Clarify trunccpy()'s src and dest must not overlap.

[nmh] / sbr / error.c

diff --git a/sbr/error.c b/sbr/error.c
index 6dc6995706dc20f23d67e59240bbf1fe5b01e252..d6d96851504420c9a8a3995075fc63f7fa016600 100644 (file)
--- a/sbr/error.c
+++ b/sbr/error.c
@@ -9,19 +9,14 @@
 
 #include <h/mh.h>
 
-#ifdef HAVE_WRITEV
-# include <sys/types.h>
-# include <sys/uio.h>
-#endif
+#include <sys/types.h>
+#include <sys/uio.h>
 
-#include <errno.h>
 
-
-/*
- * print out error message
- */
+/* advise calls advertise() with no tail to print fmt, and perhaps what,
+ * to stderr. */
 void
-advise (char *what, char *fmt, ...)
+advise (const char *what, const char *fmt, ...)
 {
     va_list ap;
 
@@ -31,11 +26,14 @@ advise (char *what, char *fmt, ...)
 }
 
 
-/*
- * print out error message and exit
- */
+/* adios calls advertise() with no tail to print fmt, and perhaps what,
+ * to stderr, and "ends" the program with an error exit status.  The
+ * route to exit is via the done function pointer and may not be
+ * straightforward.
+ * FIXME: Document if this function can ever return.  If not, perhaps an
+ * abort(3) at the end of the routine would make that more clear. */
 void
-adios (char *what, char *fmt, ...)
+adios (const char *what, const char *fmt, ...)
 {
     va_list ap;
 
@@ -46,9 +44,8 @@ adios (char *what, char *fmt, ...)
 }
 
 
-/*
- * admonish the user
- */
+/* admonish calls advertise() with a tail indicating the program
+ * continues. */
 void
 admonish (char *what, char *fmt, ...)
 {
@@ -60,83 +57,72 @@ admonish (char *what, char *fmt, ...)
 }
 
 
-/*
- * main routine for printing error messages.
- *
- * Use writev() if available, for slightly better performance.
- * Why?  Well, there are a couple of reasons.  Primarily, it
- * gives a smoother output...  More importantly though, it's a
- * sexy syscall()...
- */
+/* advertise prints fmt and ap to stderr after flushing stdout.
+ * If invo_name isn't NULL or empty, it precedes the output seperated by ": ".
+ * If what isn't NULL, errno as a string is appended.
+ * A non-empty what separates fmt from errno, surrounded by " " and ": ".
+ * BUG: No space separator before errno if what is "".
+ * If tail isn't NULL or empty then ", " and tail are appended
+ * before the finishing "\n".
+ * In summary: "invo_name: fmt what: errno, tail\n". */
 void
-advertise (char *what, char *tail, char *fmt, va_list ap)
+advertise (const char *what, char *tail, const char *fmt, va_list ap)
 {
     int        eindex = errno;
+    char buffer[BUFSIZ], errbuf[BUFSIZ], *err;
+    struct iovec iob[10], *iov;
+    size_t niov;
 
-#ifdef HAVE_WRITEV
-    char buffer[BUFSIZ], err[BUFSIZ];
-    struct iovec iob[20], *iov;
-#endif
+    iov = iob;
 
-    fflush (stdout);
+#define APPEND_IOV(p, len) \
+    iov->iov_base = (p); \
+    iov->iov_len = (len); \
+    iov++
 
-#ifdef HAVE_WRITEV
-    fflush (stderr);
-    iov = iob;
+#define ADD_LITERAL(s) APPEND_IOV((s), LEN(s))
+#define ADD_VAR(s) APPEND_IOV((s), strlen(s))
 
     if (invo_name && *invo_name) {
-       iov->iov_len = strlen (iov->iov_base = invo_name);
-       iov++;
-       iov->iov_len = strlen (iov->iov_base = ": ");
-       iov++;
+        ADD_VAR(invo_name);
+       ADD_LITERAL(": ");
     }
     
     vsnprintf (buffer, sizeof(buffer), fmt, ap);
-    iov->iov_len = strlen (iov->iov_base = buffer);
-    iov++;
+    ADD_VAR(buffer);
     if (what) {
        if (*what) {
-           iov->iov_len = strlen (iov->iov_base = " ");
-           iov++;
-           iov->iov_len = strlen (iov->iov_base = what);
-           iov++;
-           iov->iov_len = strlen (iov->iov_base = ": ");
-           iov++;
+            ADD_LITERAL(" ");
+            ADD_VAR((void *)what);
+            ADD_LITERAL(": ");
        }
-        if (!(iov->iov_base = strerror (eindex))) {
+        err = strerror(eindex);
+        if (!err) {
            /* this shouldn't happen, but we'll test for it just in case */
-           snprintf (err, sizeof(err), "Error %d", eindex);
-           iov->iov_base = err;
+           snprintf(errbuf, sizeof(errbuf), "Error %d", eindex);
+            err = errbuf;
        }
-       iov->iov_len = strlen (iov->iov_base);
-       iov++;
+        ADD_VAR(err);
     }
     if (tail && *tail) {
-       iov->iov_len = strlen (iov->iov_base = ", ");
-       iov++;
-       iov->iov_len = strlen (iov->iov_base = tail);
-       iov++;
+        ADD_LITERAL(", ");
+        ADD_VAR(tail);
     }
-    iov->iov_len = strlen (iov->iov_base = "\n");
-    iov++;
-    writev (fileno (stderr), iob, iov - iob);
-#else
-    if (invo_name && *invo_name)
-       fprintf (stderr, "%s: ", invo_name);
-    vfprintf (stderr, fmt, ap);
+    ADD_LITERAL("\n");
 
-    if (what) {
-       char *s;
-
-       if (*what)
-           fprintf (stderr, " %s: ", what);
-       if ((s = strerror(eindex)))
-           fprintf (stderr, "%s", s);
-       else
-           fprintf (stderr, "Error %d", eindex);
+#undef ADD_LITERAL
+#undef ADD_VAR
+
+    niov = iov - iob;
+    assert(niov <= DIM(iob));
+
+    fflush (stdout);
+    fflush (stderr);
+    if (writev(fileno(stderr), iob, niov) == -1) {
+        snprintf(buffer, sizeof buffer, "%s: write stderr failed: %d\n",
+            invo_name && *invo_name ? invo_name : "nmh", errno);
+        if (write(2, buffer, strlen(buffer)) == -1) {
+            /* Ignore.  if-statement needed to shut up compiler. */
+        }
     }
-    if (tail)
-       fprintf (stderr, ", %s", tail);
-    fputc ('\n', stderr);
-#endif
 }