projects/linux·blob master · refs

146 lines · 2.8 KiB

1// SPDX-License-Identifier: GPL-2.0
2#include "util/copyfile.h"
3#include "util/namespaces.h"
4#include <internal/lib.h>
5#include <sys/mman.h>
6#include <sys/stat.h>
7#include <errno.h>
8#include <fcntl.h>
9#include <stdio.h>
10#include <stdlib.h>
11#include <string.h>
12#include <unistd.h>
13
14static int slow_copyfile(const char *from, const char *to, struct nsinfo *nsi)
15{
16 int err = -1;
17 char *line = NULL;
18 size_t n;
19 FILE *from_fp, *to_fp;
20 struct nscookie nsc;
21
22 nsinfo__mountns_enter(nsi, &nsc);
23 from_fp = fopen(from, "r");
24 nsinfo__mountns_exit(&nsc);
25 if (from_fp == NULL)
26 goto out;
27
28 to_fp = fopen(to, "w");
29 if (to_fp == NULL)
30 goto out_fclose_from;
31
32 while (getline(&line, &n, from_fp) > 0)
33 if (fputs(line, to_fp) == EOF)
34 goto out_fclose_to;
35 err = 0;
36out_fclose_to:
37 fclose(to_fp);
38 free(line);
39out_fclose_from:
40 fclose(from_fp);
41out:
42 return err;
43}
44
45int copyfile_offset(int ifd, loff_t off_in, int ofd, loff_t off_out, u64 size)
46{
47 void *ptr;
48 loff_t pgoff;
49
50 pgoff = off_in & ~(page_size - 1);
51 off_in -= pgoff;
52
53 ptr = mmap(NULL, off_in + size, PROT_READ, MAP_PRIVATE, ifd, pgoff);
54 if (ptr == MAP_FAILED)
55 return -1;
56
57 while (size) {
58 ssize_t ret = pwrite(ofd, ptr + off_in, size, off_out);
59 if (ret < 0 && errno == EINTR)
60 continue;
61 if (ret <= 0)
62 break;
63
64 size -= ret;
65 off_in += ret;
66 off_out += ret;
67 }
68 munmap(ptr, off_in + size);
69
70 return size ? -1 : 0;
71}
72
73static int copyfile_mode_ns(const char *from, const char *to, mode_t mode,
74 struct nsinfo *nsi)
75{
76 int fromfd, tofd;
77 struct stat st;
78 int err;
79 char *tmp = NULL, *ptr = NULL;
80 struct nscookie nsc;
81
82 nsinfo__mountns_enter(nsi, &nsc);
83 err = stat(from, &st);
84 nsinfo__mountns_exit(&nsc);
85 if (err)
86 goto out;
87 err = -1;
88
89 /* extra 'x' at the end is to reserve space for '.' */
90 if (asprintf(&tmp, "%s.XXXXXXx", to) < 0) {
91 tmp = NULL;
92 goto out;
93 }
94 ptr = strrchr(tmp, '/');
95 if (!ptr)
96 goto out;
97 ptr = memmove(ptr + 1, ptr, strlen(ptr) - 1);
98 *ptr = '.';
99
100 tofd = mkstemp(tmp);
101 if (tofd < 0)
102 goto out;
103
104 if (st.st_size == 0) { /* /proc? do it slowly... */
105 err = slow_copyfile(from, tmp, nsi);
106 if (!err && fchmod(tofd, mode))
107 err = -1;
108 goto out_close_to;
109 }
110
111 if (fchmod(tofd, mode))
112 goto out_close_to;
113
114 nsinfo__mountns_enter(nsi, &nsc);
115 fromfd = open(from, O_RDONLY);
116 nsinfo__mountns_exit(&nsc);
117 if (fromfd < 0)
118 goto out_close_to;
119
120 err = copyfile_offset(fromfd, 0, tofd, 0, st.st_size);
121
122 close(fromfd);
123out_close_to:
124 close(tofd);
125 if (!err)
126 err = link(tmp, to);
127 unlink(tmp);
128out:
129 free(tmp);
130 return err;
131}
132
133int copyfile_ns(const char *from, const char *to, struct nsinfo *nsi)
134{
135 return copyfile_mode_ns(from, to, 0755, nsi);
136}
137
138int copyfile_mode(const char *from, const char *to, mode_t mode)
139{
140 return copyfile_mode_ns(from, to, mode, NULL);
141}
142
143int copyfile(const char *from, const char *to)
144{
145 return copyfile_mode(from, to, 0755);
146}