gdbsupport: convert FILEIO_* macros to an enum

Converting from free-form macros to an enum gives a bit of type-safety.
This caught places where we would assign host error numbers to what
should contain a target fileio error number, for instance in
target_fileio_pread.

I added the FILEIO_SUCCESS enumerator, because
remote.c:remote_hostio_parse_result initializes the remote_errno output
variable to 0.  It seems better to have an explicit enumerator than to
assign a value for which there is no enumerator.  I considered
initializing this variable to FILEIO_EUNKNOWN instead, such that if the
remote side replies with an error and omits the errno value, we'll get
an errno that represents an error instead of 0 (which reprensents no
error).  But it's not clear what the consequences of that change would
be, so I prefer to err on the side of caution and just keep the existing
behavior (there is no intended change in behavior with this patch).

Note that remote_hostio_parse_resul still reads blindly what the remote
side sends as a target errno into this variable, so we can still end up
with a nonsensical value here.  It's not good, but out of the scope of
this patch.

Convert host_to_fileio_error and fileio_errno_to_host to return / accept
a fileio_error instead of an int, and cascade the change in the whole
chain that uses that.

Change-Id: I454b0e3fcf0732447bc872252fa8e57d138b0e03

1 files changed, 4 insertions, 4 deletions

diff --git a/gdb/sparc64-tdep.c b/gdb/sparc64-tdep.c
index 7b6e991..5e69657 100644
--- a/gdb/sparc64-tdep.c
+++ b/gdb/sparc64-tdep.c
@@ -166,7 +166,7 @@ get_adi_info (pid_t pid)
 void
 sparc64_forget_process (pid_t pid)
 {
-  int target_errno;
+  fileio_error target_errno;
 
   for (auto pit = adi_proc_list.before_begin (),
 	 it = std::next (pit);
@@ -287,7 +287,7 @@ adi_tag_fd (void)
 
   char cl_name[MAX_PROC_NAME_SIZE];
   snprintf (cl_name, sizeof(cl_name), "/proc/%ld/adi/tags", (long) pid);
-  int target_errno;
+  fileio_error target_errno;
   proc->stat.tag_fd = target_fileio_open (NULL, cl_name, O_RDWR|O_EXCL, 
 					  false, 0, &target_errno);
   return proc->stat.tag_fd;
@@ -350,7 +350,7 @@ adi_read_versions (CORE_ADDR vaddr, size_t size, gdb_byte *tags)
 	    paddress (target_gdbarch (), vaddr * ast.blksize));
     }
 
-  int target_errno;
+  fileio_error target_errno;
   return target_fileio_pread (fd, tags, size, vaddr, &target_errno);
 }
 
@@ -371,7 +371,7 @@ adi_write_versions (CORE_ADDR vaddr, size_t size, unsigned char *tags)
 	    paddress (target_gdbarch (), vaddr * ast.blksize));
     }
 
-  int target_errno;
+  fileio_error target_errno;
   return target_fileio_pwrite (fd, tags, size, vaddr, &target_errno);
 }