decomp: fallback to write() if Linux vmsplice returns ENOSYS

[vlc] / modules / stream_filter / decomp.c

diff --git a/modules/stream_filter/decomp.c b/modules/stream_filter/decomp.c
index 32286165c3aafe68fc5e28a928f17fdc7b20d116..7ec7b512d02cb5ee0fa22ad2d5bee7a8fe7392ad 100644 (file)
--- a/modules/stream_filter/decomp.c
+++ b/modules/stream_filter/decomp.c
@@ -27,17 +27,22 @@
 #include <vlc_stream.h>
 #include <vlc_network.h>
 #include <unistd.h>
+#ifndef _POSIX_SPAWN
+# define _POSIX_SPAWN (-1)
+#endif
 #include <fcntl.h>
-#include <spawn.h>
+#if (_POSIX_SPAWN >= 0)
+# include <spawn.h>
+#endif
 #include <sys/wait.h>
 #include <sys/ioctl.h>
-#ifdef __linux__
+#if defined (__linux__) && defined (HAVE_VMSPLICE)
 # include <sys/uio.h>
 # include <sys/mman.h>
+#else
+# undef HAVE_VMSPLICE
 #endif
 
-#include <assert.h>
-
 static int  OpenGzip (vlc_object_t *);
 static int  OpenBzip2 (vlc_object_t *);
 static void Close (vlc_object_t *);
@@ -72,17 +77,18 @@ static void cloexec (int fd)
 extern char **environ;
 
 static const size_t bufsize = 65536;
+#ifdef HAVE_VMSPLICE
 static void cleanup_mmap (void *addr)
 {
     munmap (addr, bufsize);
 }
-
+#endif
 
 static void *Thread (void *data)
 {
     stream_t *stream = data;
     stream_sys_t *p_sys = stream->p_sys;
-#ifdef __linux__
+#ifdef HAVE_VMSPLICE
     ssize_t page_mask = sysconf (_SC_PAGE_SIZE) - 1;
 #endif
     int fd = p_sys->write_fd;
@@ -92,7 +98,7 @@ static void *Thread (void *data)
     {
         ssize_t len;
         int canc = vlc_savecancel ();
-#ifdef __linux__
+#ifdef HAVE_VMSPLICE
         unsigned char *buf = mmap (NULL, bufsize, PROT_READ|PROT_WRITE,
                                    MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
         vlc_cleanup_push (cleanup_mmap, buf);
@@ -106,7 +112,7 @@ static void *Thread (void *data)
 
         for (ssize_t i = 0, j; i < len; i += j)
         {
-#ifdef __linux__
+#ifdef HAVE_VMSPLICE
             if ((len - i) <= page_mask) /* incomplete last page */
                 j = write (fd, buf + i, len - i);
             else
@@ -114,9 +120,9 @@ static void *Thread (void *data)
                 struct iovec iov = { buf + i, (len - i) & ~page_mask, };
                 j = vmsplice (fd, &iov, 1, SPLICE_F_GIFT);
             }
-#else
-            j = write (fd, buf + i, len - i);
+            if (j == -1 && errno == ENOSYS) /* vmsplice() not supported */
 #endif
+            j = write (fd, buf + i, len - i);
             if (j <= 0)
             {
                 if (j == 0)
@@ -126,7 +132,7 @@ static void *Thread (void *data)
                 break;
             }
         }
-#ifdef __linux__
+#ifdef HAVE_VMSPLICE
         vlc_cleanup_run (); /* munmap (buf, bufsize) */
 #endif
     }
@@ -147,26 +153,31 @@ static int Read (stream_t *stream, void *buf, unsigned int buflen)
 {
     stream_sys_t *p_sys = stream->p_sys;
     block_t *peeked;
-    size_t bonus = 0;
     ssize_t length;
 
     if ((peeked = p_sys->peeked) != NULL)
-    {
-        bonus = (buflen > peeked->i_buffer) ? peeked->i_buffer : buflen;
-        memcpy (buf, peeked->p_buffer, bonus);
-        peeked->p_buffer += bonus;
-        peeked->i_buffer -= bonus;
+    {   /* dequeue peeked data */
+        length = (buflen > peeked->i_buffer) ? peeked->i_buffer : buflen;
+        memcpy (buf, peeked->p_buffer, length);
+        buf = ((char *)buf) + length;
+        buflen -= length;
+        peeked->p_buffer += length;
+        peeked->i_buffer -= length;
         if (peeked->i_buffer == 0)
         {
             block_Release (peeked);
             p_sys->peeked = NULL;
         }
+        p_sys->offset += length;
+
+        if (buflen > 0)
+            length += Read (stream, ((char *)buf) + length, buflen - length);
+        return length;
     }
 
     length = net_Read (stream, p_sys->read_fd, NULL, buf, buflen, false);
     if (length < 0)
         return 0;
-    length += bonus;
     p_sys->offset += length;
     return length;
 }
@@ -254,6 +265,8 @@ static int Open (stream_t *stream, const char *path)
     int ret = VLC_EGENERIC;
     int comp[2];
 
+    /* We use two pipes rather than one stream socket pair, so that we can
+     * use vmsplice() on Linux. */
     if (pipe (comp) == 0)
     {
         cloexec (comp[1]);
@@ -265,6 +278,7 @@ static int Open (stream_t *stream, const char *path)
             cloexec (uncomp[0]);
             p_sys->read_fd = uncomp[0];
 
+#if (_POSIX_SPAWN >= 0)
             posix_spawn_file_actions_t actions;
             if (posix_spawn_file_actions_init (&actions) == 0)
             {
@@ -288,6 +302,25 @@ static int Open (stream_t *stream, const char *path)
                 }
                 posix_spawn_file_actions_destroy (&actions);
             }
+#else /* _POSIX_SPAWN */
+            switch (p_sys->pid = fork ())
+            {
+                case -1:
+                    msg_Err (stream, "Cannot fork (%m)");
+                    break;
+                case 0:
+                    dup2 (comp[0], 0);
+                    close (comp[0]);
+                    dup2 (uncomp[1], 1);
+                    close (uncomp[1]);
+                    execlp (path, path, (char *)NULL);
+                    exit (1); /* if we get, execlp() failed! */
+                default:
+                    if (vlc_clone (&p_sys->thread, Thread, stream,
+                                   VLC_THREAD_PRIORITY_INPUT) == 0)
+                        ret = VLC_SUCCESS;
+            }
+#endif /* _POSIX_SPAWN < 0 */
             close (uncomp[1]);
             if (ret != VLC_SUCCESS)
                 close (uncomp[0]);