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, size_t *maxsz_p)
  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         size_t maxsz = *maxsz_p;
  22
  23         while (1) {
  24                 ch = fgetc(file);
  25                 if (ch == EOF) {
  26                         if (idx == 0)
  27                                 return linebuf; /* NULL */
  28                         break;
  29                 }
  30
  31                 if (idx >= linebufsz) {
  32                         linebufsz += 200;
  33                         linebuf = xrealloc(linebuf, linebufsz);
  34                         if (idx >= maxsz) {
  35                                 linebuf[idx] = ch;
  36                                 idx++;
  37                                 break;
  38                         }
  39                 }
  40
  41                 linebuf[idx] = ch;
  42                 idx++;
  43
  44                 /* Check for terminating string */
  45                 end_string_offset = idx - term_length;
  46                 if (end_string_offset >= 0
  47                  && memcmp(&linebuf[end_string_offset], terminating_string, term_length) == 0
  48                 ) {
  49                         if (chop_off)
  50                                 idx -= term_length;
  51                         break;
  52                 }
  53         }
  54         /* Grow/shrink *first*, then store NUL */
  55         linebuf = xrealloc(linebuf, idx + 1);
  56         linebuf[idx] = '\0';
  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         size_t maxsz = INT_MAX - 4095;
  68         return xmalloc_fgets_internal(file, terminating_string, 0, &maxsz);
  69 }
  70
  71 char* FAST_FUNC xmalloc_fgets_str_len(FILE *file, const char *terminating_string, size_t *maxsz_p)
  72 {
  73         size_t maxsz;
  74
  75         if (!maxsz_p) {
  76                 maxsz = INT_MAX - 4095;
  77                 maxsz_p = &maxsz;
  78         }
  79         return xmalloc_fgets_internal(file, terminating_string, 0, maxsz_p);
  80 }
  81
  82 char* FAST_FUNC xmalloc_fgetline_str(FILE *file, const char *terminating_string)
  83 {
  84         size_t maxsz = INT_MAX - 4095;
  85         return xmalloc_fgets_internal(file, terminating_string, 1, &maxsz);
  86 }