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Merge pull request #19007 from rootbeer/glibc-c-test
test/link/glibc_compat: Add C test case for glibc versions
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‎lib/libc/glibc/README.md‎

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@@ -31,7 +31,9 @@ The GNU C Library supports a very wide set of platforms and architectures.
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The current Zig support for glibc only includes Linux.
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Zig supports glibc versions back to v2.17 (2012) as the Zig standard
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library depends on symbols that were introduced in 2.17.
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library depends on symbols that were introduced in 2.17. When used as a C
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or C++ compiler (i.e., `zig cc`) zig supports glibc versions back to
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v2.2.5.
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## Glibc stubs
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‎lib/std/zig/target.zig‎

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@@ -12,7 +12,7 @@ pub const available_libcs = [_]ArchOsAbi{
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.{ .arch = .aarch64_be, .os = .linux, .abi = .gnu, .glibc_min = .{ .major = 2, .minor = 17, .patch = 0 } },
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.{ .arch = .aarch64_be, .os = .linux, .abi = .musl },
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.{ .arch = .aarch64_be, .os = .windows, .abi = .gnu },
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.{ .arch = .aarch64, .os = .linux, .abi = .gnu },
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.{ .arch = .aarch64, .os = .linux, .abi = .gnu, .glibc_min = .{ .major = 2, .minor = 17, .patch = 0 } },
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.{ .arch = .aarch64, .os = .linux, .abi = .musl },
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.{ .arch = .aarch64, .os = .windows, .abi = .gnu },
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.{ .arch = .aarch64, .os = .macos, .abi = .none, .os_ver = .{ .major = 11, .minor = 0, .patch = 0 } },

‎test/link/glibc_compat/build.zig‎

Lines changed: 108 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -28,7 +28,114 @@ pub fn build(b: *std.Build) void {
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test_step.dependOn(&exe.step);
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}
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// Build & run against a sampling of supported glibc versions
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// Build & run a C test case against a sampling of supported glibc versions
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for ([_][]const u8{
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// "native-linux-gnu.2.0", // fails with a pile of missing symbols.
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"native-linux-gnu.2.2.5",
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"native-linux-gnu.2.4",
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"native-linux-gnu.2.12",
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"native-linux-gnu.2.16",
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"native-linux-gnu.2.22",
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"native-linux-gnu.2.28",
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"native-linux-gnu.2.33",
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"native-linux-gnu.2.38",
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"native-linux-gnu",
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}) |t| {
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const target = b.resolveTargetQuery(std.Target.Query.parse(
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.{ .arch_os_abi = t },
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) catch unreachable);
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const glibc_ver = target.result.os.version_range.linux.glibc;
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// only build test if glibc version supports the architecture
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if (target.result.cpu.arch.isAARCH64()) {
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if (glibc_ver.order(.{ .major = 2, .minor = 17, .patch = 0 }) == .lt) {
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continue;
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}
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}
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const exe = b.addExecutable(.{
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.name = t,
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.target = target,
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});
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exe.addCSourceFile(.{ .file = b.path("glibc_runtime_check.c") });
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exe.linkLibC();
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// Only try running the test if the host glibc is known to be good enough. Ideally, the Zig
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// test runner would be able to check this, but see https://github.com/ziglang/zig/pull/17702#issuecomment-1831310453
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if (running_glibc_ver) |running_ver| {
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if (glibc_ver.order(running_ver) == .lt) {
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const run_cmd = b.addRunArtifact(exe);
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run_cmd.skip_foreign_checks = true;
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run_cmd.expectExitCode(0);
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test_step.dependOn(&run_cmd.step);
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}
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}
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const check = exe.checkObject();
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// __errno_location is always a dynamically linked symbol
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check.checkInDynamicSymtab();
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT __errno_location");
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// before v2.32 fstat redirects through __fxstat, afterwards its a
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// normal dynamic symbol
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check.checkInDynamicSymtab();
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if (glibc_ver.order(.{ .major = 2, .minor = 32, .patch = 0 }) == .lt) {
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT __fxstat");
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check.checkInSymtab();
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check.checkContains("FUNC LOCAL HIDDEN fstat");
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} else {
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT fstat");
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check.checkInSymtab();
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check.checkNotPresent("__fxstat");
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}
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// before v2.26 reallocarray is not supported
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check.checkInDynamicSymtab();
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if (glibc_ver.order(.{ .major = 2, .minor = 26, .patch = 0 }) == .lt) {
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check.checkNotPresent("reallocarray");
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} else {
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT reallocarray");
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}
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// before v2.38 strlcpy is not supported
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check.checkInDynamicSymtab();
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if (glibc_ver.order(.{ .major = 2, .minor = 38, .patch = 0 }) == .lt) {
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check.checkNotPresent("strlcpy");
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} else {
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT strlcpy");
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}
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// v2.16 introduced getauxval()
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check.checkInDynamicSymtab();
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if (glibc_ver.order(.{ .major = 2, .minor = 16, .patch = 0 }) == .lt) {
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check.checkNotPresent("getauxval");
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} else {
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT getauxval");
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}
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// Always have dynamic "exit", "pow", and "powf" references
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check.checkInDynamicSymtab();
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT exit");
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check.checkInDynamicSymtab();
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT pow");
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check.checkInDynamicSymtab();
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT powf");
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// An atexit local symbol is defined, and depends on undefined dynamic
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// __cxa_atexit.
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check.checkInSymtab();
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check.checkContains("FUNC LOCAL HIDDEN atexit");
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check.checkInDynamicSymtab();
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check.checkExact("0 0 UND FUNC GLOBAL DEFAULT __cxa_atexit");
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test_step.dependOn(&check.step);
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}
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// Build & run a Zig test case against a sampling of supported glibc versions
32139
for ([_][]const u8{
33140
"native-linux-gnu.2.17", // Currently oldest supported, see #17769
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"native-linux-gnu.2.23",

