Add an option for finding sparse files.

Reviewed by:	iedowse
MFC after:	3 weeks

usr.bin/find/extern.h

@@ -73,6 +73,7 @@ creat_f	c_regex;
 creat_f	c_samefile;
 creat_f	c_simple;
 creat_f	c_size;
+creat_f	c_sparse;
 creat_f	c_type;
 creat_f	c_user;
 creat_f	c_xdev;
@@ -109,6 +110,7 @@ exec_f	f_prune;
 exec_f	f_quit;
 exec_f	f_regex;
 exec_f	f_size;
+exec_f	f_sparse;
 exec_f	f_type;
 exec_f	f_user;
 

usr.bin/find/find.1

@@ -816,6 +816,10 @@ terabytes (1024 gigabytes)
 .It Cm P
 petabytes (1024 terabytes)
 .El
+.It Ic -sparse
+True if the current file is sparse,
+i.e. has fewer blocks allocated than expected based on its size in bytes.
+This might also match files that have been compressed by the filesystem.
 .It Ic -type Ar t
 True if the file is of the specified type.
 Possible file types are as follows:
@@ -997,7 +1001,7 @@ and
 as well as
 .Ic -amin , -anewer , -cmin , -cnewer , -delete , -empty , -fstype ,
 .Ic -iname , -inum , -iregex , -ls , -maxdepth , -mindepth , -mmin ,
-.Ic -path , -print0 , -regex
+.Ic -path , -print0 , -regex, -sparse
 and all of the
 .Ic -B*
 birthtime related primaries are extensions to

usr.bin/find/function.c

@@ -1496,6 +1496,29 @@ c_size(OPTION *option, char ***argvp)
 	return new;
 }
 
+/*
+ * -sparse functions --
+ *
+ *      Check if a file is sparse by finding if it occupies fewer blocks
+ *      than we expect based on its size.
+ */
+int
+f_sparse(PLAN *plan __unused, FTSENT *entry)
+{
+	off_t expected_blocks;
+
+	expected_blocks = (entry->fts_statp->st_size + 511) / 512;
+	return entry->fts_statp->st_blocks < expected_blocks;
+}
+
+PLAN *
+c_sparse(OPTION *option, char ***argvp __unused)
+{
+	ftsoptions &= ~FTS_NOSTAT;
+
+	return palloc(option);
+}
+
 /*
  * -type c functions --
  *

usr.bin/find/option.c

@@ -145,6 +145,7 @@ static OPTION const options[] = {
 	{ "-regex",	c_regex,	f_regex,	0 },
 	{ "-samefile",	c_samefile,	f_inum,		0 },
 	{ "-size",	c_size,		f_size,		0 },
+	{ "-sparse",	c_sparse,	f_sparse,	0 },
 	{ "-true",	c_simple,	f_always_true,	0 },
 	{ "-type",	c_type,		f_type,		0 },
 	{ "-uid",	c_user,		f_user,		0 },