Problem while opening a file in C on linux - c

Question

I'm having problems with my C program which works perfectly on Windows but not on Linux. I use the following method for reading line by line a file:
char * getLineOfAnySize(FILE* fp, size_t typicalSize, int *endOfLineDetected,size_t *nrOfCharRead){
char *line; // buffer for our string
int ch; // we will read line character by character
size_t len = 0; // number of characters read (character counter)
size_t lineSize = typicalSize; // initial size of the buffer allocated for the line
*nrOfCharRead = 0;
if(!fp) return NULL; // protection
// allocating the buffer
line = realloc(NULL, sizeof(char)*lineSize); // expected size of the line is pathHead to typicalSize
if (!line) return line; // protection, if we fail to allocate the memory we will return NULL
while (1) { // loop forever
ch = fgetc(fp); // getting character by character from file
if (ch == '\n') break; // end of line detected - breaking the loop
if( ch == EOF) {
*endOfLineDetected = 1;
break; // end of file detected - breaking the loop
}
line[len++] = ch; // store the character in the line buffer, increase character counter
if (len == lineSize){ // we reached the end of line buffer (no more room)
lineSize = lineSize + 64; // we have to increase the line size
line = realloc(line, sizeof(char)*(lineSize)); // line buffer has new size now
if (!line) return line; // if we fail to allocate memory we will return NULL
}
if( (len == 0) && *endOfLineDetected){ // empty file
*endOfLineDetected = 1;
break;
}
}
line[len++] ='\0'; // ending the string (notice there is no '\n' in the string)
*nrOfCharRead = len;
return line; // return the string
}
The workflow of my program is the following: I gave in input a path, the file correspondent to the path contains in each line others file path that I read with the function above and put into a structure. On each i apply the KMP algorithm to get the occurrences of a string.
The problem comes in my program when I try to open the files that correspond to the paths I saved earlier:
FILE *fp = NULL;
fp = fopen(list->path, "r");
if(fp == NULL){
fprintf(stderr, "Cannot open %s, exiting. . .\n", list->path);
exit(1);
}
On the screen is displayed:
, exiting ...
This is so weird because of file opening problem the output should be:
Cannot open "list->path content", exiting. . .
Even though I don't know why it gives me this error while opening the path read from the input file. During compiling there's no problem. I was thinking about buffer problems derived by the function "getLineOfAnySize. I'm not a Linux user, I was just trying to run the program in order to make sure it will run on both OS. Don't think about design issues or logical issues because on Windows everything works perfectly. Big up to everyone who will help me! Please ask further information about the code if needed.
EDIT:
The content of the input file is:
/home/xxx/Scrivania/find/try
/home/xxx/Scrivania/find/try1
Note that find is the directory of the project.
The following is a sample of my program in order to make more sense of variable and construct:
foo.c :
#include "foo.h"
FILE *fInput = NULL;
FILE *fp = NULL;
char *line1;
char *line2;
int endOfLineDetected = 0;
size_t nrOfCharRead = 0;
char ch;
fWord *w = NULL;
fWord *wordHead = NULL;
fWord *wordTail = NULL;
fList *list = NULL;
fList *listHead = NULL;
fList *listTail = NULL;
fPath *pathHead = NULL;
fPath *pathTail = NULL;
fPosition *positionHead = NULL;
fPosition *head = NULL;
fPosition *current = NULL;
char * getLineOfAnySize(FILE* fp, size_t typicalSize, int *endOfLineDetected,size_t *nrOfCharRead);
int main(int argc, char *argv[]){
fInput = fopen(argv[1], "r"); //the file that contains the path of the file in which search.
