Hi All,
Reading release-notes 18.08 it states that RAM_FS and VFS are supposed to be equal.
However, I don't get any errors when I replace my ram_fs config with this vfs:
<start name="pdf_share"> <binary name="vfs"/> <resource name="RAM" quantum="128M"/> <provides> <service name="File_system"/> </provides> <config verbose="yes"> <vfs> <ram /> </vfs> <default-policy root="/" writeable="yes" /> </config> </start>
It perfectly reports the filename and contents in the report_rom. :-)
Now the next step: create a dynamic ROM to start the pdf_view component on demand. Any pointers to run files that help me get going?
Cheers, Guido.
On 5/20/19 1:27 PM, Guido Witmond wrote:
Hi Genodians,
I'm working on my HnH19-project to create a component listening on a shared filesystem to open each pdf file into a separate instance of mupdf. Goal is to tie the share to a linux-vm in vbox so firefox and thunderbird can have a simple 'cp' command to get pdfs rendered outside that vm.
I add a RAM-FS, FS-QUERY and REPORT-ROM to mupdf.run. The file gets put in the ram-fs, fs-query should pick that up and report it to the report-rom.
<start name="pdf_share"> <binary name="ram_fs"/> <resource name="RAM" quantum="128M"/> <provides> <service name="File_system"/> </provides> <config verbose="yes"> <default-policy root="/" writeable="yes" /> </config> </start>
<start name="report_new_pdf"> <binary name="report_rom"/> <resource name="RAM" quantum="1M"/> <provides> <service name="Report"/> <service name="ROM"/>
</provides> <config verbose="yes"/> </start>
<start name="fs_query"> <resource name="RAM" quantum="1M"/> <config verbose="yes"> <vfs> <fs writeable="yes"/> </vfs> <query path="/" content="yes"/> </config> </start>
I change the test-scenario to copy a pdf into the share and start the pdf-viewer. The viewer picks up the pdf and renders it. So far so good.
The problem is that while the 'add'-test copies the file, it gets detected by fs_query but fs_query thinks it's gone:
[init -> test -> add] --- noux started --- [init -> fs_query] Error: failed to watch '//foo.pdf' [init -> fs_query] Warning: could not obtain content of nonexistent file foo.pdf
(The error comes from gems/vfs.h L556, the warning from fs_query/main.cc L80.)
Fs_quey does send a new report but does not show the file, it show an empty directory.
[init -> report_new_pdf] report 'fs_query -> listing' [init -> report_new_pdf] <listing> [init -> report_new_pdf] <dir path="/"/> [init -> report_new_pdf] </listing>
However, a ls -laR shows it's there:
[init -> test -> ls-after] /dest: [init -> test -> ls-after] total 1 [init -> test -> ls-after] drwxr-xr-x 0 root 0 0 Jan 1 00:00 . [init -> test -> ls-after] drwxr-xr-x 0 root 0 0 Jan 1 00:00 .. [init -> test -> ls-after] -rwxrwxrwx 0 root 0 8192 Jan 1 00:00 foo.pdf
Now the race condition:
When I set the fs-query option to show the content to "no", it gives the same error: failed to watch '//foo.pdf' but it now it does send the file name to the report:
[init -> report_new_pdf] <file name="foo.pdf"/>
So it seems that somehow that fs_query watch learns there is a file while the contents are not yet committed. Accessing that triggers a file-not-found error.
Did I discover a race condition or am I doing something wrong?
With regards, Guido.
PS. I added the complete run-file and logs for completeness. (log-1 shows the contents-flag to no). PPS. I'm testing with Qemu in a linux VM on my AMD nixos host.
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