[vlc-devel] [PATCH v2] compat: add qsort_r()

[Romain Vimont]

Add qsort_r() based on qsort() with Thread Local Storage to store the
comparison context.
---
 compat/qsort_r.c     | 47 ++++++++++++++++++++++++++++++++++++++++++++
 configure.ac         |  2 +-
 include/vlc_fixups.h |  7 +++++++
 3 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 compat/qsort_r.c

diff --git a/compat/qsort_r.c b/compat/qsort_r.c
new file mode 100644
index 0000000000..9519ddafc6
--- /dev/null
+++ b/compat/qsort_r.c
@@ -0,0 +1,47 @@
+/**
+ * @file qsort_r.c
+ * @brief replacement for GNU qsort_r()
+ */
+/*****************************************************************************
+ * Copyright (C) 2018 VLC authors and VideoLAN
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <stdlib.h>
+
+static thread_local struct qsort_r_context
+{
+    int (*compar)(const void *, const void *, void *);
+    void *arg;
+} qsort_r_ctx;
+
+static int qsort_cmp(const void *lhs, const void *rhs)
+{
+    return qsort_r_ctx.compar(lhs, rhs, qsort_r_ctx.arg);
+}
+
+void qsort_r(void *base, size_t nmemb, size_t size,
+             int (*compar)(const void *, const void *, void *),
+             void *arg)
+{
+    qsort_r_ctx.compar = compar;
+    qsort_r_ctx.arg = arg;
+    qsort(base, nmemb, size, qsort_cmp);
+}
diff --git a/configure.ac b/configure.ac
index 8cf88a4ec6..1f33f5dc88 100644
--- a/configure.ac
+++ b/configure.ac
@@ -581,7 +581,7 @@ need_libc=false
 
 dnl Check for usual libc functions
 AC_CHECK_FUNCS([accept4 daemon fcntl flock fstatvfs fork getenv getpwuid_r isatty memalign mkostemp mmap open_memstream newlocale openat pipe2 pread posix_fadvise posix_madvise posix_memalign setlocale stricmp strnicmp strptime uselocale])
-AC_REPLACE_FUNCS([aligned_alloc atof atoll dirfd fdopendir flockfile fsync getdelim getpid lfind lldiv memrchr nrand48 poll recvmsg rewind sendmsg setenv strcasecmp strcasestr strdup strlcpy strndup strnlen strnstr strsep strtof strtok_r strtoll swab tdestroy tfind timegm timespec_get strverscmp pathconf])
+AC_REPLACE_FUNCS([aligned_alloc atof atoll dirfd fdopendir flockfile fsync getdelim getpid lfind lldiv memrchr nrand48 poll qsort_r recvmsg rewind sendmsg setenv strcasecmp strcasestr strdup strlcpy strndup strnlen strnstr strsep strtof strtok_r strtoll swab tdestroy tfind timegm timespec_get strverscmp pathconf])
 AC_REPLACE_FUNCS([gettimeofday])
 AC_CHECK_FUNC(fdatasync,,
   [AC_DEFINE(fdatasync, fsync, [Alias fdatasync() to fsync() if missing.])
diff --git a/include/vlc_fixups.h b/include/vlc_fixups.h
index ad8f692271..c7f06063c5 100644
--- a/include/vlc_fixups.h
+++ b/include/vlc_fixups.h
@@ -468,6 +468,13 @@ struct msghdr;
 ssize_t sendmsg(int, const struct msghdr *, int);
 #endif
 
+/* qsort_r */
+#ifndef HAVE_QSORT_R
+void qsort_r(void *base, size_t nmemb, size_t size,
+             int (*compar)(const void *, const void *, void *),
+             void *arg);
+#endif
+
 /* search.h */
 #ifndef HAVE_SEARCH_H
 typedef struct entry {
-- 
2.19.1