[newlib-cygwin/main] RISC-V: fix setting up std streams in init_semihosting()

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=c419bbb341528a97d2de88539caf200c9dec1ffb

commit c419bbb341528a97d2de88539caf200c9dec1ffb
Author:     Venkata Ramanaiah Nalamothu <quic_vnalamot@quicinc.com>
AuthorDate: Wed Jan 3 12:22:16 2024 +0530
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Wed Jan 10 10:46:56 2024 +0100

    RISC-V: fix setting up std streams in init_semihosting()
    
    Currently init_semihosting() assumes the return value from _open()
    call as the file descriptor handle and that is incorrect.
    
    The semihost _open() call returns the fdtable index returned by the
    __add_fdentry() for the file opened.

Diff:
---
 libgloss/riscv/semihost-sys_fdtable.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/libgloss/riscv/semihost-sys_fdtable.c b/libgloss/riscv/semihost-sys_fdtable.c
index 152c92d1513b..d62e3f9708fe 100644
--- a/libgloss/riscv/semihost-sys_fdtable.c
+++ b/libgloss/riscv/semihost-sys_fdtable.c
@@ -24,25 +24,26 @@ static struct fdentry fdtable[RISCV_MAX_OPEN_FILES];
 void __attribute__ ((constructor))
 init_semihosting ()
 {
-  int handle;
+  int i;
 
-  for (int i=0; i<RISCV_MAX_OPEN_FILES; i++)
+  for (i=0; i<RISCV_MAX_OPEN_FILES; i++)
     fdtable[i].handle = -1;
 
-  /* Set up std streams.  */
+  /* Set up std streams. Note that the semihost _open() call returns an index
+     into the fdtable.  */
   /* stdin.  */
-  handle = _open (":tt", O_RDONLY);
-  fdtable[STDIN_FILENO].handle = handle;
+  i = _open (":tt", O_RDONLY);
+  fdtable[STDIN_FILENO].handle = fdtable[i].handle;
   fdtable[STDIN_FILENO].pos = 0;
 
   /* stdout.  */
-  handle = _open (":tt", O_WRONLY|O_CREAT|O_TRUNC);
-  fdtable[STDOUT_FILENO].handle = handle;
+  i = _open (":tt", O_WRONLY|O_CREAT|O_TRUNC);
+  fdtable[STDOUT_FILENO].handle = fdtable[i].handle;
   fdtable[STDOUT_FILENO].pos = 0;
 
   /* stderr.  */
-  handle = _open (":tt", O_WRONLY|O_CREAT|O_APPEND);
-  fdtable[STDERR_FILENO].handle = handle;
+  i = _open (":tt", O_WRONLY|O_CREAT|O_APPEND);
+  fdtable[STDERR_FILENO].handle = fdtable[i].handle;
   fdtable[STDERR_FILENO].pos = 0;
 }