Replace ERRIO with STDERR_FILENO

While working on fixing issue #1079 I noticed the ERRIO symbol that is
simply an obscure alias for the standard STDERR_FILENO symbol. So replace
the former with the latter.

If we ever get a build failure on a system that does not provide the
industry standard STDERR_FILENO symbol we can implement a build time test
for its availability and provide a fallback. Although in that case we
should also ensure the same magic constant via a compile time symbol is
also used in the SFIO code. Hint: At the moment ERRIO is unique to the
ksh code (i.e., not used in the SFIO code) and is not defined in terms
of a SFIO constant.

Related #1079

src/cmd/ksh93/edit/edit.c

@@ -272,7 +272,7 @@ int ed_window(void) {
 //
 void ed_flush(Edit_t *ep) {
     int n = ep->e_outptr - ep->e_outbase;
-    int fd = ERRIO;
+    int fd = STDERR_FILENO;
 
     if (n <= 0) return;
     write(fd, ep->e_outbase, (unsigned)n);
@@ -282,7 +282,7 @@ void ed_flush(Edit_t *ep) {
 //
 // Send the bell character ^G to the terminal.
 //
-void ed_ringbell(void) { write(ERRIO, bellchr, 1); }
+void ed_ringbell(void) { write(STDERR_FILENO, bellchr, 1); }
 
 //
 // Send a carriage return line feed to the terminal.

src/cmd/ksh93/edit/emacs.c

@@ -176,7 +176,7 @@ int ed_emacsread(void *context, int fd, char *buff, int scend, int reedit) {
     Prompt = prompt;
     ep->screen = Screen;
     ep->lastdraw = FINAL;
-    if (tty_raw(ERRIO, 0) < 0) {
+    if (tty_raw(STDERR_FILENO, 0) < 0) {
         return reedit ? reedit : ed_read(context, fd, buff, scend, 0);
     }
     raw = 1;
@@ -207,7 +207,7 @@ int ed_emacsread(void *context, int fd, char *buff, int scend, int reedit) {
             draw(ep, FINAL);
             ed_flush(ep->ed);
         }
-        tty_cooked(ERRIO);
+        tty_cooked(STDERR_FILENO);
         if (i == UEOF) return 0;  // EOF
         return -1;                // some other error
     }
@@ -266,7 +266,7 @@ int ed_emacsread(void *context, int fd, char *buff, int scend, int reedit) {
             }
             case EOFCHAR: {
                 ed_flush(ep->ed);
-                tty_cooked(ERRIO);
+                tty_cooked(STDERR_FILENO);
                 return 0;
             }
             case '\t': {
@@ -600,7 +600,7 @@ int ed_emacsread(void *context, int fd, char *buff, int scend, int reedit) {
         *out = '\0';
     }
     draw(ep, FINAL);
-    tty_cooked(ERRIO);
+    tty_cooked(STDERR_FILENO);
     if (ed->e_nlist) {
         ed->e_nlist = 0;
         stakset(ed->e_stkptr, ed->e_stkoff);

src/cmd/ksh93/edit/vi.c

@@ -194,7 +194,9 @@ int ed_viread(void *context, int fd, char *shbuf, int nchar, int reedit) {
     shbuf[reedit] = 0;
 
     // Set raw mode.
-    if (tty_raw(ERRIO, 0) < 0) return reedit ? reedit : ed_read(context, fd, shbuf, nchar, 0);
+    if (tty_raw(STDERR_FILENO, 0) < 0) {
+        return reedit ? reedit : ed_read(context, fd, shbuf, nchar, 0);
+    }
     i = last_virt - 1;
 
     // Initialize some things.
@@ -246,7 +248,7 @@ int ed_viread(void *context, int fd, char *shbuf, int nchar, int reedit) {
             sync_cursor(vp);
         }
         virtual[0] = '\0';
-        tty_cooked(ERRIO);
+        tty_cooked(STDERR_FILENO);
 
         if (i == UEOF) return 0;    // EOF
         if (i == UINTR) return -1;  // interrupt
@@ -263,7 +265,7 @@ int ed_viread(void *context, int fd, char *shbuf, int nchar, int reedit) {
     vigetline(vp, APPEND);
     if (vp->ed->e_multiline) cursor(vp, last_phys);
     // Add a new line if user typed unescaped \n to cause the shell to process the line.
-    tty_cooked(ERRIO);
+    tty_cooked(STDERR_FILENO);
     if (ed->e_nlist) {
         ed->e_nlist = 0;
         stkset(ed->sh->stk, ed->e_stkptr, ed->e_stkoff);

src/cmd/ksh93/include/io.h

@@ -29,9 +29,6 @@
 #define IOBSIZE (SF_BUFSIZE * _ast_sizeof_pointer)
 #define IOMAXTRY 20
 
-// Used for output of shell errors.
-#define ERRIO 2
-
 #define IOREAD 001
 #define IOWRITE 002
 #define IODUP 004

src/cmd/ksh93/sh/io.c

@@ -2306,15 +2306,15 @@ static_fn void sftrack(Sfio_t *sp, int flag, void *data) {
 #ifdef DEBUG
     if (flag == SF_READ || flag == SF_WRITE) {
         char *z = fmtbase((long)getpid(), 0, 0);
-        write(ERRIO, z, strlen(z));
-        write(ERRIO, ": ", 2);
-        write(ERRIO, "attempt to ", 11);
+        write(STDERR_FILENO, z, strlen(z));
+        write(STDERR_FILENO, ": ", 2);
+        write(STDERR_FILENO, "attempt to ", 11);
         if (flag == SF_READ) {
-            write(ERRIO, "read from", 9);
+            write(STDERR_FILENO, "read from", 9);
         } else {
-            write(ERRIO, "write to", 8);
+            write(STDERR_FILENO, "write to", 8);
         }
-        write(ERRIO, " locked stream\n", 15);
+        write(STDERR_FILENO, " locked stream\n", 15);
         return;
     }
 #endif

src/cmd/ksh93/sh/main.c

@@ -139,7 +139,7 @@ int sh_main(int ac, char *av[], Shinit_f userinit) {
         // Decide whether shell is interactive.
         if (!sh_isoption(shp, SH_INTERACTIVE) && !sh_isoption(shp, SH_TFLAG) &&
             !sh_isoption(shp, SH_CFLAG) && sh_isoption(shp, SH_SFLAG) && tty_check(0) &&
-            tty_check(ERRIO)) {
+            tty_check(STDERR_FILENO)) {
             sh_onoption(shp, SH_INTERACTIVE);
         }
         if (sh_isoption(shp, SH_INTERACTIVE)) {

src/cmd/ksh93/sh/xec.c

@@ -1102,7 +1102,7 @@ int sh_exec(Shell_t *shp, const Shnode_t *t, int flags) {
                             shp->exitval = (*shp->bltinfun)(argn, com, (void *)bp);
                             sfsync(NULL);
                         }
-                        if (error_info.flags & ERROR_INTERACTIVE) tty_check(ERRIO);
+                        if (error_info.flags & ERROR_INTERACTIVE) tty_check(STDERR_FILENO);
                         ((Shnode_t *)t)->com.comstate = shp->bltindata.data;
                         bp->data = (void *)save_data;
                         if (shp->exitval && errno == EINTR && shp->lastsig) {