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 static void *gzip_thread(void *ptr)
  45 {
  46         struct gzip_handle *zh = ptr;
  47         char buf[4096];
  48         int len = 0, 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         return NULL;
  68 }
  69
  70 int gzip_exec(struct gzip_handle *zh, const char *filename)
  71 {
  72         int rpipe[2] = { -1, -1 }, wpipe[2] = {
  73         -1, -1};
  74         struct sigaction pipe_sa = {.sa_handler = SIG_IGN };
  75
  76         zh->rfd = -1;
  77         zh->wfd = -1;
  78
  79         if (sigaction(SIGPIPE, &pipe_sa, &zh->pipe_sa) < 0)
  80                 return -1;
  81
  82         if (pipe(rpipe) < 0)
  83                 return -1;
  84
  85         if (!filename && pipe(wpipe) < 0) {
  86                 close(rpipe[0]);
  87                 close(rpipe[1]);
  88                 return -1;
  89         }
  90
  91         zh->pid = vfork();
  92
  93         switch (zh->pid) {
  94         case -1:
  95                 return -1;
  96
  97         case 0:
  98                 to_devnull(STDERR_FILENO);
  99
 100                 if (filename) {
 101                         to_devnull(STDIN_FILENO);
 102                 } else {
 103                         dup2(wpipe[0], STDIN_FILENO);
 104                         close(wpipe[0]);
 105                         close(wpipe[1]);
 106                 }
 107
 108                 dup2(rpipe[1], STDOUT_FILENO);
 109                 close(rpipe[0]);
 110                 close(rpipe[1]);
 111
 112                 execlp("gzip", "gzip", "-d", "-c", filename, NULL);
 113                 exit(-1);
 114
 115         default:
 116                 zh->rfd = rpipe[0];
 117                 zh->wfd = wpipe[1];
 118
 119                 fcntl(zh->rfd, F_SETFD, fcntl(zh->rfd, F_GETFD) | FD_CLOEXEC);
 120                 close(rpipe[1]);
 121
 122                 if (zh->wfd >= 0) {
 123                         fcntl(zh->wfd, F_SETFD,
 124                               fcntl(zh->wfd, F_GETFD) | FD_CLOEXEC);
 125                         close(wpipe[0]);
 126                         pthread_create(&zh->thread, NULL, gzip_thread, zh);
 127                 }
 128         }
 129
 130         return 0;
 131 }
 132
 133 ssize_t gzip_read(struct gzip_handle * zh, void *buf, ssize_t len)
 134 {
 135         ssize_t ret;
 136
 137         do {
 138                 ret = read(zh->rfd, buf, len);
 139         } while (ret == -1 && errno != EINTR);
 140
 141         return ret;
 142 }
 143
 144 ssize_t gzip_copy(struct gzip_handle * zh, FILE * out, ssize_t len)
 145 {
 146         char buf[4096];
 147         ssize_t rlen, total = 0;
 148
 149         while (len > 0) {
 150                 rlen = gzip_read(zh, buf,
 151                                  (len > sizeof(buf)) ? sizeof(buf) : len);
 152
 153                 if (rlen <= 0)
 154                         break;
 155
 156                 if (out != NULL) {
 157                         if (fwrite(buf, 1, rlen, out) != rlen)
 158                                 break;
 159                 }
 160
 161                 len -= rlen;
 162                 total += rlen;
 163         }
 164
 165         return total;
 166 }
 167
 168 FILE *gzip_fdopen(struct gzip_handle * zh, const char *filename)
 169 {
 170         memset(zh, 0, sizeof(*zh));
 171
 172         if (!filename || gzip_exec(zh, filename) < 0)
 173                 return NULL;
 174
 175         fcntl(zh->rfd, F_SETFL, fcntl(zh->rfd, F_GETFL) & ~O_NONBLOCK);
 176
 177         return fdopen(zh->rfd, "r");
 178 }
 179
 180 int gzip_close(struct gzip_handle *zh)
 181 {
 182         int code = -1;
 183
 184         if (zh->rfd >= 0)
 185                 close(zh->rfd);
 186
 187         if (zh->wfd >= 0)
 188                 close(zh->wfd);
 189
 190         if (zh->pid > 0) {
 191                 kill(zh->pid, SIGKILL);
 192                 waitpid(zh->pid, &code, 0);
 193         }
 194
 195         if (zh->file)
 196                 fclose(zh->file);
 197
 198         if (zh->thread)
 199                 pthread_join(zh->thread, NULL);
 200
 201         sigaction(SIGPIPE, &zh->pipe_sa, NULL);
 202
 203         return WIFEXITED(code) ? WEXITSTATUS(code) : -1;
 204 }