1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
<head>
<title>Manual Page</title>
</head>
<body>
<pre>
<a href="ef_expand_file.html"><b>ef_expand_file</b></a> <a href="ef_expand_file.html"><b>ef_expand_file</b></a>
</pre><h2>NAME</h2><pre>
ef_expand_file, del_ExpandFile, ef_last_error, ef_list_expansions,
new_ExpandFile - expand filenames containing ~user/$envvar and wildcard
expressions
</pre><h2>SYNOPSIS</h2><pre>
#include <libtecla.h>
ExpandFile *new_ExpandFile(void);
ExpandFile *del_ExpandFile(ExpandFile *ef);
FileExpansion *ef_expand_file(ExpandFile *ef,
const char *path,
int pathlen);
int ef_list_expansions(FileExpansion *result, FILE *fp,
int term_width);
const char *ef_last_error(ExpandFile *ef);
</pre><h2>DESCRIPTION</h2><pre>
The ef_expand_file() function is part of the tecla library (see the
<a href="libtecla.html"><b>libtecla</b></a> man page). It expands a specified filename,
converting ~user/ and ~/ expressions at the start of the filename to
the corresponding home directories, replacing $envvar with the value of
the corresponding environment variable, and then, if there are any
wildcards, matching these against existing filenames. Backslashes in
the input filename are interpreted as escaping any special meanings of
the characters that follow them. Only backslahes that are themselves
preceded by backslashes are preserved in the expanded filename.
In the presence of wildcards, the returned list of filenames only
includes the names of existing files which match the wildcards. Other-
wise, the original filename is returned after expansion of tilde and
dollar expressions, and the result is not checked against existing
files. This mimics the file-globbing behavior of the unix tcsh shell.
The supported wildcards and their meanings are:
* - Match any sequence of zero or more characters.
? - Match any single character.
[chars] - Match any single character that appears in
'chars'. If 'chars' contains an expression of
the form a-b, then any character between a and
b, including a and b, matches. The '-'
character looses its special meaning as a
range specifier when it appears at the start
of the sequence of characters. The ']'
character also looses its significance as the
terminator of the range expression if it
appears immediately after the opening '[', at
which point it is treated one of the
characters of the range. If you want both '-'
and ']' to be part of the range, the '-'
should come first and the ']' second.
[^chars] - The same as [chars] except that it matches any
single character that doesn't appear in
'chars'.
Note that wildcards never match the initial dot in filenames that start
with '.'. The initial '.' must be explicitly specified in the filename.
This again mimics the globbing behavior of most unix shells, and its
rational is based in the fact that in unix, files with names that start
with '.' are usually hidden configuration files, which are not listed
by default by the ls command.
The following is a complete example of how to use the file expansion
function.
#include <stdio.h>
#include <libtecla.h>
int main(int argc, char *argv[])
{
ExpandFile *ef; /* The expansion resource object */
char *filename; /* The filename being expanded */
FileExpansion *expn; /* The results of the expansion */
int i;
ef = new_ExpandFile();
if(!ef)
return 1;
for(arg = *(argv++); arg; arg = *(argv++)) {
if((expn = ef_expand_file(ef, arg, -1)) == NULL) {
fprintf(stderr, "Error expanding %s (%s).\n", arg,
ef_last_error(ef));
} else {
printf("%s matches the following files:\n", arg);
for(i=0; i<expn->nfile; i++)
printf(" %s\n", expn->files[i]);
}
}
ef = del_ExpandFile(ef);
return 0;
}
Descriptions of the functions used above are as follows:
ExpandFile *new_ExpandFile(void)
This function creates the resources used by the ef_expand_file() func-
tion. In particular, it maintains the memory that is used to record the
array of matching filenames that is returned by ef_expand_file(). This
array is expanded as needed, so there is no built in limit to the num-
ber of files that can be matched.
ExpandFile *del_ExpandFile(ExpandFile *ef)
This function deletes the resources that were returned by a previous
call to new_ExpandFile(). It always returns NULL (ie a deleted object).
It does nothing if the ef argument is NULL.
A container of the following type is returned by ef_expand_file().
typedef struct {
int exists; /* True if the files in files[] exist */
int nfile; /* The number of files in files[] */
char **files; /* An array of 'nfile' filenames. */
} FileExpansion;
FileExpansion *ef_expand_file(ExpandFile *ef,
const char *path,
int pathlen)
The ef_expand_file() function performs filename expansion, as docu-
mented at the start of this section. Its first argument is a resource
object returned by new_ExpandFile(). A pointer to the start of the
filename to be matched is passed via the path argument. This must be a
normal NUL terminated string, but unless a length of -1 is passed in
pathlen, only the first pathlen characters will be used in the filename
expansion. If the length is specified as -1, the whole of the string
will be expanded.
The function returns a pointer to a container who's contents are the
results of the expansion. If there were no wildcards in the filename,
the nfile member will be 1, and the exists member should be queried if
it is important to know if the expanded file currently exists or not.
If there were wildcards, then the contained files[] array will contain
the names of the nfile existing files that matched the wildcarded file-
name, and the exists member will have the value 1. Note that the
returned container belongs to the specified ef object, and its contents
will change on each call, so if you need to retain the results of more
than one call to ef_expand_file(), you should either make a private
copy of the returned results, or create multiple file-expansion
resource objects via multiple calls to new_ExpandFile().
On error, NULL is returned, and an explanation of the error can be
determined by calling ef_last_error(ef).
const char *ef_last_error(ExpandFile *ef)
This function returns the message which describes the error that
occurred on the last call to ef_expand_file(), for the given (Expand-
File *ef) resource object.
int ef_list_expansions(FileExpansion *result, FILE *fp,
int terminal_width);
The ef_list_expansions() function provides a convenient way to list the
filename expansions returned by ef_expand_file(). Like the unix ls com-
mand, it arranges the filenames into equal width columns, each column
having the width of the largest file. The number of columns used is
thus determined by the length of the longest filename, and the speci-
fied terminal width. Beware that filenames that are longer than the
specified terminal width are printed without being truncated, so output
longer than the specified terminal width can occur. The list is written
to the stdio stream specified by the fp argument.
</pre><h2>THREAD SAFETY</h2><pre>
In multi-threaded programs, you should use the libtecla_r.a version of
the library. This uses POSIX reentrant functions where available (hence
the _r suffix), and disables features that rely on non-reentrant system
functions. Currently there are no features disabled in this module.
Using the libtecla_r.a version of the library, it is safe to use the
facilities of this module in multiple threads, provided that each
thread uses a separately allocated ExpandFile object. In other words,
if two threads want to do file expansion, they should each call
new_ExpandFile() to allocate their own file-expansion objects.
</pre><h2>FILES</h2><pre>
libtecla.a - The tecla library
libtecla.h - The tecla header file.
</pre><h2>SEE ALSO</h2><pre>
<a href="libtecla.html"><b>libtecla</b></a>, <a href="gl_get_line.html"><b>gl_get_line</b></a>, <a href="cpl_complete_word.html"><b>cpl_complete_word</b></a>,
<a href="pca_lookup_file.html"><b>pca_lookup_file</b></a>
</pre><h2>AUTHOR</h2><pre>
Martin Shepherd (mcs@astro.caltech.edu)
<a href="ef_expand_file.html"><b>ef_expand_file</b></a>
</pre>
</body>
|
