tools/perf/util/copyfile.c

   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
  14 static 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;
  36 out_fclose_to:
  37         fclose(to_fp);
  38         free(line);
  39 out_fclose_from:
  40         fclose(from_fp);
  41 out:
  42         return err;
  43 }
  44
  45 int 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
  73 static 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);
 123 out_close_to:
 124         close(tofd);
 125         if (!err)
 126                 err = link(tmp, to);
 127         unlink(tmp);
 128 out:
 129         free(tmp);
 130         return err;
 131 }
 132
 133 int copyfile_ns(const char *from, const char *to, struct nsinfo *nsi)
 134 {
 135         return copyfile_mode_ns(from, to, 0755, nsi);
 136 }
 137
 138 int copyfile_mode(const char *from, const char *to, mode_t mode)
 139 {
 140         return copyfile_mode_ns(from, to, mode, NULL);
 141 }
 142
 143 int copyfile(const char *from, const char *to)
 144 {
 145         return copyfile_mode(from, to, 0755);
 146 }