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chromium: Fix font rendering with glibc-2.33
A change in the fstat syscall in glibc-2.33 causes font rendering issues when sandbox is enabled. It now handles __NR_newfstatat and __NR_fstatat64 properly in the sandbox. Taken from fedora upstream: https://src.fedoraproject.org/rpms/chromium/ c/82ff440ce80f6a03b150f768a2cba9469a8ec4f4?branch=rawhide #473 Signed-off-by: Yi Fan Yu <yifan.yu@windriver.com>
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‎meta-chromium/recipes-browser/chromium/chromium-gn.inc

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@@ -19,6 +19,7 @@ SRC_URI += " \
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file://0009-RandBytes-Stop-including-sys-random.h-on-Linux.patch \
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file://0010-avoid-link-latomic-failure-on-CentOS-8-host.patch \
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file://0011-Fix-use-of-DCHECK-with-std-unique_ptr.patch \
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file://0012-Fix-font-rendering-with-glibc-2.33.patch \
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"
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SRC_URI_append_libc-musl = "\

‎meta-chromium/recipes-browser/chromium/files/0012-Fix-font-rendering-with-glibc-2.33.patch

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From 4efced4055a8836eba14199745ef2129717247b5 Mon Sep 17 00:00:00 2001
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From: Yi Fan Yu <yifan.yu@windriver.com>
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Date: Tue, 6 Apr 2021 15:30:58 -0400
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Subject: [PATCH] Fix font rendering with glibc-2.33
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A change in the fstat syscall in glibc-2.33
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causes font rendering issues when sandbox is enabled.
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This patch is used by both fedora33 and archlinux
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in their chromium builds.
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Directly taken from:
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https://src.fedoraproject.org/rpms/chromium/c/
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82ff440ce80f6a03b150f768a2cba9469a8ec4f4?branch=rawhide
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Upstream-Status: Submitted [https://bugs.chromium.org/p/chromium/issues/detail?id=1164975]
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Original Author: Kevin Kofler <Kevin@tigcc.ticalc.org>
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This fix was pointed out by MarkusVolk in
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https://github.com/OSSystems/meta-browser/issues/473
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Signed-off-by: Yi Fan Yu <yifan.yu@windriver.com>
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---
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.../seccomp-bpf-helpers/baseline_policy.cc | 12 +++++++
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.../seccomp-bpf-helpers/sigsys_handlers.cc | 35 +++++++++++++++++++
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.../seccomp-bpf-helpers/sigsys_handlers.h | 5 +++
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sandbox/linux/services/syscall_wrappers.cc | 9 +++++
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sandbox/linux/services/syscall_wrappers.h | 4 +++
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5 files changed, 65 insertions(+)
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diff --git a/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc b/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc
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index e00e3125993..722eb6796b7 100644
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--- a/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc
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+++ b/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc
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@@ -261,6 +261,18 @@ ResultExpr EvaluateSyscallImpl(int fs_denied_errno,
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return RestrictKillTarget(current_pid, sysno);
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}
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+#if defined(__NR_newfstatat)
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+ if (sysno == __NR_newfstatat) {
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+ return RewriteFstatatSIGSYS();
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+ }
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+#endif
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+
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+#if defined(__NR_fstatat64)
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+ if (sysno == __NR_fstatat64) {
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+ return RewriteFstatatSIGSYS();
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+ }
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+#endif
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+
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if (SyscallSets::IsFileSystem(sysno) ||
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SyscallSets::IsCurrentDirectory(sysno)) {
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return Error(fs_denied_errno);
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diff --git a/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc b/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc
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index 76eb32493f5..09aa3f0b11c 100644
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--- a/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc
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+++ b/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc
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@@ -6,6 +6,8 @@
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#include "sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h"
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+#include <errno.h>
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+#include <fcntl.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <string.h>
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@@ -355,6 +357,35 @@ intptr_t SIGSYSSchedHandler(const struct arch_seccomp_data& args,
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return -ENOSYS;
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}
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+intptr_t SIGSYSFstatatHandler(const struct arch_seccomp_data& args,
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+ void* aux) {
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+ switch (args.nr) {
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+#if defined(__NR_newfstatat)
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+ case __NR_newfstatat:
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+#endif
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+#if defined(__NR_fstatat64)
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+ case __NR_fstatat64:
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+#endif
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+#if defined(__NR_newfstatat) || defined(__NR_fstatat64)
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+ if (*reinterpret_cast<const char *>(args.args[1]) == '\0'
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+ && args.args[3] == static_cast<uint64_t>(AT_EMPTY_PATH)) {
