GRASS GIS 7 Programmer's Manual  7.7.svn(2018)-r73574
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Pages
asprintf.c
Go to the documentation of this file.
1 
2 /*!
3  * \file lib/gis/asprintf.c
4  *
5  * \brief GIS Library - GRASS implementation of asprintf().
6  *
7  * Eric G. Miller - Thu, 2 May 2002 17:51:54 -0700
8  *
9  * Rewritten by Glynn Clements, Sat, 6 Feb 2010
10  * Assumes that vsnprintf() is available
11  *
12  * (C) 2002-2014 by the GRASS Development Team
13  * (C) 2010 by Glynn Clements
14  *
15  * This program is free software under the GNU General Public License
16  * (>=v2). Read the file COPYING that comes with GRASS for details.
17  */
18 
19 #define _GNU_SOURCE /* enable asprintf */
20 #include <stdio.h>
21 #include <stdarg.h>
22 #include <string.h>
23 #include <grass/gis.h>
24 
25 #ifndef G_asprintf
26 
27 /**
28  * \brief Safe replacement for <i>asprintf()</i>.
29  *
30  * Allocate a string large enough to hold the new output, including the
31  * terminating NULL, and return the number of characters printed. The
32  * pointer out is set to the output string and should be passed to
33  * <i>G_free()</i> to release the allocated storage when it is no longer
34  * needed.
35  *
36  * \param[out] out
37  * \param[in] fmt
38  * \param ap
39  * \return number of bytes written
40  */
41 
42 int G_vasprintf(char **out, const char *fmt, va_list ap)
43 {
44 #ifdef HAVE_ASPRINTF
45  return vasprintf(out, fmt, ap);
46 #else
47  size_t size = strlen(fmt) + 50;
48  char *buf = G_malloc(size);
49  int count;
50 
51  for (;;) {
52  /* BUG: according to man vsnprintf,
53  * va_start() should be called immediately before vsnprintf(),
54  * and va_end() immediately after vsnprintf()
55  * otherwise there will be memory corruption */
56  count = vsnprintf(buf, size, fmt, ap);
57  if (count >= 0 && count < size)
58  break;
59  size *= 2;
60  buf = G_realloc(buf, size);
61  }
62 
63  buf = G_realloc(buf, count + 1);
64  *out = buf;
65 
66  return count;
67 #endif /* HAVE_ASPRINTF */
68 }
69 
70 int G_asprintf(char **out, const char *fmt, ...)
71 {
72  va_list ap;
73  int count;
74 
75  va_start(ap, fmt);
76  count = G_vasprintf(out, fmt, ap);
77  va_end(ap);
78 
79  return count;
80 }
81 
82 #endif /* G_asprintf */
83 
84 /**
85  * \brief Reallocating version of <i>asprintf()</i>.
86  *
87  * Reallocate a string large enough to hold the output, including the
88  * terminating NULL, and return the number of characters printed.
89  * Contrary to <i>G_asprintf()</i>, any existing buffer pointed to by
90  * out of size osize is used to hold the output and enlarged if
91  * necessary. This is useful when <i>G_rasprintf</i> is called many
92  * times in a loop.
93  *
94  * \param[out] out
95  * \param[out] osize
96  * \param[in] fmt
97  * \param ap
98  * \return number of bytes written
99  */
100 
101 int G_rasprintf(char **out, size_t *size, const char *fmt, ...)
102 {
103  va_list ap;
104  int count;
105  char *buf = *out;
106  size_t osize = *size;
107 
108  if (osize < strlen(fmt) + 50) {
109  osize = strlen(fmt) + 50;
110  buf = G_realloc(buf, osize);
111  }
112 
113  for (;;) {
114  va_start(ap, fmt);
115  count = vsnprintf(buf, osize, fmt, ap);
116  va_end(ap);
117  if (count >= 0 && count < osize)
118  break;
119  if (count > -1)
120  osize = count + 1;
121  else
122  osize *= 2;
123 
124  buf = G_realloc(buf, osize);
125  }
126 
127  *out = buf;
128  *size = osize;
129 
130  return count;
131 }
int G_rasprintf(char **out, size_t *size, const char *fmt,...)
Reallocating version of asprintf().
Definition: asprintf.c:101
int count
int G_asprintf(char **out, const char *fmt,...)
Definition: asprintf.c:70
int G_vasprintf(char **out, const char *fmt, va_list ap)
Safe replacement for asprintf().
Definition: asprintf.c:42