perf tools: Introduce copyfile_offset() function

The copyfile_offset() function is to copy source data from given offset
to a destination file with an offset.  It'll be used to build an indexed
data file.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20150304145824.GD7519@krava.brq.redhat.com
Link: http://lkml.kernel.org/r/1431909055-21442-4-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 29 insertions, 9 deletions

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 6104afb7e1ef..0c264bc685ac 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -145,11 +145,38 @@ out:
         return err;
 }
 
+int copyfile_offset(int ifd, loff_t off_in, int ofd, loff_t off_out, u64 size)
+{
+        void *ptr;
+        loff_t pgoff;
+
+        pgoff = off_in & ~(page_size - 1);
+        off_in -= pgoff;
+
+        ptr = mmap(NULL, off_in + size, PROT_READ, MAP_PRIVATE, ifd, pgoff);
+        if (ptr == MAP_FAILED)
+                return -1;
+
+        while (size) {
+                ssize_t ret = pwrite(ofd, ptr + off_in, size, off_out);
+                if (ret < 0 && errno == EINTR)
+                        continue;
+                if (ret <= 0)
+                        break;
+
+                size -= ret;
+                off_in += ret;
+                off_out -= ret;
+        }
+        munmap(ptr, off_in + size);
+
+        return size ? -1 : 0;
+}
+
 int copyfile_mode(const char *from, const char *to, mode_t mode)
 {
         int fromfd, tofd;
         struct stat st;
-        void *addr;
         int err = -1;
 
         if (stat(from, &st))
@@ -166,15 +193,8 @@ int copyfile_mode(const char *from, const char *to, mode_t mode)
         if (tofd < 0)
                 goto out_close_from;
 
-        addr = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fromfd, 0);
-        if (addr == MAP_FAILED)
-                goto out_close_to;
-
-        if (write(tofd, addr, st.st_size) == st.st_size)
-                err = 0;
+        err = copyfile_offset(fromfd, 0, tofd, 0, st.st_size);
 
-        munmap(addr, st.st_size);
-out_close_to:
         close(tofd);
         if (err)
                 unlink(to);