1explain_calloc(3)          Library Functions Manual          explain_calloc(3)
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NAME

6       explain_calloc - explain calloc(3) errors
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SYNOPSIS

9       #include <libexplain/calloc.h>
10       const char *explain_calloc(size_t nmemb, size_t size);
11       const char *explain_errno_calloc(int errnum, size_t nmemb, size_t
12       size);
13       void explain_message_calloc(char *message, int message_size, size_t
14       nmemb, size_t size);
15       void explain_message_errno_calloc(char *message, int message_size, int
16       errnum, size_t nmemb, size_t size);
17

DESCRIPTION

19       These functions may be used to obtain explanations for errors  returned
20       by the calloc(3) system call.
21
22   explain_calloc
23       const char *explain_calloc(size_t nmemb, size_t size);
24
25       The  explain_calloc  function  is  used  to obtain an explanation of an
26       error returned by the calloc(3) system call. The least the message will
27       contain  is  the  value of strerror(errno), but usually it will do much
28       better, and indicate the underlying cause in more detail.
29
30       The errno global variable will be used to obtain the error value to  be
31       decoded.
32
33       nmemb   The  original  nmemb, exactly as passed to the calloc(3) system
34               call.
35
36       size    The original size, exactly as passed to  the  calloc(3)  system
37               call.
38
39       Returns:
40               The message explaining the error. This message buffer is shared
41               by all libexplain functions which do not  supply  a  buffer  in
42               their argument list.  This will be overwritten by the next call
43               to any libexplain function which shares this buffer,  including
44               other threads.
45
46       Note: This function is not thread safe, because it shares a return buf‐
47       fer across all threads, and many other functions in this library.
48
49       Example: This function is intended to be used in a fashion  similar  to
50       the following example:
51              errno = 0;
52              void *result = calloc(nmemb, size);
53              if (!result && errno != 0)
54              {
55                  fprintf(stderr, "%s\n", explain_calloc(nmemb, size));
56                  exit(EXIT_FAILURE);
57              }
58
59       The  above  code  example is available pre-packaged as the explain_cal‐
60       loc_or_die(3) function.
61
62   explain_errno_calloc
63       const char *explain_errno_calloc(int errnum, size_t nmemb, size_t
64       size);
65
66       The  explain_errno_calloc  function is used to obtain an explanation of
67       an error returned by the calloc(3) system call. The least  the  message
68       will  contain  is  the value of strerror(errno), but usually it will do
69       much better, and indicate the underlying cause in more detail.
70
71       errnum  The error value to be decoded, usually obtained from the  errno
72               global  variable  just  before this function is called. This is
73               necessary if you need to call any code between the system  call
74               to  be explained and this function, because many libc functions
75               will alter the value of errno.
76
77       nmemb   The original nmemb, exactly as passed to the  calloc(3)  system
78               call.
79
80       size    The  original  size,  exactly as passed to the calloc(3) system
81               call.
82
83       Returns:
84               The message explaining the error. This message buffer is shared
85               by  all  libexplain  functions  which do not supply a buffer in
86               their argument list.  This will be overwritten by the next call
87               to  any libexplain function which shares this buffer, including
88               other threads.
89
90       Note: This function is not thread safe, because it shares a return buf‐
91       fer across all threads, and many other functions in this library.
92
93       Example:  This  function is intended to be used in a fashion similar to
94       the following example:
95              errno = 0;
96              void *result = calloc(nmemb, size);
97              if (!result && errno != 0)
98              {
99                  int err = errno;
100                  fprintf(stderr, "%s\n", explain_errno_calloc(err, nmemb,
101                  size));
102                  exit(EXIT_FAILURE);
103              }
104
105       The  above  code  example is available pre-packaged as the explain_cal‐
106       loc_or_die(3) function.
107
108   explain_message_calloc
109       void explain_message_calloc(char *message, int message_size, size_t
110       nmemb, size_t size);
111
112       The explain_message_calloc function is used to obtain an explanation of
113       an error returned by the calloc(3) system call. The least  the  message
114       will  contain  is  the value of strerror(errno), but usually it will do
115       much better, and indicate the underlying cause in more detail.
116
117       The errno global variable will be used to obtain the error value to  be
118       decoded.
119
120       message The location in which to store the returned message. If a suit‐
121               able message return buffer is supplied, this function is thread
122               safe.
123
124       message_size
125               The  size  in  bytes  of  the  location  in  which to store the
126               returned message.
127
128       nmemb   The original nmemb, exactly as passed to the  calloc(3)  system
129               call.
130
131       size    The  original  size,  exactly as passed to the calloc(3) system
132               call.
133
134       Example: This function is intended to be used in a fashion  similar  to
135       the following example:
136              errno = 0;
137              void *result = calloc(nmemb, size);
138              if (!result && errno != 0)
139              {
140                  char message[3000];
141                  explain_message_calloc(message, sizeof(message), nmemb,
142                  size);
143                  fprintf(stderr, "%s\n", message);
144                  exit(EXIT_FAILURE);
145              }
146
147       The above code example is available pre-packaged  as  the  explain_cal‐
148       loc_or_die(3) function.
149
150   explain_message_errno_calloc
151       void explain_message_errno_calloc(char *message, int message_size, int
152       errnum, size_t nmemb, size_t size);
153
154       The explain_message_errno_calloc function is used to obtain an explana‐
155       tion  of  an error returned by the calloc(3) system call. The least the
156       message will contain is the value of strerror(errno),  but  usually  it
157       will do much better, and indicate the underlying cause in more detail.
158
159       message The location in which to store the returned message. If a suit‐
160               able message return buffer is supplied, this function is thread
161               safe.
162
163       message_size
164               The  size  in  bytes  of  the  location  in  which to store the
165               returned message.
166
167       errnum  The error value to be decoded, usually obtained from the  errno
168               global  variable  just  before this function is called. This is
169               necessary if you need to call any code between the system  call
170               to  be explained and this function, because many libc functions
171               will alter the value of errno.
172
173       nmemb   The original nmemb, exactly as passed to the  calloc(3)  system
174               call.
175
176       size    The  original  size,  exactly as passed to the calloc(3) system
177               call.
178
179       Example: This function is intended to be used in a fashion  similar  to
180       the following example:
181              errno = 0;
182              void *result = calloc(nmemb, size);
183              if (!result && errno != 0)
184              {
185                  int err = errno;
186                  char message[3000];
187                  explain_message_errno_calloc(message, sizeof(message), err,
188                  nmemb, size);
189                  fprintf(stderr, "%s\n", message);
190                  exit(EXIT_FAILURE);
191              }
192
193       The above code example is available pre-packaged  as  the  explain_cal‐
194       loc_or_die(3) function.
195

SEE ALSO

197       calloc(3)
198               Allocate and clear memory
199
200       explain_calloc_or_die(3)
201               Allocate and clear memory and report errors
202
204       libexplain version 0.40
205       Copyright (C) 2010 Peter Miller
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209                                                             explain_calloc(3)
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