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
|
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define __USE_BSD
#include <unistd.h>
#include <errno.h>
#define FALSE 0
#define TRUE 1
int double_buffers( size_t s, char** b1, char** b2, char** b3, char** b4 ) {
char* n;
n = realloc( *b1, s*2 );
if ( n == NULL ) return FALSE;
else *b1 = n;
n = realloc( *b2, s*2 );
if ( n == NULL ) return FALSE;
else *b2 = n;
n = realloc( *b3, s*2 );
if ( n == NULL ) return FALSE;
else *b3 = n;
n = realloc( *b4, s*2 );
if ( n == NULL ) return FALSE;
else *b4 = n;
return TRUE;
}
int main(void) {
size_t sz_buffs = 1000;
char *buffer = malloc(sz_buffs); /* user's input */
char *cwd = malloc(sz_buffs); /* expanded dirname */
char *basename = malloc(sz_buffs); /* basename */
char *last = malloc(sz_buffs); /* directory the link was in */
char *pch;
if ( buffer == NULL ) return EXIT_FAILURE;
if ( cwd == NULL ) return EXIT_FAILURE;
if ( basename == NULL ) return EXIT_FAILURE;
for(;;) {
if ( fgets(buffer, sz_buffs, stdin) == NULL ) break;
for ( pch = buffer + strlen(buffer) - 1;
*pch != '\n' && pch == buffer + sz_buffs - 2;
pch += strlen(pch) - 1 )
{
assert( pch[1] == '\0' );
if ( double_buffers( sz_buffs, &buffer, &cwd, &basename, &last )) {
sz_buffs *= 2;
} else {
break;
}
pch = buffer + strlen(buffer) - 1;
if ( fgets(pch+1, sz_buffs/2+1, stdin) == NULL ) break;
}
assert( pch == buffer + strlen(buffer) - 1 );
if ( *pch == '\n' ) *pch = '\0';
for ( ; pch > buffer && *pch != '/'; pch-- )
;
if ( buffer[0] != '/' ) { /* don't even try relative paths */
if (printf("%s\n", buffer) < 0)
return EXIT_FAILURE;
continue;
}
strncpy( last, buffer, pch - buffer + 1 );
last[pch-buffer+1] = '\0';
for(;;) {
int numchars;
/* basename == link */
numchars = readlink( buffer, basename, sz_buffs - 1 );
if ( numchars != -1 && (unsigned)numchars < sz_buffs - 1 ) {
chdir(last);
basename[numchars] = 0;
strcpy(buffer,basename);
break;
}
if ( (unsigned)numchars == sz_buffs - 1 || errno == ENAMETOOLONG ) {
if (double_buffers( sz_buffs, &buffer, &cwd,
&basename, &last )) {
sz_buffs *= 2;
} else {
fprintf( stderr, "Error. Out of memory." );
exit(EXIT_FAILURE);
}
} else {
break;
}
}
for ( pch = buffer+strlen(buffer);
pch > buffer && *pch != '/';
pch-- )
;
if ( *pch != '/' ) { /* then buffer = "xyzzy", w/o a dir */
strcpy( basename, buffer );
strcpy( buffer, "./" );
} else {
strcpy( basename, pch + 1 );
*(pch+1) = '\0';
}
if ( 0 == chdir( buffer ) ) {
while ( NULL == getcwd( cwd, sz_buffs ) ) {
if ( double_buffers( sz_buffs, &buffer, &cwd,
&basename, &last ) )
{
sz_buffs *= 2;
} else {
break;
}
}
pch = cwd + strlen(cwd) - 1;
if ( *pch != '/' ) {
pch[1] = '/'; pch[2] = '\0';
}
} else {
if ( buffer[0] == '/' ) {
strcpy( cwd, buffer );
} else {
strcpy( cwd, last );
strcat( cwd, buffer ); /* may overflow XXXXX */
}
pch = cwd + strlen(cwd) - 1;
if ( *pch != '/' ) {
pch[1] = '/'; pch[2] = '\0';
}
}
if (printf("%s%s\n", cwd, basename) < 0)
return EXIT_FAILURE;
}
if (fclose(stdout) != 0)
return EXIT_FAILURE;
free(cwd);
free(buffer);
free(basename);
return 0;
}
|
