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-rw-r--r--src/stdio/ftell.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/src/stdio/ftell.c b/src/stdio/ftell.c
new file mode 100644
index 00000000..aa1f5381
--- /dev/null
+++ b/src/stdio/ftell.c
@@ -0,0 +1,35 @@
+#include "stdio_impl.h"
+
+off_t __ftello_unlocked(FILE *f)
+{
+ off_t pos = f->seek(f, 0, SEEK_CUR);
+ if (pos < 0) {
+ FUNLOCK(f);
+ return pos;
+ }
+ /* Adjust for data in buffer. */
+ return pos - (f->rend - f->rpos) + (f->wpos - f->wbase);
+}
+
+off_t __ftello(FILE *f)
+{
+ off_t pos;
+ FLOCK(f);
+ pos = __ftello_unlocked(f);
+ FUNLOCK(f);
+ return pos;
+}
+
+long ftell(FILE *f)
+{
+ off_t pos = __ftello(f);
+ if (pos > LONG_MAX) {
+ errno = EOVERFLOW;
+ return -1;
+ }
+ return pos;
+}
+
+weak_alias(__ftello, ftello);
+
+LFS64(ftello);