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- Use nullness checks when calling weakly linked functions. - Avoid typedef for reasons described in Linux Kernel style guide. - Avoid enum in in Windows headers. Earlier in Cosmo's history all one hundred files in libc/nt/enum/ used to be enums and it resulted in gigabytes of DWARF data almost as large as everything else in the codebase combined. - Bitfields aren't our friends. They have frequent ABI breakages, inconsistent arithmetic across compilers, and different endianness between cpus. Compiler authors also haven't invested much roi into making bit fields go fast so they produce poor assembly. - Use memccpy() instead of strncpy() or snprintf() for length-bounded copying of C strings. strncpy() is a misunderstood function and snprintf() is awesome but memccpy() deserves more love. |
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| .. | ||
| calls | ||
| consts | ||
| errfuns | ||
| machcalls | ||
| consts.sh | ||
| errfuns.h | ||
| errfuns.sh | ||
| g_syscount.S | ||
| gen.sh | ||
| machcalls.sh | ||
| macros.internal.h | ||
| README.md | ||
| restorert.S | ||
| syscall.S | ||
| syscalls.sh | ||
| systemfive.S | ||
| 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