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
| #include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/errno.h>
ssize_t read_ex(int fd, void *buf, size_t nbyte){
size_t read_remain = nbyte;
unsigned char *read_start = (unsigned char*)buf;
ssize_t read_num = -1;
ssize_t total_num = 0;
while(read_remain) {
read_num = read(fd, read_start, read_remain);
if(-1 == read_num){
return -1;
}
else if(0 == read_num){
break;
}
else{
read_remain -= read_num;
read_start += read_num;
total_num += read_num;
}
}
return total_num;
}
ssize_t write_ex(int fd, const void *buf, size_t nbyte){
size_t write_remain = nbyte;
unsigned char *write_start = (unsigned char*)buf;
ssize_t write_num = -1;
ssize_t total_num = 0;
while(write_remain) {
write_num = write(fd, write_start, write_remain);
if(-1 == write_num){
return -1;
}
else{
write_remain -= write_num;
write_start += write_num;
total_num += write_num;
}
}
return total_num;
}
int my_cp(const char *from, const char *to)
{
int fd1 = -1, fd2 = -1;
int rev = -1;
unsigned char *buffer = NULL, *buffer_zero = NULL;
long pagesize = 0;
long long blocks, blksize, size;
int read_num, write_num, write_remain, have_holes = 0;
struct stat st;
fd1 = open(from, O_RDONLY);
if(-1 == fd1){
perror("open file1 faild");
goto err;
}
if(fstat(fd1, &st) !=0) {
perror("fstat: ");
goto err;
}
else{
#ifdef _SC_PAGESIZE
pagesize = sysconf(_SC_PAGESIZE);
if (pagesize < 0) {
if (errno != 0) {
if (errno == EINVAL) {
fputs(" (not supported)\n", stdout);
pagesize = st.st_blksize;
}
else {
perror("sysconf error");
goto err;
}
} else {
fputs(" (no limit)\n", stdout);
pagesize = st.st_blksize;
}
}
printf("pagesize: %ld\n", pagesize);
#else
pagesize = st.st_blksize;
#endif
blocks = st.st_blocks;
blksize = st.st_blksize;
size = st.st_size;
printf("st.st_blocks: %lld\n", blocks);
printf("st.st_blksize: %lld\n", blksize);
printf("st.st_size: %lld\n", size);
if(S_ISREG(st.st_mode) && (size / pagesize + (size%pagesize?1:0)) * pagesize > 512 * blocks) {
have_holes = 1;
printf("%s is a sparse-block file!\n", from);
} else{
have_holes = 0;
printf("%s is not a sparse-block file!\n", from);
}
}
buffer = malloc(pagesize);
buffer_zero = malloc(pagesize);
if(buffer == NULL || buffer_zero == NULL) {
perror ("malloc fail");
goto err;
}
memset(buffer, '\0', pagesize);
memset(buffer_zero, '\0', pagesize);
fd2 = open(to, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
if (-1 == fd2) {
perror ("open file2 faild");
goto err;
}
while((read_num = read_ex(fd1, buffer, pagesize)) > 0) {
if(have_holes && !memcmp(buffer_zero, buffer, read_num)){
if(-1 == lseek(fd2, read_num, SEEK_CUR)){
perror("lseek file2 fail");
goto err;
}
}
else{
write_num = write_ex(fd2, buffer, read_num);
if (-1 == write_num){
perror( "write file2 error");
goto err;
}
}
}
if(-1 == read_num){
perror("read file1 error");
goto err;
}
rev = 0;
err:
if(buffer) free(buffer);
if(buffer_zero) free(buffer_zero);
close(fd1);
close(fd2);
return rev;
}
int main(int argc, char *argv[])
{
if(argc < 3) {
printf("Usage: %s file1 file2\n", argv[0]);
return -1;
}
my_cp(argv[1], argv[2]);
return 0;
}
|
v1.5.2