compat/snprintf.c

   1 #include "../git-compat-util.h"
   2
   3 /*
   4  * The size parameter specifies the available space, i.e. includes
   5  * the trailing NUL byte; but Windows's vsnprintf expects the
   6  * number of characters to write, and does not necessarily write the
   7  * trailing NUL.
   8  */
   9 #ifndef SNPRINTF_SIZE_CORR
  10 #if defined(__MINGW32__) && defined(__GNUC__) && __GNUC__ < 4
  11 #define SNPRINTF_SIZE_CORR 1
  12 #else
  13 #define SNPRINTF_SIZE_CORR 0
  14 #endif
  15 #endif
  16
  17 #undef vsnprintf
  18 int git_vsnprintf(char *str, size_t maxsize, const char *format, va_list ap)
  19 {
  20         char *s;
  21         int ret = -1;
  22
  23         if (maxsize > 0) {
  24                 ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, ap);
  25                 if (ret == maxsize-1)
  26                         ret = -1;
  27                 /* Windows does not NUL-terminate if result fills buffer */
  28                 str[maxsize-1] = 0;
  29         }
  30         if (ret != -1)
  31                 return ret;
  32
  33         s = NULL;
  34         if (maxsize < 128)
  35                 maxsize = 128;
  36
  37         while (ret == -1) {
  38                 maxsize *= 4;
  39                 str = realloc(s, maxsize);
  40                 if (! str)
  41                         break;
  42                 s = str;
  43                 ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, ap);
  44                 if (ret == maxsize-1)
  45                         ret = -1;
  46         }
  47         free(s);
  48         return ret;
  49 }
  50
  51 int git_snprintf(char *str, size_t maxsize, const char *format, ...)
  52 {
  53         va_list ap;
  54         int ret;
  55
  56         va_start(ap, format);
  57         ret = git_vsnprintf(str, maxsize, format, ap);
  58         va_end(ap);
  59
  60         return ret;
  61 }
  62