add errmsg API

CHANGES

@@ -1,3 +1,6 @@
+0.20:
+  add errmsg API
+
 0.19.2:
   for some reason, a botched dependency slipped in the the Makefile
 

buffer/errmsg_cvt.c

@@ -0,0 +1,29 @@
+#include <stdarg.h>
+#include <sys/uio.h>
+#include "errmsg.h"
+#include "str.h"
+
+/* the people who defined stdarg.h need to be taken behind the barn and shot */
+int errmsg_cvt(struct iovec* x,const char* message, va_list a) {
+  int i,j;
+  j=0;
+  if (argv0) {
+    x[0].iov_base=(char*)argv0;
+    x[0].iov_len=str_len(argv0);
+    x[1].iov_base=": ";
+    x[1].iov_len=2;
+    j=2;
+  }
+  x[j].iov_base=(char*)message; x[j].iov_len=str_len(message); ++j;
+
+  for (i=0; j<22; ++i) {
+    const char* t=va_arg(a,const char*);
+    if (!t) break;
+    x[j].iov_base=(char*)t;
+    x[j].iov_len=str_len(t);
+    ++j;
+  }
+  x[j].iov_base="\n";
+  x[j].iov_len=1;
+  return j+1;
+}

buffer/errmsg_iam.c

@@ -0,0 +1,8 @@
+#include "errmsg.h"
+
+const char* argv0;
+
+void errmsg_iam(const char* who) {
+  argv0=who;
+}
+

buffer/errmsg_warn.c

@@ -0,0 +1,14 @@
+#include <stdarg.h>
+#include <sys/uio.h>
+#include "errmsg.h"
+#include "str.h"
+
+extern int errmsg_cvt(struct iovec* x,const char* message, va_list a);
+
+void errmsg_warn(const char* message, ...) {
+  struct iovec x[23];
+  va_list a;
+  va_start(a,message);
+  writev(2,x,errmsg_cvt(x,message,a));
+  va_end(a);
+}

buffer/errmsg_warnsys.c

@@ -0,0 +1,28 @@
+#include <stdarg.h>
+#include <sys/uio.h>
+#include "errmsg.h"
+#include "str.h"
+#include <string.h>
+#include <errno.h>
+
+extern int errmsg_cvt(struct iovec* x,const char* message, va_list a);
+
+void errmsg_warnsys(const char* message, ...) {
+  struct iovec x[25];
+  va_list a;
+  int i;
+  va_start(a,message);
+  i=errmsg_cvt(x,message,a);
+
+  x[i-1].iov_base=": ";
+  x[i-1].iov_len=2;
+
+  x[i].iov_base=strerror(errno);
+  x[i].iov_len=str_len(x[i].iov_base);
+
+  x[i+1].iov_base="\n";
+  x[i+1].iov_len=1;
+
+  writev(2,x,i+2);
+  va_end(a);
+}

errmsg.h

@@ -0,0 +1,27 @@
+#ifndef ERRMSG_H
+#define ERRMSG_H
+
+#ifdef __dietlibc__
+#include <sys/cdefs.h>
+#else
+#define __attribute__(x)
+#endif
+
+/* These use file descriptor 2, not buffer_2!
+ * Call buffer_flush(buffer_2) before calling these! */
+
+extern const char* argv0;
+
+void errmsg_iam(const char* who);	/* set argv0 */
+
+/* terminate with NULL. */
+/* newline is appended automatically. */
+void errmsg_warn(const char* message, ...);
+void errmsg_warnsys(const char* message, ...);
+
+#define carp(...) errmsg_warn(__VA_ARGS__,0)
+#define carpsys(...) errmsg_warnsys(__VA_ARGS__,0)
+#define die(n,...) { errmsg_warn(__VA_ARGS__,0); exit(n); }
+#define diesys(n,...) { errmsg_warnsys(__VA_ARGS__,0); exit(n); }
+
+#endif

t.c

@@ -19,17 +19,29 @@
 #include <errno.h>
 #include <string.h>
 #include <assert.h>
+#include <errmsg.h>
 
 #define rdtscl(low) \
      __asm__ __volatile__ ("rdtsc" : "=a" (low) : : "edx")
 
 int main(int argc,char* argv[]) {
+  char* c="fnord";
+  int fd=open_read(c);
+  errmsg_iam(argv[0]);
+  carp("could not open file `",c,"'");
+  diesys(23,"could not open file `",c,"'");
+#if 0
+  errmsg_warn("could not open file `",c,"'",0);
+  errmsg_warnsys("could not open file `",c,"'",0);
+#endif
+#if 0
   char buf[100]="/usr/bin/sh";
   int len=str_len(buf);
   assert(byte_rchr(buf,len,'/')==8);
   assert(byte_rchr(buf,len,'@')==len);
   assert(byte_rchr(buf,len,'h')==len-1);
   printf("%d\n",byte_rchr("x",1,'x'));
+#endif
 #if 0
   char buf[IP6_FMT+100];
   int i;