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, 15 insertions, 14 deletions

diff --git a/gdb/target.h b/gdb/target.h
index 7e52716..0b78427 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -81,6 +81,7 @@ struct inferior;
 #include "command.h"
 #include "disasm-flags.h"
 #include "tracepoint.h"
+#include "gdbsupport/fileio.h"
 
 #include "gdbsupport/break-common.h" /* For enum target_hw_bp_type.  */
 
@@ -952,28 +953,28 @@ struct target_ops
        *TARGET_ERRNO).  */
     virtual int fileio_open (struct inferior *inf, const char *filename,
 			     int flags, int mode, int warn_if_slow,
-			     int *target_errno);
+			     fileio_error *target_errno);
 
     /* Write up to LEN bytes from WRITE_BUF to FD on the target.
        Return the number of bytes written, or -1 if an error occurs
        (and set *TARGET_ERRNO).  */
     virtual int fileio_pwrite (int fd, const gdb_byte *write_buf, int len,
-			       ULONGEST offset, int *target_errno);
+			       ULONGEST offset, fileio_error *target_errno);
 
     /* Read up to LEN bytes FD on the target into READ_BUF.
        Return the number of bytes read, or -1 if an error occurs
        (and set *TARGET_ERRNO).  */
     virtual int fileio_pread (int fd, gdb_byte *read_buf, int len,
-			      ULONGEST offset, int *target_errno);
+			      ULONGEST offset, fileio_error *target_errno);
 
     /* Get information about the file opened as FD and put it in
        SB.  Return 0 on success, or -1 if an error occurs (and set
        *TARGET_ERRNO).  */
-    virtual int fileio_fstat (int fd, struct stat *sb, int *target_errno);
+    virtual int fileio_fstat (int fd, struct stat *sb, fileio_error *target_errno);
 
     /* Close FD on the target.  Return 0, or -1 if an error occurs
        (and set *TARGET_ERRNO).  */
-    virtual int fileio_close (int fd, int *target_errno);
+    virtual int fileio_close (int fd, fileio_error *target_errno);
 
     /* Unlink FILENAME on the target, in the filesystem as seen by
        INF.  If INF is NULL, use the filesystem seen by the debugger
@@ -981,7 +982,7 @@ struct target_ops
        -1 if an error occurs (and set *TARGET_ERRNO).  */
     virtual int fileio_unlink (struct inferior *inf,
 			       const char *filename,
-			       int *target_errno);
+			       fileio_error *target_errno);
 
     /* Read value of symbolic link FILENAME on the target, in the
        filesystem as seen by INF.  If INF is NULL, use the filesystem
@@ -990,7 +991,7 @@ struct target_ops
        occurs (and set *TARGET_ERRNO).  */
     virtual gdb::optional<std::string> fileio_readlink (struct inferior *inf,
 							const char *filename,
-							int *target_errno);
+							fileio_error *target_errno);
 
     /* Implement the "info proc" command.  Returns true if the target
        actually implemented the command, false otherwise.  */
@@ -2165,29 +2166,29 @@ extern bool target_filesystem_is_local ();
 extern int target_fileio_open (struct inferior *inf,
 			       const char *filename, int flags,
 			       int mode, bool warn_if_slow,
-			       int *target_errno);
+			       fileio_error *target_errno);
 
 /* Write up to LEN bytes from WRITE_BUF to FD on the target.
    Return the number of bytes written, or -1 if an error occurs
    (and set *TARGET_ERRNO).  */
 extern int target_fileio_pwrite (int fd, const gdb_byte *write_buf, int len,
-				 ULONGEST offset, int *target_errno);
+				 ULONGEST offset, fileio_error *target_errno);
 
 /* Read up to LEN bytes FD on the target into READ_BUF.
    Return the number of bytes read, or -1 if an error occurs
    (and set *TARGET_ERRNO).  */
 extern int target_fileio_pread (int fd, gdb_byte *read_buf, int len,
-				ULONGEST offset, int *target_errno);
+				ULONGEST offset, fileio_error *target_errno);
 
 /* Get information about the file opened as FD on the target
    and put it in SB.  Return 0 on success, or -1 if an error
    occurs (and set *TARGET_ERRNO).  */
 extern int target_fileio_fstat (int fd, struct stat *sb,
-				int *target_errno);
+				fileio_error *target_errno);
 
 /* Close FD on the target.  Return 0, or -1 if an error occurs
    (and set *TARGET_ERRNO).  */
-extern int target_fileio_close (int fd, int *target_errno);
+extern int target_fileio_close (int fd, fileio_error *target_errno);
 
 /* Unlink FILENAME on the target, in the filesystem as seen by INF.
    If INF is NULL, use the filesystem seen by the debugger (GDB or,
@@ -2195,7 +2196,7 @@ extern int target_fileio_close (int fd, int *target_errno);
    occurs (and set *TARGET_ERRNO).  */
 extern int target_fileio_unlink (struct inferior *inf,
 				 const char *filename,
-				 int *target_errno);
+				 fileio_error *target_errno);
 
 /* Read value of symbolic link FILENAME on the target, in the
    filesystem as seen by INF.  If INF is NULL, use the filesystem seen
@@ -2203,7 +2204,7 @@ extern int target_fileio_unlink (struct inferior *inf,
    Return a null-terminated string allocated via xmalloc, or NULL if
    an error occurs (and set *TARGET_ERRNO).  */
 extern gdb::optional<std::string> target_fileio_readlink
-    (struct inferior *inf, const char *filename, int *target_errno);
+    (struct inferior *inf, const char *filename, fileio_error *target_errno);
 
 /* Read target file FILENAME, in the filesystem as seen by INF.  If
    INF is NULL, use the filesystem seen by the debugger (GDB or, for