‎test/link/glibc_compat/glibc_runtime_check.c‎

Lines changed: 114 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,114 @@
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/*
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* Exercise complicating glibc symbols from C code. Complicating symbols
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* are ones that have moved between glibc versions, or use floating point
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* parameters, or have otherwise tripped up the Zig glibc compatibility
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* code.
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*/
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#include <assert.h>
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#include <errno.h>
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#include <features.h>
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#include <fcntl.h>
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
14+
#include <string.h>
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#include <sys/auxv.h>
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#include <sys/stat.h>
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#include <unistd.h>
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/* errno is compilcated (thread-local, dynamically provided, etc). */
20+
static void check_errno()
21+
{
22+
int invalid_fd = open("/doesnotexist", O_RDONLY);
23+
assert(invalid_fd == -1);
24+
assert(errno == ENOENT);
25+
}
26+
27+
/* fstat has moved around in glibc (between libc_nonshared and libc) */
28+
static void check_fstat()
29+
{
30+
int self_fd = open("/proc/self/exe", O_RDONLY);
31+
32+
struct stat statbuf = {0};
33+
int rc = fstat(self_fd, &statbuf);
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assert(rc == 0);
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assert(statbuf.st_dev != 0);
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assert(statbuf.st_ino != 0);
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assert(statbuf.st_mode != 0);
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assert(statbuf.st_size > 0);
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assert(statbuf.st_blocks > 0);
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assert(statbuf.st_ctim.tv_sec > 0);
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close(self_fd);
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}
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/* Some targets have a complicated ABI for floats and doubles */
48+
static void check_fp_abi()
49+
{
50+
// Picked "pow" as it takes and returns doubles
51+
assert(pow(10.0, 10.0) == 10000000000.0);
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assert(powf(10.0f, 10.0f) == 10000000000.0f);
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}
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/* strlcpy introduced in glibc 2.38 */
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static void check_strlcpy()
57+
{
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#if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 38) || (__GLIBC__ > 2)
59+
char target[4] = {0};
60+
strlcpy(target, "this is a source string", 4);
61+
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assert(strcmp(target, "thi") == 0);
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#endif
64+
}
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/* reallocarray introduced in glibc 2.26 */
67+
static void check_reallocarray()
68+
{
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#if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 26) || (__GLIBC__ > 2)
70+
const size_t el_size = 32;
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void* base = reallocarray(NULL, 10, el_size);
72+
void* grown = reallocarray(base, 100, el_size);
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assert(base != NULL);
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assert(grown != NULL);
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free(grown);
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#endif
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}
80+
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/* getauxval introduced in glibc 2.16 */
82+
static void check_getauxval()
83+
{
84+
#if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 16) || (__GLIBC__ > 2)
85+
int pgsz = getauxval(AT_PAGESZ);
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assert(pgsz >= 4*1024);
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#endif
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}
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/* atexit() is part of libc_nonshared */
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static void force_exit_0()
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{
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exit(0);
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}
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static void check_atexit()
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{
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int rc = atexit(force_exit_0);
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assert(rc == 0);
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}
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int main() {
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int rc;
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check_errno();
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check_fstat();
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check_fp_abi();
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check_strlcpy();
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check_reallocarray();
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check_getauxval();
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check_atexit();
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exit(99); // exit code overridden by atexit handler
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}

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