path: root/glibc-readdir-corefx.patch

From 335b1f8553107a73077ae0a2dcf094911d390ece Mon Sep 17 00:00:00 2001
From: "R. Fontenot" <nfontenot27@gmail.com>
Date: Sun, 14 Aug 2016 23:56:00 -0500
Subject: [PATCH 1/5] Replace readdir_r() with readdir()

readdir_r() is deprecated in glibc >= v2.24
---
 src/Native/System.Native/pal_io.cpp | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/Native/System.Native/pal_io.cpp b/src/Native/System.Native/pal_io.cpp
index 7da1bff..9bd0ec8 100644
--- a/src/Native/System.Native/pal_io.cpp
+++ b/src/Native/System.Native/pal_io.cpp
@@ -339,27 +339,28 @@ extern "C" int32_t SystemNative_ReadDirR(DIR* dir, void* buffer, int32_t bufferS
         return ERANGE;
     }

-    dirent* result = nullptr;
-    dirent* entry = static_cast<dirent*>(buffer);
-    int error = readdir_r(dir, entry, &result);
+    // readdir returns a pointer to memory that may be staticly allocated
+    // by glibc. Data returned by readdir may be overwritten by other readdir
+    // calls for the same directory stream.
+    errno = 0;
+    dirent* entry = readdir(dir);

     // positive error number returned -> failure
-    if (error != 0)
+    if (errno != 0)
     {
-        assert(error > 0);
+        assert(error == EBADF); // Invalid directory stream discriptor dir.
         *outputEntry = {}; // managed out param must be initialized
-        return error;
+        return errno;
     }

     // 0 returned with null result -> end-of-stream
-    if (result == nullptr)
+    if (entry == nullptr)
     {
         *outputEntry = {}; // managed out param must be initialized
         return -1;         // shim convention for end-of-stream
     }

-    // 0 returned with non-null result (guaranteed to be set to entry arg) -> success
-    assert(result == entry);
+    memcpy(buffer,entry,static_cast<size_t>(bufferSize));
     ConvertDirent(*entry, outputEntry);
     return 0;
 }
--
2.9.2

From a74fa9876a8479e206a3357c481ffbe574b9fa9c Mon Sep 17 00:00:00 2001
From: "R. Fontenot" <nfontenot27@gmail.com>
Date: Mon, 15 Aug 2016 10:42:54 -0500
Subject: [PATCH 2/5] Clean up discrepancies in the documentation.

---
 src/Native/System.Native/pal_io.cpp | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/Native/System.Native/pal_io.cpp b/src/Native/System.Native/pal_io.cpp
index 9bd0ec8..6977f0d 100644
--- a/src/Native/System.Native/pal_io.cpp
+++ b/src/Native/System.Native/pal_io.cpp
@@ -321,12 +321,15 @@ extern "C" int32_t SystemNative_GetDirentSize()
 //    size of the dirent struct.
 // 2) The managed code creates a byte[] buffer of the size of the native dirent
 //    and passes a pointer to this buffer to this function.
-// 3) This function passes input byte[] buffer to the OS to fill with dirent data
-//    which makes the 1st strcpy.
-// 4) The ConvertDirent function will set a pointer to the start of the inode name
-//    in the byte[] buffer so the managed code and find it and copy it out of the
+// 3) This function gets a pointer to the possibly staticly allocated directory entry.
+// 4) Then, byte[] entry is copied into the byte[] buffer for bufferSize bytes.
+//    This makes the 1st strcpy.
+// 5) The ConvertDirent function will set a pointer to the start of the inode name
+//    in the byte[] buffer so the managed code can find it and copy it out of the
 //    buffer into a managed string that the caller of the framework can use, making
 //    the 2nd and final strcpy.
+//
+//    To make this function thread safe ensure calls on the same DIR* dir never happen concurrently.
 extern "C" int32_t SystemNative_ReadDirR(DIR* dir, void* buffer, int32_t bufferSize, DirectoryEntry* outputEntry)
 {
     assert(buffer != nullptr);
@@ -339,10 +342,10 @@ extern "C" int32_t SystemNative_ReadDirR(DIR* dir, void* buffer, int32_t bufferS
         return ERANGE;
     }

-    // readdir returns a pointer to memory that may be staticly allocated
-    // by glibc. Data returned by readdir may be overwritten by other readdir
-    // calls for the same directory stream.
     errno = 0;
+    // returns a pointer to memory that may be staticly allocated by glibc.
+    // Data returned by readdir may be overwritten by other readdir calls
+    // on the same directory stream.
     dirent* entry = readdir(dir);

     // positive error number returned -> failure
--
2.9.2

From 53f6a769d1a1269b4936cbd4dc7b359d48729ed7 Mon Sep 17 00:00:00 2001
From: "R. Fontenot" <nfontenot27@gmail.com>
Date: Tue, 16 Aug 2016 09:36:08 -0500
Subject: [PATCH 3/5] Add readdir_r cxx_check_source_compiles

