[binutils-gdb] gdb, btrace: fix error diagnostics

[Markus Metzger]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b792eb47f25f577ccef365fc9a5c20d55fad42d5

commit b792eb47f25f577ccef365fc9a5c20d55fad42d5
Author: Markus Metzger <markus.t.metzger@intel.com>
Date:   Fri Feb 18 13:53:31 2022 +0100

    gdb, btrace: fix error diagnostics
    
    When we improved error messages in
    
        cd393cec3ab gdb, btrace: improve error messages
    
    we cleared the original errno.  When the error reason can not be explained
    in a more detailed error message, and we fall back to the default error
    message, it now gives Success as error.
    
    Restore the original errno to fix that.

Diff:
---
 gdb/nat/linux-btrace.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/gdb/nat/linux-btrace.c b/gdb/nat/linux-btrace.c
index 50de2415589..f8352b62b8b 100644
--- a/gdb/nat/linux-btrace.c
+++ b/gdb/nat/linux-btrace.c
@@ -422,7 +422,8 @@ cpu_supports_bts (void)
 static void
 diagnose_perf_event_open_fail ()
 {
-  switch (errno)
+  int orig_errno = errno;
+  switch (orig_errno)
     {
     case EPERM:
     case EACCES:
@@ -443,7 +444,7 @@ diagnose_perf_event_open_fail ()
       break;
     }
 
-  error (_("Failed to start recording: %s"), safe_strerror (errno));
+  error (_("Failed to start recording: %s"), safe_strerror (orig_errno));
 }
 
 /* Get the linux version of a btrace_target_info.  */