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plugins/elements/gstfilesrc.c: Do not use mmap() by default since there are a number of error conditions that we woul...

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Original commit message from CVS:
* plugins/elements/gstfilesrc.c: (gst_file_src_class_init):
Do not use mmap() by default since there are a number of error
conditions that we would like to handle in a non-fatal way that
will result in a SIGBUS if we use mmap(). Examples: external
devices (USB harddrive, portable music player) being unplugged
while in use; file on mounted CD/DVD that can't be read because
the medium is partly damaged. Fixes #348455 and #348475.
This commit is contained in:
Tim-Philipp Müller 2006-07-27 10:54:29 +00:00
parent 4c30bdfb0e
commit 55a6159205
2 changed files with 34 additions and 4 deletions
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10
ChangeLog
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@ -1,3 +1,13 @@
2006-07-27 Tim-Philipp Müller <tim at centricular dot net>
* plugins/elements/gstfilesrc.c: (gst_file_src_class_init):
Do not use mmap() by default since there are a number of error
conditions that we would like to handle in a non-fatal way that
will result in a SIGBUS if we use mmap(). Examples: external
devices (USB harddrive, portable music player) being unplugged
while in use; file on mounted CD/DVD that can't be read because
the medium is partly damaged. Fixes #348455 and #348475.
2006-07-27 Jan Schmidt <thaytan@mad.scientist.com>
* gst/gstquery.h:

28
plugins/elements/gstfilesrc.c
View file

@ -24,8 +24,7 @@
* @short_description: read from arbitrary point in a file
* @see_also: #GstFileSrc
*
* Read data from a file in the local file system. The implementation is using
* mmap(2) to read chunks from the file in an efficient way.
* Read data from a file in the local file system.
*/
#ifdef HAVE_CONFIG_H
@ -81,6 +80,9 @@ static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
* GStreamer Default File Source
* Theory of Operation
*
* Update: see GstFileSrc:use-mmap property documentation below
* for why use of mmap() is disabled by default.
*
* This source uses mmap(2) to efficiently load data from a file.
* To do this without seriously polluting the applications' memory
* space, it must do so in smaller chunks, say 1-4MB at a time.
@ -132,7 +134,7 @@ enum
#define DEFAULT_BLOCKSIZE 4*1024
#define DEFAULT_MMAPSIZE 4*1024*1024
#define DEFAULT_TOUCH TRUE
#define DEFAULT_USEMMAP TRUE
#define DEFAULT_USEMMAP FALSE
#define DEFAULT_SEQUENTIAL FALSE
enum
@ -221,9 +223,27 @@ gst_file_src_class_init (GstFileSrcClass * klass)
g_param_spec_boolean ("touch", "Touch mapped region read data",
"Touch mmapped data regions to force them to be read from disk",
DEFAULT_TOUCH, G_PARAM_READWRITE));
/**
* GstFileSrc:use-mmap
*
* Whether to use mmap(). Set to TRUE to force use of mmap() instead of
* read() for reading data.
*
* Use of mmap() is disabled by default since with mmap() there are a
* number of occasions where the process/application will be notified of
* read errors via a SIGBUS signal from the kernel, which will lead to
* the application being killed if not handled by the application. This
* is something that is difficult to work around for a library like
* GStreamer, hence use of mmap() is disabled by default. Said errors
* can occur for example when an external device (e.g. an external hard
* drive or a portable music player) are unplugged while in use, or when
* a CD/DVD medium cannot be be read because the medium is scratched or
* otherwise damaged.
*
**/
g_object_class_install_property (gobject_class, ARG_USEMMAP,
g_param_spec_boolean ("use-mmap", "Use mmap to read data",
"Whether to use mmap. FALSE to force normal read() calls",
"Whether to use mmap() instead of read()",
DEFAULT_USEMMAP, G_PARAM_READWRITE));
g_object_class_install_property (gobject_class, ARG_SEQUENTIAL,
g_param_spec_boolean ("sequential", "Optimise for sequential mmap access",