src/compat/stdio.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #ifndef _BABELTRACE_COMPAT_STDIO_H
   8 #define _BABELTRACE_COMPAT_STDIO_H
   9
  10 #include <stdio.h>
  11 #include <errno.h>
  12 #include <stdlib.h>
  13 #include <limits.h>
  14 #include "common/assert.h"
  15
  16 #define BT_GETLINE_MINBUFLEN    64
  17
  18 static inline
  19 char * _bt_getline_bufalloc(char **lineptr, size_t *n, size_t linelen)
  20 {
  21         size_t buflen = *n;
  22         char *buf = *lineptr;
  23
  24         if (buflen >= linelen && buf) {
  25                 return buf;
  26         }
  27         if (!buf) {
  28                 buflen = BT_GETLINE_MINBUFLEN;
  29         } else {
  30                 buflen = buflen << 1;
  31                 if (buflen < BT_GETLINE_MINBUFLEN) {
  32                         buflen = BT_GETLINE_MINBUFLEN;
  33                 }
  34         }
  35         /* Check below not strictly needed, extra safety. */
  36         if (buflen < linelen) {
  37                 buflen = linelen;
  38         }
  39         buf = realloc(buf, buflen);
  40         if (!buf) {
  41                 errno = ENOMEM;
  42                 return NULL;
  43         }
  44         *n = buflen;
  45         *lineptr = buf;
  46         return buf;
  47 }
  48
  49 /*
  50  * Returns line length (including possible final \n, excluding final
  51  * \0). On end of file, returns -1 with nonzero feof(stream) and errno
  52  * set to 0. On error, returns -1 with errno set.
  53  *
  54  * This interface is similar to the getline(3) man page part of the
  55  * Linux man-pages project, release 3.74. One major difference from the
  56  * Open Group POSIX specification is that this implementation does not
  57  * necessarily set the ferror() flag on error (because it is internal to
  58  * libc).
  59  */
  60 static inline
  61 ssize_t bt_getline(char **lineptr, size_t *n, FILE *stream)
  62 {
  63         size_t linelen = 0;
  64         char *buf;
  65         int found_eof = 0;
  66
  67         if (!lineptr || !n) {
  68                 errno = EINVAL;
  69                 return -1;
  70         }
  71         for (;;) {
  72                 char c;
  73                 int ret;
  74
  75                 ret = fgetc(stream);
  76                 if (ret == EOF) {
  77                         if (ferror(stream)) {
  78                                 /* ferror() is set, errno set by fgetc(). */
  79                                 return -1;
  80                         }
  81                         BT_ASSERT_DBG(feof(stream));
  82                         found_eof = 1;
  83                         break;
  84                 }
  85                 c = (char) ret;
  86                 if (linelen == SSIZE_MAX) {
  87                         errno = EOVERFLOW;
  88                         return -1;
  89                 }
  90                 buf = _bt_getline_bufalloc(lineptr, n, ++linelen);
  91                 if (!buf) {
  92                         return -1;
  93                 }
  94                 buf[linelen - 1] = c;
  95                 if (c == '\n') {
  96                         break;
  97                 }
  98         }
  99         if (!linelen && found_eof) {
 100                 /* feof() is set. */
 101                 errno = 0;
 102                 return -1;
 103         }
 104         buf = _bt_getline_bufalloc(lineptr, n, ++linelen);
 105         if (!buf) {
 106                 return -1;
 107         }
 108         buf[linelen - 1] = '\0';
 109         return linelen - 1;     /* Count don't include final \0. */
 110 }
 111
 112 #endif /* _BABELTRACE_COMPAT_STDIO_H */