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}