1 /*
2 * tmpname.c
3 * Original Author: G. Haley
4 */
5 /*
6 FUNCTION
7 <<tmpnam>>, <<tempnam>>---name for a temporary file
8
9 INDEX
10 tmpnam
11 INDEX
12 tempnam
13 INDEX
14 _tmpnam_r
15 INDEX
16 _tempnam_r
17
18 SYNOPSIS
19 #include <stdio.h>
20 char *tmpnam(char *<[s]>);
21 char *tempnam(char *<[dir]>, char *<[pfx]>);
22 char *_tmpnam_r(struct _reent *<[reent]>, char *<[s]>);
23 char *_tempnam_r(struct _reent *<[reent]>, char *<[dir]>, char *<[pfx]>);
24
25 DESCRIPTION
26 Use either of these functions to generate a name for a temporary file.
27 The generated name is guaranteed to avoid collision with other files
28 (for up to <<TMP_MAX>> calls of either function).
29
30 <<tmpnam>> generates file names with the value of <<P_tmpdir>>
31 (defined in `<<stdio.h>>') as the leading directory component of the path.
32
33 You can use the <<tmpnam>> argument <[s]> to specify a suitable area
34 of memory for the generated filename; otherwise, you can call
35 <<tmpnam(NULL)>> to use an internal static buffer.
36
37 <<tempnam>> allows you more control over the generated filename: you
38 can use the argument <[dir]> to specify the path to a directory for
39 temporary files, and you can use the argument <[pfx]> to specify a
40 prefix for the base filename.
41
42 If <[dir]> is <<NULL>>, <<tempnam>> will attempt to use the value of
43 environment variable <<TMPDIR>> instead; if there is no such value,
44 <<tempnam>> uses the value of <<P_tmpdir>> (defined in `<<stdio.h>>').
45
46 If you don't need any particular prefix to the basename of temporary
47 files, you can pass <<NULL>> as the <[pfx]> argument to <<tempnam>>.
48
49 <<_tmpnam_r>> and <<_tempnam_r>> are reentrant versions of <<tmpnam>>
50 and <<tempnam>> respectively. The extra argument <[reent]> is a
51 pointer to a reentrancy structure.
52
53 WARNINGS
54 The generated filenames are suitable for temporary files, but do not
55 in themselves make files temporary. Files with these names must still
56 be explicitly removed when you no longer want them.
57
58 If you supply your own data area <[s]> for <<tmpnam>>, you must ensure
59 that it has room for at least <<L_tmpnam>> elements of type <<char>>.
60
61 RETURNS
62 Both <<tmpnam>> and <<tempnam>> return a pointer to the newly
63 generated filename.
64
65 PORTABILITY
66 ANSI C requires <<tmpnam>>, but does not specify the use of
67 <<P_tmpdir>>. The System V Interface Definition (Issue 2) requires
68 both <<tmpnam>> and <<tempnam>>.
69
70 Supporting OS subroutines required: <<close>>, <<fstat>>, <<getpid>>,
71 <<isatty>>, <<lseek>>, <<open>>, <<read>>, <<sbrk>>, <<write>>.
72
73 The global pointer <<environ>> is also required.
74 */
75
76 #include <_ansi.h>
77 #include <stdio.h>
78 #include <stdlib.h>
79 #include <string.h>
80 #include <fcntl.h>
81 #include <errno.h>
82 #include <unistd.h>
83
84 /* Try to open the file specified, if it can't be opened then try
85 another one. Return nonzero if successful, otherwise zero. */
86
87 static int
worker(struct _reent * ptr,char * result,const char * part1,const char * part2,int part3,int * part4)88 worker (struct _reent *ptr,
89 char *result,
90 const char *part1,
91 const char *part2,
92 int part3,
93 int *part4)
94 {
95 /* Generate the filename and make sure that there isn't one called
96 it already. */
97
98 while (1)
99 {
100 int t;
101 _sprintf_r (ptr, result, "%s/%s%x.%x", part1, part2, part3, *part4);
102 (*part4)++;
103 t = open (result, O_RDONLY, 0);
104 if (t == -1)
105 {
106 if (__errno_r(ptr) == ENOSYS)
107 {
108 result[0] = '\0';
109 return 0;
110 }
111 break;
112 }
113 close (t);
114 }
115 return 1;
116 }
117
118 #define _TMPNAM_SIZE 25
119
120 static NEWLIB_THREAD_LOCAL char _tmpnam_buf[_TMPNAM_SIZE];
121
122 char *
_tmpnam_r(struct _reent * p,char * s)123 _tmpnam_r (struct _reent *p,
124 char *s)
125 {
126 char *result;
127 int pid;
128
129 if (s == NULL)
130 {
131 /* ANSI states we must use an internal static buffer if s is NULL */
132 result = _tmpnam_buf;
133 }
134 else
135 {
136 result = s;
137 }
138 pid = getpid ();
139
140 if (worker (p, result, P_tmpdir, "t", pid, &p->_inc))
141 {
142 p->_inc++;
143 return result;
144 }
145
146 return NULL;
147 }
148
149 char *
_tempnam_r(struct _reent * p,const char * dir,const char * pfx)150 _tempnam_r (struct _reent *p,
151 const char *dir,
152 const char *pfx)
153 {
154 char *filename;
155 int length;
156 const char *prefix = (pfx) ? pfx : "";
157 if (dir == NULL && (dir = getenv ("TMPDIR")) == NULL)
158 dir = P_tmpdir;
159
160 /* two 8 digit numbers + . / */
161 length = strlen (dir) + strlen (prefix) + (4 * sizeof (int)) + 2 + 1;
162
163 filename = malloc (length);
164 if (filename)
165 {
166 if (! worker (p, filename, dir, prefix,
167 getpid () ^ (int) (_POINTER_INT) p, &p->_inc))
168 return NULL;
169 }
170 return filename;
171 }
172
173 #ifndef _REENT_ONLY
174
175 char *
tempnam(const char * dir,const char * pfx)176 tempnam (const char *dir,
177 const char *pfx)
178 {
179 return _tempnam_r (_REENT, dir, pfx);
180 }
181
182 char *
tmpnam(char * s)183 tmpnam (char *s)
184 {
185 return _tmpnam_r (_REENT, s);
186 }
187
188 #endif
189