source: trunk/libs/newlib/src/newlib/libc/sys/sysvi386/exec.c

#include <sys/unistd.h>
#include <errno.h>

extern char **environ;

int
execv (const char *path, char * const *args) {
        extern int execve (const char *, char * const *, char * const*);
        return execve (path, args, environ);
}

int
execl(const char *path, const char *arg1, ...) {
        return execv (path, &arg1);
}

/*
 * Copy string, until c or <nul> is encountered.
 * NUL-terminate the destination string (s1).
 */

static char *
strccpy (char *s1, char *s2, char c) {
        char *dest = s1;
        while (*s2 && *s2 != c) {
                *s1++ = *s2++;
        }
        *s1 = 0;
        return dest;
}

int
execvp(const char *file, char * const *args) {
        extern char *getenv (const char *);  
        char *path = getenv ("PATH");
        char buf[MAXNAMLEN];

        if (file[0] == '/') {   /* absolute pathname -- easy out */
                return execv (file, args);
        }

        buf[0] = 0;     /* lots of initialization here 8-) */
        while (*path) {
                strccpy (buf, path, ':');
                strcat (buf, "/");
                strcat (buf, file);
                execv (buf, args);
                if (errno != ENOENT)
                        return -1;
                while (*path && *path != ':')
                        path++;
        }
        return -1;
}