libbb/gzip.c

   1 /*
   2  *  Copyright (C) 2016 Jo-Philipp Wich <jo@mein.io>
   3  *  Copyright (C) 2016 Felix Fietkau <nbd@nbd.name>
   4  *
   5  *  Zlib decrompression utility routines.
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; either version 2 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU Library General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with this program; if not, write to the Free Software
  19  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20  */
  21
  22 #include <string.h>
  23 #include <errno.h>
  24 #include <fcntl.h>
  25 #include <unistd.h>
  26 #include <poll.h>
  27 #include <stdlib.h>
  28 #include <sys/stat.h>
  29 #include <sys/wait.h>
  30
  31 #include "gzip.h"
  32
  33 static void to_devnull(int fd)
  34 {
  35         int devnull = open("/dev/null", fd ? O_WRONLY : O_RDONLY);
  36
  37         if (devnull >= 0)
  38                 dup2(devnull, fd);
  39
  40         if (devnull > STDERR_FILENO)
  41                 close(devnull);
  42 }
  43
  44 void *gzip_thread(void *ptr)
  45 {
  46         struct gzip_handle *zh = ptr;
  47         char buf[4096];
  48         int len, ret;
  49
  50         while (1) {
  51                 if (zh->file)
  52                         len = fread(buf, 1, sizeof(buf), zh->file);
  53                 else if (zh->gzip)
  54                         len = gzip_read(zh->gzip, buf, sizeof(buf));
  55
  56                 if (len <= 0)
  57                         break;
  58
  59                 do {
  60                         ret = write(zh->wfd, buf, len);
  61                 } while (ret == -1 && errno == EINTR);
  62         }
  63
  64         close(zh->wfd);
  65         zh->wfd = -1;
  66 }
  67
  68 int gzip_exec(struct gzip_handle *zh, const char *filename)
  69 {
  70         int rpipe[2] = { -1, -1 }, wpipe[2] = {
  71         -1, -1};
  72         struct sigaction pipe_sa = {.sa_handler = SIG_IGN };
  73
  74         zh->rfd = -1;
  75         zh->wfd = -1;
  76
  77         if (sigaction(SIGPIPE, &pipe_sa, &zh->pipe_sa) < 0)
  78                 return -1;
  79
  80         if (pipe(rpipe) < 0)
  81                 return -1;
  82
  83         if (!filename && pipe(wpipe) < 0) {
  84                 close(rpipe[0]);
  85                 close(rpipe[1]);
  86                 return -1;
  87         }
  88
  89         zh->pid = vfork();
  90
  91         switch (zh->pid) {
  92         case -1:
  93                 return -1;
  94
  95         case 0:
  96                 to_devnull(STDERR_FILENO);
  97
  98                 if (filename) {
  99                         to_devnull(STDIN_FILENO);
 100                 } else {
 101                         dup2(wpipe[0], STDIN_FILENO);
 102                         close(wpipe[0]);
 103                         close(wpipe[1]);
 104                 }
 105
 106                 dup2(rpipe[1], STDOUT_FILENO);
 107                 close(rpipe[0]);
 108                 close(rpipe[1]);
 109
 110                 execlp("gzip", "gzip", "-d", "-c", filename, NULL);
 111                 exit(-1);
 112
 113         default:
 114                 zh->rfd = rpipe[0];
 115                 zh->wfd = wpipe[1];
 116
 117                 fcntl(zh->rfd, F_SETFD, fcntl(zh->rfd, F_GETFD) | FD_CLOEXEC);
 118                 close(rpipe[1]);
 119
 120                 if (zh->wfd >= 0) {
 121                         fcntl(zh->wfd, F_SETFD,
 122                               fcntl(zh->wfd, F_GETFD) | FD_CLOEXEC);
 123                         close(wpipe[0]);
 124                         pthread_create(&zh->thread, NULL, gzip_thread, zh);
 125                 }
 126         }
 127
 128         return 0;
 129 }
 130
 131 ssize_t gzip_read(struct gzip_handle * zh, char *buf, ssize_t len)
 132 {
 133         ssize_t ret;
 134
 135         do {
 136                 ret = read(zh->rfd, buf, len);
 137         } while (ret == -1 && errno != EINTR);
 138
 139         return ret;
 140 }
 141
 142 ssize_t gzip_copy(struct gzip_handle * zh, FILE * out, ssize_t len)
 143 {
 144         char buf[4096];
 145         ssize_t rlen, total = 0;
 146
 147         while (len > 0) {
 148                 rlen = gzip_read(zh, buf,
 149                                  (len > sizeof(buf)) ? sizeof(buf) : len);
 150
 151                 if (rlen <= 0)
 152                         break;
 153
 154                 if (out != NULL) {
 155                         if (fwrite(buf, 1, rlen, out) != rlen)
 156                                 break;
 157                 }
 158
 159                 len -= rlen;
 160                 total += rlen;
 161         }
 162
 163         return total;
 164 }
 165
 166 FILE *gzip_fdopen(struct gzip_handle * zh, const char *filename)
 167 {
 168         memset(zh, 0, sizeof(*zh));
 169
 170         if (!filename || gzip_exec(zh, filename) < 0)
 171                 return NULL;
 172
 173         fcntl(zh->rfd, F_SETFL, fcntl(zh->rfd, F_GETFL) & ~O_NONBLOCK);
 174
 175         return fdopen(zh->rfd, "r");
 176 }
 177
 178 int gzip_close(struct gzip_handle *zh)
 179 {
 180         int code = -1;
 181
 182         if (zh->rfd >= 0)
 183                 close(zh->rfd);
 184
 185         if (zh->wfd >= 0)
 186                 close(zh->wfd);
 187
 188         if (zh->pid > 0) {
 189                 kill(zh->pid, SIGKILL);
 190                 waitpid(zh->pid, &code, 0);
 191         }
 192
 193         if (zh->file)
 194                 fclose(zh->file);
 195
 196         if (zh->thread)
 197                 pthread_join(zh->thread, NULL);
 198
 199         sigaction(SIGPIPE, &zh->pipe_sa, NULL);
 200
 201         return WIFEXITED(code) ? WEXITSTATUS(code) : -1;
 202 }