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 tarball for details.
   9  */
  10
  11 #include "libbb.h"
  12
  13 static char *xmalloc_fgets_internal(FILE *file, const char *terminating_string, int chop_off)
  14 {
  15         char *linebuf = NULL;
  16         const int term_length = strlen(terminating_string);
  17         int end_string_offset;
  18         int linebufsz = 0;
  19         int idx = 0;
  20         int ch;
  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                 }
  34
  35                 linebuf[idx] = ch;
  36                 idx++;
  37
  38                 /* Check for terminating string */
  39                 end_string_offset = idx - term_length;
  40                 if (end_string_offset >= 0
  41                  && memcmp(&linebuf[end_string_offset], terminating_string, term_length) == 0
  42                 ) {
  43                         if (chop_off)
  44                                 idx -= term_length;
  45                         break;
  46                 }
  47         }
  48         /* Grow/shrink *first*, then store NUL */
  49         linebuf = xrealloc(linebuf, idx + 1);
  50         linebuf[idx] = '\0';
  51         return linebuf;
  52 }
  53
  54 /* Read up to TERMINATING_STRING from FILE and return it,
  55  * including terminating string.
  56  * Non-terminated string can be returned if EOF is reached.
  57  * Return NULL if EOF is reached immediately.  */
  58 char* FAST_FUNC xmalloc_fgets_str(FILE *file, const char *terminating_string)
  59 {
  60         return xmalloc_fgets_internal(file, terminating_string, 0);
  61 }
  62
  63 char* FAST_FUNC xmalloc_fgetline_str(FILE *file, const char *terminating_string)
  64 {
  65         return xmalloc_fgets_internal(file, terminating_string, 1);
  66 }