为什么gdb显示/stdlib/strtol_l.c：没有这样的文件或目录？我是否缺少要安装的东西？

Question

我尝试使用 -g 进行编译，然后运行 ​​gdb 来查找导致分段错误的行，但错误消息让我感到困惑。

Program received signal SIGSEGV, Segmentation fault.
__GI_____strtol_l_internal (nptr=0x0, endptr=endptr@entry=0x0, base=base@entry=10, group=group@entry=0, loc=0x7ffff7fb04a0 <_nl_global_locale>)
    at ../stdlib/strtol_l.c:292
292     ../stdlib/strtol_l.c: No such file or directory.

我尝试重新安装 gdb 以使其再次工作，但失败了。它仍然显示相同的错误消息。后来我自己发现了这个问题，并在下面的代码中标记出来。我只是好奇为什么当我尝试调试某些字符串函数时有时会发生这样的事情？例如 strdup、strtok、strtol 等。我是否缺少要安装的东西？我希望我能彻底解决这个问题。

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

char buff[255];
#define NUM_BUCKETS 32

typedef struct Customer {
    char* email;
    char* name;
    int shoesize;
    char* food;
    struct Customer* next;
} Customer ;

unsigned long hash(char *str) {
    unsigned long hash = 0;
    int c;

    while (*str != '\0') {
        c = *str;
        hash = ((hash << 5) + hash) + (unsigned char)c;
        str++;
    }
    return hash;
}

Customer *add_friend_to_list(char *email, char *name, int shoesize, char *food, Customer *bucket) {
    Customer* customer;

    customer = malloc(sizeof(Customer));
    customer->name = strdup(name);
    customer->food = strdup(food);
    customer->shoesize = shoesize;
    customer->email = strdup(email);
    customer->next = bucket;

    return customer;
}

void add_consumer_to_hashtable(char *name, char *food, char *email, int shoesize, Customer **buckets, size_t num_buckets) {
    size_t which_bucket = hash(name) % num_buckets;
    buckets[which_bucket] = add_friend_to_list(email, name, shoesize, food, buckets[which_bucket]);
}

int main() {
    Customer* buckets[NUM_BUCKETS] = {NULL};
    int ittime = 0;
    FILE *fp = NULL;
    fp = fopen("customers.tsv", "r");
    while (true) {
        fgets(buff, 255, fp);
        if (feof(fp)) {
            break;
        }
        ittime++;
    }
    
    fclose(fp);

    fp = NULL;
    char *email = (char *)malloc(5 * sizeof(char));
    char *name = (char *)malloc(5 * sizeof(char));
    int shoesize;
    char *food = (char *)malloc(5 * sizeof(char));
    const char s[2] = "\t";
 
    fp = fopen("customers.tsv", "r");
    for (int i = 0; i < ittime + 1; i++) {        //This line cause the Segmentation Fault
        fgets(buff, 255, fp);
        char *token;

        token = strtok(buff, s);
        email = token;
        token = strtok(NULL, s);
        name = token;
        token = strtok(NULL, s);
        shoesize = atoi(token);
        token = strtok(NULL, s);
        food = token;
        add_consumer_to_hashtable(name, food, email, shoesize, buckets, NUM_BUCKETS);
    }

    fclose(fp);

    while (true) {
        char *cmd = (char *)malloc(5 * sizeof(char));

        printf("command: ");
        scanf("%s", cmd);
        if (strcmp(cmd, "add") == 0) {
            char *email1 = (char *)malloc(5 * sizeof(char));
            char *name1 = (char *)malloc(5 * sizeof(char));
            int shoesize1;
            char *food1 = (char *)malloc(5 * sizeof(char));

