[binutils-gdb] Fix remote serial read

[Tom Tromey <tromey@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=74d8fa2df7e7844f9b1b8fac27fe7d0b82100ab0

commit 74d8fa2df7e7844f9b1b8fac27fe7d0b82100ab0
Author: Сергей Чернов <klen_s@mail.ru>
Date:   Fri Jan 19 11:01:18 2024 -0700

    Fix remote serial read
    
    After closing "Bug 30770 - serial.c does not preserve errno correctly"
    https://sourceware.org/bugzilla/show_bug.cgi?id=30770
    remote debugging became impossible due to an attempt to recv() by a call intended for the socket, and not for the character device file. The
    documentation implicitly states that it is possible to use the read() call to work with a socket. But this does not mean in the general case that it is
    permissible to use recv in the case of a non-socket.
    
    condition:
    os: Distributor ID:    Ubuntu
    Description:    Ubuntu 23.10
    Release:    23.10
    Codename:    mantic
    
    libc:
    ldd (Ubuntu GLIBC 2.38-1ubuntu6) 2.38
    kernel:
    Linux klen-dev-um790pro 6.5.0-14-generic #14-Ubuntu SMP PREEMPT_DYNAMIC Tue Nov 14 14:59:49 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
    gdb: build from trank at 15.0.50.20231226-git
    
    GDB output:
    $ arm-kgp-eabi-gdb
    GNU gdb (Klen's_GNU_package_(KGP)_for_target::arm-kgp-eabi<rmprofile/lto>_host::x86_64-kgp-linux-gnu_znver4-avx512<<ílex>>)
    15.0.50.20231226-git
    ....
    (gdb) tar ext /dev/ttyACM1
    Remote debugging using /dev/ttyACM1
    Remote communication error.  Target disconnected: error while reading: Socket operation on non-socket.
    (gdb)
    
    after fix gdb work fine
    
    $ arm-kgp-eabi-gdb -q
    (gdb) tar ext /dev/ttyACM0
    Remote debugging using /dev/ttyACM0
    (gdb) mon swd
    Target voltage: 0.0V
    Available Targets:
    No. Att Driver
           STM32F40x M4
    (gdb) att 1
    Attaching to Remote target
    warning: No executable has been specified and target does not support
    determining executable automatically.  Try using the "file" command.
    0x08020c80 in ?? ()
    (gdb)
    
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30770

Diff:
---
 gdb/ser-unix.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/ser-unix.c b/gdb/ser-unix.c
index f917aa85e3d..bc8b087b6eb 100644
--- a/gdb/ser-unix.c
+++ b/gdb/ser-unix.c
@@ -574,7 +574,7 @@ when debugging using remote targets."),
 int
 ser_unix_read_prim (struct serial *scb, size_t count)
 {
-  int result = recv (scb->fd, scb->buf, count, 0);
+  int result = read (scb->fd, scb->buf, count);
   if (result == -1 && errno != EINTR)
     perror_with_name ("error while reading");
   return result;