791f79fcb3
- We now serialize the file descriptor table when spawning / executing processes on Windows. This means you can now inherit more stuff than just standard i/o. It's needed by bash, which duplicates the console to file descriptor #255. We also now do a better job serializing the environment variables, so you're less likely to encounter E2BIG when using your bash shell. We also no longer coerce environ to uppercase - execve() on Windows now remotely controls its parent process to make them spawn a replacement for itself. Then it'll be able to terminate immediately once the spawn succeeds, without having to linger around for the lifetime as a shell process for proxying the exit code. When process worker thread running in the parent sees the child die, it's given a handle to the new child, to replace it in the process table. - execve() and posix_spawn() on Windows will now provide CreateProcess an explicit handle list. This allows us to remove handle locks which enables better fork/spawn concurrency, with seriously correct thread safety. Other codebases like Go use the same technique. On the other hand fork() still favors the conventional WIN32 inheritence approach which can be a little bit messy, but is *controlled* by guaranteeing perfectly clean slates at both the spawning and execution boundaries - sigset_t is now 64 bits. Having it be 128 bits was a mistake because there's no reason to use that and it's only supported by FreeBSD. By using the system word size, signal mask manipulation on Windows goes very fast. Furthermore @asyncsignalsafe funcs have been rewritten on Windows to take advantage of signal masking, now that it's much more pleasant to use. - All the overlapped i/o code on Windows has been rewritten for pretty good signal and cancelation safety. We're now able to ensure overlap data structures are cleaned up so long as you don't longjmp() out of out of a signal handler that interrupted an i/o operation. Latencies are also improved thanks to the removal of lots of "busy wait" code. Waits should be optimal for everything except poll(), which shall be the last and final demon we slay in the win32 i/o horror show. - getrusage() on Windows is now able to report RUSAGE_CHILDREN as well as RUSAGE_SELF, thanks to aggregation in the process manager thread. |
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| .. | ||
| calls | ||
| consts | ||
| dos2errno | ||
| errfuns | ||
| consts.sh | ||
| describeos.greg.c | ||
| dos2errno.sh | ||
| errfun.S | ||
| errfun2.c | ||
| errfuns.h | ||
| errfuns.sh | ||
| errno.c | ||
| gen.sh | ||
| hostos.S | ||
| macros.internal.h | ||
| README.md | ||
| restorert.S | ||
| strace.greg.c | ||
| syscall2.S | ||
| syscall3.S | ||
| syscall4.S | ||
| syscalls.sh | ||
| syscon.S | ||
| syscount.S | ||
| syslib.S | ||
| sysret.c | ||
| systemfive.S | ||
| sysv.c | ||
| sysv.mk | ||
SYNOPSIS
System Five Import Libraries
OVERVIEW
Bell System Five is the umbrella term we use to describe Linux, FreeBSD, OpenBSD, and Mac OS X which all have nearly-identical application binary interfaces that stood the test of time, having definitions nearly the same as those of AT&T back in the 1980's.
Cosmopolitan aims to help you build apps that can endure over the course of decades, just like these systems have: without needing to lift a finger for maintenance churn, broken builds, broken hearts.
The challenge to System V binary compatibility basically boils down to numbers. All these systems agree on what services are provided, but tend to grant them wildly different numbers.
We address this by putting all the numbers in a couple big shell scripts, ask the GNU Assembler to encode them into binaries using an efficient LEB128 encoding, unpacked by _init(), and ref'd via extern const. It gives us good debuggability, and any costs are gained back by fewer branches in wrapper functions.z