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libc: use File_descriptor::lock in pread/pwrite

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Replace the static lock with the file descriptor lock because recursive
calls of p{read,write} would result in a deadlock when using multiple
libc-plugins at the same time.

Fixes #948.
This commit is contained in:
Josef Söntgen 2013-11-13 13:56:58 +01:00 committed by Norman Feske
parent 36f91c2007
commit d0ddc11c09
1 changed files with 14 additions and 12 deletions
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26
libports/src/lib/libc/pread_pwrite.cc
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@ -13,6 +13,7 @@
/* Genode includes */ /* Genode includes */
#include <base/lock.h> #include <base/lock.h>
#include <libc-plugin/fd_alloc.h>
/* libc includes */ /* libc includes */
#include <sys/types.h> #include <sys/types.h>
@ -20,31 +21,32 @@
#include <unistd.h> #include <unistd.h>
static Genode::Lock rw_lock;
struct Read struct Read
{ {
ssize_t operator()(int fd, void *buf, size_t count) ssize_t operator()(int fd, void *buf, size_t count)
{ {
return read(fd, buf, count); return read(fd, buf, count);
} }
}; };
struct Write struct Write
{ {
ssize_t operator()(int fd, const void *buf, size_t count) ssize_t operator()(int fd, const void *buf, size_t count)
{ {
return write(fd, buf, count); return write(fd, buf, count);
} }
}; };
template <typename Rw_func, typename Buf_type> template <typename Rw_func, typename Buf_type>
static ssize_t pread_pwrite_impl(Rw_func rw_func, int fd, Buf_type buf, ::size_t count, ::off_t offset) static ssize_t pread_pwrite_impl(Rw_func rw_func, int fd, Buf_type buf, ::size_t count, ::off_t offset)
{ {
Genode::Lock_guard<Genode::Lock> rw_lock_guard(rw_lock); Libc::File_descriptor *fdesc = Libc::file_descriptor_allocator()->find_by_libc_fd(fd);
if (fdesc == 0)
return -1;
Genode::Lock_guard<Genode::Lock> rw_lock_guard(fdesc->lock);
off_t old_offset = lseek(fd, 0, SEEK_CUR); off_t old_offset = lseek(fd, 0, SEEK_CUR);