This option directs the library to only use simple stdio APIs instead
of using fileno to get the file descriptor for use with POSIX APIs.
Signed-off-by: Keith Packard <kei...@keithp.com>
---
libstdc++-v3/ChangeLog | 13 ++++++
libstdc++-v3/acinclude.m4 | 13 ++++++
libstdc++-v3/config/io/basic_file_stdio.cc | 46 +++++++++++++++++++---
libstdc++-v3/configure.ac | 1 +
4 files changed, 68 insertions(+), 5 deletions(-)
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index d3ee18ed7d1..7f6b0697534 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1147,6 +1147,19 @@
* include/bits/uniform_int_dist.h (uniform_int_distribution::_S_nd):
Use qualified-id to refer to static member functions.
+2020-11-04 Keith Packard <kei...@keithp.com>
+
+ * acinclude.m4: Add GLIBCXX_ENABLE_PURE_STDIO for
+ --enable-libstdcxx-pure-stdio
+ * configure.ac: Use GLIBCXX_ENABLE_PURE_STDIO for
+ --enable-libstdcxx-pure-stdio
+ * configure: regenerate
+ * config.h.in: regenerate
+ * config/io/basic_file_stdio.cc: Add support for
+ _GLIBCXX_USE_PURE_STDIO. This makes libstdc++ use only defined
+ stdio entry points for all I/O operations, without direct calls to
+ underlying POSIX functions.
+
2020-11-03 Jonathan Wakely <jwak...@redhat.com>
* include/std/syncstream: Include <bits/std_mutex.h>
diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index fcd9ea3d23a..863695e68e7 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -2889,6 +2889,19 @@ AC_DEFUN([GLIBCXX_ENABLE_CSTDIO], [
])
+dnl
+dnl Check whether to use 'pure' stdio (no POSIX calls at all)
+dnl
+dnl Default is 'no'
+AC_DEFUN([GLIBCXX_ENABLE_PURE_STDIO], [
+ GLIBCXX_ENABLE(libstdcxx-pure-stdio,$1,,[use only stdio APIs])
+ if test $enable_libstdcxx_pure_stdio = yes; then
+ AC_DEFINE(_GLIBCXX_USE_PURE_STDIO, 1,
+ [Define to restrict code to stdio APIs.])
+ fi
+])
+
+
dnl
dnl Check for "unusual" flags to pass to the compiler while building.
dnl
diff --git a/libstdc++-v3/config/io/basic_file_stdio.cc
b/libstdc++-v3/config/io/basic_file_stdio.cc
index ba830fb9e97..d31da8497f4 100644
--- a/libstdc++-v3/config/io/basic_file_stdio.cc
+++ b/libstdc++-v3/config/io/basic_file_stdio.cc
@@ -111,13 +111,21 @@ namespace
// Wrapper handling partial write.
static std::streamsize
+#ifdef _GLIBCXX_USE_PURE_STDIO
+ xwrite(FILE *__file, const char* __s, std::streamsize __n)
+#else
xwrite(int __fd, const char* __s, std::streamsize __n)
+#endif
{
std::streamsize __nleft = __n;
for (;;)
{
+#ifdef _GLIBCXX_USE_PURE_STDIO
+ const std::streamsize __ret = fwrite(__file, 1, __nleft, __file);
+#else
const std::streamsize __ret = write(__fd, __s, __nleft);
+#endif
if (__ret == -1L && errno == EINTR)
continue;
if (__ret == -1L)
@@ -133,7 +141,7 @@ namespace
return __n - __nleft;
}
-#ifdef _GLIBCXX_HAVE_WRITEV
+#if defined(_GLIBCXX_HAVE_WRITEV) && !defined(_GLIBCXX_USE_PURE_STDIO)
// Wrapper handling partial writev.
