Fix truncate prefix bug and add truncate test suite entry.

2 files changed, 31 insertions, 2 deletions

diff --git a/tests/truncate.test b/tests/truncate.test
new file mode 100755
index 00000000..ee2b2bb8
--- /dev/null
+++ b/tests/truncate.test
@@ -0,0 +1,28 @@
+#!/bin/bash
+
+[ -f testing.sh ] && . testing.sh
+
+#testing "name" "command" "result" "infile" "stdin"
+
+SIZE='&& stat -c %s freep'
+testing "truncate 0" "truncate -s 0 freep $SIZE" "0\n" "" ""
+testing "truncate 12345" "truncate -s 12345 freep $SIZE" "12345\n" "" ""
+testing "truncate 1m" "truncate -s 1m freep $SIZE" "1048576\n" "" ""
+testing "truncate is sparse" "truncate -s 1g freep && stat -c %b freep" \
+	"0\n" "" ""
+testing "truncate +" "truncate -s 1k freep && truncate -s +1k freep $SIZE" \
+	"2048\n" "" ""
+testing "truncate -" "truncate -s 4k freep && truncate -s -1k freep $SIZE" \
+	"3072\n" "" ""
+testing "truncate < hit" \
+	"truncate -s 5k freep && truncate -s \<4k freep $SIZE" "4096\n" "" ""
+testing "truncate < miss" \
+	"truncate -s 4k freep && truncate -s \<6k freep $SIZE" "4096\n" "" ""
+testing "truncate > hit" \
+	"truncate -s 3k freep && truncate -s \>4k freep $SIZE" "4096\n" "" ""
+testing "truncate > miss" \
+	"truncate -s 4k freep && truncate -s \>2k freep $SIZE" "4096\n" "" ""
+testing "truncate /" "truncate -s 7k freep && truncate -s /3k freep $SIZE" \
+	"6144\n" "" ""
+testing "truncate %" "truncate -s 7k freep && truncate -s %3k freep $SIZE" \
+	"9216\n" "" ""
diff --git a/toys/other/truncate.c b/toys/other/truncate.c
index 2b3d4795..bfe1f10c 100644
--- a/toys/other/truncate.c
+++ b/toys/other/truncate.c
@@ -16,7 +16,7 @@ config TRUNCATE
     -s	New size (with optional prefix and suffix)
 
     SIZE prefix: + add, - subtract, < shrink to, > expand to,
-                 / block size rounding down, % block size rounding up
+                 / multiple rounding down, % multiple rounding up
     SIZE suffix: k=1024, m=1024^2, g=1024^3, t=1024^4, p=1024^5, e=1024^6
 */
 
@@ -41,7 +41,8 @@ static void do_truncate(int fd, char *name)
     size = fdlength(fd);
     if (TT.type<2) size += TT.size*(1-(2*TT.type));
     else if (TT.type<4) {
-      if ((TT.type==3) ? size > TT.size : size < TT.size) size = TT.size;
+      if ((TT.type==2) ? (size <= TT.size) : (size >= TT.size)) return;
+      size = TT.size;
     } else {
       size = (size+(TT.type-4)*(TT.size-1))/TT.size;
       size *= TT.size;