1explain_malloc(3) Library Functions Manual explain_malloc(3)
2
6 explain_malloc - explain malloc(3) errors
7
9 #include <libexplain/malloc.h>
10 const char *explain_malloc(size_t size);
11 const char *explain_errno_malloc(int errnum, size_t size);
12 void explain_message_malloc(char *message, int message_size, size_t
13 size);
14 void explain_message_errno_malloc(char *message, int message_size, int
15 errnum, size_t size);
16
18 These functions may be used to obtain explanations for errors returned
19 by the malloc(3) system call.
20 explain_malloc
22 const char *explain_malloc(size_t size);
23 The explain_malloc function is used to obtain an explanation of an
25 error returned by the malloc(3) system call. The least the message
26 will contain is the value of strerror(errno), but usually it will do
27 much better, and indicate the underlying cause in more detail.
28 The errno global variable will be used to obtain the error value to be
30 decoded.
31 This function is intended to be used in a fashion similar to the fol‐
33 lowing example:
34 if (malloc(size) < 0)
35 {
36 fprintf(stderr, "%s\n", explain_malloc(size));
37 exit(EXIT_FAILURE);
38 }
39 The above code example is available pre‐packaged as the explain_mal‐
41 loc_or_die(3) function.
42 size The original size, exactly as passed to the malloc(3) system
44 call.
45 Returns:
47 The message explaining the error. This message buffer is
48 shared by all libexplain functions which do not supply a buffer
49 in their argument list. This will be overwritten by the next
50 call to any libexplain function which shares this buffer,
51 including other threads.
52 Note: This function is not thread safe, because it shares a return buf‐
54 fer across all threads, and many other functions in this library.
55 explain_errno_malloc
57 const char *explain_errno_malloc(int errnum, size_t size);
58 The explain_errno_malloc function is used to obtain an explanation of
60 an error returned by the malloc(3) system call. The least the message
61 will contain is the value of strerror(errnum), but usually it will do
62 much better, and indicate the underlying cause in more detail.
63 This function is intended to be used in a fashion similar to the fol‐
65 lowing example:
66 if (malloc(size) < 0)
67 {
68 int err = errno;
69 fprintf(stderr, "%s\n", explain_errno_malloc(err, size));
70 exit(EXIT_FAILURE);
71 }
72 The above code example is available pre‐packaged as the explain_mal‐
74 loc_or_die(3) function.
75 errnum The error value to be decoded, usually obtained from the errno
77 global variable just before this function is called. This is
78 necessary if you need to call any code between the system call
79 to be explained and this function, because many libc functions
80 will alter the value of errno.
81 size The original size, exactly as passed to the malloc(3) system
83 call.
84 Returns:
86 The message explaining the error. This message buffer is
87 shared by all libexplain functions which do not supply a buffer
88 in their argument list. This will be overwritten by the next
89 call to any libexplain function which shares this buffer,
90 including other threads.
91 Note: This function is not thread safe, because it shares a return buf‐
93 fer across all threads, and many other functions in this library.
94 explain_message_malloc
96 void explain_message_malloc(char *message, int message_size, size_t
97 size);
98 The explain_message_malloc function may be used to obtain an explana‐
100 tion of an error returned by the malloc(3) system call. The least the
101 message will contain is the value of strerror(errno), but usually it
102 will do much better, and indicate the underlying cause in more detail.
103 The errno global variable will be used to obtain the error value to be
105 decoded.
106 This function is intended to be used in a fashion similar to the fol‐
108 lowing example:
109 if (malloc(size) < 0)
110 {
111 char message[3000];
112 explain_message_malloc(message, sizeof(message), size);
113 fprintf(stderr, "%s\n", message);
114 exit(EXIT_FAILURE);
115 }
116 The above code example is available pre‐packaged as the explain_mal‐
118 loc_or_die(3) function.
119 message The location in which to store the returned message. If a
121 suitable message return buffer is supplied, this function is
122 thread safe.
123 message_size
125 The size in bytes of the location in which to store the
126 returned message.
127 size The original size, exactly as passed to the malloc(3) system
129 call.
130 explain_message_errno_malloc
132 void explain_message_errno_malloc(char *message, int message_size, int
133 errnum, size_t size);
134 The explain_message_errno_malloc function may be used to obtain an
136 explanation of an error returned by the malloc(3) system call. The
137 least the message will contain is the value of strerror(errnum), but
138 usually it will do much better, and indicate the underlying cause in
139 more detail.
140 This function is intended to be used in a fashion similar to the fol‐
142 lowing example:
143 if (malloc(size) < 0)
144 {
145 int err = errno;
146 char message[3000];
147 explain_message_errno_malloc(message, sizeof(message), err, size);
148 fprintf(stderr, "%s\n", message);
149 exit(EXIT_FAILURE);
150 }
151 The above code example is available pre‐packaged as the explain_mal‐
153 loc_or_die(3) function.
154 message The location in which to store the returned message. If a
156 suitable message return buffer is supplied, this function is
157 thread safe.
158 message_size
160 The size in bytes of the location in which to store the
161 returned message.
162 errnum The error value to be decoded, usually obtained from the errno
164 global variable just before this function is called. This is
165 necessary if you need to call any code between the system call
166 to be explained and this function, because many libc functions
167 will alter the value of errno.
168 size The original size, exactly as passed to the malloc(3) system
170 call.
171
173 malloc(3)
174 Allocate and free dynamic memory
175 explain_malloc_or_die(3)
177 Allocate and free dynamic memory and report errors
178
180 libexplain version 1.4
181 Copyright (C) 2009 Peter Miller
182 explain_malloc(3)