            printf("email address? ");
            scanf("%s", email1);
            printf("name? ");
            scanf(" %[^\n]", name1);
            printf("shoe size? ");
            scanf("%d", &shoesize1);
            printf("favorite food? ");
            scanf("%s", food1);
            add_consumer_to_hashtable(name1, food1, email1, shoesize1, buckets, NUM_BUCKETS);
            free(name1);
            free(food1);
            free(email1);
        } else if (strcmp(cmd, "lookup") == 0) {
            char *Email = (char *)malloc(5 * sizeof(char));
            printf("email address? ");
            scanf("%s", Email);
            bool exist = false;
            for (int i = 0; i < 32; i++) {
                Customer *cus = buckets[i];
                if (buckets[i] == NULL) {
                    continue;
                }
                while ((cus != NULL)) {
                    if (cus->shoesize == EOF) {
                        break;
                    }
                    if (strcmp(cus->email, Email) == 0) {
                        printf("email: %s\n", cus->email);
                        printf("name: %s\n", cus->name);
                        printf("shoesize: %d\n", cus->shoesize);
                        printf("food: %s\n", cus->food);
                        exist = true;
                        break;
                    }
                    if (cus->next != NULL) {
                        cus = cus->next;
                    } else {
                        break;
                    }
                }
            }
            if (exist == false) {
                printf("user not found!\n");
            }
        } else if (strcmp(cmd, "delete") == 0) {
            char *Email = (char *)malloc(5 * sizeof(char));
            printf("email address? ");
            scanf("%s", Email);
            bool exist = false;
            for (int i = 0; i < 32; i++) {
                Customer *cus = buckets[i];
                if (buckets[i] == NULL) {
                    continue;
                }
                while ((cus != NULL)) {
                    if (cus->shoesize == EOF) {
                        break;
                    }
                    if (strcmp(cus->email, Email) == 0) {
                        free(cus->email);
                        free(cus->food);
                        free(cus->name);
                        free(cus);
                        cus->shoesize = EOF;
                        cus = NULL;
                        exist = true;
                        break;
                    }
                    if (cus->next != NULL) {
                        cus = cus->next;
                    } else {
                        break;
                    }
                }
            }
            if (exist == false) {
                printf("user not found!\n");
            }
        } else if (strcmp(cmd, "list") == 0) {
            for (int i = 0; i < 32; i++) {
                Customer *cus = buckets[i];
                if (buckets[i] == NULL) {
                    continue;
                }
                while ((cus != NULL) && ((cus->shoesize) != EOF)) {
                    printf("email: %s\n", cus->email);
                    printf("name: %s\n", cus->name);
                    printf("shoesize: %d\n", cus->shoesize);
                    printf("food: %s\n", cus->food);
                    if (cus->next != NULL) {
                        cus = cus->next;
                        printf("\n");
                    } else {
                        break;
                    }
                }
            }
        } else if (strcmp(cmd, "quit") == 0) {
            break;
        } else if (strcmp(cmd, "save") == 0) {
            fp = fopen("customers.tsv", "w");
            for (int i = 0; i < 32; i++) {
                Customer *cus = buckets[i];
                if (buckets[i] == NULL) {
                    continue;
                }
                while ((cus != NULL) && ((cus->shoesize) != EOF)) {
                    fprintf(fp, "%s\t%s\t%d\t%s", cus->email, cus->name, cus->shoesize, cus->food);
                    if (cus->next != NULL) {
                        cus = cus->next;
                        fprintf(fp, "\n");
                    } else {
                        break;
                    }
                }
            }
            fclose(fp);
        } else {
            printf("unknown command\n");
        }
    }
    for (int i = 0; i < 32; i++) {
        Customer *tmp;
        Customer *cus = buckets[i];
        if (cus == NULL) {
            continue;
        }
        if (cus->next != NULL) {
            tmp = cus;
            cus = cus->next;
        } else {
            break;
        }
        while ((tmp != NULL)) {
            if (tmp->shoesize != EOF) {
                free(tmp->email);
                free(tmp->food);
                free(tmp->name);
                free(tmp);
            }
            cus->shoesize = EOF;
            cus = NULL;
        }
        if (tmp != NULL) {
            free(tmp);
        }
        if (cus != NULL) {
            free(cus);
        }
    }

    return 0;
}

Answer 1

我尝试使用 -g 进行编译，然后运行 ​​gdb 来查找导致分段错误的行，但错误消息让我感到困惑。

错误消息的意思是：

• 崩溃发生在 GLIBC strtol_l_internal() 函数内部
• GDB 无法显示该函数的源代码，因为未安装 libc6-src （或类似）包。

现在，查看 strtol_l_internal() 的源代码不会有任何帮助 - 问题的根本原因是您使用不正确的参数调用它。

您应该阅读 man strtol 并验证您是否满足其先决条件。

看起来您调用了 strtol(NULL, NULL, ...)，这不是有效的操作。您可以使用(gdb) up命令来找出错误调用的来源，并修复调用者。

Answer 2

我遇到了这个错误，结果是命令行参数没有被 gdb 传入。查看使用 gdb 调用程序时从命令行传入参数的规则。