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[gdb.git] / libiberty / vsnprintf.c
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1 /* Implement the vsnprintf function.
2 Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
3 Written by Kaveh R. Ghazi <ghazi@caip.rutgers.edu>.
5 This file is part of the libiberty library. This library is free
6 software; you can redistribute it and/or modify it under the
7 terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 2, or (at your option)
9 any later version.
11 This library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
20 As a special exception, if you link this library with files
21 compiled with a GNU compiler to produce an executable, this does not cause
22 the resulting executable to be covered by the GNU General Public License.
23 This exception does not however invalidate any other reasons why
24 the executable file might be covered by the GNU General Public License. */
28 @deftypefn Supplemental int vsnprintf (char *@var{buf}, size_t @var{n}, const char *@var{format}, va_list @var{ap})
30 This function is similar to vsprintf, but it will print at most
31 @var{n} characters. On error the return value is -1, otherwise it
32 returns the number of characters that would have been printed had
33 @var{n} been sufficiently large, regardless of the actual value of
34 @var{n}. Note some pre-C99 system libraries do not implement this
35 correctly so users cannot generally rely on the return value if the
36 system version of this function is used.
38 @end deftypefn
42 #include "config.h"
43 #include "ansidecl.h"
45 #include <stdarg.h>
46 #ifdef HAVE_STRING_H
47 #include <string.h>
48 #endif
49 #ifdef HAVE_STDLIB_H
50 #include <stdlib.h>
51 #endif
53 #include "libiberty.h"
55 /* This implementation relies on a working vasprintf. */
56 int
57 vsnprintf (char *s, size_t n, const char *format, va_list ap)
59 char *buf = 0;
60 int result = vasprintf (&buf, format, ap);
62 if (!buf)
63 return -1;
64 if (result < 0)
66 free (buf);
67 return -1;
70 result = strlen (buf);
71 if (n > 0)
73 if ((long) n > result)
74 memcpy (s, buf, result+1);
75 else
77 memcpy (s, buf, n-1);
78 s[n - 1] = 0;
81 free (buf);
82 return result;
85 #ifdef TEST
86 /* Set the buffer to a known state. */
87 #define CLEAR(BUF) do { memset ((BUF), 'X', sizeof (BUF)); (BUF)[14] = '\0'; } while (0)
88 /* For assertions. */
89 #define VERIFY(P) do { if (!(P)) abort(); } while (0)
91 static int ATTRIBUTE_PRINTF_3
92 checkit (char *s, size_t n, const char *format, ...)
94 int result;
95 VA_OPEN (ap, format);
96 VA_FIXEDARG (ap, char *, s);
97 VA_FIXEDARG (ap, size_t, n);
98 VA_FIXEDARG (ap, const char *, format);
99 result = vsnprintf (s, n, format, ap);
100 VA_CLOSE (ap);
101 return result;
104 extern int main (void);
106 main (void)
108 char buf[128];
109 int status;
111 CLEAR (buf);
112 status = checkit (buf, 10, "%s:%d", "foobar", 9);
113 VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
115 CLEAR (buf);
116 status = checkit (buf, 9, "%s:%d", "foobar", 9);
117 VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
119 CLEAR (buf);
120 status = checkit (buf, 8, "%s:%d", "foobar", 9);
121 VERIFY (status==8 && memcmp (buf, "foobar:\0XXXXXX\0", 15) == 0);
123 CLEAR (buf);
124 status = checkit (buf, 7, "%s:%d", "foobar", 9);
125 VERIFY (status==8 && memcmp (buf, "foobar\0XXXXXXX\0", 15) == 0);
127 CLEAR (buf);
128 status = checkit (buf, 6, "%s:%d", "foobar", 9);
129 VERIFY (status==8 && memcmp (buf, "fooba\0XXXXXXXX\0", 15) == 0);
131 CLEAR (buf);
132 status = checkit (buf, 2, "%s:%d", "foobar", 9);
133 VERIFY (status==8 && memcmp (buf, "f\0XXXXXXXXXXXX\0", 15) == 0);
135 CLEAR (buf);
136 status = checkit (buf, 1, "%s:%d", "foobar", 9);
137 VERIFY (status==8 && memcmp (buf, "\0XXXXXXXXXXXXX\0", 15) == 0);
139 CLEAR (buf);
140 status = checkit (buf, 0, "%s:%d", "foobar", 9);
141 VERIFY (status==8 && memcmp (buf, "XXXXXXXXXXXXXX\0", 15) == 0);
143 return 0;
145 #endif /* TEST */