root/src/pkg/runtime/env_posix.c

DEFINITIONS

1. runtime·getenv
2. syscall·setenv_c

// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows

#include "runtime.h"
#include "arch_GOARCH.h"
#include "malloc.h"

Slice syscall·envs;

byte*
runtime·getenv(int8 *s)
{
        int32 i, j;
        intgo len;
        byte *v, *bs;
        String* envv;
        int32 envc;

        bs = (byte*)s;
        len = runtime·findnull(bs);
        envv = (String*)syscall·envs.array;
        envc = syscall·envs.len;
        for(i=0; i<envc; i++){
                if(envv[i].len <= len)
                        continue;
                v = envv[i].str;
                for(j=0; j<len; j++)
                        if(bs[j] != v[j])
                                goto nomatch;
                if(v[len] != '=')
                        goto nomatch;
                return v+len+1;
        nomatch:;
        }
        return nil;
}

void (*_cgo_setenv)(byte**);

// Update the C environment if cgo is loaded.
// Called from syscall.Setenv.
void
syscall·setenv_c(String k, String v)
{
        byte *arg[2];
        uintptr len;

        if(_cgo_setenv == nil)
                return;

        // Objects that are explicitly freed must be at least 16 bytes in size,
        // so that they are not allocated using tiny alloc.
        len = k.len + 1;
        if(len < TinySize)
                len = TinySize;
        arg[0] = runtime·malloc(len);
        runtime·memmove(arg[0], k.str, k.len);
        arg[0][k.len] = 0;

        len = v.len + 1;
        if(len < TinySize)
                len = TinySize;
        arg[1] = runtime·malloc(len);
        runtime·memmove(arg[1], v.str, v.len);
        arg[1][v.len] = 0;

        runtime·asmcgocall((void*)_cgo_setenv, arg);
        runtime·free(arg[0]);
        runtime·free(arg[1]);
}