libbb: use external gzip command as I/O layer

[oweals/opkg-lede.git] / libbb / gzip.c

diff --git a/libbb/gzip.c b/libbb/gzip.c
new file mode 100644 (file)
index 0000000..ecdb5cb
--- /dev/null
+++ b/libbb/gzip.c
@@ -0,0 +1,208 @@
+/*
+ *  Copyright (C) 2016 Jo-Philipp Wich <jo@mein.io>
+ *  Copyright (C) 2016 Felix Fietkau <nbd@nbd.name>
+ *
+ *  Zlib decrompression utility routines.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Library General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+
+#include "gzip.h"
+
+static void
+to_devnull(int fd)
+{
+       int devnull = open("/dev/null", fd ? O_WRONLY : O_RDONLY);
+
+       if (devnull >= 0)
+               dup2(devnull, fd);
+
+       if (devnull > STDERR_FILENO)
+               close(devnull);
+}
+
+void *
+gzip_thread(void *ptr)
+{
+       struct gzip_handle *zh = ptr;
+       char buf[4096];
+       int len, ret;
+
+       while (1) {
+               if (zh->file)
+                       len = fread(buf, 1, sizeof(buf), zh->file);
+               else if (zh->gzip)
+                       len = gzip_read(zh->gzip, buf, sizeof(buf));
+
+               if (len <= 0)
+                       break;
+
+               do {
+                       ret = write(zh->wfd, buf, len);
+               } while (ret == -1 && errno == EINTR);
+       }
+
+       close(zh->wfd);
+       zh->wfd = -1;
+}
+
+int
+gzip_exec(struct gzip_handle *zh, const char *filename)
+{
+       int rpipe[2] = { -1, -1 }, wpipe[2] = { -1, -1 };
+       struct sigaction pipe_sa = { .sa_handler = SIG_IGN };
+
+       zh->rfd = -1;
+       zh->wfd = -1;
+
+       if (sigaction(SIGPIPE, &pipe_sa, &zh->pipe_sa) < 0)
+               return -1;
+
+       if (pipe(rpipe) < 0)
+               return -1;
+
+       if (!filename && pipe(wpipe) < 0) {
+               close(rpipe[0]);
+               close(rpipe[1]);
+               return -1;
+       }
+
+       zh->pid = vfork();
+
+       switch (zh->pid) {
+               case -1:
+                       return -1;
+
+               case 0:
+                       to_devnull(STDERR_FILENO);
+
+                       if (filename) {
+                               to_devnull(STDIN_FILENO);
+                       }
+                       else {
+                               dup2(wpipe[0], STDIN_FILENO);
+                               close(wpipe[0]);
+                               close(wpipe[1]);
+                       }
+
+                       dup2(rpipe[1], STDOUT_FILENO);
+                       close(rpipe[0]);
+                       close(rpipe[1]);
+
+                       execlp("gzip", "gzip", "-d",  "-c", filename, NULL);
+                       exit(-1);
+
+               default:
+                       zh->rfd = rpipe[0];
+                       zh->wfd = wpipe[1];
+
+                       fcntl(zh->rfd, F_SETFD, fcntl(zh->rfd, F_GETFD) | FD_CLOEXEC);
+                       close(rpipe[1]);
+
+                       if (zh->wfd >= 0) {
+                               fcntl(zh->wfd, F_SETFD, fcntl(zh->wfd, F_GETFD) | FD_CLOEXEC);
+                               close(wpipe[0]);
+                               pthread_create(&zh->thread, NULL, gzip_thread, zh);
+                       }
+       }
+
+       return 0;
+}
+
+ssize_t
+gzip_read(struct gzip_handle *zh, char *buf, ssize_t len)
+{
+       ssize_t ret;
+
+       do {
+               ret = read(zh->rfd, buf, len);
+       } while (ret == -1 && errno != EINTR);
+
+       return ret;
+}
+
+ssize_t
+gzip_copy(struct gzip_handle *zh, FILE *out, ssize_t len)
+{
+       char buf[4096];
+       ssize_t rlen, total = 0;
+
+       while (len > 0) {
+               rlen = gzip_read(zh, buf,
+                                   (len > sizeof(buf)) ? sizeof(buf) : len);
+
+               if (rlen <= 0)
+                       break;
+
+               if (out != NULL) {
+                       if (fwrite(buf, 1, rlen, out) != rlen)
+                               break;
+               }
+
+               len -= rlen;
+               total += rlen;
+       }
+
+       return total;
+}
+
+FILE *
+gzip_fdopen(struct gzip_handle *zh, const char *filename)
+{
+       memset(zh, 0, sizeof(*zh));
+
+       if (!filename || gzip_exec(zh, filename) < 0)
+               return NULL;
+
+       fcntl(zh->rfd, F_SETFL, fcntl(zh->rfd, F_GETFL) & ~O_NONBLOCK);
+
+       return fdopen(zh->rfd, "r");
+}
+
+int
+gzip_close(struct gzip_handle *zh)
+{
+       int code = -1;
+
+       if (zh->rfd >= 0)
+               close(zh->rfd);
+
+       if (zh->wfd >= 0)
+               close(zh->wfd);
+
+       if (zh->pid > 0) {
+               kill(zh->pid, SIGKILL);
+               waitpid(zh->pid, &code, 0);
+       }
+
+       if (zh->file)
+               fclose(zh->file);
+
+       if (zh->thread)
+               pthread_join(zh->thread, NULL);
+
+       sigaction(SIGPIPE, &zh->pipe_sa, NULL);
+
+       return WIFEXITED(code) ? WEXITSTATUS(code) : -1;
+}