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Doubled the performance of getenv()/__findenv() by rewriting it to not

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use strncmp()..
This commit is contained in:
David Greenman 1995-10-17 21:37:41 +00:00
parent 030fc19811
commit 283e0c0eb7
1 changed files with 37 additions and 33 deletions
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70
lib/libc/stdlib/getenv.c
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@ -39,7 +39,43 @@ static char sccsid[] = "@(#)getenv.c 8.1 (Berkeley) 6/4/93";
#include <stddef.h>
#include <string.h>
char *__findenv __P((const char *, int *));
inline char *__findenv __P((const char *, int *));
/*
* __findenv --
* Returns pointer to value associated with name, if any, else NULL.
* Sets offset to be the offset of the name/value combination in the
* environmental array, for use by setenv(3) and unsetenv(3).
* Explicitly removes '=' in argument name.
*
* This routine *should* be a static; don't use it.
*/
inline char *
__findenv(name, offset)
register const char *name;
int *offset;
{
extern char **environ;
register int len, i;
register const char *np;
register char **p, *cp;
if (name == NULL || environ == NULL)
return (NULL);
for (np = name; *np && *np != '='; ++np)
continue;
len = np - name;
for (p = environ; (cp = *p) != NULL; ++p) {
for (np = name, i = len; i && *cp; i--)
if (*cp++ != *np++)
break;
if (i == 0 && *cp++ == '=') {
*offset = p - environ;
return (cp);
}
}
return (NULL);
}
/*
* getenv --
@ -53,35 +89,3 @@ getenv(name)
return (__findenv(name, &offset));
}
/*
* __findenv --
* Returns pointer to value associated with name, if any, else NULL.
* Sets offset to be the offset of the name/value combination in the
* environmental array, for use by setenv(3) and unsetenv(3).
* Explicitly removes '=' in argument name.
*
* This routine *should* be a static; don't use it.
*/
char *
__findenv(name, offset)
register const char *name;
int *offset;
{
extern char **environ;
register int len;
register const char *np;
register char **p, *c;
if (name == NULL || environ == NULL)
return (NULL);
for (np = name; *np && *np != '='; ++np)
continue;
len = np - name;
for (p = environ; (c = *p) != NULL; ++p)
if (strncmp(c, name, len) == 0 && c[len] == '=') {
*offset = p - environ;
return (c + len + 1);
}
return (NULL);
}