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FishMarket 1.0
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cnewssrc
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cnews.src.lzh
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putenv.c
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C/C++ Source or Header
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1980-01-01
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1KB
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54 lines
/*
* putenv - add a variable to the environment, as in SysV
*/
#include <stdio.h>
#include <sys/types.h>
#include "libc.h"
#define YES 1
#define NO 0
/* peculiar return values */
#define WORKED 0
#define FAILED 1
int
putenv(var) /* put var in the environment */
char *var;
{
register char **envp, **newenv;
register int oldenvcnt;
extern char **environ;
/* count variables, look for var */
for (envp = environ; *envp != 0; envp++) {
register char *varp = var, *ep = *envp;
register int namesame;
namesame = NO;
for (; *varp == *ep && *varp != '\0'; ++ep, ++varp)
if (*varp == '=')
namesame = YES;
if (*varp == *ep && *ep == '\0')
return WORKED; /* old & new var's are the same */
if (namesame) {
*envp = var; /* replace var with new value */
return WORKED;
}
}
oldenvcnt = envp - environ;
/* allocate new environment with room for one more variable */
newenv = (char **)malloc((unsigned)((oldenvcnt+1+1)*sizeof(*envp)));
if (newenv == NULL)
return FAILED;
/* copy old environment pointers, add var, switch environments */
(void) memcpy((char *)newenv, (char *)environ, oldenvcnt*sizeof(*envp));
newenv[oldenvcnt] = var;
newenv[oldenvcnt+1] = NULL;
environ = newenv;
return WORKED;
}