Question

Im making an application that uses of API-threads in C, The program takes N-files (N>2) with names disordered,per each file is generated a thread of execution which sort the files using the function qsort, after being ordered files, each thread should create a file keeping the original file intact and displaying the sorted file to another file with the extension <.sorted>. The program sorts the numbers without problems, even if I put standard output displays the result on screen, but when I try to create the output file with extension .sorted the program breaks out.

this is my code file.c

#include <stdio.h>              /* Standard buffered input/output        */
#include <stdlib.h>             /* Standard library functions            */
#include <string.h>             /* String operations                     */
#include <pthread.h>        /* Thread related functions              */
#include "pf1.h"        /* Header specific to this app           */



pthread_attr_t attr;

void *thread_worker(void *name_file)
{

FILE *entrada, *salida;
char* nombres = (char*)name_file; 
int numero;
char temp [10000];

int i;
stats_t estadisticas;

printf ("File_name:%s\n", nombres);
entrada = fopen(nombres, "r");
salida =  fopen (strcat(nombres, ".sorted"), "w");

while (!feof(entrada)){
fscanf (entrada, "%s\n",temp);
numero++;
}

char* lista[numero]; //array to sort the file
rewind (entrada);

    for (i=0;i<numero;i++) 
    {

        fscanf(entrada," %[^\n]", temp);


        lista[i] = (char*)malloc((strlen(temp)+1)*sizeof(char));

        strcpy(lista[i], temp);

    }


size_t large = sizeof(lista) / sizeof(char *);



qsort(lista,large ,sizeof(char *) ,cstring_cmp );

printf ("Archivo Ordenado\n", i+1);

for (i=0;i<large;i++)


printf("%s\n",lista[i]);


 pthread_exit(NULL);
}


int main(int argc, char *argv [])
{

stats_t **stats;
int i, rc;
 pthread_t my_threads[argc-1]; 
 pthread_attr_init(&attr);

if (argc <3) {
printf ("|files| > 2\n");
}else{
printf("files to sorted: %d\n", argc - 1);

for (i = 1; i < argc; i++){ 

    //printf("%s%s\n", argv[i], (i < argc-1) ? " " : "");

rc = pthread_create(&my_threads[i], &attr, thread_worker, (void *)argv[i]);
      if (rc){
         printf("ERROR; return code from pthread_create() is %d\n",rc);
         return -1;
      }
}

}
  return 0;

} /*end main */

this is mi file.h

#ifndef PF1_H_

#define PF1_H_





typedef struct _stats_t

{

    char *longest, *shortest;

    unsigned int numlines;

} stats_t;

int cstring_cmp(const void *a, const void *b)

{

    const char **ia = (const char **)a;

    const char **ib = (const char **)b;

    return -strcasecmp(*ia, *ib);

    /* strcmp functions works exactly as expected from

    comparison function */

}


void print_cstring_array(char **array, size_t len)

{

    size_t i;



    for(i=0; i<len; i++)

        printf("%s | ", array[i]);



    putchar('\n');

}




#endif /* PF1_1_H_ */

I would like some help with this problem because I can not see which is the fault … thanks to all in advance and excuse my English

Answer 1

This line here may be your problem:

salida =  fopen (strcat(nombres, ".sorted"), "w");

From what I can tell, that nombres variable is coming from argv. Since you’re not the one allocating memory for argv, you don’t know that there will be extra space for the “.sorted” (and there probably won’t be). If you strcpy it to your own buffer with space for the “.sorted”, you should be fine.

#define EXT_LEN 7
#define MAX_TOTAL_LEN 250
#define MAX_FILE_LEN 242 //MAX_TOTAL_LEN - EXT_LEN - 1

char *name_ptr;
char nombres[MAX_TOTAL_LEN];
int len;

name_ptr = (char*)name_file;
len = strlen(name_ptr);
if (len > MAX_FILE_LEN) {
    len = MAX_FILE_LEN;
}
strncpy(nombres, name_ptr, len);
strcpy(nombres+len, ".sorted");
salida =  fopen (nombres, "w");