c - Program using read() entering into an infinite loop -

1oid readbinary(char *infile,hxmap* assetmap) {     int fd;     size_t bytes_read, bytes_expected = 100000000*sizeof(char);     char *data;     if ((fd = open(infile,o_rdonly)) < 0)        err(ex_noinput, "%s", infile);      if ((data = malloc(bytes_expected)) == null)       err(ex_oserr, "data malloc");     bytes_read = read(fd, data, bytes_expected);     if (bytes_read != bytes_expected)        printf("read %d of %d bytes %d\n", \          bytes_read, bytes_expected,ex_dataerr);     /* ... operate on data ... */     printf("\n");     int i=0;     int counter=0;     char ch=data[0];     char message[512];     message* newmessage;     while(i!=bytes_read)     {          while(ch!='\n')         {         message[counter]=ch;         i++;         counter++;         ch =data[i];         }     message[counter]='\n';     message[counter+1]='\0'; //---------------------------------------------------     newmessage = (message*)parser(message);     messageprocess(newmessage,assetmap); //--------------------------------------------------         //printf("idnum %e\n",newmessage->idnum);     free(newmessage);     i++;     counter=0;     ch =data[i];     }    free(data);    } 

here, have allocated 100mb of data malloc, , passed file big enough(not 500mb) size of 926kb about. when pass small files, reads , exits charm, when pass big enough file, program executes till point after hangs. suspect either entered infinite loop, or there memory leak.

edit better understanding stripped away unnecessary function calls, , checked happens, when given large file input. have attached modified code

void readbinary(char *infile,hxmap* assetmap) {     int fd;     size_t bytes_read, bytes_expected = 500000000*sizeof(char);     char *data;     if ((fd = open(infile,o_rdonly)) < 0)        err(ex_noinput, "%s", infile);      if ((data = malloc(bytes_expected)) == null)       err(ex_oserr, "data malloc");     bytes_read = read(fd, data, bytes_expected);     if (bytes_read != bytes_expected)        printf("read %d of %d bytes %d\n", \          bytes_read, bytes_expected,ex_dataerr);     /* ... operate on data ... */     printf("\n");     int i=0;     int counter=0;     char ch=data[0];     char message[512];     while(i<=bytes_read)     {          while(ch!='\n')         {         message[counter]=ch;         i++;         counter++;         ch =data[i];         }     message[counter]='\n';     message[counter+1]='\0';     i++;     printf("idnum \n");     counter=0;     ch =data[i];     }    free(data);    } 

what looks is, prints whole lot of idnum's , poof segmentation fault

i think interesting behaviour, , me looks there problem memory

further edit changed i!=bytes_read gives no segmentation fault. when check i<=bytes_read blows past limits in innerloop.(courtesy gdb)

try following loop. basically, refactors implementation there 1 place i incremented. having 2 places what's causing trouble.

#include <stdio.h> #include <string.h>  int main() {     const char* data = "first line\nsecond line\nthird line";     unsigned int bytes_read = strlen(data);      unsigned int = 0;     unsigned int counter = 0;     char message[512];      while (i < bytes_read)     {         message[counter] = data[i];         ++counter;         if (data[i] == '\n')         {             message[counter] = '\0';             printf("%s", message);             counter = 0;         }         ++i;     }      // if data didn't end newline     if (counter)     {         message[counter] = '\0';         printf("%s\n", message);     }      return 0; } 

or, take "don't reinvent wheel" approach , use standard strtok call:

#include <stdio.h> #include <string.h>  int main() {     char data[] = "first line\nsecond line\nthird line";     char* message = strtok(data, "\n");      while (message)     {         printf("%s\n", message);         message = strtok(null, "\n");     }          return 0; }