snprinterr.c

   1 /* snprinterr.c */
   2 /* Copyright Gerhard Rieger and contributors (see file CHANGES) */
   3
   4 /* a function similar to vsnprintf() but it just handles %m */
   5
   6 #include "config.h"
   7
   8 #include <stddef.h>     /* ptrdiff_t */
   9 #include <ctype.h>      /* isdigit() */
  10 #include <stdarg.h>
  11 #include <stdlib.h>
  12 #include <errno.h>
  13 #if HAVE_SYSLOG_H
  14 #include <syslog.h>
  15 #endif
  16 #include <sys/utsname.h>
  17 #include <time.h>       /* time_t, strftime() */
  18 #include <sys/time.h>   /* gettimeofday() */
  19 #include <stdio.h>
  20 #include <string.h>
  21 #if HAVE_UNISTD_H
  22 #include <unistd.h>
  23 #endif
  24
  25 #include "snprinterr.h"
  26
  27 #define HAVE_STRERROR_R 0
  28 /* replace %m in format with actual strerror() message, write result to *str.
  29    keep other % formats unchanged!
  30    writes at most size chars including the terminating \0 to *str
  31    returns the number of bytes in the output without terminating \0
  32    result is always \0 terminated except when size==0
  33  */
  34 int snprinterr(char *str, size_t size, const char *format) {
  35    char c;
  36    int full = 0;        /* 1 means: there is no space left in * str for more data or \0 */
  37    int count = 0;
  38    if (size == 0)  return 0;
  39    if (count >= size)  full = 1;
  40    while (c = *format++) {
  41       if (c == '%') {
  42          c = *format++;
  43          switch (c) {
  44          case '\0':
  45             ++count; if (!full) { (*str++ = '%'); if (count+1 >= size) full = 1; }
  46             break;
  47          default:
  48             ++count; if (!full) { (*str++ = '%'); if (count+1 >= size) full = 1; }
  49             ++count; if (!full) { (*str++ = c);   if (count+1 >= size) full = 1; }
  50             break;
  51          case 'm':
  52             {
  53 #if HAVE_STRERROR_R
  54 #              define BUFLEN 64
  55                char buf[BUFLEN] = "";
  56 #endif /* HAVE_STRERROR_R */
  57                char *bufp;
  58 #if !HAVE_STRERROR_R
  59                bufp = strerror(errno);
  60 #else
  61                /* there are two versions floating around... */
  62 #  if 1 /* GNU version */
  63                bufp = strerror_r(errno, buf, BUFLEN);
  64 #  else /* standard version */
  65                strerror_r(errno, buf, BUFLEN);
  66                bufp = buf;
  67 #  endif
  68 #endif /* HAVE_STRERROR_R */
  69                while ((c = *bufp++) != '\0') {
  70                   ++count; if (!full) { (*str++ = c);   if (count+1 >= size) full = 1; }
  71                }
  72             }
  73             c = ' ';    /* not \0 ! */
  74             break;
  75          }
  76          if (c == '\0')  break;
  77       } else {
  78          ++count; if (!full) { (*str++ = c); if (count+1 >= size)  full = 1; }
  79       }
  80    }
  81    *str++ = '\0';       /* always write terminating \0 */
  82    return count;
  83 #undef BUFLEN
  84 }
  85