diff --git a/libports/lib/mk/libc.mk b/libports/lib/mk/libc.mk
index 82bc6cbf7f..a7c7bb99ff 100644
--- a/libports/lib/mk/libc.mk
+++ b/libports/lib/mk/libc.mk
@@ -14,7 +14,7 @@ SRC_CC = atexit.cc dummies.cc rlimit.cc sysctl.cc readlink.cc munmap.cc \
issetugid.cc errno.cc gai_strerror.cc clock_gettime.cc \
gettimeofday.cc malloc.cc progname.cc fd_alloc.cc file_operations.cc \
plugin.cc plugin_registry.cc select.cc exit.cc environ.cc nanosleep.cc \
- libc_mem_alloc.cc writev.cc
+ libc_mem_alloc.cc writev.cc pread_pwrite.cc
#
# Files from string library that are not included in libc-raw_string because
diff --git a/libports/src/lib/libc/pread_pwrite.cc b/libports/src/lib/libc/pread_pwrite.cc
new file mode 100644
index 0000000000..3d90fdab69
--- /dev/null
+++ b/libports/src/lib/libc/pread_pwrite.cc
@@ -0,0 +1,75 @@
+/*
+ * \brief 'pread()' and 'pwrite()' implementations
+ * \author Christian Prochaska
+ * \date 2012-07-11
+ */
+
+/*
+ * Copyright (C) 2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+/* Genode includes */
+#include
+
+/* libc includes */
+#include
+#include
+#include
+
+
+static Genode::Lock rw_lock;
+
+
+struct Read
+{
+ ssize_t operator()(int fd, void *buf, size_t count)
+ {
+ return read(fd, buf, count);
+ }
+};
+
+
+struct Write
+{
+ ssize_t operator()(int fd, const void *buf, size_t count)
+ {
+ return write(fd, buf, count);
+ }
+};
+
+
+template
+static ssize_t pread_pwrite_impl(Rw_func rw_func, int fd, Buf_type buf, ::size_t count, ::off_t offset)
+{
+ Genode::Lock_guard rw_lock_guard(rw_lock);
+
+ off_t old_offset = lseek(fd, 0, SEEK_CUR);
+
+ if (old_offset == -1)
+ return -1;
+
+ if (lseek(fd, offset, SEEK_SET) == -1)
+ return -1;
+
+ ssize_t result = rw_func(fd, buf, count);
+
+ if (lseek(fd, old_offset, SEEK_SET) == -1)
+ return -1;
+
+ return result;
+}
+
+
+extern "C" ssize_t pread(int fd, void *buf, ::size_t count, ::off_t offset)
+{
+ return pread_pwrite_impl(Read(), fd, buf, count, offset);
+}
+
+
+extern "C" ssize_t pwrite(int fd, const void *buf, ::size_t count, ::off_t offset)
+{
+ return pread_pwrite_impl(Write(), fd, buf, count, offset);
+}
diff --git a/libports/src/test/libc_ffat/main.cc b/libports/src/test/libc_ffat/main.cc
index 6d635e401e..ecc031f796 100644
--- a/libports/src/test/libc_ffat/main.cc
+++ b/libports/src/test/libc_ffat/main.cc
@@ -39,11 +39,15 @@
int main(int argc, char *argv[])
{
int ret, fd;
+ ssize_t count;
char const *dir_name = "/testdir";
char const *file_name = "test.tst";
+ char const *file_name2 = "test2.tst";
char const *pattern = "a single line of text";
+ size_t pattern_size = strlen(pattern) + 1;
+
unsigned int iterations = 1;
try {
@@ -60,8 +64,7 @@ int main(int argc, char *argv[])
/* write pattern to a file */
CALL_AND_CHECK(fd, open(file_name, O_CREAT | O_WRONLY), fd >= 0, "file_name=%s", file_name);
- size_t count = strlen(pattern);
- CALL_AND_CHECK(ret, write(fd, pattern, count), ret > 0, "count=%zd", count);
+ CALL_AND_CHECK(count, write(fd, pattern, pattern_size), (size_t)count == pattern_size, "");
CALL_AND_CHECK(ret, close(fd), ret == 0, "");
/* query file status of new file */
@@ -76,7 +79,7 @@ int main(int argc, char *argv[])
/* read and verify file content */
CALL_AND_CHECK(fd, open(file_name, O_RDONLY), fd >= 0, "file_name=%s", file_name);
static char buf[512];
- CALL_AND_CHECK(count, read(fd, buf, sizeof(buf)), count > 0, "");
+ CALL_AND_CHECK(count, read(fd, buf, sizeof(buf)), (size_t)count == pattern_size, "");
CALL_AND_CHECK(ret, close(fd), ret == 0, "");
printf("content of file: \"%s\"\n", buf);
if (strcmp(buf, pattern) != 0) {
@@ -86,6 +89,26 @@ int main(int argc, char *argv[])
printf("file content is correct\n");
}
+ /* test 'pread()' and 'pwrite()' */
+ CALL_AND_CHECK(fd, open(file_name2, O_CREAT | O_WRONLY), fd >= 0, "file_name=%s", file_name);
+ /* write "a single line of" */
+ CALL_AND_CHECK(count, pwrite(fd, pattern, (pattern_size - 6), 0), (size_t)count == (pattern_size - 6), "");
+ /* write "line of text" at offset 9 */
+ CALL_AND_CHECK(count, pwrite(fd, &pattern[9], (pattern_size - 9), 9), (size_t)count == (pattern_size - 9), "");
+ CALL_AND_CHECK(ret, close(fd), ret == 0, "");
+ CALL_AND_CHECK(fd, open(file_name2, O_RDONLY), fd >= 0, "file_name=%s", file_name);
+ memset(buf, 0, sizeof(buf));
+ /* read "single line of text" from offset 2 */
+ CALL_AND_CHECK(count, pread(fd, buf, sizeof(buf), 2), (size_t)count == (pattern_size - 2), "");
+ CALL_AND_CHECK(ret, close(fd), ret == 0, "");
+ printf("content of file: \"%s\"\n", buf);
+ if (strcmp(buf, &pattern[2]) != 0) {
+ printf("unexpected content of file\n");
+ return -1;
+ } else {
+ printf("file content is correct\n");
+ }
+
/* read directory entries */
DIR *dir;
CALL_AND_CHECK(dir, opendir(dir_name), dir, "dir_name=\"%s\"", dir_name);