if(fInput == NULL){
fprintf(stderr, "Cannot open %s, exiting. . .\n", argv[1]);
exit(1);
}
while(!endOfLineDetected){ //read line by line the input file in order to save the path in a structure
line1 = getLineOfAnySize(fInput,128,&endOfLineDetected,&nrOfCharRead);
fList *node = malloc (sizeof(fList));
node->path = line1;
node->next = NULL;
if(listHead == NULL){
listHead = listTail = node;
}else{
listTail = listTail->next = node;
}
}
list = listHead;
fclose(fInput);
do{
fWord *app = malloc(sizeof(fWord));
printf("Insert the word to search: ");
scanf("%s", app->word);
app->totalOccurences = 0;
app->p = NULL;
app->next = NULL;
if(wordHead == NULL){
wordTail = wordHead = app;
}else{
wordTail = wordTail->next = app;
}
printf("Do you want to insert another word? (Y/N): ");
scanf(" %c", &ch);
}while(ch == 'y' || ch == 'Y');
w = wordHead;
while(w != NULL){
while(list != NULL){
w->p = malloc(sizeof(fPath));
w->p->fileOccurrences = 0;
w->p->path = list->path;
w->p->position = NULL;
w->p->next = NULL;
if(pathHead == NULL){
pathTail = pathHead = w->p;
}else{
pathTail = pathTail->next = w->p;
}
fp = fopen(w->p->path, "r");
if(fp == NULL){
fprintf(stderr, "Cannot open %s, exiting. . .\n", w->p->path);
exit(1);
}
int countLine = 0;
endOfLineDetected = 0;
while(!endOfLineDetected){
line2 = getLineOfAnySize(fp,128,&endOfLineDetected,&nrOfCharRead);
int n = strlen(line2);
int m = strlen(w->word);
w->p->fileOccurrences = w->p->fileOccurrences + KMP(line2, w->word, n, m, countLine, w->p);
countLine = countLine + 1;
}
w->totalOccurences = w->totalOccurences + w->p->fileOccurrences;
w->p->position = getHead();
w->p = w->p->next;
list = list->next;
fclose(fp);
}
w->p = pathHead;
list = listHead;
w = w->next;
pathHead = NULL;
}
w = wordHead;
while(w != NULL){
printf("WORD %s \r\n", w->word);
printf("TOTAL %d \r\n", w->totalOccurences);
pathHead = w->p;
while(w->p != NULL){
printf("FILE %s \r\n", w->p->path);
printf("OCCURENCES %d \r\n", w->p->fileOccurrences);
positionHead = w->p->position;
while (w->p->position != NULL){
printf("%d %d\r\n", w->p->position->line, w->p->position->character);
w->p->position = w->p->position->next;
}
w->p->position = positionHead;
w->p = w->p->next;
}
w->p = pathHead;
w = w->next;
}
w = wordHead;
printf("\r\n");
freeMemory();
freeKMP();
return 0;
}
char * getLineOfAnySize(FILE* fp, size_t typicalSize, int
*endOfLineDetected,size_t *nrOfCharRead){
char *line; // buffer for our string
int ch; // we will read line character by character
size_t len = 0; // number of characters read (character counter)
size_t lineSize = typicalSize; // initial size of the buffer allocated for the line
*nrOfCharRead = 0;
if(!fp) return NULL; // protection
// allocating the buffer
line = realloc(NULL, sizeof(char)*lineSize); // expected size of the line is pathHead to typicalSize
if (!line) return line; // protection, if we fail to allocate the memory we will return NULL
while (1) { // loop forever
ch = fgetc(fp); // getting character by character from file
if (ch == '\n') break; // end of line detected - breaking the loop
if( ch == EOF) {
*endOfLineDetected = 1;
break; // end of file detected - breaking the loop
}
line[len++] = ch; // store the character in the line buffer, increase character counter
if (len == lineSize){ // we reached the end of line buffer (no more room)
lineSize = lineSize + 64; // we have to increase the line size
line = realloc(line, sizeof(char)*(lineSize)); // line buffer has new size now
if (!line) return line; // if we fail to allocate memory we will return NULL
}
if( (len == 0) && *endOfLineDetected){ // empty file
*endOfLineDetected = 1;
break;
}
}
line[len++] ='\0'; // ending the string (notice there is no '\n' in the string)
*nrOfCharRead = len;
return line; // return the string
}
// Function to implement KMP algorithm
