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List:       gdb-patches
Subject:    [PATCH 2/5] Capture directory in index_cache_store_context
From:       Tom Tromey <tom () tromey ! com>
Date:       2024-01-28 16:28:06
Message-ID: 20240128-pr-31262-index-cache-race-v1-2-4fe53c5265e3 () tromey ! com
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I noticed that index_cache_store_context captures the 'enabled'
setting, but not the index cache directory.  This patch makes this
change, which avoids a possible race -- with background reading, the
user could possibly change this directory at the exact moment the
writer examines the variable.
---
 gdb/dwarf2/index-cache.c | 9 +++++----
 gdb/dwarf2/index-cache.h | 3 +++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/gdb/dwarf2/index-cache.c b/gdb/dwarf2/index-cache.c
index 645e36c66f7..a269eb46a36 100644
--- a/gdb/dwarf2/index-cache.c
+++ b/gdb/dwarf2/index-cache.c
@@ -90,7 +90,8 @@ index_cache::disable ()
 
 index_cache_store_context::index_cache_store_context (const index_cache &ic,
 						      dwarf2_per_bfd *per_bfd)
-  :  m_enabled (ic.enabled ())
+  :  m_enabled (ic.enabled ()),
+     m_dir (ic.m_dir)
 {
   if (!m_enabled)
     return;
@@ -124,7 +125,7 @@ index_cache_store_context::index_cache_store_context (const index_cache &ic,
       m_dwz_build_id_str = build_id_to_string (dwz_build_id);
     }
 
-  if (ic.m_dir.empty ())
+  if (m_dir.empty ())
     {
       warning (_("The index cache directory name is empty, skipping store."));
       m_enabled = false;
@@ -134,7 +135,7 @@ index_cache_store_context::index_cache_store_context (const index_cache &ic,
   try
     {
       /* Try to create the containing directory.  */
-      if (!mkdir_recursive (ic.m_dir.c_str ()))
+      if (!mkdir_recursive (m_dir.c_str ()))
 	{
 	  warning (_("index cache: could not make cache directory: %s"),
 		   safe_strerror (errno));
@@ -170,7 +171,7 @@ index_cache::store (dwarf2_per_bfd *per_bfd,
 
       /* Write the index itself to the directory, using the build id as the
 	 filename.  */
-      write_dwarf_index (per_bfd, m_dir.c_str (),
+      write_dwarf_index (per_bfd, ctx.m_dir.c_str (),
 			 ctx.m_build_id_str.c_str (), dwz_build_id_ptr,
 			 dw_index_kind::GDB_INDEX);
     }
diff --git a/gdb/dwarf2/index-cache.h b/gdb/dwarf2/index-cache.h
index 079ed412d2e..f66f72caea1 100644
--- a/gdb/dwarf2/index-cache.h
+++ b/gdb/dwarf2/index-cache.h
@@ -48,6 +48,9 @@ struct index_cache_store_context
   /* Captured value of enabled ().  */
   bool m_enabled;
 
+  /* Captured value of index cache directory.  */
+  std::string m_dir;
+
   /* Captured value of build id.  */
   std::string m_build_id_str;
 

-- 
2.43.0

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