[PATCH] Clean up temporary file in hardlink mode

[Tom de Vries <tdevries@suse.de>]

Hi,

Consider an executable file with hardlinks a.out and b.out.

When running dwz once:
...
$ dwz -h a.out b.out
...
a.out and b.out are updated, and remain hardlinks to the same file.

But when running dwz once more, a.out and b.out remain unchanged, and a
temporary file b.out.#dwz#.XXXXXX is left.

This is caused by the fact that the code in function dwz intended to handle
unchanged hardlinks is never triggered.  It is guarded by a "resa[n].res == 1"
condition, but res->res is set to 0 at the end of function dwz, irrespective
of whether the file changed or not.

Fix this by only setting res->res to 0 if the file changed.

OK for trunk?

[ Applies on top of trunk + "[PATCH] Don't process low-mem files in multifile
mode". ]

Thanks,
- Tom

Clean up temporary file in hardlink mode

2019-03-02  Tom de Vries  <tdevries@suse.de>

	PR dwz/24275
	* dwz.c (struct file_result): Document res field.
	(dwz): Only set res->res to 1 if changed.
	* testsuite/dwz.tests/hardlink-no-change.sh: New test.

---
 dwz.c                                     |  9 +++++++--
 testsuite/dwz.tests/hardlink-no-change.sh | 23 +++++++++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/dwz.c b/dwz.c
index ffa8e08..3673bbf 100644
--- a/dwz.c
+++ b/dwz.c
@@ -10950,6 +10950,11 @@ remove_empty_pus (void)
 /* Helper structure for hardlink discovery.  */
 struct file_result
 {
+  /* -2: Already processed under different name.
+     -1: Ignore.
+      0: Processed, changed.
+      1: Processed, unchanged.
+  */
   int res;
   dev_t dev;
   ino_t ino;
@@ -11206,6 +11211,8 @@ dwz (const char *file, const char *outfile, struct file_result *res,
 
 	  if (write_dso (dso, outfile, &st))
 	    ret = 1;
+	  else
+	    res->res = 0;
 	}
     }
 
@@ -11227,8 +11234,6 @@ dwz (const char *file, const char *outfile, struct file_result *res,
   close (fd);
 
   free (dso);
-  if (ret == 0)
-    res->res = 0;
   return ret;
 }
 
diff --git a/testsuite/dwz.tests/hardlink-no-change.sh b/testsuite/dwz.tests/hardlink-no-change.sh
new file mode 100755
index 0000000..945d220
--- /dev/null
+++ b/testsuite/dwz.tests/hardlink-no-change.sh
@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -e
+
+cp ../hello 1
+ln 1 2
+
+dwz -h 1 2
+
+dwz -h 1 2 2>/dev/null
+
+smaller-than.sh 1 ../hello
+smaller-than.sh 2 ../hello
+
+hl="$(find -samefile 1)"
+hl="$(echo $hl)"
+[ "$hl" = "./1 ./2" ]
+
+ls=$(ls)
+ls=$(echo $ls)
+[ "$ls" = "1 2" ]
+
+rm -f 1 2