字符串处理

#include <stdio.h>
#include <string.h>

#define KEYWORD "filter"
#define FILTER_FILE "/etc/key_rules.conf"

char *clearup_string1(char *buf)
{
    int len;
    char ch;
    char *ptr;

    if (NULL == buf)
        return NULL;

    /* skip space and tab */
    while(*buf)
    {
        if (*buf == ' ' || *buf == '\t')
            buf++;
        else
            break;
    }

    if (buf)
        ptr = buf;
    else
        return NULL;

    /* skip space and tab, return and new line character  */
    len = strlen(buf);
    while(len){
        ch = buf[len-1];
        if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n'){
            buf[len-1] = '\0';
            len--;
        }
        else{
            break;
        }
    }

    return ptr;
}


char *clearup_string2(char *buf)
{
    int len;
    char ch;
    char *ptr;

    if (NULL == buf)
        return NULL;

    /* skip space and tab */
    while(*buf)
    {
        if (*buf == ' ' || *buf == '\t' || *buf == '=' || *buf == '\"')
            buf++;
        else
            break;
    }

    if (buf)
        ptr = buf;
    else
        return NULL;

    /* skip space and tab, return and new line character  */
    len = strlen(buf);
    while(len){
        ch = buf[len-1];
        if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n' || ch == '=' || ch == '\"'){
            buf[len-1] = '\0';
            len--;
        }
        else{
            break;
        }
    }

    return ptr;
}

int main()
{
    FILE *fp;
    char *ptr;
    char buf[1024];

    fp = fopen(FILTER_FILE, "r");
    if (NULL == fp)
    {
        fprintf(stderr, "fopen fail.\n");
        return -1;
    }

    /* reverse file line by line */
    while(fgets(buf, sizeof(buf), fp))
    {
        if ( NULL != (ptr = clearup_string1(buf)))
        {
              if (*ptr == '#')   /* skip comment line */
                    continue;
              else if (0 == strncmp(ptr, KEYWORD, strlen(KEYWORD)) )    /* match KEYWORD */
              {
                    ptr = clearup_string2(ptr+strlen(KEYWORD));
                    if (ptr){
                    /* hanle the key */
                    }
                    else{
                        fprintf(stderr, "%s\n", ptr);
                    }
              }
              else{
                    fprintf(stderr, "%s\n", ptr);
              }
          }

    }
}