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36 .\" @(#)tmpnam.3 8.2 (Berkeley) 11/17/93
37 .\" $FreeBSD: src/lib/libc/stdio/tmpnam.3,v 1.16 2004/06/21 19:38:25 mpp Exp $
46 .Nd temporary file routines
68 returns a pointer to a stream associated with a file descriptor returned
71 The created file is unlinked before
73 returns, causing the file to be automatically deleted when the last
74 reference to it is closed.
75 The file is opened with the access value
77 If the environment variable
80 the file is created in the specified directory.
81 The default location, if
89 returns a pointer to a file name, in the
92 did not reference an existing file at some indeterminate point in the
95 is defined in the include file
101 the file name is copied to the buffer it references.
102 Otherwise, the file name is copied to a static buffer.
105 returns a pointer to the file name.
107 The buffer referenced by
109 is expected to be at least
113 is defined in the include file
121 but provides the ability to specify the directory which will
122 contain the temporary file and the file name prefix.
130 the environment variable
135 and finally, the current directory,
136 are tried, in the listed order, as directories in which to store the
143 is used to specify a file name prefix, which will be the
144 first part of the created file name.
148 allocates memory in which to store the file name; the returned pointer
149 may be used as a subsequent argument to
155 returns a pointer to an open file stream on success, and a
165 return a pointer to a file name on success, and a
173 may fail and set the global variable
175 for any of the errors specified for the library functions
185 for any of the errors specified for the library function
193 for any of the errors specified for the library functions
197 .Sh SECURITY CONSIDERATIONS
202 functions are susceptible to a race condition
203 occurring between the selection of the file name
204 and the creation of the file,
205 which allows malicious users
206 to potentially overwrite arbitrary files in the system,
207 depending on the level of privilege of the running program.
208 Additionally, there is no means by which
209 file permissions may be specified.
210 It is strongly suggested that
212 be used in place of these functions.
216 These interfaces are provided from System V and
220 Most historic implementations of these functions provide
221 only a limited number of possible temporary file names
223 before file names will start being recycled.
224 System V implementations of these functions
229 system call to determine whether or not the temporary file
231 This has obvious ramifications for setuid or setgid programs,
232 complicating the portable use of these interfaces in such programs.
236 interface should not be used in software expected to be used on other systems
237 if there is any possibility that the user does not wish the temporary file to
238 be publicly readable and writable.
239 .Sh LEGACY DESCRIPTION
240 In legacy mode, the order directories are tried by the
242 function is different; the environment variable
244 (if defined) is used first.