cosmopolitan/libc/stdio/getdelim.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/errno.h"
#include "libc/macros.h"
#include "libc/mem/mem.h"
#include "libc/stdio/internal.h"
#include "libc/stdio/stdio.h"

/**
 * Reads string from stream.
 *
 * @param line is the caller's buffer (in/out) which is extended
 *     automatically. *line may be NULL but only if *n is 0;
 *     NUL-termination is guaranteed FTMP
 * @param n is the capacity of line (in/out)
 * @param delim is the stop char (and NUL is implicitly too)
 * @return number of bytes read, including delim, excluding NUL, or -1
 *     w/ errno on EOF or error; see ferror() and feof()
 * @note this function can't punt EINTR to caller
 * @see getline(), gettok_r()
 */
ssize_t getdelim(char **line, size_t *n, int delim, FILE *f) {
  STATIC_YOINK("realloc");
  assert((*line && *n) || (!*line && !*n));
  ssize_t rc = -1;
  size_t i = 0;
  char *p2;
  size_t n2;
  int c;
  for (;;) {
    if ((c = getc(f)) == -1) {
      if (ferror(f) == EINTR) continue;
      if (feof(f) && i) rc = i;
      break;
    }
    if (i + 2 > *n) {
      n2 = MAX(11, *n);
      n2 += n2 >> 1;
      if ((p2 = realloc(*line, n2))) {
        *line = p2;
        *n = n2;
      } else {
        __fseterrno(f);
        break;
      }
    }
    if (((*line)[i++] = c) == delim) {
      rc = i;
      break;
    }
  }
  if (*line && i < *n) (*line)[i] = '\0';
  return rc;
}