genfile: improve sparse mode

* tests/genfile.c (generate_sparse_file): Handle '-' argument
(read from stdin);
If content strings starts with '=', treat it as fragment size and
use default pattern to fill it.
* doc/genfile.texi: Document changes to genfile.

2 files changed, 92 insertions, 20 deletions

diff --git a/doc/genfile.texi b/doc/genfile.texi
index e0f4e35..bd2e505 100644
--- a/doc/genfile.texi
+++ b/doc/genfile.texi
@@ -124,9 +124,8 @@ the rest of the command line specifies a so-called @dfn{file map}.
 descriptors}. Each descriptor is composed of two values: a number,
 specifying fragment offset from the end of the previous fragment or,
 for the very first fragment, from the beginning of the file, and
-@dfn{contents string}, i.e., a string of characters, specifying the
-pattern to fill the fragment with. File offset can be suffixed with
-the following quantifiers:
+@dfn{contents string}, that specifies the pattern to fill the fragment
+with. File offset can be suffixed with the following quantifiers:
 
 @table @samp
 @item k
@@ -140,17 +139,29 @@ The number is expressed in megabytes.
 The number is expressed in gigabytes.
 @end table
 
-    For each letter in contents string @command{genfile} will generate
-a @dfn{block} of data, filled with this letter and will write it to
-the fragment. The size of block is given by @option{--block-size}
-option. It defaults to 512. Thus, if the string consists of @var{n}
-characters, the resulting file fragment will contain
-@code{@var{n}*@var{block-size}} of data.
-
-    Last fragment descriptor can have only file offset part. In this
+    Contents string can be either a fragment size or a pattern.
+Fragment size is a decimal number, prefixed with an equals sign.  It
+can be suffixed with a quantifier, as discussed above.  If fragment
+size is given, the fragment of that size will be filled with the
+currently selected pattern (@pxref{Generate Mode, --pattern}) and
+written to the file.  
+
+    A pattern is a string of arbitrary ASCII characters.  For each
+of them, @command{genfile} will generate a @dfn{block} of data,
+filled with that character and will write it to the fragment. The size
+of block is given by @option{--block-size} option. It defaults to 512.
+Thus, if pattern consists of @var{n} characters, the resulting file
+fragment will contain @code{@var{n}*@var{block-size}} bytes of data.
+
+    The last fragment descriptor can have only file offset part. In this
 case @command{genfile} will create a hole at the end of the file up to
 the given offset.
 
+    A dash appearing as a fragment descriptor instructs
+@command{genfile} to read file map from the standard input.  Each line
+of input should consist of fragment offset and contents string,
+separated by any amount of whitespace.
+
     For example, consider the following invocation:
 
 @smallexample
diff --git a/tests/genfile.c b/tests/genfile.c
index fa480ef..d41336b 100644
--- a/tests/genfile.c
+++ b/tests/genfile.c
@@ -32,6 +32,7 @@
 #include <inttostr.h>
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <c-ctype.h>
 #define obstack_chunk_alloc malloc
 #define obstack_chunk_free free
 #include <obstack.h>
@@ -506,6 +507,53 @@ mksparse (int fd, off_t displ, char *marks)
     }
 }
 
+static int
+make_fragment (int fd, char *offstr, char *mapstr)
+{
+  int i;
+  off_t displ = get_size (offstr, 1);
+
+  file_length += displ;
+
+  if (!mapstr || !*mapstr)
+    {
+      mkhole (fd, displ);
+      return 1;
+    }
+  else if (*mapstr == '=')
+    {
+      off_t n = get_size (mapstr + 1, 1);
+
+      switch (pattern)
+	{
+	case DEFAULT_PATTERN:
+	  for (i = 0; i < block_size; i++)
+	    buffer[i] = i & 255;
+	  break;
+	  
+	case ZEROS_PATTERN:
+	  memset (buffer, 0, block_size);
+	  break;
+	}
+
+      if (lseek (fd, displ, SEEK_CUR) == -1)
+	error (EXIT_FAILURE, errno, "lseek");
+      
+      for (; n; n--)
+	{
+	  if (write (fd, buffer, block_size) != block_size)
+	    error (EXIT_FAILURE, errno, "write");
+	  file_length += block_size;
+	}
+    }
+  else
+    {
+      file_length += block_size * strlen (mapstr);
+      mksparse (fd, displ, mapstr);
+    }
+  return 0;
+}
+
 static void
 generate_sparse_file (int argc, char **argv)
 {
@@ -526,20 +574,33 @@ generate_sparse_file (int argc, char **argv)
 
   file_length = 0;
 
-  for (i = 0; i < argc; i += 2)
+  while (argc)
     {
-      off_t displ = get_size (argv[i], 1);
-      file_length += displ;
-
-      if (i == argc-1)
+      if (argv[0][0] == '-' && argv[0][1] == 0)
 	{
-	  mkhole (fd, displ);
-	  break;
+	  char buf[256];
+	  while (fgets (buf, sizeof (buf), stdin))
+	    {
+	      size_t n = strlen (buf);
+
+	      while (n > 0 && c_isspace (buf[n-1]))
+		buf[--n] = 0;
+	      
+	      n = strcspn (buf, " \t");
+	      buf[n++] = 0;
+	      while (buf[n] && c_isblank (buf[n]))
+		++n;
+	      make_fragment (fd, buf, buf + n);
+	    }
+	  ++argv;
+	  --argc;
 	}
       else
 	{
-	  file_length += block_size * strlen (argv[i+1]);
-	  mksparse (fd, displ, argv[i+1]);
+	  if (make_fragment (fd, argv[0], argv[1]))
+	    break;
+	  argc -= 2;
+	  argv += 2;
 	}
     }