mirror of
https://github.com/jart/cosmopolitan.git
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ff77f2a6af
- This change fixes a bug that allowed unbuffered printf() output (to streams like stderr) to be truncated. This regression was introduced some time between now and the last release. - POSIX specifies all functions as thread safe by default. This change works towards cleaning up our use of the @threadsafe / @threadunsafe documentation annotations to reflect that. The goal is (1) to use @threadunsafe to document functions which POSIX say needn't be thread safe, and (2) use @threadsafe to document functions that we chose to implement as thread safe even though POSIX didn't mandate it. - Tidy up the clock_gettime() implementation. We're now trying out a cleaner approach to system call support that aims to maintain the Linux errno convention as long as possible. This also fixes bugs that existed previously, where the vDSO errno wasn't being translated properly. The gettimeofday() system call is now a wrapper for clock_gettime(), which reduces bloat in apps that use both. - The recently-introduced improvements to the execute bit on Windows has had bugs fixed. access(X_OK) on a directory on Windows now succeeds. fstat() will now perform the MZ/#! ReadFile() operation correctly. - Windows.h is no longer included in libc/isystem/, because it confused PCRE's build system into thinking Cosmopolitan is a WIN32 platform. Cosmo's Windows.h polyfill was never even really that good, since it only defines a subset of the subset of WIN32 APIs that Cosmo defines. - The setlongerjmp() / longerjmp() APIs are removed. While they're nice APIs that are superior to the standardized setjmp / longjmp functions, they weren't superior enough to not be dead code in the monorepo. If you use these APIs, please file an issue and they'll be restored. - The .com appending magic has now been removed from APE Loader.
127 lines
4.2 KiB
ArmAsm
127 lines
4.2 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/dce.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/thread/tls.h"
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#include "libc/macros.internal.h"
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// Forks process without copying page tables.
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//
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// This function lets a process spawn another process without
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// copying the page tables. The parent process gets suspended
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// until the child calls either execve() or _Exit(), and they
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// share memory during that time. That's at least how we want
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// vfork() to work. Support for these behaviors is patchy. It
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// is also error-prone to use this function in an environment
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// with signal handlers and threads. The best way to use this
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// is by calling posix_spawn() which works around the dangers
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// and determines at runtime the best way to pass error codes
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//
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// @return pid of child process or 0 if forked process
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// @returnstwice
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// @vforksafe
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.ftrace1
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vfork:
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.ftrace2
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#ifdef __SANITIZE_ADDRESS__
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jmp fork
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#endif
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#ifdef __x86_64__
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#if SupportsWindows()
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// these platforms disagree with vfork
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testb $_HOSTXNU|_HOSTOPENBSD|_HOSTWINDOWS,__hostos(%rip)
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jnz fork
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#endif
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#if !IsTiny()
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push %rbp
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mov %rsp,%rbp
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#ifdef SYSDEBUG
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ezlea .Llog,di
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call __stracef
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#endif
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pop %rbp
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#endif
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mov %fs:0,%r9 // get thread information block
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mov 0x3c(%r9),%r8d // avoid question of @vforksafe errno
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pop %rsi // saves return address in a register
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mov __NR_vfork(%rip),%eax
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#if SupportsBsd()
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clc
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#endif
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syscall
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#if SupportsBsd()
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jnc 0f
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neg %rax
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0:
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#endif
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push %rsi // note it happens twice in same page
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cmp $-4095,%eax
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jae systemfive_error
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mov %r8d,0x3c(%r9) // restore errno
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1: test %eax,%eax
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jnz .Lpar
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.Lchi: orb $TIB_FLAG_VFORKED,0x40(%r9)
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ret
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.Lpar: andb $~TIB_FLAG_VFORKED,0x40(%r9)
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ret
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#elif defined(__aarch64__)
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adrp x0,__hostos
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ldr w0,[x0,#:lo12:__hostos]
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tbz x0,3,1f // bit 3 is xnu
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b fork // which doesn't support vfork()
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1: mov x8,#220 // __NR_clone
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mov x0,#0x4111 // SIGCHLD | CLONE_VM | CLONE_VFORK
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mov x1,#0
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svc 0
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// if (!rc) {
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// __get_tls()->tib_flags |= TIB_FLAG_VFORKED;
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// } else {
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// __get_tls()->tib_flags &= ~TIB_FLAG_VFORKED;
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// }
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sub x1,x28,#0x80 // RELIES ON TLS TIB ABI!
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ldr x2,[x1,64]
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cbnz x0,2f
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orr x2,x2,#TIB_FLAG_VFORKED
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1: str x2,[x1,64]
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b 3f
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2: and x2,x2,#~TIB_FLAG_VFORKED
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b 1b
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// if (rc < 0) errno = -rc, rc = -1;
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3: .hidden _sysret
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b _sysret
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#else
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#error "architecture unsupported"
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#endif
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.endfn vfork,globl
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#ifdef SYSDEBUG
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.rodata.str1.1
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.Llog: .ascii STRACE_PROLOGUE
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.asciz "vfork()\n"
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.previous
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#endif /* DEBUGSYS */
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