github.com/xushiwei/go@v0.0.0-20130601165731-2b9d83f45bc9/src/pkg/runtime/env_posix.c (about)

     1  // Copyright 2012 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build darwin freebsd linux netbsd openbsd windows
     6  
     7  #include "runtime.h"
     8  
     9  Slice syscall·envs;
    10  
    11  byte*
    12  runtime·getenv(int8 *s)
    13  {
    14  	int32 i, j, len;
    15  	byte *v, *bs;
    16  	String* envv;
    17  	int32 envc;
    18  
    19  	bs = (byte*)s;
    20  	len = runtime·findnull(bs);
    21  	envv = (String*)syscall·envs.array;
    22  	envc = syscall·envs.len;
    23  	for(i=0; i<envc; i++){
    24  		if(envv[i].len <= len)
    25  			continue;
    26  		v = envv[i].str;
    27  		for(j=0; j<len; j++)
    28  			if(bs[j] != v[j])
    29  				goto nomatch;
    30  		if(v[len] != '=')
    31  			goto nomatch;
    32  		return v+len+1;
    33  	nomatch:;
    34  	}
    35  	return nil;
    36  }
    37  
    38  void (*_cgo_setenv)(byte**);
    39  
    40  // Update the C environment if cgo is loaded.
    41  // Called from syscall.Setenv.
    42  void
    43  syscall·setenv_c(String k, String v)
    44  {
    45  	byte *arg[2];
    46  
    47  	if(_cgo_setenv == nil)
    48  		return;
    49  
    50  	arg[0] = runtime·malloc(k.len + 1);
    51  	runtime·memmove(arg[0], k.str, k.len);
    52  	arg[0][k.len] = 0;
    53  
    54  	arg[1] = runtime·malloc(v.len + 1);
    55  	runtime·memmove(arg[1], v.str, v.len);
    56  	arg[1][v.len] = 0;
    57  
    58  	runtime·asmcgocall((void*)_cgo_setenv, arg);
    59  	runtime·free(arg[0]);
    60  	runtime·free(arg[1]);
    61  }