kdb_set

/*
 * kdb_set - This function implements the 'set' command.  Alter an
 *  existing environment variable or create a new one.
 */
int kdb_set(int argc, const char **argv)
{
    int i;
    char *ep;
    size_t varlen, vallen;
 
    /*
     * we can be invoked two ways:
     *   set var=value    argv[1]="var", argv[2]="value"
     *   set var = value  argv[1]="var", argv[2]="=", argv[3]="value"
     * - if the latter, shift 'em down.
     */
    if (argc == 3) {
        argv[2] = argv[3];
        argc--;
    }
 
    if (argc != 2)
        return KDB_ARGCOUNT;
 
    /*
     * Check for internal variables
     */
    if (strcmp(argv[1], "KDBDEBUG") == 0) {
        unsigned int debugflags;
        char *cp;
 
        debugflags = simple_strtoul(argv[2], &cp, 0);
        if (cp == argv[2] || debugflags & ~KDB_DEBUG_FLAG_MASK) {
            kdb_printf("kdb: illegal debug flags '%s'\n",
                    argv[2]);
            return 0;
        }
        kdb_flags = (kdb_flags &
                 ~(KDB_DEBUG_FLAG_MASK << KDB_DEBUG_FLAG_SHIFT))
            | (debugflags << KDB_DEBUG_FLAG_SHIFT);
 
        return 0;
    }
 
    /*
     * Tokenizer squashed the '=' sign.  argv[1] is variable
     * name, argv[2] = value.
     */
    varlen = strlen(argv[1]);
    vallen = strlen(argv[2]);
    ep = kdballocenv(varlen + vallen + 2);
    if (ep == (char *)0)
        return KDB_ENVBUFFULL;
 
    sprintf(ep, "%s=%s", argv[1], argv[2]);
 
    ep[varlen+vallen+1] = '\0';
 
    for (i = 0; i < __nenv; i++) {
        if (__env[i]
         && ((strncmp(__env[i], argv[1], varlen) == 0)
           && ((__env[i][varlen] == '\0')
            || (__env[i][varlen] == '=')))) {
            __env[i] = ep;
            return 0;
        }
    }
 
    /*
     * Wasn't existing variable.  Fit into slot.
     */
    for (i = 0; i < __nenv-1; i++) {
        if (__env[i] == (char *)0) {
            __env[i] = ep;
            return 0;
        }
    }
 
    return KDB_ENVFULL;
}
函数源码