---
 src/Native/configure.cmake | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/Native/configure.cmake b/src/Native/configure.cmake
index 017d75f..abc0360 100644
--- a/src/Native/configure.cmake
+++ b/src/Native/configure.cmake
@@ -174,6 +174,20 @@ check_cxx_source_compiles(

 check_cxx_source_compiles(
     "
+    #include <dirent.h>
+    int main(void)
+    {
+	DIR* dir;
+        struct dirent* entry;
+	struct dirent* result;
+        readdir_r(dir,entry,&result);
+	return 0;
+    }
+    "
+    HAVE_GNU_READDIR_R)
+
+check_cxx_source_compiles(
+    "
     #include <sys/types.h>
     #include <sys/event.h>
     int main(void)
--
2.9.2

From ed8510abf9cebb4d0d5d00c28bfb355768bb0c9b Mon Sep 17 00:00:00 2001
From: "R. Fontenot" <nfontenot27@gmail.com>
Date: Tue, 16 Aug 2016 09:54:38 -0500
Subject: [PATCH 4/5] Add copy of SystemNative_ReadDirR() from master

---
 src/Native/System.Native/pal_io.cpp | 51 ++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/src/Native/System.Native/pal_io.cpp b/src/Native/System.Native/pal_io.cpp
index 6977f0d..b7908b5 100644
--- a/src/Native/System.Native/pal_io.cpp
+++ b/src/Native/System.Native/pal_io.cpp
@@ -316,6 +316,56 @@ extern "C" int32_t SystemNative_GetDirentSize()
     return sizeof(dirent);
 }

+#if defined HAVE_GNU_READDIR_R
+// To reduce the number of string copies, this function calling pattern works as follows:
+// 1) The managed code calls GetDirentSize() to get the platform-specific
+//    size of the dirent struct.
+// 2) The managed code creates a byte[] buffer of the size of the native dirent
+//    and passes a pointer to this buffer to this function.
+// 3) This function passes input byte[] buffer to the OS to fill with dirent data
+//    which makes the 1st strcpy.
+// 4) The ConvertDirent function will set a pointer to the start of the inode name
+//    in the byte[] buffer so the managed code and find it and copy it out of the
+//    buffer into a managed string that the caller of the framework can use, making
+//    the 2nd and final strcpy.
+extern "C" int32_t SystemNative_ReadDirR(DIR* dir, void* buffer, int32_t bufferSize, DirectoryEntry* outputEntry)
+{
+    assert(buffer != nullptr);
+    assert(dir != nullptr);
+    assert(outputEntry != nullptr);
+
+    if (bufferSize < static_cast<int32_t>(sizeof(dirent)))
+    {
+        assert(false && "Buffer size too small; use GetDirentSize to get required buffer size");
+        return ERANGE;
+    }
+
+    dirent* result = nullptr;
+    dirent* entry = static_cast<dirent*>(buffer);
+    int error = readdir_r(dir, entry, &result);
+
+    // positive error number returned -> failure
+    if (error != 0)
+    {
+        assert(error > 0);
+        *outputEntry = {}; // managed out param must be initialized
+        return error;
+    }
+
+    // 0 returned with null result -> end-of-stream
+    if (result == nullptr)
+    {
+        *outputEntry = {}; // managed out param must be initialized
+        return -1;         // shim convention for end-of-stream
+    }
+
+    // 0 returned with non-null result (guaranteed to be set to entry arg) -> success
+    assert(result == entry);
+    ConvertDirent(*entry, outputEntry);
+    return 0;
+}
+
+#else
 // To reduce the number of string copies, this function calling pattern works as follows:
 // 1) The managed code calls GetDirentSize() to get the platform-specific
 //    size of the dirent struct.
@@ -367,6 +417,7 @@ extern "C" int32_t SystemNative_ReadDirR(DIR* dir, void* buffer, int32_t bufferS
     ConvertDirent(*entry, outputEntry);
     return 0;
 }
+#endif

 extern "C" DIR* SystemNative_OpenDir(const char* path)
 {
--
2.9.2

From 59bd06622e1d0894954ce7e625ccf019953831e8 Mon Sep 17 00:00:00 2001
From: "R. Fontenot" <nfontenot27@gmail.com>
Date: Tue, 16 Aug 2016 09:56:47 -0500
Subject: [PATCH 5/5] Fix assert

---
 src/Native/System.Native/pal_io.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Native/System.Native/pal_io.cpp b/src/Native/System.Native/pal_io.cpp
index b7908b5..e5e7a4f 100644
--- a/src/Native/System.Native/pal_io.cpp
+++ b/src/Native/System.Native/pal_io.cpp
@@ -401,7 +401,7 @@ extern "C" int32_t SystemNative_ReadDirR(DIR* dir, void* buffer, int32_t bufferS
     // positive error number returned -> failure
     if (errno != 0)
     {
-        assert(error == EBADF); // Invalid directory stream discriptor dir.
+        assert(errno == EBADF); // Invalid directory stream discriptor dir.
         *outputEntry = {}; // managed out param must be initialized
         return errno;
     }
--
2.9.2