archive/bz2: unlock the archive mutex and lock the file mutex

Fixes deadlock because FileInputStream::Read() unlocks the mutex (which was not locked) and then locks it, keeping it locked. This can result in a deadlock. This happens because the archive and the file mutex are different.

archive/bz2: unlock the archive mutex and lock the file mutex
4b18460b · Max Kellermann · 412c0a96 · 4b18460b · 4b18460b
Commit 4b18460b authored Dec 22, 2017 by Max Kellermann
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Showing with 5 additions and 2 deletions

NEWS NEWS +2 -0

Bzip2ArchivePlugin.cxx src/archive/plugins/Bzip2ArchivePlugin.cxx +3 -2

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--- a/NEWS
+++ b/NEWS
 ver 0.20.14 (not yet released)
 * database
  - simple: fix file corruption in the presence of mount points
+* archive
+  - bz2: fix deadlock
 * fix Solaris build failure

 ver 0.20.13 (2017/12/18)

--- a/src/archive/plugins/Bzip2ArchivePlugin.cxx
+++ b/src/archive/plugins/Bzip2ArchivePlugin.cxx
@@ -162,7 +162,7 @@ Bzip2InputStream::FillBuffer()
 	if (bzstream.avail_in > 0)
 		return true;

-	size_t count = archive->istream->Read(buffer, sizeof(buffer));
+	size_t count = archive->istream->LockRead(buffer, sizeof(buffer));
 	if (count == 0)
 		return false;

@@ -174,6 +174,8 @@ Bzip2InputStream::FillBuffer()
 size_t
 Bzip2InputStream::Read(void *ptr, size_t length)
 {
+	const ScopeUnlock unlock(mutex);
+
 	int bz_result;
 	size_t nbytes = 0;

@@ -224,4 +226,3 @@ const ArchivePlugin bz2_archive_plugin = {
 	bz2_open,
 	bz2_extensions,
 };
-