#ifndef lint
static char *rcs = "$Header: string.c,v 1.1 88/01/15 13:05:31 simpson Rel $";
#endif
/*
$Log:	string.c,v $
 * Revision 1.1  88/01/15  13:05:31  simpson
 * initial release
 * 
 * Revision 0.2  87/12/18  11:35:41  simpson
 * added extractinteger function
 * 
 * Revision 0.1  87/12/11  18:31:21  simpson
 * beta test
 * 
*/

/* String related routines */

#include <stdio.h>
#include <pwd.h>
#include <local/standard.h>

/* Return tail of a pathname (Ex: /usr/shar.c => shar.c) */
char *tail(s)
char	*s;
{
    char 	*t;
    char	*rindex();

    return((t = rindex(s, '/')) ? ++t : s);
}

/* Set a certain environment variable.  If the variable is already set,
 * it is reset.
 */
void setenv(variable, value)
char	*variable;
char	*value;
{
    extern char	    **environ;
    int		    i;
    char	    **p, **head, **hptr;
    char	    *malloc(), *strcpy();
    char	    temp[81];
    
    if (!variable)
	return;
    for (i = 0, p = environ; *p; p++, i++)
	;
    hptr = head = (char **)malloc((unsigned)((i + 2) * sizeof(char *)));
    for (p = environ; *p; p++) {
	(void)sprintf(temp, "%s=", variable);
	if (EQN(temp, *p, strlen(temp)))
	    continue;
	*hptr++ = *p;
    }
    if (!value)
	(void)sprintf(temp, "%s=", variable);
    else
	(void)sprintf(temp, "%s=%s", variable, value);
    (void)strcpy(*hptr++ = malloc((unsigned)(strlen(temp)+1)), temp);
    *hptr = NULL;
    environ = head;
}

/* Returns next component from a list of ':' separated fields such as that
 * found in a $PATH variable.  The return value is static and overwritten
 * after each call.  The passed string value is incremented to point to the
 * next path.  NULL is returned if there is no next component.
 */
char *nextcomponent(s)
char	**s;
{
    static char	    comp[81];
    int		    i;

    if (!s || !*s)
	return NULL;
    while (**s == ':')
	++*s;
    if (**s == '\0')
	return NULL;
    for (i = 0; **s != ':' && **s != '\0'; ++*s, i++)
	comp[i] = **s;
    comp[i] = '\0';
    return comp;
}

/* Returns an expanded file name.  An expanded file name is a file name
 * with a preceding ~ expanded.  If a name is not given after the tilde,
 * the current effective user id is used to look up the name and expand the
 * file name.
 */
char *expandtilde(filename)
char *filename;
{
    char	    pathname[81];
    char	    name[81];
    char	    *endptr, *index(), *strcpy(), *strncpy(), *strcat();
    struct passwd   *p;

    if (!filename || strlen(filename) == 0 || filename[0] != '~')
	return filename;
    pathname[0] = '\0';
    if (filename[1] == '\0' || filename[1] == '/') {
	if (!(p = getpwuid(geteuid())))
	    return filename;
	if (p->pw_dir)
	    (void)strcpy(pathname, p->pw_dir);
	(void)strcat(pathname, &filename[1]);
    } else {
	if (!(endptr = index(&filename[1], '/')))
	    (void)strcpy(name, &filename[1]);
	else
	    (void)strncpy(name, &filename[1], endptr - &filename[1]);
	if (!(p = getpwnam(name)))
	    return filename;
	if (p->pw_dir)
	    (void)strcpy(pathname, p->pw_dir);
	(void)strcat(pathname, endptr);
    }
    (void)strcpy(filename, pathname);
    return filename;
}

/* Returns and expanded file name.  An expanded file name is a file name
 * with a preceding $HOME expanded.  For example, the file name
 * "$HOME/.login" would be expanded to "/staff1/simpson/.login" if the
 * current effective user id is that of simpson.
 */
char *expandhome(filename)
char *filename;
{
    char	    s[80], *strcpy(), *strcat();
    struct passwd   *p;

    if (!filename || strlen(filename) < 5 || !EQN(filename, "$HOME", 5))
	return filename;
    if (!(p = getpwuid(geteuid())))
	return filename;
    s[0] = '\0';
    if (p->pw_dir)
	(void)strcpy(s, p->pw_dir);
    (void)strcat(s, &filename[5]);
    (void)strcpy(filename, s);
    return filename;
}

/* Returns the next integer contained in the string or NULL if no integers
 * are left.  The updated string pointer is returned.
 */
char *extractinteger(s, i)
char	*s;
int	*i;
{
    Boolean	negative = FALSE;
    char	*p = s;

    while (p && *p && (*p < '0' || *p > '9') && *p != '-')
        p++;
    if (!p || !*p)
        return NULL;
    if (*p == '-') {
	negative = TRUE;
	p++;
    }
    *i = 0;
    if (*p < '0' || *p > '9')
        return p;
    do {
	*i = *i * 10 + (*p - '0');
	p++;
    } while ('0' <= *p && *p <= '9');
    if (negative)
    	*i = -*i;
    return p;
}