Merge pull request #17702 from rootbeer/correct-libc-nonshared

Fix libc_nonshared.a

lib/libc/glibc/README.md

@@ -0,0 +1,83 @@
+# Zig GNU C Library ("glibc") Support
+
+Zig supports building binaries that will dynamically link against the
+[GNU C Library ("glibc")](https://www.gnu.org/software/libc/) when run.
+This support extends across a range of glibc versions.
+
+By default, Zig binaries will not depend on any external C library, but
+they can be linked against one with the `-lc` option.  The target ABI defines
+which C library: `musl` for the [musl C library](https://musl.libc.org/) or
+`gnu` for the GNU C library.
+
+A specific GNU C library version can be chosen with an appropriate
+`-target`.  For example, `-target native-native-gnu.2.19` will use the
+default CPU and OS targets, but will link in a run-time dependency on
+glibc v2.19 (or later).  Use `zig env` to show the default target and
+version.
+
+Glibc symbols are defined in the `std.c.` namespace in Zig, though the
+`std.os.` namespace is generally what should be used to access C-library
+APIs in Zig code (it is defined depending on the linked C library).
+
+See `src/glibc.zig` for how Zig will build the glibc components.  The
+generated shared object files are sufficient only for compile-time
+linking. They are stub libraries that only indicate that which symbols
+will be present at run-time, along with their type and size.  The symbols
+do not reference an actual implementation.
+
+## Targets
+
+The GNU C Library supports a very wide set of platforms and architectures.
+The current Zig support for glibc only includes Linux.
+
+Zig supports glibc versions back to v2.17 (2012) as the Zig standard
+library depends on symbols that were introduced in 2.17.
+
+## Glibc stubs
+
+The file `lib/libc/glibc/abilist` is a Zig-specific binary blob that
+defines the supported glibc versions and the set of symbols each version
+must define.  See https://github.com/ziglang/glibc-abi-tool for the
+tooling to generate this blob.  The code in `glibc.zig` parses the abilist
+to build version-specific stub libraries on demand.
+
+The generated stub library is used for compile-time linking, with the
+expectation that at run-time the real glibc library will provide the
+actual symbol implementations.
+
+### Public Headers
+
+The glibc headers are in `lib/libc/include/generic-glibc/`.  These are
+customized and have a couple Zig-specific `#ifdef`s to make the single set
+of headers represent any of the supported glibc versions.  There are
+currently a handful of patches to these headers to represent new features
+(e.g. `reallocarray`) or changes in implementation (e.g., the `stat()`
+family of functions).
+
+The related Zig https://github.com/ziglang/universal-headers is a project
+designed to more robustly build multi-version header files suitable for
+compilation across a variety of target C library versions.
+
+## Glibc static C-Runtime object files and libraries
+
+Linking against glibc also implies linking against several, generally
+"invisible" glibc C Runtime libraries: `crti.o`, `crtn.o`, `Scrt1.o` and
+`libc_nonshared.a`.  These objects are linked into generated Zig binaries
+and are not run-time linking dependencies.  Generally they provide
+bootstrapping, initialization, and mapping of un-versioned public APIs to
+glibc-private versioned APIs.
+
+Like the public headers, these files contain a couple customiziations for
+Zig to be able to build for any supported glibc version.  E.g., for glibc
+versions before v2.32, `libc_nonshared.a` contained stubs that directed
+the `fstat()` call to a versioned `__fxstat()` call.
+
+These files used for these objects are in `lib/libc/glibc`.  See the
+`tools/update_glibc.zig` tool for updating content in here from the
+upstream glibc.
+
+# More Information
+
+See
+https://github.com/ziglang/zig/commit/2314051acaad37dd5630dd7eca08571d620d6496
+for an example commit that updates glibc (to v2.38).

lib/libc/glibc/include/libc-symbols.h

@@ -155,6 +155,18 @@
   extern __typeof (name) aliasname __attribute__ ((weak, alias (#name))) \
     __attribute_copy__ (name);
 
