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#include "getline.h"
#include <cstdlib> // malloc()
#include <errno.h> // errno
ssize_t getline(char** lineptr, size_t* n, FILE* stream) {
if ((n == nullptr) or
(lineptr == nullptr) or
(stream == nullptr)) {
/* Bad arguments (n or lineptr is nullptr, or stream is not valid). */
errno = EINVAL;
return -1;
}
/* If *lineptr is set to nullptr before the call, then getline() will
* allocate a buffer for storing the line. This buffer should be
* freed by the user program even if getline() failed.
*/
const size_t buflen = 128;
char* bufptr = *lineptr;
ssize_t size = *n;
if (bufptr == nullptr) {
bufptr = static_cast<char*>(malloc(buflen));
if (bufptr == nullptr) {
/* Allocation or reallocation of the line buffer failed. */
errno = ENOMEM;
return -1;
}
size = buflen;
}
int c = fgetc(stream);
if (c == EOF) {
/* Bad arguments (stream is not valid). */
errno = EINVAL;
return -1;
}
char* p = bufptr;
while (c != EOF) {
if ((p - bufptr) > (size - 1)) {
size += buflen;
bufptr = static_cast<char*>(realloc(bufptr, size));
if (bufptr == nullptr) {
/* Allocation or reallocation of the line buffer failed. */
errno = ENOMEM;
return -1;
}
}
*p++ = c;
if (c == '\n')
break;
c = fgetc(stream);
}
*p++ = 0;
/* on a successful call, *lineptr and *n will be updated to reflect the
* buffer address and allocated size respectively.
*/
errno = 0;
*lineptr = bufptr;
*n = size;
/* On success, getline() returns the number of characters read, including
* the delimiter character, but not including the terminating null byte ('\0').
*/
return p - bufptr - 1;
}
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