if (CDIO_CD_FRAMESIZE_RAW == p_iso->i_framesize) {
-    const int pre_user_data=CDIO_CD_SYNC_SIZE +  CDIO_CD_HEADER_SIZE 
-      + CDIO_CD_SUBHEADER_SIZE;
-    char buf[pre_user_data];
-    
-    i_byte_offset -= pre_user_data;
-    
+    char buf[CDIO_CD_SYNC_SIZE + CDIO_CD_HEADER_SIZE + CDIO_CD_SUBHEADER_SIZE];
+
+    i_byte_offset -= CDIO_CD_SYNC_SIZE + CDIO_CD_HEADER_SIZE + 
CDIO_CD_SUBHEADER_SIZE;
+
     if ( DRIVER_OP_SUCCESS != cdio_stream_seek (p_iso->stream, i_byte_offset, 
                                                SEEK_SET) )
       return;
@@ -739,7 +737,7 @@ _iso9660_dir_to_statbuf (iso9660_dir_t *p_iso9660_dir, 
bool_3way_t b_xa,
 
   if (!dir_len) return NULL;
 
-  i_fname  = from_711(p_iso9660_dir->filename_len);
+  i_fname  = from_711(p_iso9660_dir->filename.len);
 
   /* .. string in statbuf is one longer than in p_iso9660_dir's listing '\1' */
   stat_len      = sizeof(iso9660_stat_t)+i_fname+2;
@@ -784,15 +782,15 @@ _iso9660_dir_to_statbuf (iso9660_dir_t *p_iso9660_dir, 
bool_3way_t b_xa,
       }
       strncpy(p_stat->filename, rr_fname, i_rr_fname+1);
     } else {
-      if ('\0' == p_iso9660_dir->filename[0] && 1 == i_fname)
+      if ('\0' == p_iso9660_dir->filename.str[1] && 1 == i_fname)
        strncpy (p_stat->filename, ".", sizeof("."));
-      else if ('\1' == p_iso9660_dir->filename[0] && 1 == i_fname)
+      else if ('\1' == p_iso9660_dir->filename.str[1] && 1 == i_fname)
        strncpy (p_stat->filename, "..", sizeof(".."));
 #ifdef HAVE_JOLIET
       else if (i_joliet_level) {
        int i_inlen = i_fname;
        cdio_utf8_t *p_psz_out = NULL;
-       if (cdio_charset_to_utf8(p_iso9660_dir->filename, i_inlen,
+       if (cdio_charset_to_utf8(&p_iso9660_dir->filename.str[1], i_inlen,
                              &p_psz_out, "UCS-2BE")) {
           strncpy(p_stat->filename, p_psz_out, i_fname);
           free(p_psz_out);
@@ -804,7 +802,7 @@ _iso9660_dir_to_statbuf (iso9660_dir_t *p_iso9660_dir, 
bool_3way_t b_xa,
       }
 #endif /*HAVE_JOLIET*/
       else {
-       strncpy (p_stat->filename, p_iso9660_dir->filename, i_fname);
+       strncpy (p_stat->filename, &p_iso9660_dir->filename.str[1], i_fname);
       }
     }
   }
@@ -878,12 +876,12 @@ iso9660_dir_to_name (const iso9660_dir_t *iso9660_dir)
 
   /* (iso9660_dir->file_flags & ISO_DIRECTORY) */
   
-  if (iso9660_dir->filename[0] == '\0')
+  if (iso9660_dir->filename.str[1] == '\0')
     return strdup(".");
-  else if (iso9660_dir->filename[0] == '\1')
+  else if (iso9660_dir->filename.str[1] == '\1')
     return strdup("..");
   else {
-    return strdup(iso9660_dir->filename);
+    return strdup(&iso9660_dir->filename.str[1]);
   }
 }
 
diff --git a/lib/iso9660/rock.c b/lib/iso9660/rock.c
index 1a91297..1a887c3 100644
--- a/lib/iso9660/rock.c
+++ b/lib/iso9660/rock.c
@@ -105,7 +105,7 @@ realloc_symlink(/*in/out*/ iso9660_stat_t *p_stat, uint8_t 
i_grow)
 