+/* Zig patch.  weak_hidden_alias was removed from glibc v2.36 (v2.37?), Zig
+   needs it for the v2.32 and earlier {f,l,}stat wrappers, so only include
+   in this header for 2.32 and earlier. */
+#if (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 32) || __GLIBC__ < 2
+# define weak_hidden_alias(name, aliasname) \
+  _weak_hidden_alias (name, aliasname)
+# define _weak_hidden_alias(name, aliasname) \
+  extern __typeof (name) aliasname \
+    __attribute__ ((weak, alias (#name), __visibility__ ("hidden"))) \
+    __attribute_copy__ (name);
+#endif
+
 /* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined).  */
 # define weak_extern(symbol) _weak_extern (weak symbol)
 # define _weak_extern(expr) _Pragma (#expr)

lib/libc/glibc/io/fstat-2.32.c

@@ -0,0 +1,55 @@
+/* Copyright (C) 1996-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library 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.
+
+   In addition to the permissions in the GNU Lesser General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file with other
+   programs, and to distribute those programs without any restriction
+   coming from the use of this file. (The GNU Lesser General Public
+   License restrictions do apply in other respects; for example, they
+   cover modification of the file, and distribution when not linked
+   into another program.)
+
+   Note that people who make modified versions of this file are not
+   obligated to grant this special exception for their modified
+   versions; it is their choice whether to do so. The GNU Lesser
+   General Public License gives permission to release a modified
+   version without this exception; this exception also makes it
+   possible to release a modified version which carries forward this
+   exception.
+
+   The GNU C Library 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 the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sys/stat.h>
+
+/* This definition is only used if inlining fails for this function; see
+   the last page of <sys/stat.h>.  The real work is done by the `x'
+   function which is passed a version number argument.  We arrange in the
+   makefile that when not inlined this function is always statically
+   linked; that way a dynamically-linked executable always encodes the
+   version number corresponding to the data structures it uses, so the `x'
+   functions in the shared library can adapt without needing to recompile
+   all callers.  */
+
+#undef fstat
+#undef __fstat
+int
+attribute_hidden
+__fstat (int fd, struct stat *buf)
+{
+  return __fxstat (_STAT_VER, fd, buf);
+}
+
+weak_hidden_alias (__fstat, fstat)

lib/libc/glibc/io/fstat64-2.32.c

@@ -0,0 +1,52 @@
+/* Copyright (C) 1996-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library 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.
+
+   In addition to the permissions in the GNU Lesser General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file with other
+   programs, and to distribute those programs without any restriction
+   coming from the use of this file. (The GNU Lesser General Public
+   License restrictions do apply in other respects; for example, they
+   cover modification of the file, and distribution when not linked
+   into another program.)
+
+   Note that people who make modified versions of this file are not
+   obligated to grant this special exception for their modified
+   versions; it is their choice whether to do so. The GNU Lesser
+   General Public License gives permission to release a modified
+   version without this exception; this exception also makes it
+   possible to release a modified version which carries forward this
+   exception.
+
+   The GNU C Library 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 the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sys/stat.h>
+
+/* This definition is only used if inlining fails for this function; see
+   the last page of <sys/stat.h>.  The real work is done by the `x'
+   function which is passed a version number argument.  We arrange in the
+   makefile that when not inlined this function is always statically
+   linked; that way a dynamically-linked executable always encodes the
+   version number corresponding to the data structures it uses, so the `x'
+   functions in the shared library can adapt without needing to recompile
+   all callers.  */
+
+#undef fstat64
+int
+attribute_hidden
+fstat64 (int fd, struct stat64 *buf)
+{
+  return __fxstat64 (_STAT_VER, fd, buf);
+}