static std::streamsize
xwritev(int __fd, const char* __s1, std::streamsize __n1,
@@ -286,9 +294,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__basic_file<char>::is_open() const throw ()
{ return _M_cfile != 0; }
+#ifndef _GLIBCCXX_USE_PURE_STDIO
int
__basic_file<char>::fd() throw ()
{ return fileno(_M_cfile); }
+#endif
__c_file*
__basic_file<char>::file() throw ()
@@ -315,28 +325,46 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
streamsize __ret;
do
+#ifdef _GLIBCXX_USE_PURE_STDIO
+ __ret = fread(__s, 1, __n, this->file());
+#else
__ret = read(this->fd(), __s, __n);
+#endif
while (__ret == -1L && errno == EINTR);
return __ret;
}
streamsize
__basic_file<char>::xsputn(const char* __s, streamsize __n)
- { return xwrite(this->fd(), __s, __n); }
+ {
+#ifdef _GLIBCXX_USE_PURE_STDIO
+ return xwrite(this->file(), __s, __n);
+#else
+ return xwrite(this->fd(), __s, __n);
+#endif
+ }
streamsize
__basic_file<char>::xsputn_2(const char* __s1, streamsize __n1,
const char* __s2, streamsize __n2)
{
streamsize __ret = 0;
-#ifdef _GLIBCXX_HAVE_WRITEV
+#if defined(_GLIBCXX_HAVE_WRITEV) && !defined(_GLIBCXX_USE_PURE_STDIO)
__ret = xwritev(this->fd(), __s1, __n1, __s2, __n2);
#else
if (__n1)
+#ifdef _GLIBCXX_USE_PURE_STDIO
+ __ret = xwrite(this->file(), __s1, __n1);
+#else
__ret = xwrite(this->fd(), __s1, __n1);
+#endif
if (__ret == __n1)
+#ifdef _GLIBCXX_USE_PURE_STDIO
+ __ret += xwrite(this->file(), __s2, __n2);
+#else
__ret += xwrite(this->fd(), __s2, __n2);
+#endif
#endif
return __ret;
}
@@ -350,7 +378,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
if (__off > numeric_limits<off_t>::max()
|| __off < numeric_limits<off_t>::min())
return -1L;
+#ifdef _GLIBCXX_USE_PURE_STDIO
+ return fseek(this->file(), __off, __way);
+#else
return lseek(this->fd(), __off, __way);
+#endif
#endif
}
@@ -361,7 +393,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
streamsize
__basic_file<char>::showmanyc()
{
-#ifndef _GLIBCXX_NO_IOCTL
+#if !defined(_GLIBCXX_NO_IOCTL) && !defined(_GLIBCXX_USE_PURE_STDIO)
#ifdef FIONREAD
// Pipes and sockets.
int __num = 0;
@@ -371,7 +403,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif
#endif
-#ifdef _GLIBCXX_HAVE_POLL
+#if defined(_GLIBCXX_HAVE_POLL) && !defined(_GLIBCXX_USE_PURE_STDIO)
// Cheap test.
struct pollfd __pfd[1];
__pfd[0].fd = this->fd();
@@ -395,8 +427,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
struct stat __buffer;
const int __err = fstat(this->fd(), &__buffer);
if (!__err && _GLIBCXX_ISREG(__buffer.st_mode))
+#ifdef _GLIBCXX_USE_PURE_STDIO
+ return __buffer.st_size - fseek(this->file(), 0, ios_base::cur);
+#else
return __buffer.st_size - lseek(this->fd(), 0, ios_base::cur);
#endif
+#endif
#endif
return 0;
}
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index cbfdf4c6bad..733154d070b 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -179,6 +179,7 @@ GLIBCXX_ENABLE_EXTERN_TEMPLATE([yes])
GLIBCXX_ENABLE_PYTHON
GLIBCXX_ENABLE_WERROR([no])
GLIBCXX_ENABLE_VTABLE_VERIFY([no])
+GLIBCXX_ENABLE_PURE_STDIO
# Checks for operating systems support that doesn't require linking.
GLIBCXX_CHECK_STDIO_PROTO
--
2.29.2
