libbb/fgets_str.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) many different people.
   6  * If you wrote this, please acknowledge your work.
   7  *
   8  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   9  */
  10 #include "libbb.h"
  11
  12 static char *xmalloc_fgets_internal(FILE *file, const char *terminating_string, int chop_off, size_t *maxsz_p)
  13 {
  14         char *linebuf = NULL;
  15         const int term_length = strlen(terminating_string);
  16         int end_string_offset;
  17         int linebufsz = 0;
  18         int idx = 0;
  19         int ch;
  20         size_t maxsz = maxsz_p ? *maxsz_p : INT_MAX - 4095;
  21
  22         while (1) {
  23                 ch = fgetc(file);
  24                 if (ch == EOF) {
  25                         if (idx == 0)
  26                                 return linebuf; /* NULL */
  27                         break;
  28                 }
  29
  30                 if (idx >= linebufsz) {
  31                         linebufsz += 200;
  32                         linebuf = xrealloc(linebuf, linebufsz);
  33                         if (idx >= maxsz) {
  34                                 linebuf[idx] = ch;
  35                                 idx++;
  36                                 break;
  37                         }
  38                 }
  39
  40                 linebuf[idx] = ch;
  41                 idx++;
  42
  43                 /* Check for terminating string */
  44                 end_string_offset = idx - term_length;
  45                 if (end_string_offset >= 0
  46                  && memcmp(&linebuf[end_string_offset], terminating_string, term_length) == 0
  47                 ) {
  48                         if (chop_off)
  49                                 idx -= term_length;
  50                         break;
  51                 }
  52         }
  53         /* Grow/shrink *first*, then store NUL */
  54         linebuf = xrealloc(linebuf, idx + 1);
  55         linebuf[idx] = '\0';
  56         if (maxsz_p)
  57                 *maxsz_p = idx;
  58         return linebuf;
  59 }
  60
  61 /* Read up to TERMINATING_STRING from FILE and return it,
  62  * including terminating string.
  63  * Non-terminated string can be returned if EOF is reached.
  64  * Return NULL if EOF is reached immediately.  */
  65 char* FAST_FUNC xmalloc_fgets_str(FILE *file, const char *terminating_string)
  66 {
  67         return xmalloc_fgets_internal(file, terminating_string, 0, NULL);
  68 }
  69
  70 char* FAST_FUNC xmalloc_fgets_str_len(FILE *file, const char *terminating_string, size_t *maxsz_p)
  71 {
  72         return xmalloc_fgets_internal(file, terminating_string, 0, maxsz_p);
  73 }
  74
  75 char* FAST_FUNC xmalloc_fgetline_str(FILE *file, const char *terminating_string)
  76 {
  77         return xmalloc_fgets_internal(file, terminating_string, 1, NULL);
  78 }