lib/libc/glibc/io/fstatat-2.32.c

@@ -0,0 +1,52 @@
+/* Copyright (C) 2005-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library 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.
+
+   In addition to the permissions in the GNU Lesser General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file with other
+   programs, and to distribute those programs without any restriction
+   coming from the use of this file. (The GNU Lesser General Public
+   License restrictions do apply in other respects; for example, they
+   cover modification of the file, and distribution when not linked
+   into another program.)
+
+   Note that people who make modified versions of this file are not
+   obligated to grant this special exception for their modified
+   versions; it is their choice whether to do so. The GNU Lesser
+   General Public License gives permission to release a modified
+   version without this exception; this exception also makes it
+   possible to release a modified version which carries forward this
+   exception.
+
+   The GNU C Library 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 the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sys/stat.h>
+
+/* This definition is only used if inlining fails for this function; see
+   the last page of <sys/stat.h>.  The real work is done by the `x'
+   function which is passed a version number argument.  We arrange in the
+   makefile that when not inlined this function is always statically
+   linked; that way a dynamically-linked executable always encodes the
+   version number corresponding to the data structures it uses, so the `x'
+   functions in the shared library can adapt without needing to recompile
+   all callers.  */
+
+#undef fstatat
+int
+attribute_hidden
+fstatat (int fd, const char *file, struct stat *buf, int flag)
+{
+  return __fxstatat (_STAT_VER, fd, file, buf, flag);
+}

lib/libc/glibc/io/fstatat64-2.32.c

@@ -0,0 +1,52 @@
+/* Copyright (C) 2005-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library 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.
+
+   In addition to the permissions in the GNU Lesser General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file with other
+   programs, and to distribute those programs without any restriction
+   coming from the use of this file. (The GNU Lesser General Public
+   License restrictions do apply in other respects; for example, they
+   cover modification of the file, and distribution when not linked
+   into another program.)
+
+   Note that people who make modified versions of this file are not
+   obligated to grant this special exception for their modified
+   versions; it is their choice whether to do so. The GNU Lesser
+   General Public License gives permission to release a modified
+   version without this exception; this exception also makes it
+   possible to release a modified version which carries forward this
+   exception.
+
+   The GNU C Library 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 the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sys/stat.h>
+
+/* This definition is only used if inlining fails for this function; see
+   the last page of <sys/stat.h>.  The real work is done by the `x'
+   function which is passed a version number argument.  We arrange in the
+   makefile that when not inlined this function is always statically
+   linked; that way a dynamically-linked executable always encodes the
+   version number corresponding to the data structures it uses, so the `x'
+   functions in the shared library can adapt without needing to recompile
+   all callers.  */
+
+#undef fstatat64
+int
+attribute_hidden
+fstatat64 (int fd, const char *file, struct stat64 *buf, int flag)
+{
+  return __fxstatat64 (_STAT_VER, fd, file, buf, flag);
+}

lib/libc/glibc/io/lstat-2.32.c

@@ -0,0 +1,55 @@
+/* Copyright (C) 1996-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library 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.
+
+   In addition to the permissions in the GNU Lesser General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file with other
+   programs, and to distribute those programs without any restriction
+   coming from the use of this file. (The GNU Lesser General Public
+   License restrictions do apply in other respects; for example, they
+   cover modification of the file, and distribution when not linked
+   into another program.)
+
+   Note that people who make modified versions of this file are not
+   obligated to grant this special exception for their modified
+   versions; it is their choice whether to do so. The GNU Lesser
+   General Public License gives permission to release a modified
+   version without this exception; this exception also makes it
+   possible to release a modified version which carries forward this
+   exception.
+
+   The GNU C Library 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 the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sys/stat.h>
+
+/* This definition is only used if inlining fails for this function; see
+   the last page of <sys/stat.h>.  The real work is done by the `x'
+   function which is passed a version number argument.  We arrange in the
+   makefile that when not inlined this function is always statically
+   linked; that way a dynamically-linked executable always encodes the
+   version number corresponding to the data structures it uses, so the `x'
+   functions in the shared library can adapt without needing to recompile
+   all callers.  */
+
+#undef lstat
+#undef __lstat
+int
+attribute_hidden
+__lstat (const char *file, struct stat *buf)
+{
+  return __lxstat (_STAT_VER, file, buf);
+}
+
+weak_hidden_alias (__lstat, lstat)