From C

This code reads in an arbitrarily long string without calling malloc more than once by calling itself recursively.

/* This code was originally taken from comp.lang.c * news:pan.2005.11.28.12.14.54.651503@erinye.com * It has been fairly heavily modified. * * A bug/feature remains: malloc failures are not propagated. The * feature is that only the part of the line for which there is enough * memory available is allocated. The rest of the line is unavoidably lost. * * The better solution is to propagate any memory allocation failure all * the way back up to rfgets(). Then, the caller would be responsible * for calling feof and ferror to see whether EOF, or malloc failure or * input error caused the NULL return. */ /* * rfgets.c * dynamically allocating fgets * daniel.fischer at iitb.fraunhofer.de */ #include <stdio.h> #include <stdlib.h> #include <string.h> enum { RFGETS_CHUNK_SIZE = 32 }; static char *rfg(FILE *f, size_t n) { char b[RFGETS_CHUNK_SIZE + 1], *const e = b + sizeof b - 2, *p; size_t x; /* store '\0' in the second-to-last character of b */ *e = '\0'; /* read into b */ if (!fgets(b, sizeof b, f)) return 0; /* check for an incomplete line */ if (*e != '\0' && *e != '

' && (p = rfg(f, n + (x = sizeof b - 1)))) return memcpy(p - x, b, x); /* this is the end of the line (or EOF); allocate a buffer for the line */ else if ((p = malloc(n + (x = strlen(b) + 1)))) return memcpy(p + n, b, x); else return 0; } char *rfgets(FILE *f) { return rfg(f, 0); } int main(void) { char *line; for (; line = rfgets(stdin); free(line)) printf(">>%s<<

", line); if (!feof(stdin)) puts("Error?"); return 0; }