1 /* gmp_vasprintf -- formatted output to an allocated space. 2 3 Copyright 2001 Free Software Foundation, Inc. 4 5 This file is part of the GNU MP Library. 6 7 The GNU MP Library is free software; you can redistribute it and/or modify 8 it under the terms of the GNU Lesser General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or (at your 10 option) any later version. 11 12 The GNU MP Library is distributed in the hope that it will be useful, but 13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 15 License for more details. 16 17 You should have received a copy of the GNU Lesser General Public License 18 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 19 20 #include "config.h" 21 22 #if HAVE_STDARG 23 #include <stdarg.h> 24 #else 25 #include <varargs.h> 26 #endif 27 28 #include <stdio.h> 29 #include <stdlib.h> 30 #include <string.h> 31 32 #include "gmp.h" 33 #include "gmp-impl.h" 34 35 #if ! HAVE_VSNPRINTF 36 #define vsnprintf __gmp_replacement_vsnprintf 37 #endif 38 39 40 /* vasprintf isn't used since we prefer all GMP allocs to go through 41 __gmp_allocate_func, and in particular we don't want the -1 return from 42 vasprintf for out-of-memory, instead __gmp_allocate_func should handle 43 that. Using vsnprintf unfortunately means we might have to re-run it if 44 our current space is insufficient. 45 46 The initial guess for the needed space is an arbitrary 256 bytes. If 47 that (and any extra GMP_ASPRINTF_T_NEED might give) isn't enough then an 48 ISO C99 standard vsnprintf will tell us what we really need. 49 50 GLIBC 2.0.x vsnprintf returns either -1 or space-1 to indicate overflow, 51 without giving any indication how much is really needed. In this case 52 keep trying with double the space each time. 53 54 A return of space-1 is success on a C99 vsnprintf, but we're not 55 bothering to identify which style vsnprintf we've got, so just take the 56 pessimistic option and assume it's glibc 2.0.x. 57 58 Notice the use of ret+2 for the new space in the C99 case. This ensures 59 the next vsnprintf return value will be space-2, which is unambiguously 60 successful. But actually GMP_ASPRINTF_T_NEED() will realloc to even 61 bigger than that ret+2. 62 63 vsnprintf might trash it's given ap, so copy it in case we need to use it 64 more than once. See comments with gmp_snprintf_format. */ 65 66 static int 67 gmp_asprintf_format (struct gmp_asprintf_t *d, const char *fmt, 68 va_list orig_ap) 69 { 70 int ret; 71 va_list ap; 72 size_t space = 256; 73 74 for (;;) 75 { 76 GMP_ASPRINTF_T_NEED (d, space); 77 space = d->alloc - d->size; 78 va_copy (ap, orig_ap); 79 ret = vsnprintf (d->buf + d->size, space, fmt, ap); 80 if (ret == -1) 81 { 82 ASSERT (strlen (d->buf + d->size) == space-1); 83 ret = space-1; 84 } 85 86 /* done if output fits in our space */ 87 if (ret < space-1) 88 break; 89 90 if (ret == space-1) 91 space *= 2; /* possible glibc 2.0.x, so double */ 92 else 93 space = ret+2; /* C99, so now know space required */ 94 } 95 96 d->size += ret; 97 return ret; 98 } 99 100 const struct doprnt_funs_t __gmp_asprintf_funs = { 101 (doprnt_format_t) gmp_asprintf_format, 102 (doprnt_memory_t) __gmp_asprintf_memory, 103 (doprnt_reps_t) __gmp_asprintf_reps, 104 (doprnt_final_t) __gmp_asprintf_final 105 }; 106 107 int 108 gmp_vasprintf (char **result, const char *fmt, va_list ap) 109 { 110 struct gmp_asprintf_t d; 111 GMP_ASPRINTF_T_INIT (d, result); 112 return __gmp_doprnt (&__gmp_asprintf_funs, &d, fmt, ap); 113 } 114