I have a simple code which does some computation by matching string patterns.
In brief:
1. The code reads .dat and .txt files.
2. .dat files are huge text files and .txt files contain some important words.
3. I am just doing strstr to find the patterns.
4. The function returns the address of number_of_words
5. The problem is after executing the code, I am getting this error which I am finding it hard to decipher. I reckon its the problem with malloc(), free() pair.
I reckon its the problem with malloc(), free() pair.
Memory corruption is normally due to you straying outside the bounds of an array - not with malloc()/free() statements matching up. You've probably overwritten some of the space next to a malloc()'d portion of memory that glibc expects to be able to use for keeping track of the memory region - go through with a debugger and have a look for bounds errors.
As an aside, here's the sort of thing you can expect if you did have a problem with malloc()/free() pairs:
Thanks a lot. I spent hours debugging my code and found that the problem was with the chomp() function. SO, I changed the chomp() function and it worked. Here's my code. And yes, I was wrong about memory corruption.
Code:
//Match patterns from several files.
#define _GNU_SOURCE
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<inttypes.h>
char *chomp ( char * );
void read_file ( char * , int32_t * );
int32_t main ( int32_t argc , char ** argv )
{
char *dat_line = NULL;
char *txt_line = NULL;
char *file_name_txt = NULL;
char *file_name_dat = NULL;
char *entire_dat_file = NULL;
char *line_from_txt_file = NULL;
char *chomped_line = NULL;
unsigned long int summation = 0;
unsigned long int value = 1;
float average = 0.0;
float scope = 0;
unsigned long int dat_len = 0;
unsigned long int read;
unsigned long int txt_len = 0;
unsigned long int number_of_characters = 0;
unsigned long int number_of_words = 0;
unsigned long int i = 0;
FILE *open_dat_file = NULL;
FILE *open_txt_file = NULL;
FILE *output = NULL;
//let get the TXT files...
system ("ls -1 *.txt > text_files.tmp" );
//lets get the DAT files...
system ( "ls -1 *.dat > dat_files.tmp" );
//Outer look is for the DAT files and inner loop is for the TXT
//files...
FILE *txt_pointer = NULL;
txt_pointer = fopen ( "text_files.tmp" , "r" );
if ( txt_pointer == NULL )
{
fprintf ( stderr , "The file list for text files does not exist\n" );
}
FILE *dat_pointer = NULL;
dat_pointer = fopen ( "dat_files.tmp" , "r" );
if ( dat_pointer == NULL )
{
fprintf ( stderr , "The file list for the dat files does not exist\n" );
}
output = fopen ( "average_values.res" , "a" );
if ( output == NULL )
{
fprintf ( stderr , "File append error\n" );
}
while ( ( read = getline ( &dat_line , &dat_len , dat_pointer ) ) != -1 )
{
file_name_dat = chomp ( dat_line );
open_dat_file = fopen ( file_name_dat , "r" );
( void ) fseek ( open_dat_file , 0L , SEEK_END );
number_of_characters = ftell ( open_dat_file );
entire_dat_file = ( char * ) malloc ( ( number_of_characters + 1 ) * sizeof ( char ) );
if ( entire_dat_file == NULL )
{
fprintf ( stderr , "malloc() memory allocation failure in entire_dat_file\n" );
}
rewind ( open_dat_file );
read_file ( file_name_dat , &number_of_words );
fgets ( entire_dat_file , number_of_characters , open_dat_file );
while ( ( read = getline ( &txt_line , &txt_len , txt_pointer ) ) != -1 )
{
file_name_txt = chomp ( txt_line );
open_txt_file = fopen ( file_name_txt , "r" );
//Now read to read the txt files one by one and search for the pattern...
while ( ( read = getline ( &line_from_txt_file , &txt_len , open_txt_file ) ) != 1 && !feof ( open_txt_file ) )
{
chomped_line = chomp ( line_from_txt_file );
if ( strstr ( entire_dat_file , chomped_line ) != NULL )
{
summation = summation + value;
}
value ++;
}
value = 1;
fclose ( open_txt_file );
memset ( file_name_txt , 0 , strlen ( file_name_txt ) );
}
average = ( float ) summation / ( number_of_words + 1 );
average = - average;
scope = powf ( 2.71828183 , average );
fprintf ( output , "%f\n" , scope );
number_of_words = 0;
summation = 0;
value = 0;
average = 0;
scope = 0;
number_of_characters = 0;
rewind ( txt_pointer );
free ( entire_dat_file );
fclose ( open_dat_file );
memset ( file_name_dat , 0 , strlen ( file_name_dat ) );
}
fclose ( output );
if ( txt_line )
{
free ( txt_line );
}
if ( dat_line )
{
free ( dat_line );
}
fclose ( dat_pointer );
fclose (txt_pointer );
return ( EXIT_SUCCESS );
}
char *chomp ( char *s )
{
unsigned long int len = 0;
len = strlen ( s );
if ( s [ len - 1 ] == '\n' )
{
s [ len - 1 ] = 0;
}
return ( s );
}
void read_file ( char *path , int32_t *number_of_words )
{
FILE *pointer = NULL;
char ch;
pointer = fopen ( path , "r" );
if ( pointer == NULL)
{
perror ( "File read error " );
}
(*number_of_words) = 0;
while ( !feof ( pointer ) )
{
ch = fgetc ( pointer );
if ( ch == ' ' && ch != EOF )
{
(*number_of_words) ++;
}
}
fclose ( pointer );
}
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09-11-2011
