[Libcdio-devel] [PATCH] Fix extract.c sample for LFS

[Pete Batard]

Without this patch, the extract.c sample will fail on 32 bit machines 
when extracting a file that is larger than 2 GB (EFBIG in fwrite = file 
too large).

This is due from _FILE_OFFSET_BITS not being picked up due to config.h 
being missing (NB: udffile.c does include config.h already so doesn't 
need a fix).

You'll see that I also added an info message to notify users about 
missing LFS. Maybe this is something that would be better added to 
udf_open()?

The expectation is that most people dealing with UDF will require LFS 
support, so a cdio_info/cdio_warn in udf_open(), if LFS is not detected 
may help non LFS libcdio users troubleshoot LFS related issues more easily.

With this patch and the previous one, UDF extraction on Linux 32 bit 
should be sorted. I'll probably send a couple more patches, that aren't 
critical for libcdio operations, and then move to MinGW fixes (where the 
bad surprise is that, rather astonishingly, the current version of 
MinGW32 has NO transparent support for LFS whatsoever).

Regards,

/Pete

From 15dbcac9a29d69d11ece44c1d0ea4fe24341cdc5 Mon Sep 17 00:00:00 2001
From: Pete Batard <address@hidden>
Date: Tue, 24 Jan 2012 17:05:21 +0000
Subject: [PATCH] Fix extract.c sample for LFS

* also add user warning if LFS is not detected
* also elaborate on write error, as they may be relevant for LFS
---
 example/extract.c |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/example/extract.c b/example/extract.c
index 913634d..6b5e03a 100644
--- a/example/extract.c
+++ b/example/extract.c
@@ -20,6 +20,13 @@
    TODO: timestamp preservation, file permissions, Unicode
  */
 
+/* To handle files > 2 GB, we may need the Large File Support settings
+   defined in config.h. Comes first, as stdio.h depends on it. */
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+# define __CDIO_CONFIG_H__ 1
+#endif
+
 #include <stdio.h>
 #include <string.h>
 #include <malloc.h>
@@ -100,7 +107,7 @@ static int udf_extract_files(udf_t *p_udf, udf_dirent_t 
*p_udf_dirent, const cha
         }
         fwrite(buf, (size_t)MIN(i_file_length, i_read), 1, fd);
         if (ferror(fd)) {
-          fprintf(stderr, "  Error writing file\n");
+          fprintf(stderr, "  Error writing file: %s\n", strerror(errno));
           goto out;
         }
         i_file_length -= i_read;
@@ -174,7 +181,7 @@ static int iso_extract_files(iso9660_t* p_iso, const char 
*psz_path)
         }
         fwrite(buf, (size_t)MIN(i_file_length, ISO_BLOCKSIZE), 1, fd);
         if (ferror(fd)) {
-          fprintf(stderr, "  Error writing file\n");
+          fprintf(stderr, "  Error writing file: %s\n", strerror(errno));
           goto out;
         }
         i_file_length -= ISO_BLOCKSIZE;
@@ -208,6 +215,11 @@ int main(int argc, char** argv)
     fprintf(stderr, "Usage: extract <iso_image> <extraction_dir>\n");
     return 1;
   }
+  
+  /* Warn if LFS doesn't appear to be enabled */
+  if (sizeof(off_t) < 8) {
+    fprintf(stderr, "INFO: Large File Support not detected (required for files 
>2GB)\n");
+  }
 
   psz_extract_dir = argv[2];
   if (_mkdir(psz_extract_dir) == 0) {
-- 
1.7.8.msysgit.0