recoding getline function on C -

i need function reproduce basic of getline function program, function should able read fp , without huge buffer (256 should enough here) have 2 problem on code below - function start return wrong info when buffer exeeded, file example http://pastebin.com/bxj3sh92 ( ./a.out < file ) - when call function without giving file should work cat stop after press first enter key ( ./a.out )

here code:

#define moar_buf 256  #include <stdlib.h> #include <fcntl.h> #include <string.h> #include <stdio.h>  char            *my_getline(const int fd) {   static char   save[moar_buf];   static int    = moar_buf;   int           g;   int           f;   char          *save2;    save2 = null;   g = 0;   f = 0;   if (g == 0 && >= (moar_buf -1))     {       = 0;       g = read(fd, save, moar_buf + 1);       save[g] = '\0';     }   if (i <= moar_buf && save[i] != '\0')     {       save2 = malloc((sizeof(*save2) * moar_buf));       while(save[i] != '\n' && save[i] != '\0')         save2[f++] = save[i++];       save2[f] = '\0';       if (save[i] != '\0')         = + 1;     }   return(save2); }  int             main() {   int           i;   char          **converted_map;   char          *map;    = 0;   converted_map = malloc(sizeof(*converted_map) * 30);   while(map = my_getline(0))     {       converted_map[i] = strdup(map);       printf("%s\n", converted_map[i]);       i++;     } } 

static char   save[moar_buf];  g = read(fd, save, moar_buf); save[g] = '\0'; 

you tell read read moar_buf bytes, , when succeeds reading many, 0-termination writes past end of array, invoking undefined behaviour.

you need tell read read fewer bytes, moar_buf - 1 example, or make buffer larger, moar_buf + 1, example.

then, in main,

while(map = my_getline(0)) {   printf("%s\n", converted_map[i]);   converted_map[i] = strdup(map);   i++; } 

you print out converted_map[i] before assigned, that's more undefined behaviour. need first strdup(map) converted_map[i], then can print it.