 #define SETUP_ROCK_RIDGE(DE,CHR,LEN)                           \
   {                                                            \
-    LEN= sizeof(iso9660_dir_t) + DE->filename_len;             \
+    LEN= sizeof(iso9660_dir_t) + DE->filename.len;             \
     if(LEN & 1) LEN++;                                         \
     CHR = ((unsigned char *) DE) + LEN;                                \
     LEN = *((unsigned char *) DE) - LEN;                       \
@@ -178,10 +178,10 @@ get_rock_ridge_filename(iso9660_dir_t * p_iso9660_dir,
        break;
       case SIG('C','E'): 
        {
-         iso711_t i_fname = from_711(p_iso9660_dir->filename_len);
-         if ('\0' == p_iso9660_dir->filename[0] && 1 == i_fname)
+         iso711_t i_fname = from_711(p_iso9660_dir->filename.len);
+         if ('\0' == p_iso9660_dir->filename.str[1] && 1 == i_fname)
            break;
-         if ('\1' == p_iso9660_dir->filename[0] && 1 == i_fname)
+         if ('\1' == p_iso9660_dir->filename.str[1] && 1 == i_fname)
            break;
        }
        CHECK_CE;
-- 
1.7.8.msysgit.0

>From 2d92744537978446cea3cd4bfe4ae583c3747995 Mon Sep 17 00:00:00 2001
From: Pete Batard <address@hidden>
Date: Sun, 29 Jan 2012 17:21:08 +0000
Subject: [PATCH 2/3] UDF: fix ecma_167.h header for MSVC compatibility

* multiple zero sized arrays are not allowed with MSVC
* use an union of zero sized arrays instead
---
 include/cdio/ecma_167.h |   22 ++++++++++++++--------
 lib/udf/udf_fs.c        |    2 +-
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/include/cdio/ecma_167.h b/include/cdio/ecma_167.h
index 9c7c1bb..b97cba7 100644
--- a/include/cdio/ecma_167.h
+++ b/include/cdio/ecma_167.h
@@ -499,9 +499,11 @@ struct logvol_integrity_desc_s
   udf_Uint8_t     logvol_contents_use[32];
   udf_Uint32_t    i_partitions;
   udf_Uint32_t    imp_use_len;
-  udf_Uint32_t    freespace_table[0];
-  udf_Uint32_t    size_table[0];
-  udf_Uint8_t     imp_use[0];
+  union { /* MSVC workaround for multiple zero sized arrays */
+    udf_Uint32_t  freespace_table[0];
+    udf_Uint32_t  size_table[0];
+    udf_Uint8_t   imp_use[0];
+  } u;
 } GNUC_PACKED;
 
 /** Integrity Type (ECMA 167r3 3/10.10.3) */
@@ -571,9 +573,11 @@ struct udf_fileid_desc_s
   udf_Uint8_t  i_file_id;
   udf_long_ad_t        icb;
   udf_Uint16_t i_imp_use;
-  udf_Uint8_t  imp_use[0];
-  udf_Uint8_t  file_id[0];
-  udf_Uint8_t  padding[0];
+  union { /* MSVC workaround for multiple zero sized arrays */
+    udf_Uint8_t        imp_use[0];
+    udf_Uint8_t        file_id[0];
+    udf_Uint8_t        padding[0];
+  } u;
 } GNUC_PACKED;
 
 typedef struct udf_fileid_desc_s udf_fileid_desc_t;
@@ -991,8 +995,10 @@ struct extended_file_entry
   udf_Uint64_t    unique_ID;
   udf_Uint32_t    length_extended_attr;
   udf_Uint32_t    length_alloc_descs;
-  udf_Uint8_t     ext_attr[0];
-  udf_Uint8_t     alloc_descs[0];
+  union { /* MSVC workaround for multiple zero sized arrays */
+    udf_Uint8_t   ext_attr[0];
+    udf_Uint8_t   alloc_descs[0];
+  } u;
 } GNUC_PACKED;
 
 PRAGMA_END_PACKED
diff --git a/lib/udf/udf_fs.c b/lib/udf/udf_fs.c
index 1669bc2..d99c9a4 100644
--- a/lib/udf/udf_fs.c
+++ b/lib/udf/udf_fs.c
@@ -681,7 +681,7 @@ udf_readdir(udf_dirent_t *p_udf_dirent)
          p_udf_dirent->psz_name = (char *)
            realloc(p_udf_dirent->psz_name, sizeof(char)*i_len+1);
        
-       unicode16_decode(p_udf_dirent->fid->imp_use 
+       unicode16_decode(p_udf_dirent->fid->u.imp_use 
                         + p_udf_dirent->fid->i_imp_use, 
                         i_len, p_udf_dirent->psz_name);
       }
-- 
1.7.8.msysgit.0