int KMP(const char* X, const char* Y, int m, int n, int line, fPath *app){
int count = 0;
// next[i] stores the index of next best partial match
int next[n + 1];
for (int i = 0; i < n + 1; i++)
next[i] = 0;
for (int i = 1; i < n; i++){
int j = next[i + 1];
while (j > 0 && Y[j] != Y[i])
j = next[j];
if (j > 0 || Y[j] == Y[i])
next[i + 1] = j + 1;
}
for (int i = 0, j = 0; i < m; i++){
if(X[i] == Y[j]){
if (++j == n){
count = count + 1; //conta le occorrenze della parola nella riga in input
fPosition *node = malloc (sizeof(fPosition));
node->line = line;
node->character = i - j + 1;
node->next = NULL;
if(head == NULL){
current = head = node;
}else{
current = current->next = node;
}
app->position = current;
}
}
else if (j > 0) {
j = next[j];
i--; // since i will be incremented in next iteration
}
}
return count;
}
fPosition * getHead(){ //rimette il puntatore alla testa della lista
fPosition *app = head;
head = NULL;
return app;
}
void freeKMP(){
free(head);
free(current);
}
void freeMemory(){
list = listHead;
fList *tempL = NULL;
while(list != NULL){
tempL = list;
list = list->next;
free(tempL);
}
w = wordHead;
fWord *tempW = NULL;
fPath *tempP = NULL;
fPosition *tempO = NULL;
while(w != NULL){
while(w->p != NULL){
while(w->p->position != NULL){
tempO = w->p->position;
w->p->position = w->p->position->next;
free(tempO);
}
tempP = w->p;
w->p = w->p->next;
free(tempP);
}
tempW = w;
w = w->next;
free(tempW);
}
free(w);
free(line1);
free(line2);
free(wordHead);
free(wordTail);
free(listHead);
free(listTail);
free(pathHead);
free(pathTail);
free(positionHead);
}
foo.h:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
struct fileList{
char *path;
struct fileList *next;
};
struct filePath{
char *path;
int fileOccurrences;
struct OccurrencesPosition *position;
struct filePath *next;
};
struct fileWord{
char word[50];
int totalOccurences;
struct filePath *p;
struct fileWord *next;
};
struct OccurrencesPosition{
int line;
int character;
struct OccurrencesPosition *next;
};
typedef struct filePath fPath;
typedef struct fileWord fWord;
typedef struct OccurrencesPosition fPosition;
typedef struct fileList fList;
fPosition * getHead();
int KMP(const char* X, const char* Y, int m, int n, int line, fPath *app);
void freeMemory();
void freeKMP();
Maybe also the way I free memory isn't correct.

Answer 1

This is not a full answer, but a hint for further analysis.
I tested the program with the input file contents as shown in the question and entered one or two words.
If the first file does not exist, I get an error message as expected:
Cannot open /home/yuripaoloni/Scrivania/find/try, exiting. . .
Then I modified the input file to list two files that exist on my system and get an error message
Cannot open , exiting. . .
I extended the code that tries to open the file to get more output:
fp = fopen(w->p->path, "r");
if(fp == NULL){
fprintf(stderr, "Cannot open %s, exiting. . .\n", w->p->path);
perror("fopen");
exit(1);
} else {
printf("Successfully opened %s\n", w->p->path);
}
This prints
$ ./foo input
Insert the word to search: foo
Do you want to insert another word? (Y/N): y
Insert the word to search: bar
Do you want to insert another word? (Y/N): y
Insert the word to search: baz
Do you want to insert another word? (Y/N): n
Successfully opened /home/username/tmp/try
Successfully opened /home/username/tmp/try1
Cannot open , exiting. . .
fopen: No such file or directory
Apparently your program tries to open a third file after the existing file names. w->p->path might be a NULL pointer or may point to an empty string.
The same error occurs when I enter only one word. I did not further analyze the error.
To find out why your program tries to open a file with an empty name, you can run it in a debugger or add more output to see how many loop cycles are executed when processing the lists and which data you find.