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+ return sandbox::sys_fstat64(static_cast<int>(args.args[0]),
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+ reinterpret_cast<struct stat64 *>(args.args[2]));
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+ } else {
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+ errno = EACCES;
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+ return -1;
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+ }
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+ break;
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+#endif
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+ }
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+
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+ CrashSIGSYS_Handler(args, aux);
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+
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+ // Should never be reached.
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+ RAW_CHECK(false);
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+ return -ENOSYS;
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+}
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+
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bpf_dsl::ResultExpr CrashSIGSYS() {
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return bpf_dsl::Trap(CrashSIGSYS_Handler, NULL);
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}
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@@ -387,6 +418,10 @@ bpf_dsl::ResultExpr RewriteSchedSIGSYS() {
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return bpf_dsl::Trap(SIGSYSSchedHandler, NULL);
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}
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+bpf_dsl::ResultExpr RewriteFstatatSIGSYS() {
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+ return bpf_dsl::Trap(SIGSYSFstatatHandler, NULL);
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+}
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+
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void AllocateCrashKeys() {
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#if !defined(OS_NACL_NONSFI)
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if (seccomp_crash_key)
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diff --git a/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h b/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h
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index 7a958b93b27..d0bfab74bb9 100644
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--- a/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h
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+++ b/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h
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@@ -62,6 +62,10 @@ SANDBOX_EXPORT intptr_t SIGSYSPtraceFailure(const arch_seccomp_data& args,
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// sched_setparam(), sched_setscheduler()
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SANDBOX_EXPORT intptr_t SIGSYSSchedHandler(const arch_seccomp_data& args,
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void* aux);
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+// If the fstatat syscall is actually a disguised fstat, calls the regular fstat
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+// syscall, otherwise, crashes in the same way as CrashSIGSYS_Handler.
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+SANDBOX_EXPORT intptr_t SIGSYSFstatatHandler(const struct arch_seccomp_data& args,
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+ void* aux);
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// Variants of the above functions for use with bpf_dsl.
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SANDBOX_EXPORT bpf_dsl::ResultExpr CrashSIGSYS();
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@@ -72,6 +76,7 @@ SANDBOX_EXPORT bpf_dsl::ResultExpr CrashSIGSYSKill();
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SANDBOX_EXPORT bpf_dsl::ResultExpr CrashSIGSYSFutex();
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SANDBOX_EXPORT bpf_dsl::ResultExpr CrashSIGSYSPtrace();
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SANDBOX_EXPORT bpf_dsl::ResultExpr RewriteSchedSIGSYS();
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+SANDBOX_EXPORT bpf_dsl::ResultExpr RewriteFstatatSIGSYS();
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// Allocates a crash key so that Seccomp information can be recorded.
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void AllocateCrashKeys();
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diff --git a/sandbox/linux/services/syscall_wrappers.cc b/sandbox/linux/services/syscall_wrappers.cc
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index fcfd2aa129d..5396b36da9f 100644
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--- a/sandbox/linux/services/syscall_wrappers.cc
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+++ b/sandbox/linux/services/syscall_wrappers.cc
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@@ -261,4 +261,13 @@ int sys_sigaction(int signum,
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#endif // defined(MEMORY_SANITIZER)
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+SANDBOX_EXPORT int sys_fstat64(int fd, struct stat64 *buf)
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+{
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+#if defined(__NR_fstat64)
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+ return syscall(__NR_fstat64, fd, buf);
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+#else
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+ return syscall(__NR_fstat, fd, buf);
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+#endif
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+}
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+
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} // namespace sandbox
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diff --git a/sandbox/linux/services/syscall_wrappers.h b/sandbox/linux/services/syscall_wrappers.h
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index 1975bfbd88a..ed7ee5a1c16 100644
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--- a/sandbox/linux/services/syscall_wrappers.h
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+++ b/sandbox/linux/services/syscall_wrappers.h
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@@ -17,6 +17,7 @@ struct sock_fprog;
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struct rlimit64;
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struct cap_hdr;
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struct cap_data;
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+struct stat64;
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namespace sandbox {
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@@ -84,6 +85,9 @@ SANDBOX_EXPORT int sys_sigaction(int signum,
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const struct sigaction* act,
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struct sigaction* oldact);
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+// Recent glibc rewrites fstat to fstatat.
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+SANDBOX_EXPORT int sys_fstat64(int fd, struct stat64 *buf);
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+
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} // namespace sandbox
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#endif // SANDBOX_LINUX_SERVICES_SYSCALL_WRAPPERS_H_

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