【发布时间】：2012-04-26 04:03:46
【问题描述】：
我想不通。当我在我的 Windows 机器上使用 Code::Blocks 编译这段代码时，它工作得很好，但是当我尝试在 Cygwin 或学校的实际 Unix 机器下使用 Make 编译它时，我得到了下面的奇怪行为。我将“client1.txt”传递给 translate()。
void translate(char* filepath){
char output_filepath[181];
strcpy(output_filepath, filepath);
printf("%s\n", output_filepath); //this prints out "client1.txt" which is correct
char* ptr = strcat(output_filepath, ".translated");
printf("%s\n", output_filepath); //this prints out ".translated" which is wrong
printf("%s\n", ptr); //also prints out ".translated" wrong again
...more stuff...
}
当尝试在 output_filepath 上使用 fgets 时，这会导致分段错误。有谁知道发生了什么？我需要解释更多吗？它必须能够在 Unix 下编译。
这是整个程序，我希望它不会太长。这是我的老师给我们的一个程序，但我什至无法运行它。它只是给了我一个分段错误，我已经在上面的部分中找到了它。
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
struct tparam{
int tid;
};
int NTHREADS = 5;
#define LOOPS 10000
int qfilled = 0;
int qin = 0;
int qout = 0;
char queue[3000][2][161];
char dic[7000][2][161];
int dic_size = 0;
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t flag_mutex = PTHREAD_MUTEX_INITIALIZER;
char * dummystatus[10];
char * lookup(char * word)
{
int i;
for(i = 0; i < dic_size; ++i)
{
if(strcmp(word, dic[i][0])==0)
return dic[i][1];
}
return word;
}
void translate(char filepath[])
{
char output_filepath[181];
strcpy(output_filepath, filepath);
strcat(output_filepath, ".translated");
FILE * client_file = fopen(filepath,"r");
FILE * translated_client_file = fopen(output_filepath,"w");
char line [161];
char * tmpPtr;
char * token;
while((tmpPtr=fgets(line, 160, client_file))!= NULL) {
if(strcmp(line,"\n") == 0 || line == NULL)
continue;
token = strtok_r(line, " \t\n", dummystatus);
while(token != NULL && strcmp(token,"\n") != 0){
fputs(lookup(token), translated_client_file);
fputs(" ", translated_client_file);
token = strtok_r(NULL, " \t\n", dummystatus);
}
fputs("\n", translated_client_file);
}
fclose(client_file);
}
void *do_work(void * p) {
struct tparam * param = (struct tparam *)p;
while(qfilled != 1);//wait for queue to be filled
int cindex;
while(1){
//check for more clients
pthread_mutex_lock(&mutex);
if(qout >= qin){
pthread_mutex_unlock(&mutex);
break;
}
//process client
cindex = qout;
printf("Thread %d is handling client %s\n",param->tid, queue[cindex][1]);
qout++;
pthread_mutex_unlock(&mutex);
char filepath[161];
if(queue[cindex][0][strlen(queue[cindex][0])-1] == '\n')
strncpy(filepath,queue[cindex][0],strlen(queue[cindex][0])-1);
else
strcpy(filepath,queue[cindex][0]);
translate(filepath);
printf("Thread %d finished handling client %s\n",param->tid, queue[cindex][1]);
//usleep(rand()%100000+10000);
}
pthread_exit(NULL);
}
void addDicEntry(char line[]){
char * first = strtok_r(line, " \t", dummystatus);
char * second = strtok_r(NULL, " \t", dummystatus);
char englishWord[161];
if(1==1 || second != NULL)
{
strcpy(dic[dic_size][0], first);
strncpy(englishWord, second, strlen(second)-1);
englishWord[strlen(second)-1] = '\0';
strcpy(dic[dic_size][1], englishWord);
dic_size++;
}
}
int main(int argc, char *argv[]) {
srand(time(NULL));
if(argc < 2){
printf("No dictionary file provided\n");
exit(1);
}
//read dictionary
int i;
for(i = 0; i < 10; ++i)
dummystatus[i] = (char*)malloc(10);
FILE * dic_file = fopen(argv[1],"r");
if(dic_file == NULL)
{
printf("Dictionary file does not exist\n");
exit(1);
}
char line [161];
char * tmpPtr;
while((tmpPtr=fgets(line, 160, dic_file))!= NULL) {
if(strcmp(line,"\n") == 0 || strcmp(line,"") == 0 || line == NULL)
break;
addDicEntry(line);
}
fclose(dic_file);
//End read dictionary
//Creating threads
if(argc >= 3)
NTHREADS = atoi(argv[2]);
pthread_t * threads = (pthread_t *)malloc(NTHREADS*sizeof(pthread_t));
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
for (i=0; i<NTHREADS; i++) {
struct tparam * param = (struct tparam *)malloc(sizeof(struct tparam *)*1);
param->tid = i+1;
//printf("Thread %d is being created\n",param->tid);
pthread_create(&threads[i], &attr, &do_work, param);
}
//End creating threads
//insert clients in Q
FILE * clients_file = fopen("clients.in","r");
char cid_str[10];
while((tmpPtr=fgets(line, 160, clients_file))!= NULL) {
if(strcmp(line,"\n") == 0 || strcmp(line,"") == 0 || line == NULL)
break;
pthread_mutex_lock(&mutex);
strcpy(queue[qin][0],line);
sprintf(cid_str, "%d", qin+1);
strcpy(queue[qin][1],cid_str);
qin++;
pthread_mutex_unlock(&mutex);
}
fclose(clients_file);
//for (i=0; i<qin; i++)
//printf("%s\n", queue[i][0]);
qfilled = 1;
printf("Q Filled\n");
//End insert clients in Q
//printf("Waiting for Threads\n");
for (i=0; i<NTHREADS; i++)
pthread_join(threads[i], NULL);
//printf("Threads Finished\n");
pthread_attr_destroy(&attr);
pthread_exit(NULL);
}
【问题讨论】：
-
我们刚刚在 Unix 下使用 gcc 测试了这个，它工作正常。也许您可以提供更多上下文/信息？
-
所以让我直截了当，输出是：“client1.txt\n.translated\n.translated”，但应该是“client1.txt\nclient1.txt.translated\nclient1.txt” .翻译”？后者是我得到的。就你而言，这听起来像是在调用
strcpy而不是strcat。 -
我想指出，在您的
do_work函数中（我现在将忽略那个极具描述性的名称...）您使用strncpy作为有界 @987654327 @，它实际上不是，因为它不能保证终止字符串。这可能会产生一些麻烦的极端情况，这可能不是这里的错误，但您仍然应该考虑不要使用它。 -
"希望不会太长";我会说是的。
-
尝试使用类似 valgrind 的工具来检查内存错误。